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On the case of low-emission crop rotations

Sud Kharel is modelling greenhouse gas emissions for a major Western Australian farming systems project to determine scenarios where growers can profitably achieve low-emission crop rotations.
Photo: Evan Collis

Sacrificing profit is a concern for growers considering low-emission cropping systems, but preliminary scenario modelling shows this might not be the case.

Sud Kharel is a bio-economic modeller with Western Australia’s Department of Primary Industries and Regional Development (DPIRD) investigating the impact of future climate projections on farm economics and markets. He and the team he works with are identifying tools, systems and strategies for growers to remain profitable or even increase their profitability, as pressure grows to lower greenhouse gas (GHG) emissions.

“Farmers are at the forefront of climate change and, in this respect, have the power to really affect change in GHG emissions,” Mr Kharel says.

DPIRD’s Industry and Economic Analysis, Farming System Innovation and Agriculture Climate Resilience teams have developed the EVALUS™ – Economic Valuation of Alternative Land Use Sequences model. It is a bio-economic model incorporating historical climate data, input and commodity price data and crop, livestock and pasture biological and production management parameters to simulate paddock production, profit and emission outcomes.

The tool has enabled the team to examine mixed-farming systems containing stock – high GHG emitters – in the FutureSheep Project funded by SheepLinks, a joint funding initiative of DPIRD and Meat & Livestock Australia’s Donor Company.

Since March 2023, the team has been working with DPIRD’s GRDC-supported, large ‘Farming Systems’ project to use the data generated to model and validate scenarios in cropping systems.

Lower-emission strategies may not lead to lower profitability. Changes can be made to rotations, management and to crop inputs without forgoing profits.

Nitrogen fertilisers are the single-biggest input cost for growers and can significantly boost yields in water-limited environments, but their use is under scrutiny due to the large role they play in GHG emissions.

“Nitrogen fertilisers also have large pre-farm – or scope three – emissions due to the way in which they are manufactured. So, both the type and amount of nitrogen fertiliser a grower uses can influence GHG emissions,” Mr Kharel says.

“The model will be used to investigate if there are fertiliser, rotation and lime application strategies that reduce associated emissions.”

Crop type and rotation sequence can also be altered to reduce GHG emissions. For example, canola is an intensive crop with high input demand and therefore GHG emissions, while legumes emit much less as they can fix their own nitrogen. To reduce emissions, growers might be able to optimise the mix of these crops in their rotations.

“Adoption of new technologies may also help reduce GHGs. For example, controlled traffic can lower fuel usage and zoning a farm can optimise fertiliser, herbicide and pesticide emissions, leading not only to reducing GHGs but achieving economic benefits.

“Using the EVALUS™ model, we will investigate these parameters through various scenarios and then use data from the large WA ‘Farming Systems’ trial to validate our findings in the three different environments the systems trials are based in.

“Preliminary modelling indicates that crop-dominant land use sequences are most profitable in the northern grainbelt, while mixed crop/livestock production systems are more profitable in the southern grainbelt. However, a handful of locations display no strong profit advantage. In those locations with no profit advantage, reducing sheep lowered the emissions while maintaining profitability.

“Over the life of the ‘Farming Systems’ project, we aim to use modelling to generate a list of options that growers can customise for their situation to lower their GHG emissions.”

Why should growers prioritise low-emission cropping systems?

  1. Climate change mitigation and global responsibility
    • Agriculture is a significant contributor to greenhouse gas (GHG) emissions. By taking steps to reduce emissions, growers contribute to the global effort to combat climate change.
  2. Regulatory compliance
    • Governments and international bodies are implementing stricter regulations on agricultural emissions. Compliance ensures access to certain markets and avoids possible penalties.
  3. Resource efficiency and reduced input costs
    • Sustainable practices can lead to more-efficient resource use, including water and fertiliser, and result in cost savings.
  4. Resilience to climatic extremes
    • Climate-smart practices can enhance a farm’s resilience to extreme weather conditions such as drought and frost.
  5. Improved soil health and enhanced crop yield and quality
    • Reviewing rotation and increasing legumes may increase soil health and enhance crop yield and quality at the same time as reducing GHGs.
  6. Market demand and consumer preference
    • Consumers are increasingly interested in product provenance and sustainable production. Meeting these demands can create market opportunities.
  7. Innovation and technological advances
    • Embracing emission reduction strategies encourages the adoption of innovative technologies and practices, which can increase efficiency and productivity.
  8. Access to finance
    • Climate change might affect banks’ lending practices because higher emission businesses might have limited access to certain markets for produce. Businesses that can clearly demonstrate that they are working to reduce their GHG emissions might be preferred for loans.

More information: Sud Kharel,

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