Multi-species cover cropping is the most effective way to improve soil health, and has the potential to reverse damage caused by years of conventional full-tillage farming practices, according to a report by Nuffield scholar Alex Nixon.
The method also helps to boost the sustainability of broadacre dryland cropping according to analysis of global research on sustainable farm management practices.
Supported by the Grains Research and Development Corporation, Mr Nixon researched the use of cover crops around the world, and developed a blueprint for the adoption of the emerging land management practice back home.
A third-generation farmer, Mr Nixon runs a 8500ha cattle and cropping operation near Roma in Queensland and said a desire to leave his property in good condition for future generations motivated his research.
‘‘Successful, sustainable farming businesses depend on the health of their soils. Sown after completion of a cash crop, a multi-species cover crop can greatly enhance soil health by boosting biodiversity, ground cover and soil organic matter,’’ he said.
Researching cover crop trials in the United States and a long-term soil conversion in England, Mr Nixon revealed the benefits that cover cropping could have on the amount of organic matter present in soil.
‘‘Field trials conducted in North Carolina and North Dakota revealed that several consecutive years of cover cropping had allowed organic matter to build up from 1.2 per cent to 6.7 per cent,’’ he said.
‘‘The residue from the cover crops slowly breaks down, providing food for microbes and boosting moisture retention, acting like a mulch.’’
Acknowledging that cover cropping in the Australian broadacre sector to date has been largely based on single-species crops, the report reveals that multi-species crops are more beneficial because they avoid the presence of a monoculture and boost microbial diversity and activity.
‘‘Single-species cover crops do enhance ground cover, but by adding even one or two different species into a cover crop the microbial activity can be greatly enhanced, boosting the diversity of the soil ecosystem,’’ Mr Nixon said.
‘‘Upfront costs can be an issue. Cover crop seed is very expensive, as is the investment required for machinery or contract sowing.’’
At Overbury Farms in England, long-term soil conservation had been prioritised over the short-term bank balance, and lower income was being supplemented by other revenue streams.
Mr Nixon’s report recommends that Australian farmers looking to implement a multi-species cover crop regime start small, and consider the frequency and size of cover rotations based on the benefits they can produce.