Twin-sowing gives profit boost: study

Fiona Young's fourth-year honours project, as part of her agricultural science degree at the University of WA (UWA), assessed the economics of simultaneously sowing a hard-seeded annual legume pasture under a cereal or oilseed crop.

Although clearly exhibiting the potential to reduce pasture establishment costs, the innovative technique was yet to undergo a formal economic assessment.

"My research used a whole-farm bioeconomic model, known as MIDAS, combined with sensitivity analysis to test the hypothesis that twin-sowing increases the profitability of mixed broadacre farming systems in WA's central grainbelt," Ms Young said.

"My study revealed how and in what situations twin-sowing is likely to be highly profitable and where and when it's likely to be widely adopted."

To assist her project she has been awarded the Sir Eric Smart Scholarship for Agricultural Research, which encourages bright students in UWA's Faculty of Natural and Agricultural Sciences to research ways of improving the productivity and profitability of wheat, barley, lupins or canola growing in WA's light soil types.

UWA Institute of Agriculture director Winthrop Professor Kadambot Siddique said the late Sir Eric Smart was a pioneer cereal producer in light land areas around Mingenew.

Once the world's largest individual wheat grower, Sir Eric showed his appreciation of science by endowing substantial funds upon his death in 1973 to UWA. This was later supplemented by a gift from his son, Peter.

"He wanted science to improve agricultural production and the first allocation from his bequest to UWA was to help lupin growers deal with manganese deficiency," Professor Siddique said.

Sir Eric came to WA in 1934 from South Australia. In 1949 he acquired Erregull Springs, a 10,000-hectare property at Mingenew.

More than half the farm was light sand-plain country and it was there that he experimented with superphosphate and lupins to build soil fertility of the light land for cropping.

Ms Young said the model application showed that twin-sowing boosted whole-farm profit while decreasing the area of farm optimally devoted to pasture.

"For a standard farm, the pasture area decreased by 13 per cent while profit increased significantly by 24 per cent," she said.

"Twin-sowing increased an average farm's capacity to carry sheep by up to 24 per cent and eliminated initial nitrogen fertiliser requirements for crops following a year of legume pasture."

As twin-sowing has been developed mainly for pasture establishment on sandy soils, farms with predominantly sandy soils experience the largest increase in farm profits (41 per cent at current high prices for sheepmeat and wool).

"Sensitivity analysis suggests that even if wool prices, pasture growth and sheepmeat prices decline, twin-sowing remains highly profitable compared to farming systems without this innovation," Ms Young said.

"The combination of desirable characteristics of twin-sowing highlights its potential for further trial demonstrations and adoption across different farming systems in WA."

In mixed enterprise dryland farming systems of southern Australia, sheepmeat and wool production relies on annual pastures often grown in rotation with phases of cropping.

According to Ms Young, pasture phases are becoming shorter and livestock numbers dwindling, challenging farmers to recover costs associated with pasture establishment and maintenance.

"Farm owners are therefore rethinking crop-only farming systems, as they recognise the potential opportunities sheep can provide, especially in terms of lamb production, supported by the availability of non-wool sheep breeds such as Dorpers," she said.

"This interest is sometimes thwarted because sowing pasture using conventional means can be expensive and time-consuming at a time of the year when labour is often tight."