Investigating the benefits of multispecies cover crops in low rainfall mixed farming systems.
Project Start Date: July 2021
Project End Date: Feb 2023
Project Funding: Regenerative Agriculture Alliance
Project Collaborators: Southern Cross University
Western Australian cropping systems typically involve a summer fallow kept free of weeds using herbicides. The aim is to conserve soil moisture over summer for subsequent winter crops, but given the low fallow water use efficiencies in WA (i.e. much of the water evaporates), there is an opportunity to use this water to grow multi-species cover crops during the fallow to improve soil health, and possibly improve system productivity.
The project will focus on providing outcomes to benefit cropping systems that focus on winter cash-crop production. A replicated trial will be designed to evaluate the effects of summer cover crops in the South West Western Australia near Wickepin. The trial will include single and multi-species summer cover crops compared to a typical chemical fallow. Measures will include practice profitability and a suite of soil health parameters developed by Southern Cross University. Four on-farm demonstration sites (paired paddocks) will also be established with the same parameters measured.
Trial data, and experiences of growers will be extended to Facey group members and agricultural advisors, through field presentations and discussion papers. It is expected that summer cover crops will protect soils from erosion and evaporation, suppress summer weeds, reduce soil compaction and improve structure, enhance water infiltration and water holding capacity, regulate soil temperatures, add organic matter and stimulate microbial activity, and add nitrogen and prevent it from leaching. However, growers operating in low-rainfall broadacre farming systems, where summer rainfall is scarce and unreliable, are concerned that use of stored soil moisture over summer by cover crops may impact on growth and yields of winter cash crops. The trials and demonstration sites proposed will assess this. Without tangible evidence on the economic or environmental benefits of summer cover crops in the low rainfall broadacre farming regions of WA growers will not adopt these practices, which may be a missed opportunity.