After two consecutive dry seasons, Nick Kershaw and his father Rod are watching a farming systems trial on their farm with interest to determine the profitability of various cropping sequences.

As mixed farmers, Nick and Rod crop just less than half of their 1150 hectares using a canola/wheat/lupin/wheat/canola rotation.

Every year, most of the family's cereal and canola crops are grazed by their 3000 Merino ewes during the winter when their pastures are rested.

CSIRO Agriculture and Food senior experimental scientist Tony Swan is managing the trial at Greenethorpe, which has GRDC, CSIRO and NSW Department of Primary Industries co-investment.

In 2018, he and the project's leader, CSIRO Agriculture and Food chief research scientist Dr John Kirkegaard, discovered Hyola 970 canola roots from crop sown on 4 April had penetrated the Kershaws' soil to 3.9 metres.

While this crop produced high yields, it also dried out the soil profile, leaving less stored soil moisture and nitrogen available for the 2019 crops.

"In our farming systems trial we are comparing fertiliser nitrogen with the nitrogen left behind by legumes, including both pasture legumes for grazing or hay and high-value legumes such as lentils and chickpeas," Dr Kirkegaard says.

"We know lentils and chickpeas leave a bit of water behind in the soil, so they might be a tool to help us grow early sown, long-season wheat and canola more regularly with lower risk and avoid the legacy of dry and nitrogen-depleted soils for the following season's crops."

Mr Swan says the past two years have confirmed the value of early sowing and grazing in dry seasons in terms of increased flexibility and profitability on mixed farms with grazing, hay or silage and grain options depending how the season goes.

"If you don't graze your early sown crops there's little economic benefit, unless you have a wet year and the crops can fulfill their maximum yield potential," he says.

"However, there can be significant legacy effects of dry soils and low nitrogen on the grain yield potential of early sown crops in subsequent seasons, although they still provide valuable feed at critical times when sheep prices are high, as in 2019."

Mr Swan says incorporating chickpeas or lentils into the crop sequence with early sown grazed crops could be a way to take advantage of in-season rainfall events to assist refilling of the profile with moisture for subsequent crops.

More information: Nick Kershaw, 0431 258 175, nicholas_kershaw@live.com.au; Tony Swan, 0428 145 085, tony.swan@csiro.au