Australia’s National Science Agency Water resource assessment for the Victoria catchment A report from the CSIRO Victoria River Water Resource Assessment for the National Water Grid Editors: Cuan Petheram, Seonaid Philip, Ian Watson, Caroline Bruce and Chris Chilcott ISBN 978-1-4863-2105-6 (print) ISBN 978-1-4863-2106-3 (online) Citation Petheram C, Philip S, Watson I, Bruce C and Chilcott C (eds) (2024) Water resource assessment for the Victoria catchment. A report from the CSIRO Victoria River Water Resource Assessment for the National Water Grid. CSIRO, Australia. Chapters should be cited in the format of the following example: Bruce C, Petheram C, Philip S and Watson I (2024) Chapter 1: Preamble. In: Petheram C, Philip S, Watson I, Bruce C and Chilcott C (eds) (2024) Water resource assessment for the Victoria catchment. A report from the CSIRO Victoria River Water Resource Assessment for the National Water Grid. CSIRO, Australia. Copyright © Commonwealth Scientific and Industrial Research Organisation 2024. To the extent permitted by law, all rights are reserved and no part of this publication covered by copyright may be reproduced or copied in any form or by any means except with the written permission of CSIRO. Important disclaimer CSIRO advises that the information contained in this publication comprises general statements based on scientific research. The reader is advised and needs to be aware that such information may be incomplete or unable to be used in any specific situation. No reliance or actions must therefore be made on that information without seeking prior expert professional, scientific and technical advice. To the extent permitted by law, CSIRO (including its employees and consultants) excludes all liability to any person for any consequences, including but not limited to all losses, damages, costs, expenses and any other compensation, arising directly or indirectly from using this publication (in part or in whole) and any information or material contained in it. CSIRO is committed to providing web accessible content wherever possible. If you are having difficulties with accessing this document, please contact Email CSIRO Enquiries . CSIRO Victoria River Water Resource Assessment acknowledgements This report was funded through the National Water Grid’s Science Program, which sits within the Australian Government’s Department of Climate Change, Energy, the Environment and Water. Aspects of the Assessment have been undertaken in conjunction with the Northern Territory (NT) Government. The Assessment was guided by two committees: i. The Assessment’s Governance Committee: CRC for Northern Australia/James Cook University; CSIRO; National Water Grid (Department of Climate Change, Energy, the Environment and Water); Northern Land Council; NT Department of Environment, Parks and Water Security; NT Department of Industry, Tourism and Trade; Office of Northern Australia; Queensland Department of Agriculture and Fisheries; Queensland Department of Regional Development, Manufacturing and Water ii. The Assessment’s joint Roper and Victoria River catchments Steering Committee: Amateur Fishermen’s Association of the NT; Austrade; Centrefarm; CSIRO; National Water Grid (Department of Climate Change, Energy, the Environment and Water); Northern Land Council; NT Cattlemen’s Association; NT Department of Environment, Parks and Water Security; NT Department of Industry, Tourism and Trade; NT Farmers; NT Seafood Council; Office of Northern Australia; Parks Australia; Regional Development Australia; Roper Gulf Regional Council Shire; Watertrust Responsibility for the Assessment’s content lies with CSIRO. The Assessment’s committees did not have an opportunity to review the Assessment results or outputs prior to their release. This report was reviewed by Dr Brian Keating (Independent consultant). Individual chapters were reviewed by Dr Rebecca Doble, CSIRO (Chapter 2); Dr Chris Pavey, CSIRO (Chapter 3); Dr Heather Pasley, CSIRO (Chapter 4); Mr Chris Turnadge, CSIRO (Chapter 5); Dr Nikki Dumbrell, CSIRO (Chapter 6); Dr Adam Liedloff, CSIRO (Chapter 7). The material in this report draws largely from the companion technical reports, which were themselves internally and externally reviewed. For further acknowledgements, see page xxv. Acknowledgement of Country CSIRO acknowledges the Traditional Owners of the lands, seas and waters of the area that we live and work on across Australia. We acknowledge their continuing connection to their culture and pay our respects to their Elders past and present. Photo The Victoria River is the longest singularly named river in the NT with permanent water. Photo: CSIRO – Nathan Dyer Part III Opportunities for water resource development Chapters 4 and 5 provide information on opportunities for agriculture and aquaculture in the catchment of the Victoria River. This information covers: • opportunities for irrigated agriculture and aquaculture (Chapter 4) • opportunities to extract and/or store water for use (Chapter 5). The cracking clay soils on the broad treeless alluvial plains of the West Baines River upstream of the Victoria Highway offer the greatest potential for broadacre irrigation in the Victoria catchment. Photo: CSIRO – Nathan Dyer 4 Opportunities for agriculture in the Victoria catchment Authors: Seonaid Philip, Yvette Oliver, Tiemen Rhebergen, Ian Watson, Tony Webster, Peter R Wilson, Simon Irvin Chapter 4 presents information about the opportunities for irrigated agriculture and aquaculture in the catchment of the Victoria River, describing: • land suitability for a range of crop group × season × irrigation type combinations and for aquaculture, including key soil-related management considerations • cropping and other agricultural opportunities, including crop yields and water use • gross margins at the farm scale • prospects for integration of forages and crops into existing beef enterprises • aquaculture opportunities. The key components and concepts of Chapter 4 are shown in Figure 4-1. Figure 4-1 Schematic of agriculture and aquaculture enterprises as well as crop and/or forage integration with existing beef enterprises to be considered in the establishment of a greenfield irrigation development For more information on this figure please contact CSIRO on enquiries@csiro.au 4.1 Summary This chapter provides information on land suitability and the potential for agriculture and aquaculture in the Victoria catchment. A mixture of field surveys and desktop analysis were used to generate the results presented in this chapter. For example, the land suitability results draw on extensive field visits (to describe, collect and analyse soils) and are integrated with state-of-the-art digital soil mapping. Many of the results are expressed in terms of potential. The area of land suitable for cropping or aquaculture, for example, is estimated by considering the set of relevant soil and landscape biophysical attributes at each location and determining the most limiting attribute among them. It does not include water availability; cyclone or flood risk; legislative, regulatory or tenure considerations; or ecological, social or economic drivers that will inevitably constrain the actual area of land that is developed. Crops, forages and cropping systems results are based on data analysis and simulation models, and assume good agronomic practices producing optimum yields given the soil and climate attributes in the catchment. Likewise, aquaculture is assessed in terms of potential, using a combination of land suitability and the productive capacity of a range of aquaculture species. Information is presented in a manner to enable the comparison of a variety of agricultural and aquaculture options. The results from individual components (land suitability, agriculture, aquaculture) are integrated to provide a sense of what is potentially viable in the catchment. This includes providing specific information on a wide range of crop types for agronomy, water use and land suitability for different irrigation types; analyses of economic performance, such as crop gross margins (GMs); how more-intensive mixed cropping systems might be feasible with irrigation; and analyses of what is required for different aquaculture development options to be financially viable. 4.1.1 Key findings Any agricultural resource assessment must consider two major factors: how much soil is suitable for a particular land use and where that soil is located. Based on a sample of 14 individual combinations of crop group × season of use × irrigation type, the amount of land classified as moderately suitable with considerable limitations or better ranges from 433,000 ha (Crop Group 19, wet-season furrow) to 3.1 million ha (Crop Group 3, dry-season, trickle) before constraints such as water availability, environmental and other legislation and regulations, and a range of biophysical risks are considered (crop groups are defined in Section 4.2.3). In contrast with other catchments assessed in northern Australia, the Victoria catchment has a relatively large percentage of soils classed as suitable, with minor limitations, principally the red loamy soils found on the deeply weathered low-relief Tertiary sediments in the south-western, southern and south- eastern (Sturt Plateau) parts of the catchment. Local- and intermediate-scale groundwater resources occur beneath parts of these loamy soils in the central and southern parts of the catchment (Section 2.5.2, Figure 2-27). Regional-scale groundwater resources occur beneath parts of these loamy soils in the eastern part of the catchment. Almost all licensed water use in the catchment occurs outside current water control districts or water allocation planning areas. Rainfed cropping Despite the theoretical possibility that rainfed crops could be produced using the considerable rainfall that arrives during the wet season, in practice significant agronomic and market-related challenges to rainfed crop production have prevented its expansion. Loamy Kandosols have low water-holding capacity and are hardsetting, which makes consistently achieving viable rainfed yields difficult. Areas of heavier clay soils along the West Baines River, the Victoria River and its major tributaries store more plant available water (PAW) that could support higher potential crop yields, particularly if cropped opportunistically in wetter years. However, frequent inundation and waterlogging of clay soils means that access for farming operations could be disrupted, increasing the risk to maximum yields through compromised timing of operations. Despite these challenges, higher-value crops such as pulses or cotton show potential, especially when grown in conjunction with irrigated farming. Irrigated cropping Irrigation reduces crop water stress and provides greater control over scheduling of crop operations to optimise production, including the option of growing through the cooler months of the dry season. Analyses of the performance of 19 potential irrigated cropping options in the Victoria catchment indicate that achievable annual GMs could be up to about $5000/ha for broadacre crops, $4000/ha for annual row crop horticulture, $6000/ha for perennial fruit tree horticulture and $3000/ha for silviculture (plantation trees). While GMs are a key partial metric of farm performance, they should not be treated as fixed constants determined by the cropping system alone. They are a product of the farming and business management decisions, input costs and market opportunities. As such there are often niche opportunities to improve farm GMs and profitability, but these usually come at the expense of scalability. Farm financial metrics like GMs greatly amplify any fluctuations in commodity prices and input costs, so the mean GM does not accurately reflect the often substantial cashflow challenges in managing years of losses between those of windfall profits (particularly for horticulture). Crop yields and GMs presented in this chapter indicate what might be attained for each cropping option once it has achieved its sustainable agronomic potential. It is unrealistic to assume that these levels of performance would be achieved in the early years of newly established farms, and allowance should be made for an initial period of learning (Chapter 6). Potential crop species that could be grown as a single crop per year were rated and ranked for their performance in the Victoria catchment. Wet-season crops (planted December to early May) that are rated the most likely to be viable are cotton (Gossypium spp.), forages and peanuts (Arachis hypogaea). Dry-season crops (planted late March to August) that are rated the most likely to be viable are annual horticulture, cotton and mungbean (Vigna radiata). Financial viability is determined both by crop options with the highest GMs and by associated capital and fixed costs, which are higher in more-intensive farming like horticulture. The farm-scale measures of crop performance presented in this chapter are intended to be used in conjunction with the scheme- scale analyses of financial viability in Chapter 6 (as part of an integrated multi-scale approach). Sequential cropping systems involve planting more than one crop in the same year in the same field. These systems have the potential to significantly increase farm GMs. Annual broadacre and horticultural crops have been grown sequentially for many decades in tropical northern Australia. A wide range of sequential cropping options are potentially viable in the Victoria catchment. Most suitable crop sequences include wet-season mungbean, grain sorghum or peanut with dry-season annual horticulture, wet-season mungbean, peanut, soybean or sorghum with dry-season cotton, maize, chickpea or forage, and wet-season cotton with dry-season mungbean, sorghum or forage. Scheduling back-to-back crops could be operationally tight in the Victoria catchment, particularly on clay-rich soils with poor drainage. Crop selection is market driven in northern Australian regions like the Victoria catchment. Therefore, rotations and crop sequences are dynamic as growers develop an understanding of the benefits, trade-offs and management needs of different crop mixes, and adapt to changing opportunities. Integrating forages and hay into existing beef enterprises There are many theoretical benefits to growing irrigated forages and hay on-farm to enhance existing grazing enterprises. The use of on-farm irrigated forage and hay production would allow graziers greater options for marketing cattle: meeting market liveweight specifications for cattle at a younger age, meeting the specifications required for different markets than those typically targeted by cattle enterprises in the Victoria catchment and providing cattle that meet market specification at a different time of the year. Forages and hay may also allow graziers to implement management strategies, such as early weaning or weaner feeding, which should lead to flow-on benefits throughout the herd, including increased reproductive rates. Some of these strategies are already practised within the Victoria catchment but in almost all incidences are reliant on hay or other supplements purchased on the open market. By growing hay on-farm, the scale of these management interventions might be increased, at reduced net cost. Furthermore, the addition of irrigated feeds may allow graziers to increase the total number of cattle that can be sustainably carried on a property. Analysis of two irrigated hay or two irrigated forage stand-and-graze options compared to two base enterprises (with or without purchased hay, for weaners) suggested that irrigated forages or hay increased the total income and the amount of cattle liveweight sold. GMs were highest for the two base enterprises. The two stand-and-graze options returned the lowest GMs. A net present value (NPV) analysis suggested that none of the options had a positive NPV when considered at three different beef prices and two different estimates of capital costs per ha. Irrigation enterprises of the scale required involve high capital investment and additional or novel management skills. Aquaculture There are considerable opportunities for aquaculture development in northern Australia given the region’s natural advantages of a climate suited to farming valuable tropical species, the large areas identified as suitable for aquaculture, and political stability and proximity to large global markets. The main challenges to developing and operating modern and sustainable aquaculture enterprises are regulatory barriers, global cost competitiveness, and the remoteness of much of the suitable land area. The three species with the most aquaculture potential in the Victoria catchment are black tiger prawns (Penaeus monodon), barramundi (Lates calcarifer) and red claw (Cherax quadricarinatus). Suitable land for lined ponds for freshwater species is widespread throughout the catchment due to the extensive distribution of favourable soil and land characteristics (flat land, non-rocky, deep soil). In contrast, options for freshwater species in earthen ponds are restricted to the impermeable alluvial clays to allow retention of water. The range for marine aquaculture is restricted to the tidal zones of the catchment and on the coastal plain within 2000 m of access to marine water. High annual operating costs (which can exceed the initial capital costs of development) mean that managing cashflow in the establishment years is challenging, especially for products that require multi-year grow-out periods. Input costs scale with increasing productivity, so improving production efficiency (such as feed conversion rate or labour-efficient operations) is much more important than increasing yields for aquaculture to be viable in the Victoria catchment. It would be essential for any new aquaculture development to refine the production system and achieve the required levels of operational efficiency (input costs per kilogram of produce) using just a few ponds before scaling the enterprise to a larger number of ponds. 4.1.2 Introduction Aspirations to expand agricultural development in the Victoria catchment are not new and across northern Australia there have been a number of initiatives to put in place large-scale agricultural developments since World War II (Ash, 2014; Ash and Watson, 2018). Ash and Watson (2018) assessed 11 such agricultural developments, four of which continue to operate at a regionally relevant scale, namely the Ord River Irrigation Area, the lower Burdekin, the Mareeba–Dimbulah Water Supply Scheme and the Katherine mango industry. The Lakeland Downs development also continues, although it could not be categorised as regionally significant. Ash and Watson’s assessment included both irrigated and rainfed developments and considered natural, human, physical, financial and social capitals. Key points to emerge from these analyses include the following: • The natural environment (climate, soils, pests and diseases) makes agriculture in northern Australia challenging, but these inherent environmental factors are not generally the primary reason for a lack of success. • The speed with which many of the developments were undertaken did not allow for a ‘learning by doing’ approach, leading at times to costly mistakes. • Physical capital, in the form of on-farm infrastructure, supply chain infrastructure and crop varieties, was a significant and ongoing impediment to success. For broadacre commodities that require processing facilities, these facilities need to be within a reasonable distance of production sites and at a scale to make them viable in the long term. • Financial plans tended to over estimate early production and returns on capital, and assumed overly optimistic expectations of the ability to scale up rapidly. This led to financial pressure on investors and a premature end to some developments. Furthermore, the need to have well- connected and well-paying markets was often not fully appreciated. In more remote regions, higher-value products such as fruit, vegetables and niche crops proved more successful, although high supply chain costs to both domestic and export markets remain as impediments to expansion. • Most of the developments began in areas with no history of agricultural development and there was no significant community of practitioners who could share experiences. • Management, planning and finances were the most important factors in determining the ongoing viability of agricultural developments. For developments to be successful, all factors relating to climate, soils, agronomy, pests, farm operations, management, planning, supply chains and markets need to be thought through in a comprehensive systems design. Particular attention needs to be paid to scaling up at a considered pace and being prepared for reasonable lags before achieving positive returns on investment. This chapter seeks to address the following questions for the Victoria catchment: • How much land is suitable for cropping and in which suitability class? • Is irrigated cropping economically viable? • Which crop options perform best and how can they be implemented in viable mixed farming systems? • Can crops and forages be economically integrated with beef enterprises? • What aquaculture production systems might be possible? The chapter is structured as follows: • Section 4.2 describes how the land suitability classes are derived from the attributes provided in Chapter 2, with results given for a set of 14 combinations of individual crop group × season × irrigation type. Versatile agricultural land is described, and a qualitative evaluation of cropping is provided for a set of specific locations within the catchment. • Section 4.3 provides detailed information on crop and forage opportunities, including irrigated crop yields, water use and GMs. Agronomic principles, such as selection of sowing time, are provided, including a cropping calendar for scheduling farm operations. The information is synthesised in an analysis of the cropping systems that could best take advantage of opportunities in the Victoria catchment environments while dealing with farming challenges. • Section 4.4 provides synopses for 11 crop and forage groups, including a focused discussion on specific example species. • Section 4.5 discusses the candidate species and likely production systems for aquaculture enterprises, including the prospects for integrating aquaculture with agriculture. 4.2 Land suitability assessment 4.2.1 Introduction The term ‘suitability’ in the Assessment refers to the potential of the land for a specific land use, such as furrow-irrigated cotton. The term ‘capability’ (not used in the Assessment) refers to the potential of the land for broadly defined land uses, such as cropping or pastoral (DSITI and DNRM, 2015). The overall suitability for a particular land use is determined by a number of environmental and soil attributes. These include, but are not limited to, climate at a given location, slope, drainage, permeability, available water capacity of the soil, pH, soil depth, surface condition and texture. Examples of some of these attributes are provided in Section 2.3. From these attributes, a set of limitations to suitability are derived, which are then considered against each potential land use. 4.2.2 Land suitability classes The overall suitability for a particular land use is calculated by considering the set of relevant attributes at each location and determining the most limiting attribute among them. This most limiting attribute then determines the overall land suitability classification. The classification is on a scale of 1 to 5 from ‘Suitable with negligible limitations’ (Class 1) to ‘Unsuitable with extreme limitations’ (Class 5), as shown in Table 4-1 (FAO, 1976, 1985). The companion technical report on digital soil mapping and land suitability (Thomas et al., 2024) provides a complete description of the land suitability assessment method, and the material presented in this section is taken from that report. Note that the land suitability maps and figures presented in this section do not consider flooding, risk of secondary salinisation or availability of water as discussed by Thomas et al. (2024). Consideration of these risks and others, along with further detailed soil physical, chemical and nutrient analyses, would be required to plan development at scheme, enterprise or property scale. Caution should therefore be employed when using these data and maps at fine scales. Table 4-1 Land suitability classes based on FAO (1976, 1985) as used in the Assessment For more information on this figure, table or equation please contact CSIRO on enquiries@csiro.au 4.2.3 Land suitability for crops, versatile agricultural land and evaluation of specific areas of interest The suitability framework used in this Assessment aggregates individual crops into a set of 21 crop groups (Table 4-2). The groups are based on the framework used by the NT Government (Andrews and Burgess, 2021), with some additions considered prospective based on previous CSIRO work in northern Australia (e.g. Thomas et al., 2018). From this set of crop groups, land suitability has been determined for 58 land use combinations of crop group × season × irrigation type (including rainfed) (Thomas et al., 2024). Table 4-2 Crop groups and individual land uses evaluated for irrigation (and rainfed) potential Crop groups and land uses are based on those used by Andrews and Burgess (2021), amended for the Victoria catchment with the addition of crop groups 18 to 21 based on CSIRO’s previous work in northern Australia. Those used in the Northern Australia Water Resource Assessment (Thomas et al., 2018) are in boldface. MAJOR CROP GROUP CROP GROUP INDIVIDUAL CROPS ASSESSED Tree crops/horticulture (fruit) 1 Monsoonal tropical tree crops (0.5 m root zone) – mango, coconut, dragon fruit, Kakadu plum, bamboo, lychee 2 Tropical citrus – lime, lemon, mandarin, pomelo, lemonade, grapefruit Intensive horticulture (vegetables, row crops) 3 Cucurbits – watermelon, honeydew melon, rockmelon, pumpkin, cucumber, Asian melons, zucchini, squash 4 Fruiting vegetable crops – Solanaceae (capsicum, chilli, eggplant, tomato), okra, snake bean, drumstick tree 5 Leafy vegetables and herbs – kangkong, amaranth, Chinese cabbage, bok choy, pak choy, choy sum, basil, coriander, dill, mint, spearmint, chives, oregano, lemon grass, asparagus Root crops 6 Carrot, onion, sweet potato, shallots, ginger, turmeric, galangal, yam bean, taro, peanut, cassava Grain and fibre crops 7 Cotton, grains – sorghum (grain), maize, millet (forage) 8 Rice (lowland and upland) Small-seeded crops 9 Hemp, chia, quinoa, medicinal poppy Pulse crops (food legumes) 10 Mungbean, soybean, chickpea, navy bean, lentil, guar Industrial 11 Sugarcane Hay and forage (annual) 12 Annual grass hay/forages – sorghum (forage), maize (silage) 13 Legume hay/forages – blue pea, burgundy bean, cowpea, lablab, Cavalcade, forage soybean Hay and forage (perennial) 14 Perennial grass hay/forage – Rhodes grass, panics Silviculture/forestry (plantation) 15 Indian sandalwood 16 African mahogany, Eucalyptus spp., Acacia spp. 17 Teak Intensive horticulture (vegetables, row crops) 18 Sweet corn Oilseeds 19 Sunflower, sesame Tree crops/horticulture 20 Banana, coffee 21 Cashew, macadamia, papaya A sample of 14 of these individual land use combinations – that covers a mixture of crops, irrigation types and seasons, grown or trialled in northern Australia – is shown in Figure 4-2. Depending on land use, the amount of land classified as Class 3 or better for these sample land uses ranges from just over 433,000 ha (Crop Group 19 under wet-season furrow irrigation) to just over 3 million ha (Crop Group 3 under dry-season trickle). Much of this land is rated as Class 3, and so has considerable limitations, although just over 2 million ha of Class 2 land is available for Crop Group 3 crops under trickle irrigation in the dry season and between about 860,000 ha and about 2 million ha of Class 2 land for the other crop groups under spray or trickle irrigation. Ranges of suitability geographic distributions are shown on maps in the crop synopses in Section 4.4. Figure 4-2 Area (ha) of the Victoria catchment mapped in each of the land suitability classes for 14 selected land use combinations (crop group × season × irrigation type) The five land suitability classes are described in Table 4-1 and more detail on the crop groups is given in Table 4-2. In order to provide an aggregated summary of the land suitability products, an index of agricultural versatility was derived for the Victoria catchment (Figure 4-3). Versatile agricultural land was calculated by identifying where the highest number of the 14 selected land use options presented in Figure 4-2 were mapped as being suitable (i.e. suitability classes 1 to 3). Qualitative observations on each of the areas mapped as ‘A’ to ‘E’ in Figure 4-3 are provided in Table 4-3. Figure 4-3 Agricultural versatility index map for the Victoria catchment High index values denote land that is likely to be suitable for more of the 14 selected land use options. The map shows specific areas of interest (A to E) from a land suitability perspective, which are discussed in Table 4-3. Note that the versality index mapped here does not consider flooding, risk of secondary salinisation or availability of water. Versatile agricultural land \\FS1-CBR.nexus.csiro.au\{lw-rowra}\work\10_Reporting\2_Victoria\1_GIS\1_Map_Docs\CR-V-Ch4-511_AgVers14_PotDev_v1_10-8.mxd For more information on this figure please contact CSIRO on enquiries@csiro.au Table 4-3 Qualitative land evaluation observations for Victoria catchment areas A to E shown in Figure 4-3 Further information on each soil generic group (SGG) and a map showing spatial distribution can be found in Section 2.3. AREA SOIL AND LOCATION SOIL DESCRIPTION, POTENTIAL LAND USES AND LIMITATIONS A Loamy soils of the Sturt Plateau, the plateau west of Kalkarindji and the southern part of the catchment Moderately permeable red loamy soils (SGG 4.1) with varying amounts of iron nodules. Moderately deep to deep loamy soils are suitable for a diverse range of irrigated horticulture and spray-irrigated grain and pulse crops, forage crops, timber crops, sugarcane and cotton. Soils with hard iron nodules may be suitable for small crops, but abundant nodules will restrict the amount of available soil water for crop growth and cultivation operations. Very shallow soils are generally unsuitable for cropping due to very low available soil water and restricted rooting depth. B Cracking clay soils on broad alluvial plains of the major rivers, particularly the Victoria and West Baines rivers Comprises rarely flooded plains on the Victoria and West Baines rivers and regularly flooded plains on the Baines, East Baines and lower West Baines rivers. Soils are mainly moderately well-drained to imperfectly drained brown or grey cracking clay soils (SGG 9) with self-mulching to hard-setting structured surfaces. The imperfectly drained clay soils of the alluvium grade to poorly drained grey clays (SGG 3) lower in the catchment. The cracking clay soils are suitable for furrow or spray-irrigated sugarcane, dry-season cotton, grain and pulse crops, and forage crops. The main limitations are flooding on the floodplains during the wet season, workability and landscape complexity due to the small and/or narrow areas limiting paddock size and irrigation infrastructure layout due to land dissection. Management of wet- season cropping needs to consider crop tolerance to seasonal wetness and flood duration, depth and frequency. C Brown, black and red cracking clay soils derived from basalt, mainly in the eastern and southern parts of the catchment Moderately deep to deep, moderately well-drained to well-drained, self-mulching cracking clay soils (SGG 9) on basalt plains, scattered throughout the eastern part of the catchment but mainly in the south. Surface gravels, cobble and stone are present. Soils are suitable for a range of spray-irrigated grain and pulse crops, mainly dry-season cropping. Wet-season cropping may be restricted by seasonal wetness and flooding. Extents are generally minor, resulting in small and/or narrow areas limiting paddock size and irrigation infrastructure layout. D Red friable loamy soils on levees of the Victoria and Wickham rivers Predominantly very deep, well-drained red and brown friable loams (SGG 2) on narrow levees. Soils are subject to severe sheet and gully erosion throughout the catchment, and wind erosion in the lower rainfall areas in the south. The narrow levees are suitable for a range of spray-irrigated grain and forage crops and trickle- irrigated horticultural crops, but the generally long, thin units of land restrict irrigation layout and machinery use in most areas. E Grey cracking clay soils of the Cenozoic alluvium scattered through the eastern, southern and western parts of the catchment Very deep, gilgaied, self-mulching, grey and occasionally grey-brown cracking clay soils (SGG 9) subject to seasonal wetness occur in the lower landscape positions of the deeply weathered plateaux and as level plains overlying a diverse range of other geologies. Suitable for dry-season furrow or spray-irrigated grain and pulse crops, forage crops and cotton. Deep gilgai microrelief may restrict land-levelling operations in some areas. Land suitability and its implications for crop management are discussed in more detail for a selection of crops in Section 4.4, where land use suitability of a given crop and irrigation combination are mapped, along with information critical to the consideration of the crop in an irrigated farm enterprise. Land suitability maps for all 58 land use combinations are presented in the companion technical report on digital soil mapping and land suitability (Thomas et al., 2024). 4.3 Crop and forage opportunities in the Victoria catchment 4.3.1 Introduction This section presents results on the farm ‘performance’ of individual crop options, where performance is quantified specifically as crop yields, the amount of applied irrigation water (including on-farm water losses) and GMs. Performance is presented with information on agronomic principles and farming practices to help interpret the viability of new (greenfield) farming opportunities in the Victoria catchment. The individual crop options are grouped into rainfed broadacre, irrigated broadacre, irrigated horticulture and plantation tree crops (sections 4.3.3 to 4.3.7), and viability is discussed in a section on cropping systems (Section 4.3.8). That section considers the mix of farming opportunities and practices, for both single and sequential cropping systems, with the greatest potential to be profitably and sustainably integrated within Victoria catchment environments. Finally, Section 4.3.9 evaluates the viability of integrating irrigated forages into existing beef production. These farm-scale analyses are intended to be used in conjunction with the scheme-scale analyses of viability in Chapter 6 (as part of an integrated multi-scale analysis). Nineteen irrigated crop options were selected to evaluate their potential performance in the Victoria catchment (Table 4-4). The crops were selected to be compatible with the land suitability crop groups (Table 4-2), provided that: (i) they had the potential to be viable in the Victoria catchment (based on knowledge of how well these crops grow in other parts of Australia), (ii) they were of commercial interest for possible development in the region and (iii) there was sufficient information on their agronomy, and farming costs and prices, for quantitative analysis. The analyses used a combination of Agricultural Production Systems sIMulator (APSIM) crop modelling and climate-informed extrapolation to estimate potential yield and water use for each crop. Those values were then used in a farm GM tool specifically designed for greenfield farming developments (like those in the Victoria catchment, where there are very few existing commercial farms or farm financial models). In particular, extrapolations used close similarities in climate and soils between possible cropping locations in the Victoria catchment and established irrigated cropping regions at similar latitudes near Katherine (NT) and the Ord River Irrigation Area (WA) (Figure 4-4). Full details of the approach are described in the companion technical report on agricultural viability and socio-economics (Webster et al., 2024). Section 4.4 provides further details on opportunities and constraints in the Victoria catchment, for example, crops in each of the agronomic crop types listed in Table 4-4. Table 4-4 Crop options for which performance was evaluated in terms of water use, yields and gross margins The methods used for estimating crop yield and irrigation water requirements are coded as: A = APSIM; E = climate- informed extrapolation. ‘A, E’ indicates that A is the primary method and E is used for sensibility testing. ‘Mango (KP)’ is Kensington Pride and ‘Mango (PVR)’ is an indicative new high-yielding variety likely to have plant variety rights (e.g. Calypso). Note that crops that are agronomically similar in terms of the commodities they produce (as categorised in the table) may differ in how they respond to soil constraints. The crop type categories in the table are therefore necessarily different to the crop groups used in the land suitability section (which are grouped according to shared soil requirements and constraints; Table 4-2). CROP TYPE CROP IRRIGATION WATER ESTIMATE METHOD YIELD ESTIMATE METHOD Broadacre Cereal Sorghum (grain) A, E A, E Maize A, E A, E Pulse Mungbean A, E A, E Chickpea A, E A, E Soybean A, E A, E Oilseed Sesame E E Peanut A, E A, E Industrial Cotton (dry season) A, E A, E Cotton (wet season) A, E A, E Hemp E E Forage Rhodes grass A, E A, E Horticulture (row) Rockmelon E E Watermelon E E Onion E E Capsicum E E Horticulture (tree) Mango (PVR) E E Mango (KP) E E Lime E E Plantation tree African mahogany E E Sandalwood E E (a) Mean monthly rainfall (b) Mean daily maximum temperature (c) Mean daily solar radiation (d) Mean daily minimum temperature Figure 4-4 Climate comparisons of Victoria catchment sites with established irrigation areas at Katherine (NT) and Kununurra (WA) Victoria catchment sites are Timber Creek, Kidman Springs, Montejinni and Wave Hill. Four locations were selected for the APSIM simulations to represent some of the best potential farming conditions across the varied environments in the Victoria catchment: • A Vertosol in the northern region, using Timber Creek (15.66°S, 130.48°E) climate. This soil represents some of the better farming conditions among the cracking clays on the alluvial plains of the major rivers (SGG 2 and 9, marked ‘B’ in Figure 4-3). The plant available water capacity (PAWC) of this soil for grain sorghum was 212 mm. Only small, dissected patches of this soil are suitable for cropping because of limitations from floodplain inundation, workability and the complex distribution of flood channels (which both break up patches that would be large enough to crop and cut off wet-season access to some larger pockets of otherwise suitable soil). • A Dermosol in the Yarralin area using the Kidman Springs (16.12°S, 130.96°E) climate. This soil represents some of the better farming conditions among the brown non-cracking clay soils and the red friable loamy clay soils (SGG 2, marked ‘C’ and ‘D’ in Figure 4-3). The PAWC of this soil for grain sorghum was 156 mm. • A Vertosol in the Top Springs area, using Montejinni (16.67°S, 131.76°E) climate. This soil is the same as the Vertosol described above (SGG 2 and 9, marked ‘E’ in Figure 4-3), with a different climate. • A Kandosol in the Kalkarindji area using the Wave Hill (17.39°S and 131.12°E) climate. This soil represents some of the better farming conditions among the loamy soils (SGG 4.1 and 4.2, Mean monthly rainfall graph \\fs1-cbr.nexus.csiro.au\{lw-rowra}\work\5_Agriculture_economics\2_Victoria\4_Data\1_Climate\ViWRA_Climate analysis_YO.xlsx For more information on this figure please contact CSIRO on enquiries@csiro.au Mean daily maximum temperature graph \\fs1-cbr.nexus.csiro.au\{lw-rowra}\work\5_Agriculture_economics\2_Victoria\4_Data\1_Climate\ViWRA_Climate analysis_YO.xlsx For more information on this figure please contact CSIRO on enquiries@csiro.au Mean daily solar radiation graph \\fs1-cbr.nexus.csiro.au\{lw-rowra}\work\5_Agriculture_economics\2_Victoria\4_Data\1_Climate\ViWRA_Climate analysis_YO.xlsx For more information on this figure please contact CSIRO on enquiries@csiro.au Mean daily minimum temperature graph \\fs1-cbr.nexus.csiro.au\{lw-rowra}\work\5_Agriculture_economics\2_Victoria\4_Data\1_Climate\ViWRA_Climate analysis_YO.xlsx For more information on this figure please contact CSIRO on enquiries@csiro.au For more information on this figure please contact CSIRO on enquiries@csiro.au marked ‘A’ in To assist with interpreting the later results, some information is first provided on agronomic principles related to the scheduling of critical farm operations such as sowing and irrigation in relation to Victoria catchment environments. 4.3.2 Cropping calendar and time of sowing Time of sowing can have a significant effect on achieving economical crop and forage yields, and on the availability and amount of water for irrigation required to meet crop demand. Cropping calendars identify optimum sowing times of different crops and are essential tools for scheduling farm operations (Figure 4-5) so that crops can be reliably and profitably grown. No cropping calendar existed for the Victoria catchment before the Assessment. Sowing windows vary in both timing and length among crops and regions, and they consider the likely suitability and constraints of weather conditions (e.g. heat and cold stress, radiation, and conditions for flowering, pollination and fruit development) during each subsequent growth stage of the crop. Limited field experience currently exists in the Victoria catchment for the majority of crops and forages evaluated. This cropping calendar (Figure 4-5) is therefore extrapolated from knowledge of crops derived from past and current agricultural experience in the Ord River Irrigation Area (WA), Katherine and Douglas–Daly regions (NT). Some annual crops have both wet-season and dry-season cropping options. Perennial crops are grown throughout the year, so growing seasons and planting windows are less well defined. Generally, perennial tree crops are transplanted as small plants, and in northern Australia this is usually timed towards the beginning of the wet season to take advantage of wet-season rainfall. The cropping calendar presented here considers the optimal climate conditions for crop growth and considers operational constraints specific to the local area. Such constraints include wet- season difficulties in access and trafficability, and limitations on the number of hectares that available farm equipment can sow or plant per trafficable day. For example, clay-rich alluvial Vertosols, such as those found along the Victoria, West Baines and East Baines rivers, are likely to present severe trafficability constraints through much of the wet season in the Victoria catchment, while sandier Kandosols would present far fewer trafficability restrictions in scheduling farming operations (Figure 4-6). Many suitable annual crops can be grown at any time of the year with irrigation in the Victoria catchment. Optimising crop yield alone is not the only consideration. Ultimately, sowing date selection must balance the need for the best growing environment (optimising solar radiation and temperature) with water availability, pest avoidance, trafficability during the growing season and at harvest, crop rotation, supply chain requirements, infrastructure development costs, market access considerations and potential commodity price. Many summer crops from temperate regions are suited to the tropical dry season (winter) because temperatures are closer to their optima and/or there is more consistent solar radiation (e.g. maize (Zea mays), chickpea (Cicer arietinum) and rice (Oryza sativa)). For sequential cropping systems (which grow more than a single crop in a year in the same field), growing at least one crop partially outside its optimal growing season can be justified if it increases total farm profit per year and there are no adverse biophysical consequences (e.g. pest build-up). Figure 4-5 Annual cropping calendar for irrigated agricultural options in the Victoria catchment WS = wet season; DS = dry season. Crop planting times \\FS1-CBR.nexus.csiro.au\{lw-rowra}\work\5_Agriculture_economics\4_S_Gulf\4_Data\2_Crops\Cropping_Windows.xlsx For more information on this figure please contact CSIRO on enquiries@csiro.au CROP TYPECROPDECJANFEBMARAPRMAYJUNJULAUGSEPOCTNOVCROP DURATION(days) Cereal cropsSorghum (WS)ssssssgggg110—140Sorghum (DS)gssssssssssggg110—140Maize (WS)ssssssggg110—140Maize (DS)gssssssssssggg110—140Rice (WS)ssssgggg120—160+ Rice (DS)ssssgggg90—135 Pulse crops (food legumes)Mungbean (WS)ssssggg70—85Mungbean (DS)ssssggg70—85Chickpeassssgggg100—120OilseedsSoybean (WS)ssssssgggg110—130Sesamessssssggg110—130Root cropsPeanut (WS)ssssssggggg100—140Peanut (DS)gssssggg100—140Cassavassssssssssssssggggg180—210Industrial cropsCotton (WS)ssssssgggg100—120Cotton (DS)ssssssggggg100—120Hemp (fibre)ssssssssgggg110—150Forage, hay, silageRhodes grassggspspspgggspspspspPerennial (regrows) Forage sorghumssssssssgggssssssgg60—80 (regrows) Forage milletssssssssgggssssssgg60—80 (regrows) Forage maizegssssssgggssssssgg75—90Forage legumesCavalcadessggggggssss150—180Lablabssssssssssggggg130—160Horticulture (row crops)Melonsssssssgggg70—110Oniongssssssssssgggg130—160Capsicum, chilli, tomatossssggggg70—90 from transplantPineapplespspspgggggggPerennialHorticulture (vine)Table grapesspspspgggggggggPerenialHorticulture (tree crops)MangospspspgggggggggPerennialAvocadospspspgggggggggPerennialBananaspspspspggggggggPerennialLimespspspgggggggggPerennialLemonspspspgggggggggPerennialOrangespspspgggggggggPerennialCashewspspspgggggggggPerennialMacadamiaspspspgggggggggPerennialPlantation trees (silviculture)Africian mahoganyspspspgggggggggPerennialIndian sandalwoodspspspgggggggggPerennial (a) 70% of PAWC threshold (b) 80% of PAWC threshold Figure 4-6 Soil wetness indices that indicate when seasonal trafficability constraints are likely to occur on Vertosols (high clay), Kandosols (sandy loam) and sand at Kidman Springs for (a) a threshold of 70% of plant available water capacity (PAWC) and (b) 80% of PAWC The indices show the proportion of years (for dates at weekly intervals) when plant available water (PAW) in the top 30 cm of the soil is below two threshold proportions (70% and 80%) of the maximum PAW value. Lower values indicate there would be fewer days at that time of year when fields would be accessible and trafficable. Estimates are from 100-year Agricultural Production Systems Simulator simulations without a crop. In actual farming situations, once a crop canopy is established later in the season, crop water extraction from the soil would assist in alleviating these constraints. Growers also manage time of sowing to optimally use stored soil water and in-season rainfall, and to avoid rain damage at maturity. In the Victoria catchment mean monthly rainfall is highly variable between the wet and dry seasons (Figure 4-4) and irrigation allows growers the flexibility in sowing date and in the choice and timing of crop or forage systems in response to seasonal climate conditions. Depending on the rooting depth of a particular species and the length of growing season, crops established at the end of the wet season may access a full profile of soil water (e.g. ≥200 mm PAWC for some Vertosols). While timing sowing to the end of the wet season to take advantage of soil water may reduce the overall irrigation requirement, it may expose crops to periods of unfavourable solar radiation or temperatures during plant development and flowering. It may also prevent the implementation of a sequential cropping system. 4.3.3 Rainfed cropping Rainfed cropping (crops grown without irrigation, relying only on rain) has been attempted by farmers in the NT for almost 100 years, yet only small areas of rainfed crop production currently occur each year. This indicates that despite the theoretical possibility of producing rainfed crops using the significant wet-season rainfall in the Victoria catchment, in practice major agronomic and market-related challenges to rainfed crop production have prevented its expansion to date. Without the certainty provided by irrigation, rainfed cropping is opportunistic in nature, relying on favourable conditions in which to establish, grow and harvest a crop. The annual cropping calendar in Figure 4-5 shows that, for many crops, the sowing window includes the month of February. For relatively short-season crops, such as grain sorghum and mungbean, this coincides with both the sowing time that provides close to maximum crop yield and the time at which the Trafficability of soil based on how often the soil is above a 70% PAWC threshold graph \\fs1-cbr.nexus.csiro.au\{lw-rowra}\work\5_Agriculture_economics\2_Victoria\4_Data\2_APSIMmodelling\ViWRA-Charts_APSIM_v0_YO.xlsx For more information on this figure please contact CSIRO on enquiries@csiro.au Trafficability of soil based on how often the soil is above a 80% PAWC threshold graph \\fs1-cbr.nexus.csiro.au\{lw-rowra}\work\5_Agriculture_economics\2_Victoria\4_Data\2_APSIMmodelling\ViWRA-Charts_APSIM_v0_YO.xlsx For more information on this figure please contact CSIRO on enquiries@csiro.au season’s water supply can be accessed with a high degree of confidence. Table 4-5 shows how plant available soil water content at sowing and subsequent rainfall in the 90 days after each sowing date varies over three different sowing dates for a Vertosol in the Victoria catchment at Kidman Springs. As sowing is delayed from February to April, the amount of stored soil water increases. However, there is a significant decrease in rainfall in the 3 months after sowing. Combining the median PAW in the soil profile at sowing, and the median rainfall received in the 90 days following sowing provides totals of 460, 262 and 166 mm for the February, March and April sowing dates, respectively. Table 4-5 Soil water content at sowing, and rainfall for the 90-day period following sowing for three sowing dates, based on a Kidman Springs climate on a Vertosol PAW = plant available water stored in soil profile. The 80%, 50% (median) and 20% probabilities of exceedance values are reported for the 100 years between 1920 and 2020. The lower-bound values (80% exceedance) occur in most years, while the upper-bound values only occur in the most exceptional upper 20% of years. SOWING DATE PAW AT SOWING DATE (mm) RAINFALL IN 90 DAYS FOLLOWING SOWING DATE (mm) TOTAL STORED SOIL WATER + RAINFALL IN SUBSEQUENT 90 DAYS (mm) 80% 50% 20% 80% 50% 20% 80% 50% 20% 1 February 129 149 194 175 310 425 330 460 606 1 March 134 154 189 50 104 231 200 262 393 1 April 128 142 185 1 13 50 138 166 213 For drier-than-average years (80% probability of exceedance), the soil water stored at sowing and the expected rainfall in the ensuing 90 days (<330 mm) would result in water stress and comparatively reduced crop yields. In wetter-than-average years (20% probability of exceedance), the amount of soil water at the end of February combined with the rainfall in the following 90 days (606 mm) is sufficient to grow a good short-season crop (noting that the timing of rainfall is also important because some rain is ‘lost’ to runoff, evaporation and deep drainage between rainfall events). Opportunistic rainfed cropping would target those wetter years where PAW at the time of sowing indicated a higher chance of harvesting a profitable crop. The success of rainfed cropping is clearly dependent on wet-season rainfall, but also the ability of the soil to store water for the crop to use as it finishes growing into the dry season. Figure 4-7 highlights the effects of diminishing water availability and increasing evapotranspiration likely to be encountered when sowing a rainfed crop at the start of April or later. This constraint is much more severe for sandier soils, which have less capacity to store PAW (like Kandosols in the Victoria catchment, Figure 4-7a), compared to finer textured soils (like the alluvial Vertosols in the Victoria catchment, Figure 4-7b). (a) Kidman Springs Kandosol (sandy loam, PAWC 129 mm) (b) Kidman Springs Vertosol (high clay, PAWC 213 mm) Figure 4-7 Influence of planting date on rainfed grain sorghum yield at Kidman Springs for a (a) Kandosol and (b) Vertosol Estimates are from Agricultural Production Systems Simulator simulations with planting dates on the 1st and 15th of each month. PAWC values are the plant available water capacities of the soil profiles. The shaded band around the median line indicates the 80% to 20% exceedance probability range in year-to-year variation. Soil is seldom uniform within a single paddock, let alone across entire districts. Without the homogenising input of irrigation to alleviate water limitations (and associated high inputs of fertilisers to alleviate nutrient limitations), yields from low-input rainfed cropping are typically much more variable (both across years and locations) than yields from irrigated agriculture. Furthermore, the capacity of the soil to supply stored water varies with soil type, and it also depends on crop type and variety because each crop’s root system has a different ability to access water, particularly deep in the profile. This makes it harder to make generalisations about the viability of rainfed cropping in the Victoria catchment as farm performance (e.g. yields and GMs) is much more sensitive to slight variations in local conditions. Rigorous estimates of rainfed crop performance on which investment decisions could be confidently made would require detailed localised soil mapping and crop trials before investment decisions could be confidently made. Despite the challenges described above, recent efforts in the NT have identified potential opportunities for rainfed farming using higher-value crops, such as pulses or cotton. A preliminary APSIM assessment of the potential for rainfed cotton in the region suggested that mean lint yields of 2.5 to 3.5 bales per ha may be possible at a range of locations in the vicinity of the Victoria catchment (Yeates and Poulton, 2019). However, there was very high variability in median yields between farms (1–5 bales/ha), depending on management and soil type. 4.3.4 Irrigated crop response and performance metrics Crops that are fully irrigated can yield substantially more than rainfed crops. Figure 4-8 shows how yields for grain sorghum grown on a Kandosol in the Victoria catchment increase as more water becomes available to alleviate water limitations and meet increasing proportions of crop demand. With sufficient irrigation, yields are highest for (wet-season sown) crops grown over the dry season when radiation tends to be less limiting (comparing plateau of lines in Figure 4-8a and b). For wet-season sowing, unirrigated yields can approach fully irrigated yields in good years (yields exceeded in the top 20% of years, marked by the upper shaded range in Figure 4-8a). However, Graph of sorghum yield versus planting date of sorghum on a Kandosol \\fs1-cbr.nexus.csiro.au\{lw-rowra}\work\5_Agriculture_economics\2_Victoria\4_Data\2_APSIMmodelling\ViWRA-Charts_APSIM_v0_YO.xlsx For more information on this figure please contact CSIRO on enquiries@csiro.au Graph of sorghum yield versus planting date of sorghum on a Vertosol \\fs1-cbr.nexus.csiro.au\{lw-rowra}\work\5_Agriculture_economics\2_Victoria\4_Data\2_APSIMmodelling\ViWRA-Charts_APSIM_v0_YO.xlsx For more information on this figure please contact CSIRO on enquiries@csiro.au irrigation allows greater flexibility in sowing dates, allows sowing in the dry season too (for crops that would then grow through the wet season) and generates more reliable (and higher median) yields. (a) 1 February sowing (wet season) (b) 1 August sowing (dry season) Figure 4-8 Influence of available irrigation water on grain sorghum yields for planting dates of (a) 1 February and (b) 1 August, for a Kandosol with a Kidman Springs climate Estimates are from 100-year Agricultural Production Systems Simulator simulations. The shaded band around the median line indicates the 80% to 20% exceedance probability range in year-to-year variation. Rainfed production is indicated by the zero point, where no allocation is available for irrigation. The simulations did not seek to ‘optimise’ supplemental irrigation strategies in years where available water was insufficient to maximise crop yields; irrigators would need to make those decisions in years where available water was insufficient to fully meet crop demand. A key advantage of irrigated dry-season cropping in northern Australia is that the availability of water in the soil profile and surface water storages for growing the crop is largely known at the time of planting (near the start of the wet season; Table 4-5). This means irrigators have good advance knowledge for planning how much area to plant, which crops to grow and which irrigation strategies to use, particularly in years where they have insufficient water to fully irrigate all fields. A mix of irrigation approaches could be used, such as expanding the scale of a core irrigated cropping area with other less intensively farmed areas, opportunistic rainfed cropping, opportunistic supplemental irrigation, opportunistic sequential cropping and/or adjusting the area of fully irrigated crops grown to match available water supplies that year. Measures of farm performance (in terms of yields, water use and GMs) are presented for the 20 cropping options that were evaluated (Table 4-4). Given the limited commercial irrigated farming currently occurring in the Victoria catchment that can provide real-world data, estimates of crop water use and yields should be considered as indicative, and to have at least a 20% margin of error at the catchment scale (with further variation expected between farms and fields). The measures of performance should be considered as an upper bound of what could be achieved under best- practice management after learning and adapting to location-specific conditions. GMs are a key partial metric of farm performance but should not be treated as fixed constants determined by the cropping system alone. They are a product of the farming and business management decisions made by individual farmers, input prices, commodity prices and market opportunities (details on calculation of GMs are in Webster et al., 2024). As such, the GMs Graph of 1st February sorghum yield versus Irrigation water application on a Kandosol \\fs1-cbr.nexus.csiro.au\{lw-rowra}\work\5_Agriculture_economics\2_Victoria\4_Data\2_APSIMmodelling\ViWRA-Charts_APSIM_v0_YO.xlsx For more information on this figure please contact CSIRO on enquiries@csiro.au Graph of 1st August sorghum yield versus Irrigation water application on a Kandosol \\fs1-cbr.nexus.csiro.au\{lw-rowra}\work\5_Agriculture_economics\2_Victoria\4_Data\2_APSIMmodelling\ViWRA-Charts_APSIM_v0_YO.xlsx For more information on this figure please contact CSIRO on enquiries@csiro.au presented in Table 4-6 should be treated as indicative of what might be attained for each cropping option once its sustainable agronomic potential has been achieved. Any divergence from assumptions about yields and costs would flow through to GM values, as would the consequences of any underperformance or overperformance in farm management. It is unrealistic to assume that the levels of performance in the results below would be achieved in the early years of newly established farms, and allowance should be made for an initial period of learning when yields and GMs are below their potential (Chapter 6). Collectively however, the GMs and other performance metrics presented here provide an objective and consistent comparison across a suite of likely cropping options for the Victoria catchment, and indicate a maximum performance that could be achievable for greenfield irrigated development for each of the groupings of crops below. 4.3.5 Irrigated broadacre crops Table 4-6 shows the farm performance (yields, water use and GMs) for the ten broadacre cropping options that were evaluated. For crops that were simulated with APSIM, estimates are provided for locations with three different soil types associated with four climates in the Victoria catchment (Vertosol at Timber Creek, Red Dermosol at Kidman Springs, Vertosol at Montejinni and Red Kandosol at Wave Hill) and include measures of variability (expressed in terms of years with yield exceedance probabilities of 80%, 50% (median) and 20%). For other crops, yield and water use estimates (and resulting GMs) were estimated based on expert experience and climate-informed extrapolation from the most similar analogue locations in northern Australia where commercial production currently occurs. The broadacre cropping options with the best GMs (>$2000/ha) were cotton (both wet-season and dry-season cropping), forages (Rhodes grass (Chloris gayana)) and peanuts. These suggest GMs of $4000/ha to $5000/ha might be achievable for broadacre cropping in the Victoria catchment, although not necessarily at scale. Grain sorghum, mungbean, soybean and maize had intermediate GMs (about $1500/ha). Simulated yields (and consequent GMs) were generally lowest on the Kandosol and highest on the Vertosol because of the increased buffering capacity that a high PAWC clay soil provides against hot weather, which triggers water stress even in irrigated crops. The Dermosol yields and GMs were slightly lower than the Vertosol due to its lower PAWC. A breakdown of the variable costs for growing broadacre crops shows that the largest two costs are the costs of inputs (mean 31%) and farm operations (mean 32%) (Table 4-7). Both of these cost categories would have similar dollar values when growing the same crop in southern parts of Australia, but the cost category that is higher and thus puts northern growers at a disadvantage is market costs (mean 26%, for freight and other costs involved in selling the crop). Total variable costs consume 77% of the gross revenue generated, which leaves sufficient margin for profitable farms to be able to temporarily absorb small declines in commodity prices or yields without creating severe cashflow problems. Table 4-6 Performance metrics for broadacre cropping options in the Victoria catchment: applied irrigation water, crop yield and gross margin (GM) for four environments Performance metrics indicate the upper bound that could be achieved after best management practices for Victoria catchment environments had been identified and implemented. All options are for dry-season (DS) irrigated crops sown between mid-March and the end of April (end of the wet season (WS)), except for the WS cotton, sown in early February. Variance in yield estimates from Agricultural Production Systems sIMulator (APSIM) simulations is indicated by providing 80%, 50% (median, highlighted) and 20% probability of exceedance values (Y80%, Y50% and Y20%, respectively), together with associated applied irrigation water (including on-farm losses) and GMs in those years. ‘na’ indicates 20% and 80% exceedance estimates that were not applicable because APSIM outputs were not available and expert estimates of just the median yield and applied irrigation water were used instead. Peanut is omitted for the Vertosol location because of the practical constraints of harvesting root crops on clay soils. Freight costs assume processing near Katherine for cotton and peanut, and that hay is sold locally. No crop model was available for sesame or hemp, so indicative estimates for the catchment were used. Cotton yields and prices are for lint bales (227 kg after ginning), not tonnes. PAWC = plant available water capacity. For more information on this figure or table please contact CSIRO on enquiries@csiro.au For more information on this figure or table please contact CSIRO on enquiries@csiro.au For more information on this figure or table please contact CSIRO on enquiries@csiro.au Table 4-7 Breakdown of variable costs relative to revenue for broadacre crop options The first eight crops (Cotton (WS) to Rhodes grass) are for the Dermosol (intermediate performance), and the last three crops are for general catchment estimates. ‘Input’ costs are mainly for fertilisers, herbicides and pesticides; the cost of farm ‘operations’ includes harvesting; ‘labour’ costs are the variable component (mainly seasonal workers) not covered in fixed costs (mainly permanent staff); ‘market’ costs include levies, commission and transport to the point of sale. WS = wet season; DS = dry season. For more information on this figure or table please contact CSIRO on enquiries@csiro.au Risk analyses were conducted for the two broadacre crops with the highest GMs: cotton and forages. The risk analysis used a narrative approach, where variable values with the potential to be different from those used in the GMs were varied and new GMs calculated. The narrative approach allows the impact of those variables to be determined. The cotton analysis explored the sensitivity of GMs to opportunities and challenges created by changes in cotton lint prices, crop yields and distance to the nearest gin (Table 4-8). Results show that high recent cotton prices (about $800/bale through 2022) have created a unique opportunity for those looking to establish new cotton farms in NT locations like the Victoria catchment, since growers could transport cotton to distant gins or produce suboptimal yields and still generate GMs above $3000/ha. At lower cotton lint prices, a local gin becomes more important for farms to remain viable. High cotton prices and the opening of a cotton gin 30 km north of Katherine in December 2023 have reduced some of the risk involved in learning to grow cotton as GMs increase from both these developments. At high yields and prices, the returns per megalitre of irrigation water may favour growing a single cotton crop per year, instead of committing limited water supplies to sequential cropping with a dry-season crop (that would likely provide lower returns per megalitre and be operationally difficult/risky to sequence). Table 4-8 Sensitivity of cotton crop gross margins ($/ha) to variation in yield, lint prices and distance to gin The base case is the Timber Creek Vertosol (Table 4-6) and is highlighted for comparison. The gin locations considered are a local gin near a new cotton farming region in the Victoria catchment, the new gin in Katherine, and two other potential gins in the NT (Adelaide River) and north-west Queensland (Richmond). Cotton lint prices include a low price for 2015–2020 ($500/bale), a mean price for 2020–2024 ($700/bale) and a high price for 2015–2020 ($800/bale). Effects of a lower yield are also tested (the 6.5 bales/ha estimated as the dry-season yield for this location versus the base case of 11.4 bales/ha for wet-season cropping). For more information on this figure or table please contact CSIRO on enquiries@csiro.au For more information on this figure or table please contact CSIRO on enquiries@csiro.au The narrative risk analysis for irrigated forages also looked at the sensitivity of farm GMs to variations in hay price and distance to markets, but here focuses on the issues of local supply and demand (Table 4-9). Forages, such as Rhodes grass, are a forgiving first crop to grow on greenfield farms as new farmers gain experience of local cropping conditions and ameliorate virgin soils while producing a crop with a ready local market in cattle. While there are limited supplies of hay in the region, growers may be able to sell hay at a reasonable price, given the large amount of beef production in the Victoria and challenges of maintaining livestock condition through the dry season, when the quality of native pastures is low. The scale of unmet local demand for hay limits opportunities for expansion of hay production without depressing local prices and/or having to sell hay further away, both of which lead to rapid declines in GMs (to below zero in many cases; Table 4-9). Another opportunity for hay is for feeding to cattle during live export, which could be integrated into an existing beef enterprise to supply their own live export livestock; this would require the hay to be pelleted. Section 4.3.9 considers how forages could be integrated into local beef production systems for direct consumption by livestock within the same enterprise. Table 4-9 Sensitivity of forage (Rhodes grass) crop gross margins ($/ha) to variation in yield and hay price The base case is the Timber Creek Vertosol (Table 4-8) and is highlighted for comparison. Transporting the hay further distances would increase opportunities for finding counter-seasonal markets paying higher prices, but this would be rapidly offset by higher freight costs. FREIGHT COST/TONNE (DISTANCE TO DELIVER) FORAGE CROP GROSS MARGIN ($/ha) HAY PRICE/TONNE $150 $220 $300 $20 (local) 1,600 4,702 8,247 $46 (300 km to Katherine) 448 3,550 7,095 $308 (2000 km to Richmond) –11,160 –8,059 4,514 4.3.6 Irrigated horticultural crops Table 4-10 shows estimates of potential performance for a range of horticultural crop options in the Victoria catchment. Upper potential GMs for annual horticulture (about $4000 per ha per year) were less than upper potential GMs for farming perennial fruit trees (about $6000 per ha per year). Capital costs of farm establishment and operating costs increase as the intensity of farming increases, so ultimate farm financial viability is not necessarily better for horticulture compared to broadacre crops with lower GMs (Chapter 6). Note also that perennial horticulture crops typically require more water than annual crops because irrigation occurs for a longer period each year (mean of 9.0 compared to 4.8 ML per ha per year, respectively in Table 4-10); this also, indirectly, affects capital costs of development since perennial crops require a larger investment in water infrastructure compared to annual crops to support the same cropped area. Table 4-10 Performance metrics for horticulture options in the Victoria catchment: annual applied irrigation water, crop yield and gross margin Applied irrigation water includes losses of water during application. Horticulture is most likely to occur on well-drained Kandosols. Product unit prices listed are for the dominant top grade of produce, but total yield was apportioned among lower graded/priced categories of produce as well in calculating total income. Transport costs assume sales of total produce are split among southern capital markets in proportion to their size. Applied irrigation water accounts for application losses assuming efficient pressurised micro irrigation systems. KP = Kensington Pride mangoes. PVR = new high-yielding mango varieties with plant variety rights (e.g. Calypso). CROP APPLIED IRRIGATION WATER CROP YIELD PRICE PRICING UNIT VARIABLE COSTS TOTAL REVENUE GROSS MARGIN (ML/ha/y) (t/ha/y) ($/unit) (unit) ($/ha/y) ($/ha/y) ($/ha/y) Row crop fruit and vegetables, annual horticulture (less capital intensive) Rockmelon 5.3 25.0 28 15 kg tray 43,699 44,000 301 Watermelon 6.0 47.0 450 500 kg box 53,449 42,300 –11,149 Capsicum 3.2 32.0 19 8 kg carton 71,959 76,000 4,041 Onion 4.7 30.0 15 10 kg bag 37,607 41,850 4,243 Fruit trees, perennial horticulture (more capital intensive) Mango (KP) 7.8 9.3 24 7 kg tray 22,242 28,398 6,156 Mango (PVR) 7.8 17.5 21 7 kg tray 43,257 47,250 3,993 Lime 11.4 28.5 18 5 kg carton 95,666 100,890 5,224 Crop yields and GMs can vary substantially among varieties, as is demonstrated here for mangoes (Mangifera indica). Mango production is well established in multiple regions of northern Australia, including in the Darwin, Douglas–Daly and Katherine regions of the NT, with a smaller area of orchards at Mataranka in the Roper catchment. For example, the well-established Kensington Pride mangoes typically produce 5 to 10 t/ha while newer varieties can produce 15 to 20 t /ha. New varieties of mango (such as Calypso) are likely to be released with plant variety rights (PVR) accreditation and are denoted as such. Selection of varieties also needs to consider consumer preferences and timing of harvest relative to seasonal gaps in market supply that can offer premium prices. Prices received for fresh fruit and vegetables can be extremely volatile (Figure 4-9) because produce is perishable and expensive to store, and because regional weather patterns can disrupt target timing of supply, causing unintended overlaps or gaps in combined supply between regions. This creates regular fluctuations between oversupply and undersupply, against inelastic consumer demand, to the extent that prices can fall so low at times that it would cost more to pick, pack and transport produce than farms receive in payment. Within this volatility are some counter-seasonal windows in southern markets (where prices are typically higher) that northern Australian growers can target. Volatility in seedless water melon prices at Melbourne markets https://www.agriculture.gov.au/abares/data/weekly-commodity-price-update/australian-horticulture-prices#daff-page-main For more information on this figure please contact CSIRO on enquiries@csiro.au Figure 4-9 Fluctuations in seedless watermelon prices at Melbourne wholesale markets from April 2020 to February 2023 Percentage change information available; however, prices are commercially sensitive and not available Source: ABARES (2023) Horticultural enterprises typically run on very narrow margins, where about 90% of gross revenue would be required just to cover variable costs of growing and marketing a crop grown in the Victoria catchment. This makes crop GMs extremely sensitive to fluctuations in variable costs, crop yield and produce prices, amplifying the effect of already volatile prices for fresh fruit and vegetables. Most of the variable costs of horticultural production occur from harvest onwards, mainly in freight, labour and packaging. This affords the opportunity to mitigate losses if market conditions are unfavourable at the time of harvest, since most costs can be avoided (at the expense of foregone revenue) by not picking the crop. A narrative risk analysis for horticulture used the crop with the lowest GM (watermelons (Citrullus lanatus);(Table 4-8) to illustrate how opportunities for reducing freight costs and targeting periods of higher produce prices could improve GMs to find niches for profitable farms (Table 4-11). Reducing freight costs by finding backloading opportunities or concentrating on just the smaller closest southern capital city market of Adelaide would substantially improve GMs. The base case already assumed that growers in the Victoria catchment would target the predictable seasonal component of watermelon price fluctuations (Figure 4-9), but any further opportunity to attain premiums in pricing could help convert an unprofitable baseline case into a profitable one. This example also highlights the issue that while there may be niche opportunities that allow an otherwise unprofitable enterprise to be viable, the scale of those niche opportunities also then limits the scale to which the industry in that location could expand, for example: (i) there is a limit to the volume of backloading capacity at cheaper rates, (ii) supplying produce to only the closest market excludes the largest markets (e.g. accessing the larger Sydney and Melbourne markets remains non-viable except when prices are high; Table 4-11) and (iii) chasing price premiums restricts the seasonal windows into which produce is sold or restricts markets to smaller niches that target specialised product specifications. Niche opportunities are seldom scalable, particularly in horticulture, which is partly why horticulture in any region usually involves a range of different crops (often on the same farm). Table 4-11 Sensitivity of watermelon crop gross margins ($/ha) to variation in melon prices and freight costs The base case (Table 4-10) is highlighted for comparison. FREIGHT COST/TONNE WATERMELON PRICE (PERCENTAGE DIFFERENCE FROM BASE PRICE) (MARKET LOCATION) $225 (–50%) $337 (–25%) $450 (BASE PRICE) $675 (+50%) $900 (+100%) $350 (backloading to Adelaide) –20,150 –11,096 –1,961 16,228 34,417 $440 (close market: Adelaide) –24,380 –15,326 –6,191 11,998 30,187 $550 (all capital cities) –29,550 –20,496 –11,361 6,828 25,017 $616 (Sydney) –32,652 –23,598 –14,463 3,726 21,915 $584 (Melbourne) –31,308 –22,254 –13,119 5,070 23,259 The risk analysis also illustrates just how much farm financial metrics like GMs amplify fluctuations to input costs and commodity prices to which they are exposed. For horticulture, far more than broadacre agriculture, it is very misleading to look just at a single ‘median’ GM for the crop, because that is a poor reflection of what is going on within an enterprise. For example, the –50% to +100% variation in watermelon prices would result in theoretical annual GMs fluctuating between –$29,550/ha and $25,017/ha (Table 4-11). Although, in practice, potentially negative GMs could be greatly mitigated (by not harvesting the crop), this still creates cashflow challenges in managing years of negative returns between years of windfall profits. This amplified volatility is another reason that horticulture farms often grow a mix of produce (as a means of spreading risk). For row crop production, another common way of mitigating risk is using staggered planting through the season, so that subsequent harvesting and marketing are spread out over a longer target window to smooth out some of the price volatility. 4.3.7 Plantation tree crops Estimates of annual performance for African mahogany (Khaya ivorensis) and sandalwood (Santalum album) are provided in Table 4-12. The best available estimates were used in the analyses, but information on plantation tree production in northern Australia is often commercially sensitive and/or not independently verified. The measures of performance presented therefore have a low degree of confidence and should be treated as broadly indicative, noting that actual commercial performance could be either lower or higher. Table 4-12 Performance metrics for plantation tree crop options in the Victoria catchment: annual applied irrigation water, crop yield and gross margin Yields are values at final harvest and for sandalwood are just for the heartwood component. African mahogany pricing unit is for an 800 kg cube, and 10% of the African mahogany yield is marketable cubes. Other values are annual averages assuming a 20-year life cycle of the crop (representing the idealised ultimate steady state of an operating farm that was set up with staggered plantings for a steady stream of harvests). No discounting is applied to account for the substantial timing offset between when costs are incurred and income is received; any investment decision would need to take that into account. African mahogany performance is for unirrigated production. CROP CROP LIFE CYCLE APPLIED IRRIGATION WATER CROP YIELD AT HARVEST PRICE PRICING UNIT VARIABLE COSTS TOTAL REVENUE GROSS MARGIN (y) (ML/ha/y) (t/ha) ($/unit) ($/ha/y) ($/ha/y) ($/ha/y) African mahogany 20 unirrigated 160 4000 cube 980 4000 3020 Sandalwood 20 4.7 4 8800 t heartwood 1100 1760 660 Plantation forestry has long life cycles with low-intensity management during most of the growth cycle, so variable costs typically consume less of the gross revenue (27%) than for broadacre or horticultural farming. However, production systems with long life cycles have additional risks over annual cropping. There is a much longer period between planting and harvest for adverse events to affect the yield quantity and/or quality, and prices of inputs and harvested products could change substantially over that period. Market access and arrangements with buyers could also change. The long lags from planting to harvest also mean that potential investors need to consider other similar competing pipeline developments (that may not be obvious because they are not yet selling product) and long-term future projections of supply and demand (for when their own plantation will start to be harvested and enter supply chains). The cashflow challenges are also significant given the long-term outlay of capital and operating costs before any revenue is generated. Carbon credits might be able to assist with some early cashflow (if the ‘average’ state of the plantation, from planting to harvest, stores more carbon than the vegetation it replaced). 4.3.8 Cropping systems This section evaluates the types of cropping systems (crop species × growing season × resource availability × management options) that are most likely to be profitable in the Victoria catchment based on the above analyses of GMs, information from companion technical reports in this Assessment, and cropping knowledge from climate-analogous regions (relative to local biophysical conditions). Cropping system choices could include growing a single crop during a 12-month period, or growing more than one crop, commonly referred to as sequential, double or rotational cropping. Since many of the issues for single cropping options were covered earlier, this section focuses on sequential cropping systems and the mix of cropping options that might be grown in sequence on a unit of land in the Victoria catchment. Cropping system considerations In addition to the challenges of choosing an individual crop to farm in the Victoria catchment, selecting two or more crops to grow in sequence increases the complexity. The rewards from successfully growing crops in sequence (versus single cropping) can be substantial if additional net annual revenue can be generated from the same initial capital investment (to establish the farm). Markets Whether growing a single crop or doing sequential cropping, the choice of crop(s) to grow is market driven. As the price received for different crops fluctuates, so too will the crops grown. In the Victoria catchment, freight costs, determined by the distance to selected markets, must also be considered. A critical scale of production may be needed for a new market opportunity or supply chain to be viable (e.g. exporting grains from Darwin would require sufficient economies of scale for the required supporting port infrastructure, and shipping routes to be viable). Crops such as cotton, peanut and sugarcane (Saccharum officinarum) require a processing facility. A consistent and critical scale of production is required for processing facilities to be viable. From 2024 cotton will have the advantage of local processing, with a gin operational 30 km north of Katherine. Transporting raw cotton from the Victoria catchment to this gin would go a long way to improving the viability of cotton production (Table 4-8). Most horticultural production from the Victoria catchment would be sent to capital city markets, often using refrigerated transport. Victoria catchment horticultural production would have to accept a high freight cost compared to the costs faced by producers in southern parts of Australia. The competitive advantage of horticultural production in the Victoria catchment is that higher market prices can be achieved from ‘out of season’ production compared to large horticultural production areas in southern Australia. Annual horticultural row crops, such as melons, would be grown sequentially, for example with fortnightly planting over 3 to 4 months, to reduce risk of exposure to low market prices and to make it more likely that very high market prices would be achieved for at least some of the produce. Operations Sequential cropping can require a trade-off against sowing at optimal times to allow crops to be grown in a back-to-back schedule. This trade-off could lead to lower yields from planting at suboptimal times. For annual horticulture crops there would be an additional limitation on the seasonal window over which produce can be sent to market (reducing opportunities to target peak prices and/or mitigate risks from price fluctuations). Growing crops sequentially depends on timely transitions between the crops, and selecting crops with growing seasons that will reliably fit into the available cropping windows. In the Victoria catchment’s variable and often intense wet season, rainfall increases operational risk because of reduced trafficability and the subsequent limited ability to conduct timely operations. A large investment in machinery (either multiple or larger machines) could increase the area that could be planted per day when fields are trafficable within a planting window. With sequential cropping, additional farm machinery and equipment may be required where there are crop-specific machinery requirements, or to help complete operations on time when there is tight scheduling between crops. Any additional capital expenditure on farm equipment would need to be balanced against the extra net farm revenue generated. Sequential cropping can also lead to a range of cumulative issues that need careful management, for example: (i) build-up of pests, diseases (particularly if the sequential cropping is of the same species or family) and weeds; (ii) pesticide resistance; (iii) increased watertable depth; and (iv) soil chemical and structural decline. Many of these challenges can be anticipated before beginning sequential cropping. Integrated pest, weed and disease management would be essential when multiple crop species are grown in close proximity (adjacent fields or farms). Many of these pests and controls are common to several crop species where pests (e.g. aphids) move between fields. Such situations are exacerbated when the growing seasons of nearby crops partially overlap or when sequential crops are grown, because both scenarios create ‘green bridges’ that facilitate the continuation of pest life cycles. When herbicides are required, it is critical to avoid products that could damage a susceptible crop the following season or sequentially. Water Sequential cropping leads to a higher annual crop water demand because: (i) the combined period of cropping is longer (compared with single cropping), (ii) it includes growing during the Victoria catchment’s dry season and (iii) PAW at planting will have been depleted by the previous crop. Typically, an additional 1 ML/ha on well-drained soils, and 1.5 ML/ha on clays, is required for sequential cropping relative to the combined water requirements of growing each of those crops individually (with the same sowing times). This additional water demand needs consideration during development where on-farm water storage is required or dry-season water extraction is necessary. Irrigating using surface water in the Victoria catchment would face issues with the reliability and the timing of water supplies. Monitored river flows need to be sufficient to allow pumping into on- farm storages for irrigation (i.e. to meet environmental flow and river height requirements). The timing of water availability is analysed in the companion technical report on river model scenario analysis (Hughes et al., 2024). The timing of water availability is therefore not well suited to crops that would need to be reliably sown by March (e.g. wet-season grain sorghum, soybean and sesame), and it would push cotton planting to the later part of the wet-season window (Figure 4-5). The availability of water for extraction each wet season reduces the options for sequencing a second crop. Soils The largest arable areas in the Victoria catchment are loamy Kandosols on the deep low-relief Tertiary sediments in the south-western, southern and south-eastern (Sturt Plateau) parts of the catchment (SGGs 4.1 and 4.2, marked ‘A’ in Figure 4-3) and the cracking clay Vertosols on the alluvial plains of the major rivers, basalt and limestone landscapes (SGG 9, marked ‘B’, ‘C’ and ‘E’ in Figure 4-3). There are good analogues of these Victoria catchment environments in successful irrigated farming areas in other parts of northern Australia: Katherine is indicative of farming systems and potential crops grown on well-drained loamy soils irrigated by pressurised systems and the Ord River Irrigation Area is indicative of furrow irrigation on heavy clay soils. The good wet-season trafficability of the well-drained loamy Kandosols (Figure 4-6) permits timely cropping operations and would enhance the implementation of sequential cropping systems. However, Kandosols also present some constraints for farming. Kandosols are inherently low in organic carbon, nitrogen, phosphorus, sulfur, zinc and potassium, and supplementation with other micronutrients (molybdenum, boron and copper) is often required. Very high fertiliser inputs are therefore required at first cultivation. Due to the high risk of leaching of soluble nutrients (e.g. nitrogen and sulfur) during the wet season, in-crop application (multiple times) of the majority of crop requirement for these nutrients is necessary. In addition, high soil temperatures and surface crusting combined with rapid drying of the soil at seed depth reduce crop establishment and seedling vigour for many broadacre species sown during the wet season and early dry season (e.g. maize, soybean and cotton). In contrast, the cracking clay Vertosols have poor trafficability following rainfall (Figure 4-6) or irrigation, disrupting cropping operations. Farm design is a major factor on cracking clay soils to minimise flooding of fields from nearby waterways, ensure prompt runoff from fields after irrigation or rain events, and maintain trafficability of farm roads. Timely in-field bed preparation can reduce delays in planting. Clay soils also have some advantages, particularly in costs of farm development by allowing lower-cost surface irrigation (versus pressurised systems) and on-farm storages (where expensive dam lining can be avoided if soils contain sufficient clay). Clay soils also typically have greater inherent fertility than Kandosols (but initial sorption by clay means that phosphorus requirements can be high for virgin soils in the first 2 years of farming). Potentially suitable cropping systems Crop species that could potentially be grown as a single crop per year were identified and rated for the Victoria catchment (Table 4-13) based on indicators of farm performance presented above (yields, water use and GMs) and considerations of growing season, experiences at climate- analogous locations, past research, and known market and resource limitations and opportunities. Annual horticulture, cotton, peanut and forages are the most likely to generate returns that could exceed farm development and growing costs (Table 4-13). Table 4-13 Likely annual irrigated crop planting windows, suitability, and viability in the Victoria catchment Crops are rated on likelihood of being financially viable: *** = likely at low-enough development costs; ** = less likely for single cropping (at current produce prices); * S = marginal but possible in a sequential cropping system. Rating qualifiers are coded as L development limitation, M market constraint, P depends on sufficient scale and distance to local processor, and B depends on distance to and type of beef (livestock production) activity it is supporting. Farm viability depends on the cost at which land and water can be developed and supplied (Chapter 6). na = not applicable. For more information on this figure or table please contact CSIRO on enquiries@csiro.au Due to good wet-season trafficability on loamy soils, there are many possible sequential cropping options for the Victoria catchment Kandosols (Table 4-14). Due to the predominance of broadleaf and legume species in many of the sequences, a grass species is desirable as an early wet-season cover crop. Although annual horticulture and cotton could individually be profitable, an annual sequence of the two would be very tight operationally. Cotton would be best grown from late January with the need to pick the crop by early August, then destroy cotton stubble, prepare land and remove volunteer cotton seedlings. That scheduling would make it challenging to fit in a late- season melon crop, which would need to be sown by late August to early September. Similar challenges would occur with cotton followed by mungbean or grain sorghum. Table 4-14 Sequential cropping options for Kandosols WET-SEASON PLANTING, DECEMBER TO EARLY MARCH DRY-SEASON PLANTING, MARCH TO AUGUST CROP GROWING SEASON CROP GROWING SEASON Mungbean Early February to late April Annual horticulture Mid-May to late October Sorghum (grain) January to April Peanut (not on clay) January to April or February to May Cotton Late January to early August Mungbean Mid-August to late October Sorghum (grain) Mid-August to mid-November Forage/silage Mid-August to early November; cut then retained as wet-season cover crop Mungbean Early February to late April Cotton Early May to early November Mungbean Peanut Sesame Soybean Early February to late April Early January to late April Early January to late April Early January to late April Maize May to October Sesame or Sorghum (grain) January to late April Chickpea May to August Mungbean Sesame Soybean Early February to late April January to late April January to late April Grass forage/silage May to early November; cut then retained as wet-season cover crop Fully irrigated sequential cropping on the Victoria catchment Vertosols would likely be opportunistic and favour combinations of short-duration crops that can be grown when irrigation water reliability is greatest (March to October), for example, annual horticulture (melons), mungbean, chickpea and grass forages (growing season 2 to 4 months). Following an unirrigated (rainfed) wet-season grain crop with an irrigated dry-season crop could also be possible. However, seasonally dependent soil wetting and drying would limit timely planting and the area planted, which means that farm yields between years would be very variable. Grain sorghum, mungbean and sesame are the species most adapted to rainfed cropping due to favourable growing season length, and their tolerance to water stress, and higher soil and air temperatures. 4.3.9 Integrating forage and hay crops into existing beef cattle enterprises A commonly held view within the northern cattle industry is that the development of water resources would allow graziers to integrate irrigated forages and hay into existing beef cattle enterprises, thereby improving their production and, potentially, their profitability. Currently, cattle graze on native pastures, which rely solely on rainfall and any consequent overland flow. During the dry season, the total standing biomass and the nutritive value of the vegetation decline. Changes in cattle liveweight closely follow this pattern, with higher growth rates over the wet season than the dry season. In many cases, cattle lose liveweight and body condition throughout the dry season until the next pulse of growth initiated by wet-season rains. Theoretically, producing on-farm irrigated forage and hay would give graziers greater options for marketing cattle, such as meeting market liveweight specifications for cattle at a younger age, meeting the specifications required for markets not typically targeted by cattle enterprises in the Victoria catchment and providing cattle that meet market specification at a different time of the year. Forages and hay may also allow graziers to implement management strategies, such as early weaning or weaner feeding, which should have flow-on benefits throughout the herd, including increased reproductive rates. Some of these strategies are already practised within the Victoria catchment but in most instances rely on hay or other supplements purchased on the open market. By growing hay on-farm, the scale of these management interventions might be increased, at reduced net cost. The addition of irrigated feeds may also allow graziers to increase the total number of cattle that can be sustainably carried on a property. Very few graziers use irrigated hay or forage production to feed cattle on-farm in the Victoria catchment (Cowley, 2014). In fact, very few cattle enterprises in northern Australia are set up to integrate on-farm irrigation, notwithstanding the theoretical benefits. Despite its apparent simplicity, fundamentally altering an existing cattle enterprise in this way brings in considerable complexity, with a range of unknowns about how best to increase productivity and profitability. There is still much to be learned about the most appropriate forage and hay species to grow, how best to manage the forages and hay to ensure high-quality feed, which cohort(s) of cattle to feed, how the feeding should be managed and which market specifications should be targeted to obtain maximum return. Because there are so few on-ground examples, modelling has been used in a number of studies to consider the integration of forages and hay into cattle enterprises (Watson et al., 2021). The most comprehensive guide to what might be possible to achieve by integrating forages into cattle enterprises can be found in the guide by Moore et al. (2021), who used a combination of industry knowledge, new research and modelling to consider the costs, returns and benefits. Bio-economic modelling was used in the Assessment to consider the impact of growing irrigated forages and hay on a representative beef cattle enterprise on the black soils of the Ivanhoe land system (Pettit, undated), using Kidman Springs as the rainfall record (see the companion technical report on agricultural viability and socio-economics (Webster et al., 2024) for more detail). The enterprise was based on a self-replacing cow–calf operation, focused on selling into the live export market. Broadly speaking, these enterprise characteristics can be thought of as an owner– manager small cattle enterprise within the Victoria catchment. Cattle numbers are lower than that of the average property in the Victoria catchment but can be scaled to represent larger herds, notwithstanding that economies of scale will result in reduced costs per head in the larger enterprises. More detail on the beef industry in the Victoria catchment can be found in Section 3.3.3. The modelling considered a number of management options: (i) a base enterprise; (ii) base enterprise plus buying in hay to feed weaners; growing forage sorghum, an annual forage grass species, and feeding either as (iii) stand and graze or (iv) as hay; (v) growing lablab (Lablab purpureus), an annual legume, and feeding as stand and graze; and (vi) growing Rhodes grass, a perennial tropical grass, and feeding as hay. Ideally, production would increase by allowing cattle to reach minimum selling weight at a younger age and allowing for greater weight gain during the dry season when animals on native pasture alone either lose weight or gain very little weight. The addition of forages and hay also allows more cattle to be carried, while still maintaining a utilisation rate of native pastures at around 20%. A GM per adult equivalent (AE) was calculated as the total revenue from cattle sales minus total variable costs (Table 4-15). A profit metric, earnings before interest, taxes, depreciation and amortisation (EBITDA), was also calculated as income minus variable and overhead costs, which allows performance to be compared independently of financing and ownership structure (McLean and Holmes, 2015) and is used in the analysis of net present value (NPV). Three sets of beef prices were considered: • LOW beef price. Beef prices were set to 275c/kg for males between 12 and 24 months old, declining across age and sex classes to 134c/kg for cows older than 108 months. • MED beef price. Beef prices were set to 350c/kg for males between 12 and 24 months old, declining across age and sex classes to 170c/kg for cows older than 108 months. • HIGH beef price. Beef prices were set to 425c/kg for males between 12 and 24 months old, declining across age and sex classes to 206c/kg for cows older than 108 months. At all three beef prices, total income was highest for the four irrigated forage or hay scenarios compared to the two baseline scenarios, but the higher costs for the irrigated scenarios led to similar or lower GMs (Table 4-15). Table 4-15 Production and financial outcomes from the different irrigated forage and beef production options for a representative property in the Victoria catchment Details for LOW, MED and HIGH beef prices are in the text above. Descriptions of the six management options are in the companion technical report on agricultural viability and socio-economics (Webster et al., 2024). AE = adult equivalent; EBITDA = earnings before interest, taxes, depreciation and amortisation. Cattle are sold twice per year for all options. Cattle are sold in May for all options. Cattle are sold in September for the two base enterprises and for lablab stand and graze. Cattle are sold in October for forage sorghum stand and graze and the two hay options. BASE ENTERPRISE BASE ENTERPRISE PLUS HAY FORAGE SORGHUM – STAND AND GRAZE FORAGE SORGHUM – HAY LABLAB – STAND AND GRAZE RHODES GRASS – HAY Forage/hay None Bought hay Forage sorghum Forage sorghum Lablab Rhodes grass Maximum number of breeders 2050 2100 2230 2380 2290 2788 Mean of herd size (AE) across calendar year 2525 2553 2943 3084 2999 3094 Pasture utilisation (%) 20.1 20.1 20.1 20.1 20.0 20.1 BASE ENTERPRISE BASE ENTERPRISE PLUS HAY FORAGE SORGHUM – STAND AND GRAZE FORAGE SORGHUM – HAY LABLAB – STAND AND GRAZE RHODES GRASS – HAY Weaning rate (%) 59.2 60.4 62.6 64.6 63.8 64.6 Mortality rate (%) 6.8 6.8 6.6 6.3 6.2 6.2 Percentage of ‘one-year-old castrate males’ (8–11 or 8–12 months old) sold in September or October 0.0 0.0 8.8 78.4 62.8 78.9 Percentage of ‘one-and-a-half-year-old castrate males’ (15–19 months old) sold in May 77.5 86.8 79.4 20.3 27.6 19.9 Percentage of ‘two-year-old castrate males’ (20–23 or 20–24 months old) sold in September or October 9.1 6.7 11.8 1.3 9.7 1.2 Percentage of ‘two-and-a-half-year-old castrate males’ (27–31 months old) sold in May 13.4 6.6 0.0 0.0 0.0 0.0 Liveweight sold per year (kg) 343,106 351,446 415,624 468,346 443,607 471,258 Gross margin ($/AE) (LOW beef price) 133 120 –6 103 30 115 Profit (EBITDA) ($) (LOW beef price) 72,596 40,766 –282,084 52,172 –173,157 91,099 Gross margin ($/AE) (MED beef price) 219 206 79 171 119 183 Profit (EBITDA) ($) (MED beef price) 288,753 262,178 –32,710 262,928 93,007 303,166 Gross margin ($/AE) (HIGH beef price) 305 294 164 239 208 252 Profit (EBITDA) ($) (HIGH beef price) 504,910 487,103 216,664 473,683 359,172 515,232 At MED beef prices, EBITDA was highest for Rhodes grass hay ($303,166/year) and the lowest for forage sorghum stand and graze (–$32,710). The Rhodes grass hay option and the forage sorghum hay option produced the most liveweight sold per year and the two highest incomes. An NPV analysis allows consideration of the capital costs involved in development, which are not captured in the gross margin or EBITDA. The analysis used two costings ($15,000 and $25,000/ha) for the capital costs of development used in the NPV analysis. The NPV analysis showed that none of the options had a positive NPV (see the companion technical report on agricultural viability and socio-economics, Webster et al., 2024). Note that cost of capital theory is complex and investors need to understand their weighted average cost of capital and the relative risk of the project compared to the enterprise’s existing project portfolio before drawing their own conclusion from an NPV analysis. A significant proportion of the animal production increases due to the irrigated forage options came from the increased number of breeders that could be carried, while still keeping the utilisation rate of native pastures at about 20% (Table 4-15). The Rhodes grass hay option allowed the highest number of breeders to be carried (2788) compared with 2050 for the base enterprise. This flowed through to the total number of AE carried. The AE for Rhodes grass hay was 22% higher than that of the base enterprise and the total liveweight sold was on average 37% higher. The irrigated options increased the herd’s weaning rate by 3.4% to 5.4% compared to the base enterprise without weaner feeding. Even an increase of several per cent is known to have lifetime benefits throughout a herd. The most obvious biophysical impact of the various feeding strategies was the increase in liveweight compared to that of the base enterprise. This allowed a greater proportion of the animals to be sold earlier. For example, for the two hay options, nearly 79% of the ‘one-year-old castrate males’ (8–12 months old) were sold in October at a minimum weight of 280 kg, while no animals from the same cohort under the two base enterprise options met the minimum weight at that time (Table 4-15). Over 77% of these animals were retained for an additional wet-season, and sold in the following May as one-and-a-half year olds’ (15–19 months old). Keeping the utilisation rate at 20.0% meant that carrying these animals for the extra period lowered the number of breeders that could be carried and the overall stocking rate (AE). In summary, three patterns of growth to reach sale weight (280 kg) occurred: • For the two base enterprises, no animals reached sale weight in September as ‘one year olds’. By the following May 77.5% (base enterprise) or 86.8% (base enterprise plus hay) had reached sale weight. The following September 9.1% (base enterprise) or 6.7% (base enterprise plus hay) were sold as ‘two-year-olds’. The remaining 13.4% (base enterprise) or 6.6% (base enterprise plus hay) were then sold in the following May as ‘two-and-a-half year olds’. • By contrast, the majority of animals in the forage sorghum hay, lablab stand and graze, and Rhodes grass hay options were sold as ‘one year olds’ in September or October. The majority of the rest (20.3%, 27.6% and 19.9%, respectively) were sold in the following May. The remainder, less than 10%, were sold in the next September or October. None of this cohort remained for sale in the following May as ‘two-and-a-half year olds’. • The forage sorghum stand and graze option sat between these two extremes. Very few were sold as ‘one year olds’ in October, most were sold as ‘one-and-a-half year olds’ in the following May (79.4%) with all of the remainder sold in the following September. While there are advantages to some form of irrigated forage or hay production, the introduction of irrigation to an existing cattle enterprise requires additional skills and resources. The options here range from an area that would require 2.25 pivots of 40 ha each to an area that would require eight 40 ha pivots. A water allocation of about 1.5 to 2.2 GL would be required to provide sufficient irrigation water. The capital cost of development would range between $1,350,000 for 90 ha of Rhodes grass hay, at a development cost of $15,000/ha, to $8,000,000 for 320 ha of lablab at a development cost of $25,000/ha. In addition, the grazing enterprise would need to develop the expertise and knowledge required to run a successful irrigation enterprise of that scale, which is quite a different enterprise to one of grazing only. This is a constraint recognised by graziers elsewhere in northern Australia (McKellar et al., 2015) and almost certainly contributes to the lack of uptake of irrigation in the Victoria catchment. 4.4 Crop synopses 4.4.1 Introduction The estimates for land suitability in these synopses represent the total areas of the catchment unconstrained by factors such as water availability, landscape complexity, land tenure, environmental and other legislation and regulations, and a range of biophysical risks such as cyclones, flooding and secondary salinisation. These are addressed elsewhere by the Assessment. The land suitability maps are designed to be used predominantly at the regional scale. Farm-scale planning would require finer-scale, more localised assessment. 4.4.2 Cereal crops Cereal production is well established in Australia. The area of land devoted to producing grass grains (e.g. wheat, barley (Hordeum vulgare), grain sorghum, maize, oats (Avena sativa), triticale (× Triticosecale)) each year has stayed relatively consistent at about 20 million ha over the decade from 2012–13 to 2021–22, yielding over 55 Mt with a value of $19 billion in 2021–22 (ABARES, 2022). Production of cereals greatly exceeds domestic demand, and in 2021–22 the majority (82% by value) ted (ABARES, 2022). Significant export markets exist for wheat, barley and grain sorghum, with combined exports valued at $15 billion in 2021–22. There are additional niche export markets for grains such as maize and oats. Among the cereals, sorghum (grain) is promising for the Victoria catchment. Sorghum is grown over the summer period, coinciding with the Victoria catchment wet season. Sorghum can be grown opportunistically using rainfed production, although the years in which this could be successfully achieved will be limited. Cereal crop production is higher and more consistent when irrigation is used. From a land suitability perspective, selected cereal crops are included in Crop Group 7 (Table 4-2; Figure 4-10). Cracking clays (Vertosols) make up nearly 12% of the Victoria catchment; they are found on alluvial plains, relict alluvial plains, and on level to gently undulating plains on basalt (marked CA1, CA2, CB1 and CB2 on Figure 2-5). These soils have very high water-holding capacity but the non-basalt Vertosols may have a restricted rooting depth due to salt levels in the subsoil. Vertosols generally have moderate to high agricultural potential, but inadequate drainage and deep gilgais in some areas reduce the prospects for furrow irrigation. Poor drainage and low permeability will cause waterlogging in the wet season, especially along the Baines, lower West Baines and East Baines rivers. Loamy soils, mostly red loams, make up more than 18% of the catchment. These soils dominate the deeply weathered sediments of the Sturt Plateau in the east to south-east (marked K1 and K2 on Figure 2-5) and other deeply weathered landscapes to the south and west of Kalkarindji. Loamy soils are typically nutrient deficient and have low to high water-holding capacity. Irrigation potential is limited to spray- and trickle-irrigated crops on the moderately deep to deep soils. In parts of the catchment, loamy soils are found on narrow flat areas dissected by stream channels and deep gullies, making the land difficult to develop for broadacre cropping. Shallow and/or rocky soils make up a little more than 57% of the catchment and are unsuitable by definition. Assuming unconstrained development, approximately 2.9 million ha of the Victoria catchment is considered to be suitable with moderate limitations (Class 3; Table 4-1) or better (Class 2 or Class 1) for irrigated cereal cropping (Crop Group 7; Table 4-2) using spray irrigation in the dry season. For spray irrigation in the wet season, nearly 2.7 million ha is suitable with moderate limitations (Class 3) or better. Land considered suitable with moderate limitations for furrow irrigation is limited to about 625,500 ha in the dry season and 423,500 ha in the wet season, due to inadequate soil drainage in clay soils (and/or because gilgais are too deep) and because the loamy soils are too permeable. There is potential for rainfed cereal production in the wet season over an area of about 880,000 ha. Note that from a land suitability perspective, Crop Group 7 contains cereal crops and cotton; the latter is considered under industrial (cotton) in these crop synopses (Section 4.4.6). The ‘winter cereals’ such as wheat and barley are not well adapted to the climate of the Victoria catchment. To grow cereal crops, farmers will require access to tillage, fertilising, planting, spraying and harvesting equipment. Harvesting is often a contract operation, and in larger growing regions other activities can also be performed under contract. Because of the low relative value of cereals, good returns are made through production at a large scale. This requires machinery to be large so that operations can be completed in a timely way. Table 4-16 provides summary information relevant to the cultivation of cereals, using sorghum (grain) (Figure 4-11) as an example. The companion technical report on agricultural viability and socio-economics (Webster et al., 2024) provides greater detail for a wider range of cereal crops. Crop suitability map – grain sorghum, maize \\FS1-CBR.nexus.csiro.au\{lw-rowra}\work\10_Reporting\2_Victoria\1_GIS\1_Map_Docs\CR-V-Ch4_501_Suit_Sorghum_Grain_Maize_Grain_v3.mxd For more information on this figure please contact CSIRO on enquiries@csiro.au Figure 4-10 Modelled land suitability for Crop Group 7 (e.g. sorghum (grain) or maize) using furrow irrigation in the (a) wet season and (b) dry season These land suitability maps do not consider flooding, risk of secondary salinisation or availability of water. The methods used to derive the reliability data in the inset maps are outlined in the companion technical report on digital soil mapping and land suitability (Thomas et al., 2024). Table 4-16 Summary information relevant to the cultivation of cereals, using sorghum (grain) as an example For more information on this figure, table or equation please contact CSIRO on enquiries@csiro.au Figure 4-11 Sorghum (grain) Photo: CSIRO 4.4.3 Pulse crops (food legume) Pulse production is well established in Australia. The area of land devoted to production of pulses (mainly chickpea, lupin (Lupinus spp.) and field pea (Pisum sativum)) each year has varied from 1.1 to 2.0 million ha over the decade from 2012–13 to 2021–22, yielding over 3.8 Mt with a value of $2.5 billion in 2021–22 (ABARES, 2022). The vast majority of pulses in 2021–22 (93% by value) were exported (ABARES, 2022). Pulses produced in the Victoria catchment would most likely be exported, although there is presently no cleaning or bulk-handling facility. Pulses often have a short growing season. They are suited to opportunistic rainfed production over the wet season or more continuous irrigated production, often in rotation with cereals. Not all pulse crops are likely to be suited to the Victoria catchment. Those that are ‘tender’, such as field peas and beans, may not be well suited to the highly desiccating environment and periodically high temperatures. Direct field experimentation in the catchment is required to confirm this for these and other species. In the Victoria catchment, mungbean and chickpea are likely to be well suited. From a land suitability perspective, pulse crops are included in Crop Group 10 (Table 4-2; Figure 4-12). Cracking clays (Vertosols) make up nearly 12% of the Victoria catchment; they are found on alluvial plains, relict alluvial plains, and on level to gently undulating plains on basalt (marked CA1, CA2, CB1 and CB2 on Figure 2-5). These soils have very high water-holding capacity but the non- basalt Vertosols may have a restricted rooting depth due to salt levels in the subsoil. Vertosols generally have moderate to high agricultural potential, but inadequate drainage and deep gilgais in some areas reduce the prospects for furrow irrigation. Poor drainage and low permeability will mean waterlogging in the wet season, especially along the Baines, lower West Baines and East Baines rivers. Loamy soils, mostly red loams, make up more than 18% of the catchment. These soils dominate the deeply weathered sediments of the Sturt Plateau (marked K1 and K2 on Figure 2-5) in the east to south-east and other deeply weathered landscapes to the south and west of Kalkarindji. Loamy soils are typically nutrient deficient and have low to high water-holding capacity. Irrigation potential is limited to spray- and trickle-irrigated crops on the moderately deep to deep soils. In parts of the catchment, loamy soils are found on narrow flat areas dissected by stream channels and deep gullies, making the land difficult to develop for broadacre cropping. Shallow and/or rocky soils make up a little more than 57% of the catchment, and are unsuitable by definition. Assuming unconstrained development, approximately 2.6 million ha of the Victoria catchment is considered to be suitable with moderate limitations (Class 3; Table 4-1) or better (Class 2 or Class 1) for irrigated pulse cropping (Crop Group 10; Table 4-2) using spray irrigation in the dry season, most of this being Class 2. Land considered suitable with moderate limitations for furrow irrigation is limited to about 395,000 ha in the dry season, due to inadequate soil drainage in clay soils (and/or because gilgais are too deep) and because the loamy soils are too permeable. There is potential for rainfed pulse production in the wet season over an area of about 570,000 ha. From a land suitability perspective, Crop Group 10 includes the pulse crops mungbean and chickpea, while soybean is considered under oilseed in these crop synopses. Pulses are often advantageous in rotation with other crops because they provide a disease break and, being legumes, can provide nitrogen for subsequent crops. Even where this is not the case, their ability to meet their own nitrogen needs can be beneficial in reducing costs of fertiliser and associated freight. Pulses such as mungbean and chickpea can also be of high value (historical prices have reached >$1000/t), so the freight costs as a percentage of the value of the crop are lower than for cereal grains. To grow pulse crops, farmers will require access to tillage, fertilising, planting, spraying and harvesting equipment. Harvesting is generally a contract operation, and in larger growing regions other activities can also be performed under contract. The equipment required for pulse crops is the same as is required for cereal crops, so farmers intending on a pulse and cereal rotation would not need to purchase pulse-specific equipment. Table 4-17 provides summary information relevant to the cultivation of many pulses, using mungbean (Figure 4-13) as an example. The companion technical report on agricultural viability and socio-economics (Webster et al., 2024) provides greater detail for a wider range of crops. Crop suitability map – mungbean \\FS1-CBR.nexus.csiro.au\{lw-rowra}\work\10_Reporting\2_Victoria\1_GIS\1_Map_Docs\CR-V-Ch4_502_Suit_Mungbean_Mungbean_v2.mxd For more information on this figure please contact CSIRO on enquiries@csiro.au Figure 4-12 Modelled land suitability for mungbean (Crop Group 10) in the dry season using (a) furrow irrigation and (b) spray irrigation These land suitability maps do not consider flooding, risk of secondary salinisation or availability of water. The methods used to derive the reliability data in the inset maps are outlined in the companion technical report on digital soil mapping and land suitability (Thomas et al., 2024). Figure 4-13 Mungbean Photo: CSIRO Table 4-17 Summary information relevant to the cultivation of pulses, using mungbean as an example For more information on this figure, table or equation please contact CSIRO on enquiries@csiro.au 4.4.4 Oilseed crops The area of land devoted to production of oilseed (predominantly canola, Brassica napus) each year has varied between 2.1 and 3.4 million ha over the decade from 2012–13 to 2021–22, yielding over 8.4 Mt with a value of $6.1 billion in 2021–22 (ABARES, 2022). Most oilseed produced in 2021–22 (98% by value) was exported (ABARES, 2022). Canola dominates Australian oilseed production, accounting for 98% of the gross value of oilseed in 2021–22. Soybean, sunflower (Helianthus annuus) and other oilseed (including peanuts) each accounted for less than 1%. Soybean, canola and sunflower are oilseed crops used to produce vegetable oils and biodiesel, and as high-protein meals for intensive animal production. Soybean is also used in processed foods such as tofu. It can provide both green manure and soil benefits in crop rotations, with symbiotic nitrogen fixation adding to soil fertility and sustainability in an overall cropping system. Soybean is used commonly as a rotation crop with sugarcane in northern Queensland, providing a disease break and nitrogen to the soil. Summer oilseed crops such as soybean, sesame and sunflower are more suited to tropical environments than are winter-grown oilseed crops such as canola. Cottonseed is also classified as an oilseed and is used for animal production. Soybean is sensitive to photoperiod (day length) and requires careful consideration in selection of the appropriate variety for a particular sowing window. From a land suitability perspective, soybean is included in Crop Group 10 (Table 4-2; Figure 4-14). Cracking clays (Vertosols) make up nearly 12% of the Victoria catchment; they are found on alluvial plains, relict alluvial plains, and on level to gently undulating plains on basalt (marked CA1, CA2, CB1 and CB2 on Figure 2-5). These soils have very high water-holding capacity but the non- basalt Vertosols may have a restricted rooting depth due to salt levels in the subsoil. Vertosols generally have moderate to high agricultural potential, but inadequate drainage and deep gilgais in some areas reduce the prospects for furrow irrigation. Poor drainage and low permeability will mean waterlogging in the wet season, especially along the Baines, lower West Baines and East Baines rivers. Loamy soils, mostly red loams, make up more than 18% of the catchment. These soils dominate the deeply weathered sediments of the Sturt Plateau (marked K1 and K2 on Figure 2-5) in the east to south-east and other deeply weathered landscapes to the south and west of Kalkarindji. Loamy soils are typically nutrient deficient and have low to high water-holding capacity. Irrigation potential is limited to spray- and trickle-irrigated crops on the moderately deep to deep soils. In parts of the catchment, loamy soils are found on narrow flat areas dissected by stream channels and deep gullies, making the land difficult to develop for broadacre cropping. Shallow and/or rocky soils make up a little more than 57% of the catchment, and are unsuitable by definition. Assuming unconstrained development, approximately 2.6 million ha of the Victoria catchment is considered to be suitable with moderate limitations (Class 3; Table 4-1) or better (Class 2 or Class 1) for irrigated pulse cropping (Crop Group 10; Table 4-2) using spray irrigation in the dry season, most of this being Class 2. Land considered suitable with moderate limitations for furrow irrigation is limited to about 395,000 ha in the dry season, due to inadequate soil drainage in clay soils (and/or because gilgais are too deep) and because the loamy soils are too permeable. There is potential for rainfed pulse production in the wet season over an area of about 570,000 ha. From a land suitability perspective, soybean is in Crop Group 10, which contains the pulse crops. Two of these, mungbean and chickpea, are considered under pulse crops (food legume) in these crop synopses. To grow oilseed crops, farmers will require access to tillage, fertilising, planting, spraying and harvesting equipment. Harvesting is generally a contract operation, and in larger growing regions other activities can also be performed under contract. The equipment required for oilseed crops is the same as is required for cereal crops, so farmers intending on an oilseed and cereal rotation would not need to purchase oilseed-specific equipment. Table 4-18 provides summary information relevant to the cultivation of oilseed crops using soybean (Figure 4-15) as an example. The companion technical report on agricultural viability and socio-economics (Webster et al., 2024) provides greater detail for a wider range of crops. Crop suitability map – soybean \\FS1-CBR.nexus.csiro.au\{lw-rowra}\work\10_Reporting\2_Victoria\1_GIS\1_Map_Docs\CR-V-Ch4_503_Suit_Soybean_Soybean_v2.mxd For more information on this figure please contact CSIRO on enquiries@csiro.au Figure 4-14 Modelled land suitability for soybean (Crop Group 10) in the dry season using (a) furrow irrigation and (b) spray irrigation These land suitability maps do not consider flooding, risk of secondary salinisation or availability of water. The methods used to derive the reliability data in the inset maps are outlined in the companion technical report on digital soil mapping and land suitability (Thomas et al., 2024). Figure 4-15 Soybean Photo: CSIRO Table 4-18 Summary information relevant to the cultivation of oilseed crops, using soybean as an example For more information on this figure, table or equation please contact CSIRO on enquiries@csiro.au 4.4.5 Root crops, including peanut Root crops, including peanut, sweet potato (Ipomoea batatas) and cassava (Manihot esculenta), are potentially well suited to the lighter soils found across the Victoria catchment. Root crops such as these are not suited to growing on heavier clay soils because they need to be pulled from the ground for harvest, and the heavy clay soils, such as cracking clays, are not conducive to mechanical pulling. While peanut is technically an oilseed crop, it has been included in the root crop category due to its similar land suitability and management requirements (i.e. the need for it to be pulled from the ground as part of the harvest operation). The most widely grown root crop in Australia, peanut is a legume crop that requires little or no nitrogen fertiliser and is very well suited to growing in rotation with cereal crops, as it is frequently able to fix atmospheric nitrogen in the soil for following crops. The Australian peanut industry currently produces approximately 15,000 to 20,000 t/year from around 11,000 ha, which is too small an industry to be reported separately in Australian Bureau of Agricultural and Resource Economics and Sciences statistics (ABARES, 2022). The Australian peanut industry is concentrated in Queensland. In northern Australia, a production area is present on the Atherton Tablelands, and peanuts could likely be grown in the Victoria catchment. The Peanut Company of Australia established a peanut-growing operation at Katherine in 2007 and examined the potential of both wet- and dry-season peanut crops, mostly in rotation with maize. Due to changing priorities within the company, coupled with some agronomic challenges (Jakku et al., 2016), the company sold its land holdings in Katherine in 2012 (and Bega bought the rest of the company in 2018). For peanuts to be successful, considerable planning would be needed in determining the best season for production and practical options for crop rotations. The nearest peanut-processing facilities to the Victoria catchment are Tolga on the Atherton Tablelands and Kingaroy in southern Queensland. From a land suitability perspective, peanut is included in Crop Group 6 (Table 4-2; Figure 4-16). Cracking clays (Vertosols) make up nearly 12% of the Victoria catchment (Figure 2-5). These soils have very high water-holding capacity but the non-basalt Vertosols may have a restricted rooting depth due to salt levels in the subsoil. Vertosols generally have moderate to high agricultural potential, but these heavier-textured soils are generally unsuited to root crops due to difficulties with pulling of crops from these soils during harvest. Loamy soils, mostly red loams, make up more than 18% of the catchment. These soils dominate the deeply weathered sediments of the Sturt Plateau in the east to south-east (marked K1 and K2 on Figure 2-5) and other deeply weathered landscapes to the south and west of Kalkarindji. Loamy soils are typically nutrient deficient and have low to high water-holding capacity. Irrigation potential is limited to spray- and trickle- irrigated crops on the moderately deep to deep soils. In parts of the catchment, loamy soils are found on narrow flat areas dissected by stream channels and deep gullies, making it difficult to develop for broadacre cropping. Shallow and/or rocky soils make up a little more than 57% of the catchment and are unsuitable by definition. Assuming unconstrained development, approximately 2.3 million ha of the Victoria catchment is considered to be suitable with moderate limitations (Class 3; Table 4-1) or better (Class 2 or Class 1) for irrigated root crops (Crop Group 6; Table 4-2) using spray irrigation in the dry season, most of this being Class 2. For spray irrigation in the wet season, nearly 1.9 million ha is suitable with moderate limitations (Class 3) or better, again most being Class 2. Furrow irrigation is not suited to either season, with wetness on the heavier-textured soils being the limitation and the lighter textured soils being too permeable, therefore furrow irrigation was not considered in the land suitability analysis. To grow root crops, farmers will require access to tillage, fertilising, planting, spraying and harvesting equipment. The harvesting operation requires specialised equipment to pull the crop from the ground, and then to pick it up after a drying period. Peanuts are usually dried soon after harvest in industrial driers. Table 4-19 provides summary information relevant to the cultivation of root crops, using peanut (Figure 4-17) as an example. The companion technical report on agricultural viability and socio- economics (Webster et al., 2024) provides greater detail for a wider range of crops. P2015#yIS1 Figure 4-16 Modelled land suitability for peanut (Crop Group 6) using spray irrigation in the (a) wet season and (b) dry season These land suitability maps do not consider flooding, risk of secondary salinisation or availability of water. The methods used to derive the reliability data in the inset maps are outlined in the companion technical report on digital soil mapping and land suitability (Thomas et al., 2024). P2018#yIS1 Figure 4-17 Peanut Photo: Shutterstock Table 4-19 Summary information relevant to the cultivation of root crops, using peanut as an example For more information on this figure, table or equation please contact CSIRO on enquiries@csiro.au 4.4.6 Industrial (cotton) Rainfed and irrigated cotton production are well established in Australia. The area of land devoted to cotton production varies widely from year to year, largely in response to availability of water. It varied from 70,000 to 600,000 ha between 2012–13 and 2021–22; a mean of 400,000 ha/year has been grown over the decade (ABARES, 2022). Likewise, the gross value of cotton lint production varied greatly between 2012–13 and 2021–22, from $0.3 billion in 2019–20 to $5.2 billion in 2021– 22. Genetically modified cotton varieties were introduced in 1996 and now account for almost all cotton produced in Australia (over 99%). Australia was the fourth largest exporter of cotton in 2022, behind the United States, India and Brazil. Cottonseed is a by-product of cotton processing and is a valuable cattle feed. Mean lint production in Australia in 2015–16 was 8.8 bales/ha (ABARES, 2022). Commercial cotton has a long but discontinuous history of production in northern Australia, including in Broome, the Fitzroy River and the Ord River Irrigation Area in WA; in Katherine and Douglas–Daly in the NT; and near Richmond and Bowen in northern Queensland. An extensive study undertaken by the Australian Cotton Cooperative Research Centre in 2001 (Yeates, 2001) noted that past ventures suffered from: • a lack of capital investment • too rapid a movement to commercial production • a failure to adopt a systems approach to development • climate variability. Mistakes in pest control were also a major issue in early projects. Since the introduction of genetically modified cotton in 1996, yields and incomes from cotton crops have increased in most regions of Australia. The key benefits of genetically modified cotton over conventional cotton are savings in insecticide and herbicide use, and improved tillage management. In addition, farmers can now forward-sell their crop as part of a risk management strategy. Growers of genetically modified cotton are required to comply with the approved practices for growing the genetically modified varieties, including preventative resistance management. Research and commercial test farming have demonstrated that the biophysical challenges are manageable if the growing of cotton is tailored to the climate and biotic conditions of northern Australia (Yeates et al., 2013). In recent years, irrigated cotton crops achieving more than 10 bales/ha have been grown successfully in the Burdekin irrigation region and experimentally in the Gilbert catchment of northern Queensland. New genetically modified cotton using CSIRO varieties that are both pest- and herbicide-resistant are an important component of these northern cotton production systems. Climate constraints will continue to limit production potential of northern cotton crops when compared to cotton grown in more favourable climate regions of NSW and Queensland. On the other hand, the low risk of rainfall occurring during late crop development favours production in northern Australia, as it minimises the likelihood of late-season rainfall, which can downgrade fibre quality and price. Demand for Australian cotton exhibiting long and fine attributes is expected to increase by 10% to 20% of the market during the next decade and presents local producers with an opportunity to target production of high-quality fibre. From a land suitability perspective, cotton is included in Crop Group 7 (Table 4-2; Figure 4-18). Cracking clays (Vertosols) make up nearly 12% of the Victoria catchment; they are found on alluvial plains, relict alluvial plains, and on level to gently undulating plains on basalt (marked CA1, CA2, CB1 and CB2 on Figure 2-5). These soils have very high water-holding capacity but the non- basalt Vertosols may have a restricted rooting depth due to salt levels in the subsoil. Vertosols generally have moderate to high agricultural potential, but inadequate drainage and deep gilgais in some areas reduce the prospects for furrow irrigation. Poor drainage and low permeability will cause waterlogging in the wet season, especially along the Baines, lower West Baines and East Baines rivers. Loamy soils, mostly red loams, make up more than 18% of the catchment. These soils dominate the deeply weathered sediments of the Sturt Plateau in the east to south-east (marked K1 and K2 on Figure 2-5) and other deeply weathered landscapes to the south and west of Kalkarindji. Loamy soils are typically nutrient deficient and have low to high water-holding capacity. Irrigation potential is limited to spray- and trickle-irrigated crops on the moderately deep to deep soils. In parts of the catchment, loamy soils are found on narrow flat areas dissected by stream channels and deep gullies, making the land difficult to develop for broadacre cropping. Shallow and/or rocky soils make up a little more than 57% of the catchment, and are unsuitable by definition. Assuming unconstrained development, approximately 2.9 million ha of the Victoria catchment is considered to be suitable with moderate limitations (Class 3; Table 4-1) or better (Class 2 or Class 1) for irrigated cotton (Crop Group 7; Table 4-2) using spray irrigation in the dry season. For spray irrigation in the wet season, nearly 2.7 million ha is suitable with moderate limitations (Class 3) or better. Land considered suitable with moderate limitations for furrow irrigation is limited to about 625,500 ha in the dry season and 423,500 ha in the wet season, due to inadequate soil drainage in clay soils (and/or because gilgais are too deep) and because the loamy soils are too permeable. There is potential for rainfed cotton production in the wet season over an area of about 880,000 ha. From a land suitability perspective, Crop Group 7 contains both cotton and cereal crops; the latter are considered in Section 4.4.2. In addition to a normal row planter and spray rig equipment used in cereal production, cotton requires access to suitable picking and module or baling equipment, as well as transport to processing facilities. Decisions on initial development costs and scale of establishing cotton production in the catchment would need to consider the need to source external contractors; this could provide an opportunity to develop local contract services to support a growing industry. Cotton production is also highly dependent on access to processing plants (cotton gins). The first cotton gin in the NT opened in December 2023 and is the closest processing facility for cotton grown in the Victoria catchment (30 km north of Katherine, approximately 140 km east of the Victoria catchment boundary). A cotton gin has also been proposed for Kununurra. Niche industrial crops, such as guar (Cyamopsis tetragonoloba) and chia (Salvia hispanica), may be feasible for the Victoria catchment, but verified agronomic and market data on these crops are limited. Past research on guar has been conducted in the NT, and trials are currently underway. Hemp is a photoperiod-sensitive summer annual with a growing season between 70 and 120 days depending on variety and temperature. Hemp is well suited to growing in rotation with legumes, as hemp can use the nitrogen fixed by the legume crop. Industrial hemp can be harvested for grain with modifications to conventional headers, otherwise all other farming machinery for ground preparation, fertilising and spraying can be used. There are legislative restrictions to growing hemp in Australia, and jurisdictions including the NT are implementing industrial hemp legislation to license growing of industrial hemp to facilitate development of the industry. The companion technical report on agricultural viability and socio-economics (Webster et al., 2024) provides greater detail for a wider range of industrial crops. Table 4-20 describes some key considerations relating to cotton production (Figure 4-19). P2090#yIS1 Figure 4-18 Modelled land suitability for cotton (Crop Group 7) using furrow irrigation in the (a) wet season and (b) dry season These land suitability maps do not consider flooding, risk of secondary salinisation or availability of water. The methods used to derive the reliability data in the inset maps are outlined in the companion technical report on digital soil mapping and land suitability (Thomas et al., 2024). Cotton P2093#yIS1 Figure 4-19 Cotton Photo: CSIRO Table 4-20 Summary information relevant to the cultivation of cotton For more information on this figure, table or equation please contact CSIRO on enquiries@csiro.au 4.4.7 Forages Forage, hay and silage are crops that are grown specifically for consumption by animals. Forage is consumed in the paddock in which it is grown, which is often referred to as ‘stand and graze’. Hay is cut, dried, baled and stored before being fed to animals at a time when natural pasture production is low (generally towards the end of the dry season). Silage use resembles that for hay, but crops are stored wet, in anaerobic conditions where fermentation occurs, to preserve the feed’s nutritional value. Rainfed and irrigated production of forage crops is well established throughout Australia, with over 20,000 producers, most of whom are not specialist forage crop producers. Approximately 85% of forage production is consumed domestically, with the rest primarily used on live export ships often in a pelleted form. The largest consumers are the horse, dairy and beef feedlot industries. Forage crops are also widely used in horticulture for mulches and for erosion control. While there is already consumption use of forages by the northern beef industry, forage costs constitute less than 5% of beef production costs (Gleeson et al., 2012), so there is likely room for further expansion of forage production. Non-leguminous forage, hay and silage The Victoria catchment is suited to rainfed or irrigated production of non-leguminous forage, hay and silage. A significant amount of rainfed hay production occurs in the Douglas–Daly region, south of Darwin. Most of the hay produced in the NT is to locally feed cattle destined for live export or used as part of feed pellets used on boats carrying live export cattle. Forage crops, both annual and perennial, include sorghum (Sorghum spp.), Rhodes grass, maize and Jarra grass (Digitaria milanjiana ‘Jarra’), with particular cultivars specific for forage. These grass forages require considerable amounts of water and nitrogen as they can be high yielding (20 to 40 t dry matter per ha per year). Given the rapid growth of grass forages, crude protein levels can decrease very quickly, reducing their value as a feed for livestock. To maintain high nutritive value, high levels of nitrogen must be applied, and in the case of hay the crop needs to be cut every 45 to 60 days. After cutting, the crop grows back without the need for resowing. The rapid growth of forage during the wet season can make it challenging to match animal stocking rates to forage growth so that it is kept leafy and nutritious, and does not become rank and of low quality. Producing rainfed hay from perennials gives producers the option of irrigating when required or, if water becomes limiting, allowing the pasture to remain dormant before water again becomes available. Silage can be made from a number of crops, such as grasses, maize and forage sorghum. From a land suitability perspective, Rhodes grass is included in Crop Group 14 (Table 4-2; Figure 4-20). Cracking clays (Vertosols) make up nearly 12% of the Victoria catchment; they are found on alluvial plains, relict alluvial plains, and on level to gently undulating plains on basalt (marked CA1, CA2, CB1 and CB2 on Figure 2-5). These soils have very high water-holding capacity but the non- basalt Vertosols may have a restricted rooting depth due to salt levels in the subsoil. Vertosols generally have moderate to high agricultural potential, but inadequate drainage and deep gilgais in some areas reduce the prospects for furrow irrigation. Poor drainage and low permeability will cause waterlogging in the wet season, especially along the Baines, lower West Baines and East Baines rivers. Loamy soils, mostly red loams, make up more than 18% of the catchment. These soils dominate the deeply weathered sediments of the Sturt Plateau in the east to south-east (marked K1 and K2 on Figure 2-5) and other deeply weathered landscapes to the south and west of Kalkarindji. Loamy soils are typically nutrient deficient and have low to high water-holding capacity. Irrigation potential is limited to spray- and trickle-irrigated crops on the moderately deep to deep soils. In parts of the catchment, loamy soils are found on narrow flat areas dissected by stream channels and deep gullies, making the land difficult to develop for broadacre cropping. Shallow and/or rocky soils make up a little more than 57% of the catchment, and are unsuitable by definition. Assuming unconstrained development, approximately 2.9 million ha of the Victoria catchment is considered to be suitable with moderate limitations (Class 3; Table 4-1) or better (Class 2 or Class 1) for irrigated cropping of annual forages (Crop Group 12; Table 4-2) using spray irrigation in the dry season, most of this being Class 2. For spray irrigation in the wet season, nearly 2.7 million ha is suitable with moderate limitations (Class 3) or better, again the majority being Class 2. Land considered suitable with moderate limitations for furrow irrigation of annual forages is limited to about 625,000 ha in the dry season and about 420,000 ha in the wet season, due to inadequate soil drainage in clay soils (and/or because gilgais are too deep) and because the loamy soils are too permeable. There is potential for rainfed production of annual forages in the wet season over an area of about 850,000 ha. For the perennial Rhodes grass, about 2.9 million ha are suitable with moderate or minor limitations under spray irrigation and about 620,000 ha under furrow irrigation. Apart from irrigation infrastructure, the equipment needed for forage production is machinery for planting and fertilising. Spraying equipment is also desirable but not necessary. Cutting crops for hay or silage requires more-specialised harvesting, cutting, baling and storage equipment. Table 4-21 describes Rhodes grass production (Figure 4-21) for hay over 1 year of a 6-year cycle. Information similar to that in Table 4-21 for grazed forage crops is presented in the companion technical report on agricultural viability and socio-economics (Webster et al., 2024). P2160#yIS1 Figure 4-20 Modelled land suitability for Rhodes grass (Crop Group 14) using (a) spray irrigation and (b) furrow irrigation These land suitability maps do not consider flooding, risk of secondary salinisation or availability of water. The methods used to derive the reliability data in the inset maps are outlined in the companion technical report on digital soil mapping and land suitability (Thomas et al., 2024). Rhodes grass P2163#yIS1 Figure 4-21 Rhodes grass Photo: CSIRO Table 4-21 Rhodes grass production for hay over 1 year of a 6-year cycle For more information on this figure, table or equation please contact CSIRO on enquiries@csiro.au Forage legume The use of forage legumes is similar to that of forage grasses. They are generally grazed by animals but can also be cut for silage or hay. Some forage legumes are well suited to the Victoria catchment and would be considered among the more promising opportunities for irrigated agriculture (Figure 4-22). Forage legumes are desirable because of their high protein content and their ability to fix atmospheric nitrogen. The nitrogen fixed during a forage legume phase is often in excess of that crop’s requirements, which leaves the soil with additional nitrogen. Forage legumes are being used by the northern cattle industry, and farmers primarily engaged in extensive cattle production could use irrigated forage legumes to increase the capacity of their enterprise, turning out more cattle from the same area. Cavalcade (Centrosema pascuorum ‘Cavalcade’) and lablab are currently grown in northern Australia and would be well suited to the Victoria catchment. Hay crops are commonly used as a component of forage pellets that are used to feed live export cattle in holding yards and on boats during transport. From a land suitability perspective, forage legumes such as Cavalcade and lablab are included in Crop Group 13 (Table 4-2; Figure 4-22). Cracking clays (Vertosols) make up nearly 12% of the Victoria catchment; they are found on alluvial plains, relict alluvial plains, and on level to gently undulating plains on basalt (marked CA1, CA2, CB1 and CB2 on Figure 2-5). These soils have very high water-holding capacity but the non-basalt Vertosols may have a restricted rooting depth due to salt levels in the subsoil. Vertosols generally have moderate to high agricultural potential, but inadequate drainage and deep gilgais in some areas reduce the prospects for furrow irrigation. Poor drainage and low permeability will cause waterlogging in the wet season, especially along the Baines, lower West Baines and East Baines rivers. Loamy soils, mostly red loams, make up more than 18% of the catchment. These soils dominate the deeply weathered sediments of the Sturt Plateau in the east to south-east (marked K1 and K2 on Figure 2-5) and other deeply weathered landscapes to the south and west of Kalkarindji. Loamy soils are typically nutrient deficient and have low to high water-holding capacity. Irrigation potential is limited to spray- and trickle- irrigated crops on the moderately deep to deep soils. In parts of the catchment, loamy soils are found on narrow flat areas dissected by stream channels and deep gullies, making the land difficult to develop for broadacre cropping. Shallow and/or rocky soils make up a little more than 57% of the catchment, and are unsuitable by definition. Assuming unconstrained development, approximately 2.9 million ha of the Victoria catchment is considered to be suitable with moderate limitations (Class 3; Table 4-1) or better (Class 2 or Class 1) for irrigated forage legumes (Crop Group 13; Table 4-2) using spray irrigation in the dry season, most of this being Class 2. For spray irrigation in the wet season, nearly 2.4 million ha is suitable with moderate limitations (Class 3) or better, again the majority being Class 2. Land considered suitable with moderate or minor limitations for furrow irrigation is limited to about 620,000 ha in the dry season and 360,000 ha in the wet season, due to inadequate soil drainage in clay soils (and/or because gilgais are too deep) and because the loamy soils are too permeable. There is potential for rainfed forage legume production in the wet season over an area of about 670,000 ha. The equipment needed for grazed forage legume production is similar to that for forage grasses: a planting method, with fertilising and spraying equipment, is desirable but not essential. Cutting crops for hay or silage requires more-specialised harvesting, cutting, baling and storage equipment. Table 4-22 describes Cavalcade production over a 1-year cycle. The comments could be applied equally to lablab production (Figure 4-23). P2228#yIS1 Figure 4-22 Modelled land suitability for Cavalcade (Crop Group 13) in the wet season using (a) spray irrigation and (b) furrow irrigation These land suitability maps do not consider flooding, risk of secondary salinisation or availability of water. The methods used to derive the reliability data in the inset maps are outlined in the companion technical report on digital soil mapping and land suitability (Thomas et al., 2024). Lablab P2231#yIS1 Figure 4-23 Lablab Photo: CSIRO Table 4-22 Cavalcade production over a 1-year cycle For more information on this figure, table or equation please contact CSIRO on enquiries@csiro.au 4.4.8 Horticulture Horticulture is an important and widespread Australian industry, occurring in every state. Horticulture production encompasses a very wide range of intensive cultivated food and ornamental crops, including a vast range of fruit and vegetable crops. Horticultural production varied between 2.9 and 3.3 Mt per year between 2012–13 and 2021–22, of which 65% to 70% was vegetables (ABARES, 2022). Unlike broadacre crops, most horticultural produce in Australia is consumed domestically. The total gross value of horticultural production was $13.2 billion in 2021–22 (up from $9.3 billion in 2012–13), of which 24% was from exports (ABARES, 2022). Horticulture is also an important source of jobs, employing approximately one-third of all people employed in agriculture. Production of horticultural crops is highly seasonal, and individual farms may grow a range of crops or the same crop with sequential planting dates. The importance of freshness in many horticultural products means seasonality of supply is important in the market. The value of horticulture crops can vary widely, with price changes occurring over very short periods of time (weeks). Part of the attraction of growing horticulture crops in the Victoria catchment is to supply southern markets when southern growing regions are unable to produce due to climate restrictions. Transport of horticulture produce can involve significant costs, so achieving a price premium for ‘out of season’ production will be required for successful production in the Victoria catchment. This requires a heightened understanding of risks, markets, transport and supply chain issues. Horticultural production systems are generally more intensive than broadacre farming, requiring higher capital investment in establishing farm infrastructure and higher ongoing inputs for production. Picking and packing operations involve significant labour. Attracting sufficient seasonal workers to the Victoria catchment for harvesting season would need consideration. Horticulture (row crops) Horticulture row crops are generally short-lived, annual crops, grown in the ground, such as watermelon, rockmelon (Cucumis melo var. cantalupensis) and sweet corn (Zea mays). Almost all produce is shipped to major markets (cities) where central markets are located. Row crops such as watermelon and rockmelon use staggered plantings over a season (e.g. every 2 to 3 weeks) to extend the period over which harvested produce is sold. This strategy allows better use of labour and better management for risks of price fluctuations. Often only a short period of time with very high prices is enough to make melon production a profitable enterprise. Horticultural row crops are well established throughout the NT. The NT melon industry, consisting of watermelons (Citrullus lanatus) alongside some varieties of rockmelon (Cucumis melo) and honeydew melons (Cucumis melo), produces approximately 25% of Australia’s melons. Melon production is well suited across many parts of the NT and would be well suited to the Victoria catchment. From a land suitability perspective, intensive horticulture row crops such as rockmelon are included in Crop Group 3 (Table 4-2). Cracking clays (Vertosols) make up nearly 12% of the Victoria catchment; they are found on alluvial plains, relict alluvial plains, and on level to gently undulating plains on basalt (marked CA1, CA2, CB1 and CB2 on Figure 2-5). These soils have very high water- holding capacity but the non-basalt Vertosols may have a restricted rooting depth due to salt levels in the subsoil. Vertosols generally have moderate to high agricultural potential, but inadequate drainage and deep gilgais in some areas reduce the prospects for furrow irrigation. Poor drainage and low permeability will cause waterlogging in the wet season, especially along the Baines, lower West Baines and East Baines rivers. In addition, disease risk is very high for horticulture row crops in the wet season. Loamy soils, mostly red loams, make up more than 18% of the catchment. These soils dominate the deeply weathered sediments of the Sturt Plateau in the east to south-east (marked K1 and K2 on Figure 2-5) and other deeply weathered landscapes to the south and west of Kalkarindji. Loamy soils are typically nutrient deficient and have low to high water-holding capacity. Irrigation potential is limited to spray- and trickle-irrigated crops on the moderately deep to deep soils. Shallow and/or rocky soils make up a little more than 57% of the catchment, and are unsuitable by definition. A wide range of horticultural row crops are considered in the land suitability analysis (crop groups 3, 4, 5, 6 and 18; Table 4-2; Figure 4-24). Assuming unconstrained development, between about 2.5 million ha and 3.1 million ha of the Victoria catchment is considered to be suitable with moderate limitations (Class 3; Table 4-1) or better (Class 2 or Class 1) using spray or trickle irrigation in the dry season. Land considered suitable with moderate limitations for furrow irrigation of sweet corn (Crop Group 18) is limited to about 750,000 ha in the dry season and 420,000 ha in the wet season, due to inadequate soil drainage in clay soils (and/or because gilgais are too deep) and because the loamy soils are too permeable. Horticulture typically requires specialised equipment and a large labour force. Therefore, a system for attracting, managing and retaining sufficient staff is also required. Harvesting is often by hand, but packing equipment is highly specialised. Irrigation is mostly with micro or trickle equipment, but overhead spray is also feasible. Leaf fungal diseases need to be more carefully managed with spray irrigation. Micro spray equipment has the advantage of also being a nutrient delivery (fertigation) mechanism, as fertiliser can be delivered with the irrigation water. Table 4-23 describes some key considerations relating to row crop horticulture production, with rockmelon (Figure 4-25) as an example. P2298#yIS1 Figure 4-24 Modelled land suitability for (a) cucurbits (e.g. rockmelon, Crop Group 3) using trickle irrigation in the dry season and (b) root crops such as onion (Crop Group 6) using spray irrigation in the wet season These land suitability maps do not consider flooding, risk of secondary salinisation or availability of water. The methods used to derive the reliability data in the inset maps are outlined in the companion technical report on digital soil mapping and land suitability (Thomas et al., 2024). P2301#yIS1 Figure 4-25 Rockmelon Photo: Shutterstock Table 4-23 Summary information relevant to row crop horticulture production, with rockmelon as an example For more information on this figure, table or equation please contact CSIRO on enquiries@csiro.au Horticulture (tree crops) Some fruit and tree crops, such as mango and citrus (Citrus spp.), are well suited to the climate of the Victoria catchment. Other species, such as avocado (Persea americana) and lychee (Litchi chinensis), are not likely to be as well adapted to the climate due to high temperatures and low humidity. Tree crops are generally not well suited to cracking clays, which make up some of the suitable soils for irrigated agriculture in the Victoria catchment. Fruit production shares many of the marketing and risk features of horticultural row crops, such as a short season of supply and highly volatile prices as a result of highly inelastic supply and demand. Managing these issues requires a heightened understanding of risks, markets, transport and supply chain issues. The added disadvantage of fruit tree production is the time lag between planting and production, meaning decisions to plant need to be made with a long time frame for production and return in mind. Mango production in the NT is buffered somewhat against large- scale competition as its crop matures earlier than the main production areas in Queensland and it can achieve high returns. Mango production in the NT had a gross value of $129 million in 2020, accounting for 38% of the $341 million total value of horticultural production in the NT and half of mangoes produced in Australia (Sangha et al., 2022). The perennial nature of tree crops makes a reliable year-round supply of water essential. However, some species, such as mango and cashew (Anacardium occidentale), can survive well under mild water stress until flowering (generally August to October for most fruit trees). It is critical for optimum fruit and nut production that trees are not water stressed from flowering through to harvest. This is the period approximately beginning in August to November and carrying through to February, depending on the species. Very little rain falls in the Victoria catchment over this period, and farmers would need to have a system in place to access irrigation water during this time. From a land suitability perspective, intensive horticultural tree crops such as mango are included in Crop Group 1, the monsoonal tropical tree crops (Table 4-2). Cracking clays (Vertosols) make up nearly 12% of the Victoria catchment. They are found on alluvial plains, relict alluvial plains, and on level to gently undulating plains on basalt (marked CA1, CA2, CB1 and CB2 on Figure 2-5). These soils have very high water-holding capacity but the non-basalt Vertosols may have a restricted rooting depth due to salt levels in the subsoil. Vertosols generally have moderate to high agricultural potential, but inadequate drainage and deep gilgais in some areas reduce the prospects for horticultural tree crops. Loamy soils, mostly red loams, make up more than 18% of the catchment. These soils dominate the deeply weathered sediments of the Sturt Plateau in the east to south-east (marked K1 and K2 on Figure 2-5) and other deeply weathered landscapes to the south and west of Kalkarindji. Loamy soils are typically nutrient deficient and have low to high water-holding capacity. Irrigation potential is limited to spray- and trickle-irrigated crops on the moderately deep to deep soils. Shallow and/or rocky soils make up a little more than 57% of the catchment and are unsuitable by definition. A wide range of horticultural tree crops are considered in the land suitability analysis (crop groups 1, 2, 20 and 21; Table 4-2; Figure 4-26). Assuming unconstrained development, between about 650,000 ha (papaya/cashew/macadamia) and 2.6 million ha (e.g. mango) of the Victoria catchment is considered to be suitable with moderate limitations (Class 3; Table 4-1) or better (Class 2 or Class 1) using spray or trickle irrigation. Furrow irrigation was not considered for horticultural tree crops. Fruit and nut tree production requires specialised equipment. The requirement for a timely and significant labour force necessitates a system for attracting, managing and retaining sufficient staff. Tree-pruning and packing equipment is highly specialised for the fruit industry. Optimum irrigation is usually using micro spray. This equipment is also able to deliver fertiliser directly to the trees through fertigation. Table 4-24 describes some key considerations relating to mango production (Figure 4-27) in the Victoria catchment, as an exemplar of the conditions relating to tree crop production more broadly. Similar information for other fruit tree crops is described in the companion technical report on agricultural viability and socio-economics (Webster et al., 2024). P2358#yIS1 Figure 4-26 Modelled land suitability for (a) mango (Crop Group 1) and (b) lime (Crop Group 2), both grown using trickle irrigation These land suitability maps do not consider flooding, risk of secondary salinisation or availability of water. The methods used to derive the reliability data in the inset maps are outlined in the companion technical report on digital soil mapping and land suitability (Thomas et al., 2024). P2361#yIS1 Figure 4-27 Mango Photo: Shutterstock Table 4-24 Summary information relevant to tree crop horticulture production, with mango as an example For more information on this figure, table or equation please contact CSIRO on enquiries@csiro.au For more information on this figure, table or equation please contact CSIRO on enquiries@csiro.au PVR = plant variety rights. 4.4.9 Plantation tree crops (silviculture) Of the potential tree crops that could be grown in the Victoria catchment, Indian sandalwood and African mahogany are the only two that would be considered economically feasible. Many other plantation species could be grown, but returns are much lower than for these two crops. African mahogany is well established in commercial plantations near Katherine, and Indian sandalwood is also grown in Katherine, the Ord River Irrigation Area (WA) and in northern Queensland. Plantation timber species require over 15 years to grow, but once established can tolerate prolonged dry periods. Irrigation water is critical in the establishment and first 2 years of a plantation. In the case of Indian sandalwood, the provision of water is for not only the trees themselves but also the leguminous host plant associated with Indian sandalwood, as it is a hemiparasite. From a land suitability perspective, plantation tree crops such as Indian sandalwood, African mahogany and teak (Tectona grandis) are included in crop groups 15, 16 and 17 (Table 4-2). Cracking clays (Vertosols) make up nearly 12% of the Victoria catchment and are found on alluvial plains, relict alluvial plains, and on level to gently undulating plains on basalt (marked CA1, CA2, CB1 and CB2 on Figure 2-5). These soils have very high water-holding capacity but the non-basalt Vertosols may have a restricted rooting depth due to salt levels in the subsoil. Vertosols generally have moderate to high agricultural potential, but inadequate drainage and deep gilgais in some areas reduce the prospects for plantation tree crops. Loamy soils, mostly red loams, make up more than 18% of the catchment. These soils dominate the deeply weathered sediments of the Sturt Plateau in the east to south-east and other deeply weathered landscapes to the south (marked K1 and K2 on Figure 2-5) and west of Kalkarindji. Loamy soils are typically nutrient deficient and have low to high water-holding capacity. Irrigation potential is limited to spray- and trickle-irrigated crops on the moderately deep to deep soils. Shallow and/or rocky soils make up a little more than 57% of the catchment and are unsuitable by definition. Depending on the specific tree species being planted and their tolerance to poorly drained soils and waterlogging, the suitable areas vary considerably. A range of silviculture trees were considered in the land suitability analysis (crop groups 15, 16 and 17; Table 4-2). Assuming unconstrained development, between about 1.9 million ha (teak) and 2.7 million ha (African mahogany) of the Victoria catchment is considered to be suitable with moderate limitations (Class 3; Table 4-1) or better (Class 2 or Class 1) using trickle irrigation (Figure 4-28). Furrow irrigation was considered for Indian sandalwood only, and 170,000 ha was assessed as suitable with moderate limitations. Table 4-25 describes Indian sandalwood (Figure 4-29) production. P2422#yIS1 Figure 4-28 Modelled land suitability for Indian sandalwood (Crop Group 15) grown using (a) trickle or (b) furrow irrigation These land suitability maps do not consider flooding, risk of secondary salinisation or availability of water. The methods used to derive the reliability data in the inset maps are outlined in the companion technical report on digital soil mapping and land suitability (Thomas et al., 2024). P2425#yIS1 Figure 4-29 Indian sandalwood and host plants Indian sandalwood trees are those with a darker trunk and leaves in a line left of centre in the image. Photo: CSIRO Table 4-25 Summary information for Indian sandalwood production For more information on this figure, table or equation please contact CSIRO on enquiries@csiro.au For more information on this figure, table or equation please contact CSIRO on enquiries@csiro.au 4.4.10 Niche crops Niche crops such as guar, chia, quinoa (Chenopodium quinoa), bush products and others may be feasible in the Victoria catchment, but limited verified agronomic and market data are available for these crops. Niche crops are niche due to the limited demand for their products. As a result, small-scale production can lead to very attractive prices, but only a small increase in productive area can flood the market, leading to greatly reduced prices and making production unsustainable. There is growing interest in bush products but insufficient publicly available information for inclusion with the analyses of irrigated crops options in this Assessment. Bush product production systems could take many forms, from culturally appropriate wild harvesting targeting Indigenous consumers to modern mechanised farming and processing, like macadamia (Macadamia integrifolia) farming. The choice of production system would have implications for the extent of Indigenous involvement throughout the supply chain (farming, processing, marketing and/or consumption), the scale of the markets that could be accessed (in turn affecting the scale of the industry for that bush product), the price premiums that produce may be able to attract and the viability of those industries. The current publicly available information on bush products mainly focuses on eliciting Indigenous aspirations, biochemical analysis (for safety, nutrition and efficacy of potential health benefits) and considerations of safeguarding Indigenous intellectual property. Analysing bush products in a comparable way to other crop options in this report would first require these issues to be resolved, for communities to agree on the preferred type of production systems (and pathways for development), and for agronomic information on yields, production practices and costs to be publicly available. Past research on guar has been conducted in the NT, and trials are underway in northern Queensland, which could prove future feasibility. There is increasing interest in non-leguminous, small-seeded crops such as chia and quinoa, which have high nutritive value. The market size for these niche crops is quite small compared with cereals and pulses, so the scale of production is likely to be small in the short to medium term. There is a small, established chia industry in the Ord River Irrigation Area of WA, but its production and marketing statistics are largely commercial in confidence. Nearly all Australian production of chia is contracted to The Chia Company of Australia or is exported to China. In Australia, The Chia Company produces whole chia seeds, chia bran, ground chia seed and chia oil for wholesale and retail sale, and it exports these products to 36 countries. The growing popularity of quinoa in recent years is attached to its marketing as a superfood. It is genetically diverse and has not been the subject of long-term breeding programs. This diversity means it is well suited to a range of environments, including northern Australia, where its greatest opportunity is as a short-season crop in the dry season under irrigation. It is a high-value crop with farm gate prices of about $1000/t. Trials of quinoa production have been conducted at the Katherine Research Station (approximately 140 km from the eastern edge of the Victoria catchment), with reasonable yields being returned. More testing is required in the northern environments of the Victoria catchment before quinoa could be recommended for commercial production. 4.5 Aquaculture 4.5.1 Introduction There are considerable opportunities for aquaculture development in northern Australia given its natural advantages of a climate suited to farming valuable tropical species, large areas identified as suitable for aquaculture, political stability and proximity to large global markets. The main challenges to developing and operating modern and sustainable aquaculture enterprises are regulatory issues, global cost competitiveness and the remoteness of much of the suitable land area. A comprehensive situational analysis of the aquaculture industry in northern Australia (Cobcroft et al., 2020) identifies key challenges, opportunities and emerging sectors. This section draws on a recent assessment of the opportunities for aquaculture in northern Australia in the Northern Australia Water Resource Assessment technical report on aquaculture (Irvin et al., 2018), summarising the three most likely candidate species (Section 4.5.2), overviewing production systems for candidate species (Section 4.5.3), land suitability for aquaculture within the Victoria catchment (Section 4.5.4) and the financial viability of different options for aquaculture development (Section 4.5.5). 4.5.2 Candidate species The three species with the most aquaculture potential in the Victoria catchment are black tiger prawns, barramundi and red claw. The first two species are suited to many marine and brackish water environments of northern Australia and have established land-based culture practices and well-established markets for harvested products. Prawns could potentially be cultured in either extensive (low density, low input) or intensive (higher density, higher input) pond-based systems in northern Australia, whereas land-based culture of barramundi would likely be intensive. Red claw is a freshwater crayfish that is currently cultured by a much smaller industry than the other two species. Black tiger prawns Black tiger prawns (Figure 4-30) are found naturally at low abundances across the waters of the western Indo-Pacific region, with wild Australian populations making up the southernmost extent of the species. Within Australia, the species is most common in the tropical north, but does occur at lower latitudes. Tiger prawns P2498#yIS1 Figure 4-30 Black tiger prawns Photo: CSIRO Barramundi Barramundi (Figure 4-31) is the most highly produced and valuable tropical fish species in Australian aquaculture. Barramundi inhabit the tropical north of Australia from the Exmouth Gulf in WA through to the Noosa River on Queensland’s east coast. It is also commonly known as the ‘Asian sea bass’ or ‘giant sea perch’ throughout its natural areas of distribution in the Persian Gulf, the western Indo-Pacific region and southern China (Schipp et al., 2007). The attributes that make barramundi an excellent aquaculture candidate are fast growth (reaching 1 kg or more in 12 months), year-round fingerling availability, well-established production methods, and hardiness (i.e. they have a tolerance to low oxygen levels, high stocking densities and handling, as well as a wide range of temperatures) (Schipp et al., 2007). In addition, barramundi are euryhaline (able to thrive and be cultured in fresh and marine water), but freshwater barramundi can have an earthy flavour. Barramundi P2503#yIS1 Figure 4-31 Barramundi Photo: CSIRO Red claw Red claw is a warm-water crayfish species that inhabits still or slow-moving water bodies. The natural distribution of red claw is from the tropical catchments of Queensland and the NT to southern New Guinea. The name ‘red claw’ is derived from the distinctive red markings present on the claws of the male crayfish. The traits of red claw that make them attractive for aquaculture production are a simple life cycle, which is beneficial because complex hatchery technology is not required (Jones et al., 1998); their tolerance of low oxygen levels (<2 mg/L), which is beneficial in terms of handling, grading and transport (Masser and Rouse, 1997); their broad thermal tolerance, with optimal growth achievable between 23 and 31 °C; and their ability to remain alive out of water for extended periods. 4.5.3 Production systems Overview Aquaculture production systems can be broadly classified into extensive, semi-intensive and intensive systems. Intensive systems require high inputs and expect high outputs: they require high capital outlay and have high running costs; they require specially formulated feed and specialised breeding, water quality and biosecurity processes; and they have high production per hectare (in the order of 5000 to 20,000 kg per ha per crop). Semi-intensive systems involve stocking seed from a hatchery, routine provision of a feed, and monitoring and management of water quality. Production is typically 1000 to 5000 kg per ha per crop. Extensive systems are characterised by low inputs and low outputs: they require less-sophisticated management and often require no supplementary feed because the farmed species live on naturally produced feed in open-air ponds. Extensive systems produce about half the volume of global aquaculture production, but there are few commercial operations in Australia. Water salinity and temperature are the key parameters that determine species selection and production potential for any given location. Suboptimal water temperature (even within tolerable limits) will prolong the production season (because of slow growth) and increase the risk of disease, reducing profitability. The primary culture units for land-based farming are purpose-built ponds. Pond structures typically include an intake channel, production pond, discharge channel and a bioremediation pond (Figure 4-32). The function of the pond is to be a containment structure, an impermeable layer between the pond water and the local surface water and groundwater. Optimal sites for farms are flat and have sufficient elevation to enable ponds to be completely drained between seasons. It is critical that all ponds and channels can be fully drained during the off (dry-out) season to enable machinery access to sterilise and undertake pond maintenance. P2513#yIS1 Figure 4-32 Schematic of marine aquaculture farm Most production ponds in Australia are earthen. Soils for earthen ponds should have low permeability and high structural stability. Ponds should be lined if the soils are permeable. Synthetic liners have a higher capital cost but are often used in high-intensity operations, which require high levels of aeration – conditions that would lead to significant erosion in earthen ponds. Farms use aerators (typically electric paddlewheels and aspirators) to help maintain optimal water quality in the pond, provide oxygen and create a current that consolidates waste into a central sludge pile (while keeping the rest of the pond floor clear). A medium-sized (50 ha) prawn farm in Australia uses around 4 GWh annually, accounting for most of an enterprise’s energy use (Paterson and Miller, 2013). Backup power capacity sufficient to run all the aerators on the farm, usually with a diesel generator, is essential to be able to cope with power failures. Extensive production systems do not require aeration in most cases. Black tiger prawns For black tiger prawns, a typical pond in the Australian industry is rectangular in shape, about 1 ha in area and about 1.5 m in depth. The ponds are either wholly earthen, lined on the banks with black plastic and earthen bottoms or (rarely in Australia) fully lined. Pond grow-out of black tiger prawns typically operates at stocking densities of 25 to 50 individuals per square metre (termed ‘intensive’ in this report). These pond systems are fitted with multiple aeration units, which could double from 8 to 16 units as the biomass of the prawn crop increases (Mann, 2012). At the start of each prawn crop, pond bottoms are dried, and unwanted sludge from the previous crop is removed. If needed, additional substrate is added. Before filling the ponds, lime is often added to buffer pH, particularly in areas with acid-sulfate soils. The ponds are then filled with filtered seawater and left for about 1 week prior to postlarval stocking. Algal blooms in the water are encouraged through addition of organic fertiliser to provide shading for prawns, discourage benthic algal growth and stimulate growth of plankton as a source of nutrition (QDPIF, 2006). Postlarvae are purchased from hatcheries and grow rapidly into small prawns in the first month after stocking, relying mainly on the natural productivity (zooplankton, copepods and algae) supported by the algal bloom for their nutrition. Approximately 1 month after the prawns are stocked, pellet feed becomes the primary nutrition source. Feed is a major cost of prawn production; around 1.5 kg of feed is required to produce 1 kg of prawns. Prawns typically reach optimal marketable size (30 g) within 6 months. After harvest, prawns are usually processed immediately, with larger farms having their own production facilities that enable grading, cooking, packaging and freezing. Effective prawn farm management involves maintaining optimal water quality conditions, which becomes progressively complex as prawn biomass and the quantity of feed added to the system increase. As prawn biomass increases, so too does the biological oxygen demand of the microbial population within the pond that is breaking down organic materials. This requires increases in mechanical aeration and water exchanges (either fresh or recycled from a bioremediation pond). In most cases water salinity is not managed, except through seawater exchange, and will increase naturally with evaporation and decrease with rainfall and flooding. Strict regulation of the quality and volume of water that can be discharged means efficient use of water is standard industry practice. Most Australian prawn farms allocate up to 30% of their productive land for water treatment by pre-release containment in settlement systems. Barramundi The main factors that determine productivity of barramundi farms are water temperature, dissolved oxygen levels, effectiveness of waste removal, expertise of farm staff and the overall health of the stock. Barramundi are susceptible to a variety of bacterial, fungal and parasitic organisms. They are at highest risk of disease when exposed to suboptimal water quality conditions (e.g. low oxygen or extreme temperatures). Due to the cost and infrastructure required, many producers elect to purchase barramundi fingerlings from independent hatcheries, moving fish straight into their nursery cycle. Regular size grading is essential during the nursery stage to minimise aggressive and cannibalistic behaviour: size grading helps to prevent mortalities and damage from predation on smaller fish, and it assists with consistent growth. Ponds are typically stocked to a biomass of about 3 kg per 1000 L. Under optimal conditions barramundi can grow to over 1 kg in 12 months and to 3 kg within 2 years (Schipp et al., 2007). The two largest Australian aquafeed manufacturers (located in Brisbane and Hobart) each produce a pellet feed that provides a specific diet promoting efficient growth and feed conversion. The industry relies heavily on these mills to provide a regular supply of high-quality feed. Cost of feed transport would be a major cost to barramundi production in the Victoria catchment. As a carnivorous species, high dietary protein levels, with fishmeal as a primary ingredient, are required for optimal growth. Barramundi typically require between 1.2 and 1.5 kg of pelleted feed for each kilogram of body weight produced. Warm water temperatures in northern Australia enable fish to be stocked in ponds year-round. Depending on the intended market, harvested product is processed whole or as fillets and delivered fresh (refrigerated or in ice slurry) or frozen. Smaller niche markets for live barramundi are available for Asian restaurants in some capital cities. Red claw Water temperature and feed availability are the variables that most affect crayfish growth. Red claw are a robust species but are most susceptible to disease (including viruses, fungi, protozoa and bacteria) when conditions in the production pond are suboptimal (Jones, 1995). In tropical regions, mature females can be egg-bearing year round. Red claw breed freely in production ponds, so complex hatchery technology (or buying juvenile stock) is not required. However, low fecundity and the associated inability to source high numbers of quality selected broodstock are an impediment to intensive expansion of the industry. Production ponds are earthen, rectangular in design and on average 1 ha in size. They slope in depth from 1.2 to 1.8 m. Sheeting is used on the pond edge to keep the red claw in the pond (they tend to migrate), and netting surrounds the pond to protect stock from predators (Jones et al., 2000). At the start of each crop, ponds are prepared (as for black tiger prawns above), then filled with fresh water and left for about 2 weeks before stocking. During this period, algal blooms in the water are encouraged through addition of organic fertiliser. Ponds are then stocked with about 250 females and 100 males that have reached sexual maturity. Natural mating results in the production of around 20,000 advanced juveniles. Red claw are omnivorous, foraging on natural production such as microbial biomass associated with decaying plants and animals. Early-stage crayfish rely almost solely on natural pond productivity (phytoplankton and zooplankton) for nutrition. As the crayfish progress through the juvenile stages, the greater part of the diet changes to organic particulates (detritus) on the bottom of the pond. Very small quantities of a commercial feed are added daily to assist with the weaning process and provide an energy source for the pond bloom. Providing adequate shelters (net bundles) is essential at this stage to improve survival (Jones, 2007). Approximately 4 months after stocking, the juveniles are harvested and graded by size and sex for stocking in production ponds. Juveniles are stocked in production ponds at 5 to 10 per square metre. Shelters are important during the grow-out stage, with 250/ha recommended. During the grow-out phase, pellet feed becomes an important nutrition source, along with the natural productivity provided by the pond. Current commercial feeds are low cost and provide a nutrition source for natural pond productivity as much as for the crayfish. Most Australian farmers use diets consisting of 25% to 30% protein. Effective farm management involves maintaining water quality conditions within ranges optimal for crayfish growth and survival as pond biomass increases. As with barramundi, management involves increasing aeration and water exchanges, while strictly managing effluent discharges. Red claw are harvested within 6 months of stocking to avoid reproduction in the production pond. At this stage the crayfish will range from 30 to 80 g. Stock are graded by size and sex into groups for market, breeding or further grow-out (Jones, 2007). Estimated water use An average crop of prawns farmed in intensive pond systems (8 t/ha over 150 days) is estimated to require 127 ML of marine water, which equates to 15.9 ML of marine water for each tonne of harvested product (Irvin et al., 2018). For pond culture of barramundi (30 t/ha over 2 years), 562 ML of marine water, or fresh water, is required per crop, equating to 18.7 ML of water for each tonne of harvested fish. For extensive red claw culture (3 t/ha over 300 days), 240 ML of fresh water is required per pond crop, equating to 16 ML of water for each harvested tonne of crayfish (Irvin et al., 2018). 4.5.4 Aquaculture land suitability The suitability of areas for aquaculture development was also assessed from the perspective of soil and land characteristics using the set of five land suitability classes in Table 4-1. The limitations considered include clay content, soil surface pH, soil thickness and rockiness. Limitations mainly relate to geotechnical considerations (e.g. construction and stability of impoundments). Other limitations, including slope, and the likely presence of gilgai microrelief and acid-sulfate soils, are indicative of more difficult, expensive and therefore less suitable development environments, and a greater degree of land preparation effort. More detail can be found in the companion technical report on digital soil mapping and land suitability (Thomas et al., 2024). Suitability was assessed for lined and earthen ponds, with earthen ponds requiring soil properties that prevent pond leakage. Soil acidity (pH) was also considered for earthen ponds, as some aquaculture species can be affected by unfavourable pH values exchanged into the water column (i.e. biological limitation). Two aquaculture species were selected to represent the environmental needs of marine species (represented by prawns) and freshwater species (red claw). Additionally, barramundi and other euryhaline species, which can tolerate a range of salinity conditions, may be suited to either marine or fresh water, depending on management choices. Except for aquaculture of marine species, which for practical purposes is restricted by proximity to sea water, no consideration was given in the analysis to proximity to suitable water for aquaculture of fresh and euryhaline species. It was not possible to include proximity to fresh water due to the large number of potential locations where water could be captured and stored within the catchment. Note also that the estimates for land suitability presented below represent the total areas of the catchment unconstrained by factors such as water availability, land tenure, environmental and other legislation and regulations, and a range of biophysical risks such as cyclones and flooding. These are addressed elsewhere by the Assessment. The land suitability maps are designed to be used predominantly at the regional scale. Planning at the enterprise scale would demand more localised assessment. Analysis of suitability of land for marine aquaculture has been restricted to locations within 2 km of a marine water source. Suitable land for aquaculture in lined ponds is restricted to the areas under tidal influence and the river margins where cracking clay and seasonally or permanently wet soils dominate (Figure 4-33a). These soils show the desired land surface characteristics such as no rockiness, suitable slope and sufficient soil thickness, but have the risk of acid-sulfate soils and must be managed accordingly. Approximately 48,500 ha (0.6% of the catchment) is suited (Class 2) to marine aquaculture in lined ponds and 67,300 ha (0.8%) as Class 3 (Table 4-1). The land suitability patterns for marine species in earthen ponds (Figure 4-33b) closely mirror those of the marine species in lined ponds, although areas are restricted to slowly permeable cracking clay soils. Approximately 4100 ha (0.05% of the catchment) is mapped as suitability Class 2 and 88,700 ha (1%) as Class 3. P2537#yIS1 Figure 4-33 Land suitability in the Victoria catchment for marine species aquaculture in (a) lined ponds and (b) earthen ponds These land suitability maps do not consider flooding, risk of secondary salinisation or availability of water. The methods used to derive the suitability data are outlined in the companion technical report on digital soil mapping and land suitability (Thomas et al., 2024). The map of aquaculture land suitabilities for freshwater species (Figure 4-34) shows significant tracts of lands with soil attributes suitable for freshwater aquaculture in lined ponds (Figure 4-34a). The large tracts of suitability Class 2 (suitable with minor limitations) coincide with level plains with deep soils and no rock. These characteristics are associated with the marine plains, alluvial plains and the level lateritic Tertiary sedimentary plains physiographic units. The Class 3 suitability areas (suitable with moderate limitations) coincide with limestone gentle plains and various gentle plains on basalt. Approximately 3170 ha (0.04% of the catchment) is highly suited (Class 1) for freshwater lined aquaculture, 1,596,200 ha (19%) is mapped as Class 2 and 1,639,000 ha (20%) is mapped as Class 3. In comparison, opportunities for freshwater species in earthen ponds in the Assessment area are fewer (Figure 4-34b), being restricted to level plains with deep impermeable, rock free clay soils. Moderately to highly permeable soils are unsuited to earthen ponds. There are minor areas of Class 2 associated with cracking clay soils mainly on the alluvial plains physiographic unit. Areas of Class 3 suitability on slowly permeable clays are found on alluvial plains, limestone gentle plains and some gentle plains on basalt. There are also significant areas of the coastal plain near the river mouth of Class 3 suitability on slowly permeable seasonally or permanently wet soils and cracking clay soils. These coastal plains have potential acid-sulfate soils that would require appropriate management. Land suitability for freshwater species using earthen ponds shows a small proportion of Class 2 suitability totalling 69,800 ha (0.85% of the catchment) and 887,500 ha (11%) as Class 3. P2542#yIS1 Figure 4-34 Land suitability in the Victoria catchment for freshwater species aquaculture in (a) lined ponds and (b) earthen ponds These land suitability maps do not consider flooding, risk of secondary salinisation or availability of water. The methods used to derive the suitability data are outlined in the companion technical report on digital soil mapping and land suitability (Thomas et al., 2024). 4.5.5 Aquaculture viability This section provides a brief, generic analysis of what would be required for new aquaculture developments in the Victoria catchment to be financially viable. First, indicative costs are provided for a range of four possible aquaculture enterprises that differ in species farmed, scale and intensity of production. The cost structure of the enterprises was based on established tools available from the Queensland Government for assessing the performance of existing or proposed aquaculture businesses (Queensland Government, 2024). Based on the ranges of these indicative capital and operating costs, gross revenue targets that a business would need to attain to be commercially viable are then calculated. Enterprise-level costs for aquaculture development Costs of establishing and running a new aquaculture business are divided here into the initial capital costs of development and ongoing operating costs. The four enterprise types analysed were chosen to portray some of the variation in cost structures between potential development options, not as a like-for-like comparison between different types of aquaculture (Table 4-26). Capital costs include all land development costs, construction, and plant and equipment accounted for in the year production commences. The types of capital development costs are largely similar across the aquaculture options with costs of constructing ponds and buildings dominating the total initial capital investment. Indicative costs were derived from the case study of Guy et al. (2014), and consultation with experts familiar with the different types of aquaculture, including updating to December 2023 dollar values (Table 4-26). Operating costs cover both overheads (which do not change with output) and variable costs (which increase as the yield of produce increases). Fixed overhead costs in aquaculture are a relatively small component of the total costs of production. Overheads consist of costs relating to licensing, approvals and other administration (Table 4-26). The remaining operating costs are variable (Table 4-26). Feed, labour and electricity typically dominate the variable costs. Aquaculture requires large volumes of feed inputs, and the efficiency with which this feed is converted to marketed produce is a key metric of business performance. Labour costs consist of salaries of permanent staff and casual staff who are employed to cover intensive harvesting and processing activities. Aerators require large amounts of energy, increasing as the biomass of produce in the ponds increases, which accounts for the large costs of electricity. Transport, although a smaller proportional cost, is important because this puts remote locations at a disadvantage relative to aquaculture businesses that are closer to feed suppliers and markets. In addition, transport costs may be higher at times if roads are cut (requiring much more expensive air freight or alternative, longer road routes) or if the closest markets become oversupplied. Packing is the smallest component of variable costs in the breakdown categories used here. Revenue for aquaculture produce typically ranges from $10 to $20 per kg (on a harvested mass basis), but prices vary depending on the quality and size classes of harvested animals and how they are processed (e.g. live, fresh, frozen or filleted). Farms are likely to deliver a mix of products targeted to the specifications of the markets they supply. Note that the mass of sold product may be substantially lower than the harvested product (e.g. fish fillets are about half the mass of harvested fish), so prices of sold product may not be directly comparable to the costs of production in Table 4-26, which are on a harvest mass basis. Table 4-26 Indicative capital and operating costs for a range of generic aquaculture development options Costs are provided both per hectare of grow-out pond and per kilogram of harvested produce, although capital costs scale mostly with the area developed and operating costs scale mainly with crop yield at harvest. Capital costs have been converted to an equivalent annualised cost assuming a 10% discount rate and that a quarter of the developed infrastructure was for 15-year life span assets and the remainder for 40-year life span assets. Indicative breakdowns of cost components are provided on a proportional basis. Costs derived from Guy et al. (2014) and adjusted to December 2023 dollar values. PARAMETER UNIT PRAWN (EXTENSIVE) PRAWN (INTENSIVE) BARRAMUNDI RED CLAW (SMALL SCALE) Scale of development Grow-out pond area ha 20 100 30 4 Total farm area ha 25 150 100 10 Yield at harvest t/y 30 800 600 32 Yield at harvest per pond area t/ha/y 1.5 8.0 20.0 3.0 Capital costs of development (scale with area of grow-out ponds developed) Land and buildings % 56 26 23 30 Vehicles % 5 2 2 11 Pond-related assets % 27 67 70 41 Other infrastructure and equipment % 11 6 5 17 PARAMETER UNIT PRAWN (EXTENSIVE) PRAWN (INTENSIVE) BARRAMUNDI RED CLAW (SMALL SCALE) Total capital cost (year 0) $/ha 74,000 142,000 147,000 163,000 Equivalent annualised cost $/kg 5.41 1.94 0.81 5.95 $/ha/y 8,108 15,558 16,106 17,859 Operating costs (vary with yield at harvest, except overheads) Nursery/juvenile costs % 12 9 7 1 Feed costs % 0 26 30 8 Labour costs % 47 13 12 57 Electricity costs % 16 24 30 9 Packing costs % 2 4 3 2 Transport costs % 6 16 16 11 Overhead costs (fixed) % 17 8 1 12 Total annual operating costs $/kg 19.31 12.47 12.46 17.80 $/ha/y 28,966 99,783 249,211 53,402 Total costs of production Total annual cost $/kg 24.72 14.42 13.27 23.75 $/ha/y 37,100 115,300 265,300 71,300 Commercial viability of new aquaculture developments Capital and operating costs differ between different types of aquaculture enterprises (Table 4-27), but these costs may differ even more between locations (depending on case-specific factors such as remoteness, soil properties, distance to water source and type of power supply). Furthermore, there can be considerable uncertainty in some costs, and prices paid for produce can fluctuate substantially over time. Given this variation among possible aquaculture developments in the Victoria catchment, a generic approach was taken to determine what would be required for new aquaculture enterprises to become commercially viable. The approach used here was to calculate the gross revenue that an enterprise would have to generate each year to achieve a target internal rate of return (IRR) for given operating costs and development costs (both expressed per hectare of grow-out ponds). Capital costs were converted to annualised equivalents on the assumption that developed assets equated to a mix of 25% 15-year assets and 75% assets with a 40-year life span (using a discount rate matching the target IRR). The target gross revenue is the sum of the annual operating costs and the equivalent annualised cost of the infrastructure development (Table 4-27). Table 4-27 Gross revenue targets required to achieve target internal rates of return (IRR) for aquaculture developments with different combinations of capital costs and operating costs All values are expressed per hectare of grow-out ponds in the development. Gross revenue is the yield per hectare of pond multiplied by the price received for produce (averaged across products and on a harvest mass basis). Capital costs were converted to an equivalent annualised cost assuming a quarter of the developed infrastructure was assets with a 15-year life span and the remainder for a 40-year life span. Targets would be higher after taking into account risks such as initial learning and market fluctuations. OPERATING COSTS ($/ha/y) GROSS REVENUE REQUIRED TO ACHIEVE TARGET IRR ($/ha/y) CAPITAL COSTS OF DEVELOPMENT ($/HA) 60,000 70,000 80,000 90,000 100,000 110,000 125,000 150,000 175,000 7% target IRR 20,000 25,022 25,859 26,696 27,533 28,371 29,208 30,463 32,556 34,648 50,000 55,022 55,859 56,696 57,533 58,371 59,208 60,463 62,556 64,648 100,000 105,022 105,859 106,696 107,533 108,371 109,208 110,463 112,556 114,648 150,000 155,022 155,859 156,696 157,533 158,371 159,208 160,463 162,556 164,648 200,000 205,022 205,859 206,696 207,533 208,371 209,208 210,463 212,556 214,648 250,000 255,022 255,859 256,696 257,533 258,371 259,208 260,463 262,556 264,648 10% target IRR 20,000 26,574 27,669 28,765 29,861 30,956 32,052 33,695 36,434 39,174 50,000 56,574 57,669 58,765 59,861 60,956 62,052 63,695 66,434 69,174 100,000 106,574 107,669 108,765 109,861 110,956 112,052 113,695 116,434 119,174 150,000 156,574 157,669 158,765 159,861 160,956 162,052 163,695 166,434 169,174 200,000 206,574 207,669 208,765 209,861 210,956 212,052 213,695 216,434 219,174 250,000 256,574 257,669 258,765 259,861 260,956 262,052 263,695 266,434 269,174 14% target IRR 20,000 28,776 30,238 31,701 33,163 34,626 36,089 38,283 41,939 45,596 50,000 58,776 60,238 61,701 63,163 64,626 66,089 68,283 71,939 75,596 100,000 108,776 110,238 111,701 113,163 114,626 116,089 118,283 121,939 125,596 150,000 158,776 160,238 161,701 163,163 164,626 166,089 168,283 171,939 175,596 200,000 208,776 210,238 211,701 213,163 214,626 216,089 218,283 221,939 225,596 250,000 258,776 260,238 261,701 263,163 264,626 266,089 268,283 271,939 275,596 In order for an enterprise to be commercially viable, the volume of produce grown each year multiplied by the sales price of that produce would need to match or exceed the target values provided above. For example, a proposed development with capital costs of $125,000/ha and operating costs of $200,000 per ha per year would need to generate gross revenue of $213,695 per ha per year to achieve a target IRR of 10% (Table 4-27). If the enterprise received $12/kg for produce (averaged across product types, on a harvest mass basis), then it would need to sustain mean long-term yields of 18 t/ha (= $213,695 per ha per year ÷ $12/kg × 1 t/1000 kg) from the first harvest. However, if prices were $20/kg, mean long-term yields would require 11 t/ha (= $213,695 per ha per year ÷ $20/kg × 1 t/1000 kg) for the same $125,000 capital costs per hectare, or only 6 t/ha harvests if the capital costs decreased to $100,000/ha (= $113,695 per ha per year ÷ $20/kg × 1 t/1000 kg). Target revenue would be higher after taking into account risks such as learning and adapting to the particular challenges of a new location, and periodic setbacks that could arise from disease, climate variability, changes in market conditions or new legislation. Key messages From this analysis, a number of key points about achieving commercial viability in new aquaculture enterprises are apparent: • Operating costs are very high, and the amount spent each year on inputs can exceed the upfront (year zero) capital cost of development (and the value of the farm assets). This means that the cost of development is a much smaller consideration for achieving profitability than ongoing operations and costs of inputs. • High operating costs also mean that substantial capital reserves are required, beyond the capital costs of development, as there will be large cash outflows for inputs in the start-up years before revenue from harvested product starts to be generated. This is particularly the case for larger size classes of product that require multi-year grow-out periods before harvest. Managing cashflows would therefore be an important consideration at establishment and as yields are subsequently scaled up. • Variable costs dominate the total costs of aquaculture production, so most costs will increase as yield increases. This means that increases in production, by itself, would contribute little to achieving profitability in a new enterprise. What is much more important is increasing production efficiency, such as feed conversion rate or labour efficiency, so inputs per unit of produce are reduced (and profit margins per kilogram are increased). • Small changes in quantities and prices of inputs and produce would have a relatively large impact on net profit margins. These values could differ substantially between different locations (e.g. varying in remoteness, available markets, soils and climate) and depend on the experience of managers. Even small differences from the indicative values provided in Table 4-27 could render an enterprise unprofitable. • Enterprise viability would therefore be very dependent on the specifics of each particular case and how the learning, scaling up and cashflow were managed during the initial establishment years of the enterprise. It would be essential for any new aquaculture development in the Victoria catchment to refine the production system and achieve the required levels of operational efficiency (input costs per kilogram of produce) using just a few ponds before scaling any enterprise. 4.6 References ABARES (2022) Agricultural commodities: September quarter 2022. Australian Bureau of Agricultural and Resource Economics and Sciences, Canberra. September CC BY 4.0. DOI: doi.org/10.25814/zs85-g927. ABARES (2023) Australian horticulture prices. Australian Bureau of Agricultural and Resource Economics and Sciences, Canberra. 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