DPIRD research addresses trade-off between emissions and profitability
Project name
This research was partly funded by the Western Australian Farming Systems Project, a GRDC and DPIRD co-investment
GRDC Code
DAW2204-003RTX
Over the past few decades there has been an increasing awareness of the impact of agricultural inputs, such as nitrogen fertiliser and lime, on greenhouse gas emissions and a growing desire to reduce emissions.
Fertiliser nitrogen is essential to productive broadacre farming of WA’s ancient soils and the usage of it has increased over the past few decades.
Alongside soil fertility, soil acidity poses a significant challenge to agricultural sustainability across vast expanses of Western Australia’s Wheatbelt soils.
Lime application effectively manages soil acidity but, like nitrogen fertiliser, the amount being applied has increased in recent decades and lime also contributes to emissions.
This creates a dilemma between farm profitability and environmental impact.
As part of the study, detailed data on production inputs, crop diversity, yields, and emissions profiles were collected and analysed.
Insights from Nitrogen strategies
Economic assessments of nitrogen and liming strategies (applying lime to soil to manage acidity) were performed using the EVALUS model and GHG emissions were estimated using PICCC’s Grains Accounting Framework (GAF) tool.
From here, 3 nitrogen application strategies were compared: Agronomic Target (AT), Economic Target (ET), and Constant Rate (CR).
AT aimed to maximise yield through sufficient nitrogen application, ET aimed to maximise gross margin, and CR applied a uniform nitrogen rate annually.
The study also explored seasonal adjusted (Adj) and unadjusted (Unadj) nitrogen options for AT and ET strategies.
Seasonal adjustment of nitrogen meant the nitrogen use efficiency was optimised, especially in the variable rainfall and low soil organic carbon regions.
This proved more profitable and less emitting.
Insights from Liming strategies
DPIRD Research Scientist Sud Kharel said bio-economic simulations compared farm profitability and emissions for various liming strategies over 30 years in different locations.
“Liming consistently led to higher profitability, despite variations across regions.
It effectively managed soil acidity, preventing yield reductions and the need to drop crops that are sensitive to acidity, such as canola and pulses, from the rotation.
In the higher rainfall regions, not liming shifted the crop rotation from a lower emitting crop to higher emitting livestock.
This caused liming to be a less emitting option in these areas.” he said.
This research highlights the importance of considering both economic viability and environmental implications when designing nitrogen and lime application strategies.
Seasonal adjustment of nitrogen and strategic liming practices emerge as effective approaches to maximise crop yields while minimising impacts of GHG emissions and soil acidity.
The findings provide valuable insights for sustainable dryland farming in Western Australia and beyond.
Continued research and implementation of optimised soil management techniques are crucial for ensuring long-term agricultural sustainability and environmental stewardship.
More information
Click here to read more about Sud Kharel
Click here to read more on the WAFS project
Contact
Sud Kharel
DPIRD Research Scientist
E: Sud.Kharel@dpird.wa.gov.au
P: 9368 3321