Professor Terry Rose from Southern Cross University is leading a Soil CRC project to investigate changes in soil resilience and carbon stocks under a range of farming practices.
“Many farmers are looking to build their soil resilience to sustainably improve productivity in an increasingly variable climate, and increasing the range and diversity of plant species grown in rotation may be one way to do this,” said Professor Rose.
This research builds on a previous Soil CRC project, ‘Plant-based solutions to improve soil performance’, which assessed a range of agronomic strategies to increase plant diversity in cropping systems, including crop rotation, intercropping, temporary intercropping, pasture (ley) phases and cover cropping.
“While the impacts on short-term changes to soil function, soil water balances and crop yields have been quantified, the longer-term impacts of these strategies on soil resilience and soil carbon dynamics, as well as productivity, remain unknown.
“The project is using existing long-term field trials to investigate how much organic material from cover crop and intercrop species is stabilised in soil and how it contributes to soil aggregation,” Professor Rose said.
Four grower groups are participating in the project, managing field sites across Australia:
- Birchip Cropping Group in Victoria are leading a trial to examine changes in soil resilience and carbon
- Herbert Cane Productivity Services in Queensland are delivering a trial that will measure the reduction in fertiliser use in cane crops following mixed species cover crops
- Riverine Plains in Victoria and Central West Farming Systems (CWFS) in New South Wales are examining plant diversity in cropping systems to enhance soil function and resilience in the medium term (four to seven years).
Photos from the CWFS site (L-R): intercrop; canola crop emergence; CWFS’s Trials Agronomist Chiara Stommel and CEO Diana Fear on site at a CWFS field day in 2024.
Photos from the Riverine Plains site (L-R): vetch-wheat temporary intercrop; pea-canola intercrop; summer cover crop.
The project began in 2023 and is now into its third growing season. Field data from the 2024 summer season has been collated and the 2025 winter crops have been sown.
The treatments used across both the earlier project and this one are yet to improve soil health or carbon. This is likely because the summer cover crops or temporary intercropping have not created a large amount of additional biomass. Conversely, significant yield penalties have not been seen either.
Moving forward, the project team will explore other measures related to soil resilience, such as disease loads, aggregation, infiltration and nitrogen fixation.
“Building soil carbon, health and resilience takes time. Due to the long-term nature of these trials, we expect to see improvements as the project progresses,” Professor Rose said.
“We’re ultimately working to identify agronomic interventions that farmers can use to increase plant diversity in cropping systems and thereby improve soil resilience to sustain or increase productivity.”
The project will continue until 2026.
Project participants
- Southern Cross University
- NSW Department of Primary Industries and Regional Development
- Central West Farming Systems
- Riverine Plains
- Birchip Cropping Group
- Herbert Cane Productivity Services
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Main image: Professor Terry Rose talking to farmers and agronomists at a CWFS field day in October 2024 (Source: Terry Rose, Southern Cross University).