Adding "friendly" bacteria to summer crops can save farmers money and improve yields, according to CSIRO.
Bacteria introduced into the root zone in the form of inoculant are needed by legumes to fix nitrogen.
"A single packet of inoculant can provide as much nitrogen as one tonne of urea at - less than one per cent of the cost," said Mr Bob Gault, CSIRO Plant Industry.
"Inoculant contains bacteria called rhizobia, which help the legumes fix nitrogen. Without the right kind of rhizobia, legumes can't fix nitrogen and will start to use up valuable soil nitrogen.
"Field trials have shown that growers using inoculant can expect these bacteria to produce between 200 and 300 kilograms of nitrogen per hectare for grain legumes," Mr Gault said.
"Each legume needs the right type of rhizobium bacteria in sufficient numbers in the soil. Most of the crops we grow are not native to Australian soil, and neither are the bacteria these crops need. So we have to artificially add the right bacteria - this is what we do when we add inoculant.
"There are two methods of introducing bacteria into the root zone - inoculant can be put on the seed through the seed box, or delivered directly into the furrow. Both techniques are equally effective.
"You have to be sure that you have the right sort of rhizobia for your crop - the type of inoculant you need varies from crop to crop and region to region. Growers should check with their district agronomist.
"The State Departments of Agriculture have a wealth of experience and provide excellent advice to help growers.
"By introducing high numbers of the live bacteria into the rootzone at the time of sowing, the legume will fix its own nitrogen. This can provide carry over nitrogen for any subsequent cereal crops and lead to big savings in fertiliser costs.
"Summer crops are big users of nitrogen, and need inoculant. Rhizobia will not always survive in the soil between crops. You can't overdo inoculation, and you need to inoculate every time you sow," Mr Gault said.
This research is supported by graingrowers through the Grains Research Development Corporation (GRDC).
More information:
Mr Bob Gault 02 6246 5148
Dr Mark Peoples 02 6246 5244
Katrina Nitschke 02 6246 5323 or 0417 240 261