Livestock bring high gains to low rainfall farming systems

STUDY: SARDI researcher Jessica Crettenden, with Brendan Wallis, spoke about the long-term impact of livestock study at the GRDC Grains Research Update in Adelaide. Picture: Supplied

STUDY: SARDI researcher Jessica Crettenden, with Brendan Wallis, spoke about the long-term impact of livestock study at the GRDC Grains Research Update in Adelaide. Picture: Supplied

A nine-year study of the impact of livestock on paddock health and farm productivity in a low rainfall environment at Minnipa has revealed that grazing generates multiple benefits for mixed enterprises.

The study demonstrated that 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 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, which began in 2008, was undertaken by the South Australian Research and Development Institute (SARDI) as part of the Grains Research and Development Corporation’s (GRDC) Grain and Graze 3 research investment.

SARDI researcher Jessica Crettenden said the trial also tested whether productivity could be improved under a higher input system of higher fertiliser and seeding rates, establishment of improved pasture compared to a lower input and more traditional system of 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 can 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 brings into the business.

“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 at the Minnipa Agricultural Centre 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 or 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,” Ms Crettenden said.

“Over the nine years, taking into account both the cropping and livestock systems, the average gross margin of each treatment was $244 for low input ungrazed, $295 for low input grazed, $293 for high input ungrazed, and $395 for high input grazed.

“The two higher input systems had 0.55 tonne/ha greater wheat grain yield than the lower input systems, and the grazed systems had 0.1 t/ha more grain yield on average.”

Ms Crettenden said grazed treatments appeared to have lowered snail and mouse populations, increased ground cover outside of the growing season and reduced summer weed height and density.

She said diversification into sheep could assist growers to better manage their risk by reducing the effects caused by seasonal and grain market variability.

“Livestock are also a reliable source of income in years when yields or grain prices are low, and recently have been proving they are as profitable as cropping gross margins, even in average years.”

The high input system carried more than twice the stocking rate as the low input system over the trial period and was more productive in both the cropping and pasture rotations.

“This indicates that increased inputs into low rainfall mixed farming systems could be more productive and lucrative than they currently are, on the Eyre Peninsula at least,” Ms Crettenden said.

“The decision to increase input rate and subsequent costs will, however, depend on the grower’s attitude to risk and whether their business can cope with extra input costs if the season is unfavourable, and for how many seasons, versus having a system set up to capitalise better on a good year.

“Maintaining a degree of flexibility to respond to seasons, by nitrogen top-dressing or grazing a crop, and markets (keep more ewe lambs or feed grain to stock) is a strategy to reduce risk.

“Decisions must be made early to optimise the outcome before prices change or an opportunity is missed.”

Ms Crettenden’s GRDC Grains Research Update paper can be viewed via https://grdc.com.au/resources-and-publications/grdc-update-papers.

More information about the Grain and Graze initiative can be found at http://www.grainandgraze3.com.au/.