A nine-year study of the impact of livestock on paddock health and farm productivity in low rainfall areas has revealed grazing generates multiple benefits for mixed enterprises.
Conducted at Minnipa, the study demonstrated many agronomic and financial advantages could be achieved by incorporating livestock into the rotation.
Apart from improved gross margins, the benefits of integrating sheep included increased nitrogen (N) cycling and water use efficiency, reduced weed and pest pressures, and added value to stubble and pastures – without negatively impacting on cereal performance or soil health.
The study was undertaken by the South Australian Research and Development Institute (SARDI), a division of Primary Industries and Regions SA, as part of the Grains Research and Development Corporation’s Grain and Graze 3 research investment.
SARDI researcher Jessica Crettenden said the trial, based on a wheat-medic rotation, also tested whether productivity could be improved under a higher input system (higher fertiliser and seeding rates, establishment of improved pasture) compared to a lower input and more traditional system (district practice seed and fertiliser inputs, volunteer pasture), and what effect this had on soil fertility.
Ms Crettenden said some growers in low rainfall areas of the Eyre Peninsula had been hesitant to increase grazing in the break phase of the rotation partly due to the perception that livestock could damage soil health, remove organic matter and induce weed germination, but also because their efforts were often concentrated on the cropping enterprise due to the income it brought into the business.
“But with prices for livestock increasing over the past decade and the valuable nutrition and disease break effect that the pasture phase provides to subsequent cereal crops, interest in the productivity and profitability of medic pasture and livestock systems has increased,” she said.
To evaluate the benefits of livestock integration, the trial compared four systems – low input grazed, low input ungrazed, high input grazed and high input ungrazed.
Medic in the ungrazed systems was left to set seed/senesce – it was not cut for hay, removed, cultivated, burnt nor manured.
“The trial showed that over a range of seasons, integrating livestock into a cropping system improved productivity and profitability, particularly in higher input farming systems,” she said.
Overall, she said diversification into sheep could assist growers to better manage their risk, by reducing the effects caused by seasonal and grain market variability.
Ms Crettenden’s GRDC Update paper is available online at grdc.com.au/resources-and-publications/grdc- update-papers.