We've been working with the Birchip Cropping Group (BCG) to develop and support Yield Prophet®, a web-based decision-support tool for grain growers. Yield Prophet® is built on the farming systems model Agricultural Production Systems Simulator (APSIM).

Using Yield Prophet® to match crop inputs to attainable yields

Yield Prophet® is an online crop production model that provides grain growers and consultants with paddock-specific yield forecasts as well as crop growth and resource information.

Yield Prophet® acts as an interface to the crop production model APSIM incorporating soil test results, growing season rainfall, crop management and historic climate data to provide accurate and objective real-time assessments of seasonal yield potential.

Using the grower's own soil test data, it estimates the probabilities of a specific paddock obtaining a range of yields. By matching crop inputs with the attainable yield in a given season, growers may avoid over- or under-investing in their crop.

All major varieties of wheat, barley and sorghum, are supported as well as, to a lesser extent, canola and oats.

Soil test data for the paddock – an essential input

Soil test information is an essential input, allowing Yield Prophet® to simulate root growth and determine what resources are available to the crop.

Crop details required are the type and amount of starting stubble, sowing date, crop type, cultivar and sowing density.

Yield Prophet® uses the past 100 years of climate data (maximum and minimum temperature, radiation, evaporation and vapour pressure) for the Bureau of Meteorology weather station nominated by the grower.

During the season, the grower can optionally enter rainfall for an individual paddock. They can also update paddock management details (cultivations, applications of nitrogen fertiliser, irrigation) as they occur.

Interpreting the yield probability curve

A yield-probability curve is the main output of Yield Prophet®. Growers can see the likely impact of different sowing dates, varieties, and irrigation and nitrogen applications by choosing different 'scenarios'.

Using the probability curve generated for each scenario, Yield Prophet® estimates the probability of achieving a higher (or lower) yield as a result of adding water or nitrogen, sowing on a different date or sowing a different variety. It can also estimate gross margin based on the predicted grain quality and price.

Yield Prophet Predicts a 6t Wheat Crop in the Southern Mallee

(This is an excerpt from a Birchip Cropping Group media release )

A six tonne wheat crop in the Southern Mallee is a rare event.

The lucky farmer, a seasoned operator, not surprisingly, was sceptical about the validity of his Yield Prophet report of August 27. An 8 per cent chance of achieving at least six tonnes per hectare at harvest? The grower’s scepticism was accentuated by the fact that the growing season was tracking Decile 1 (i.e. in the lowest 10 per cent).

The grower was so dubious that he emailed the Yield Prophet team of CSIRO scientists and BCG staff, and offered to buy each of them dinner if the Yield Prophet prediction proved to be on the money.

The Yield Prophet (YP) team took up the challenge and the controversy has kept the issue alive throughout the 2011 growing season. Is it possible to grow a 6t crop on what has turned out to be a Decile 2 growing season?

The paddock soil sample, taken on 31 March, indicated the presence of 189mm of stored soil moisture and 168kg nitrogen/ha. Over the summer fallow period between October and March, the paddock received over 400mm of rainfall, the highest amount of rainfall for that period since the beginning of records (110 years). The high rainfall, combined with a strong paddock legume history, it was clear that moisture and nitrogen test results were likely to be close to the mark. The grower had implemented sound weed control and had applied 20kg nitrogen /ha at sowing to ensure the crop got a good start.

Under such favourable conditions, the YP team was confident that the potential of the paddock was significant. Yield Prophet provided the impetus for the grower to adopt a comprehensive fungicide strategy to protect the potential of his crop. All that stood between a high crop yield was a severe frost or heat shock event or a wet harvest.

The crop is approaching full maturity and will be harvested in the next two weeks. Tension is building. What will be the outcome?

The very least that can be said is that, even if the crop does not achieve the high yields forecast by Yield Prophet, this paddock has highlighted the value of using a decision support tool. At most – certainly for the YP team - consuming a free dinner will be a source of additional satisfaction to the professional one already experienced. The farmer wins either way.

Under 'normal' circumstances Yield Prophet acts as a validation for our intuition. In this case, Yield Prophet has provided the grower with a necessary correction of his intuition which has encouraged him to invest in his crop and protect its potential.

How a South Australian grain grower saved A$20 000 using Yield Prophet®

(This is an excerpt from Managing Climate Change in Australia FARMER'S STORIES [PDF, 217KB])

The 2006 season broke early in Ardrossan, on the north coast of South Australia’s Yorke Peninsula.

Bill Long and most farmers in the region were heartened by the good rains and planted their crops as soon as they could.

The good start meant crops grew well through winter. But the last significant rain fell in the middle of July, and August and September were the driest on record. By the end of September, it was clear that yields would be disappointing.

'Many of the growers in the region cut grain crops for hay when it’s like this', says Bill. 'This cashes in on the good crop growth made with the early rains and offsets the risk of not getting the rain needed for a decent grain yield. 'But there is a trade-off. Grain fetches a higher price per tonne than hay, so if we make the wrong choice we could lose out.'

Bill’s gut feel was that he might get a greater financial return if he cut one or several of his wheat crops for hay. He decided to check his intuition with Yield Prophet® which he had been using for two years.

Yield Prophet® predicted that, even if the season finish of 2006 were to equal the driest year on record, Bill’s wheat would still achieve significant grain yields.

Given skyrocketing prices for wheat with the expanding national drought, Bill decided not to cut hay. That decision saved him A$20 000.

'I'm glad I followed Yield Prophet®’, says Bill. ‘We did get the driest year on record. The worst-case scenario happened. But Yield Prophet’s® prediction held true and we safely harvested the paddock.

'It's fantastic—having access to this kind of science to check against your gut feel is just invaluable. Models like Yield Prophet® can save the industry millions of dollars by making decisions more clear cut.'


Yield Prophet® is funded by the BCG (the Birchip Cropping Group), with added support from CSIRO, the Grains Research & Development Corporation and the national Managing Climate Variability program.

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