The inter-cropping technique typically used by subsistence farmers to maximise food production on their small blocks of land could help Australian graingrowers in their constant battle against the cost price squeeze.

According to Dr Victor Sadras, a crop scientist with South Australia's Research and Development Institute, trials in high-tech farming systems in Argentina have shown that sunflowers on 1.4 metre rows can be inter-planted with soybeans with only minor effects on sunflower yield.

So, Dr Sadras says, whatever yield is taken from the soybeans ­ and they are affected by shortage of water and by shade from the taller sunflower plants in their early stages ­ is extra productivity and profit.

The inter-cropping technique developed by Dr Pablo Calviño was explained by Dr Sadras at the recent 15th Australian Sunflower Conference in Gunnedah.

The conference's major financial supporters were the Grains Research and Development Corporation (GRDC), the Australian Oilseeds Federation and the NSW Department of Primary Industries.

Inter-cropped soybeans really get into their stride once the shading sunflower heads are harvested. Photo by Dr Pablo Calviño.

He said the ideal would be to improve farm productivity by at least as much as the decline in the terms of trade, but that would require innovative farmers and advisers, open-minded researchers, funding bodies ready to take risks and interaction between all of them.

The inter-cropping of sunflowers and soybeans in Argentina ­ which was the main subject of his presentation to the conference ­ and winter sunflowers in Spain were examples of the innovative thinking required.

Researchers in Argentina knew sunflowers could maintain yield on 1.4 metre rows and that sunflower plants had the ability to incline their stems alternatively left and right to reduce competition for radiation and effectively increase biomass production.

While sunflowers¹ ability to capture radiation was good, researchers had decided to find out whether a second crop in the same field ­ planted in that 1.4 metre gap between the sunflower rows ­ would use more of the available radiation.

Late-sown soybean was the choice for inter-cropping, partly because its critical growth period did not overlap that of sunflowers.

Trials proved sunflower yield was not affected by two inter-planted rows of soybeans but the bean crop did struggle until the shade influence of the sunflowers was removed at harvest.

Ongoing work on crop configurations was targeting this 'weak link' in the system.

Dr Sadras said large farms in Argentina were now using the inter-cropping system and, in some cases, attaining close to the ideal yield sunflowers might achieve when planted on their own.

The Argentine trials were in an area with an annual rainfall of about 900 millimetres and possibly more relevant to irrigation growers in Australia.

But the system was an excellent example of innovative thinking turning a subsistence farming concept into a high-tech solution to productivity.