Nitrous Oxide Emissions are Low from Sandy Cropping Soils in a Semiarid Region in Australia
Tracks
| Wednesday, July 23, 2025 |
| 9:12 AM - 9:24 AM |
Overview
Speaker
Dr Louise Barton
Associate Professor
The University of Western Australia
Nitrous Oxide Emissions are Low from Sandy Cropping Soils in a Semiarid Region in Australia
Abstract
Nitrous oxide emissions are low from sandy cropping soils in a semiarid region in Australia
Louise Barton
School of Agriculture and Environment, The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia, 6009, louise.barton@uwa.edu.au
Achieving net zero targets requires understanding the contribution of agricultural production to greenhouse gas (GHG) emissions. Soil nitrous oxide (N₂O) emissions can be a significant source of on-farm GHG from cropping systems where nitrogen fertiliser is applied. International default factors estimate that 1% of applied nitrogen fertiliser will be emitted as N₂O, regardless of soil texture. Western Australia’s grainbelt covers 7 million hectares of arable land. The region’s soils originate from highly weathered parent materials, are predominantly coarse-textured, and are low in soil organic carbon (SOC). With a semi-arid climate characterised by winter-dominant rainfall and hot, dry summers, crop cultivation is restricted to the winter months, leaving soils fallow between crops. A decade of field-based measurements using automated chambers at three locations found soil N₂O emissions were minimal (0.04–0.27 kg N ha⁻¹ yr⁻¹) in the Western Australian grainbelt, representing less than 0.12% of applied nitrogen fertiliser. Incorporating grain legumes into crop rotations did not lead to increased N₂O emissions during the growing season or post-harvest. While increasing SOC increased soil N₂O emissions, losses remained below 0.12% of applied nitrogen. Measuring and mitigating N₂O emissions from sandy soils in the region is challenging, as 55% to 85% of annual emissions occurred during the dry fallow in response to summer rainfall rather than direct nitrogen fertiliser application. Strategies that regulate soil nitrogen supply from nitrification following soil wetting or immobilise excess inorganic nitrogen through microbial or plant uptake could decrease the availability of nitrogen for subsequent N₂O losses. Our findings indicate that improving the efficiency of the nitrification process by increasing soil pH through liming can decrease N₂O emissions from acidic, sandy soils after summer rainfall. Improved quantification of soil N₂O fluxes in this region has demonstrated that on-farm soil N₂O emissions are low from grain production on sandy soils.
Louise Barton
School of Agriculture and Environment, The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia, 6009, louise.barton@uwa.edu.au
Achieving net zero targets requires understanding the contribution of agricultural production to greenhouse gas (GHG) emissions. Soil nitrous oxide (N₂O) emissions can be a significant source of on-farm GHG from cropping systems where nitrogen fertiliser is applied. International default factors estimate that 1% of applied nitrogen fertiliser will be emitted as N₂O, regardless of soil texture. Western Australia’s grainbelt covers 7 million hectares of arable land. The region’s soils originate from highly weathered parent materials, are predominantly coarse-textured, and are low in soil organic carbon (SOC). With a semi-arid climate characterised by winter-dominant rainfall and hot, dry summers, crop cultivation is restricted to the winter months, leaving soils fallow between crops. A decade of field-based measurements using automated chambers at three locations found soil N₂O emissions were minimal (0.04–0.27 kg N ha⁻¹ yr⁻¹) in the Western Australian grainbelt, representing less than 0.12% of applied nitrogen fertiliser. Incorporating grain legumes into crop rotations did not lead to increased N₂O emissions during the growing season or post-harvest. While increasing SOC increased soil N₂O emissions, losses remained below 0.12% of applied nitrogen. Measuring and mitigating N₂O emissions from sandy soils in the region is challenging, as 55% to 85% of annual emissions occurred during the dry fallow in response to summer rainfall rather than direct nitrogen fertiliser application. Strategies that regulate soil nitrogen supply from nitrification following soil wetting or immobilise excess inorganic nitrogen through microbial or plant uptake could decrease the availability of nitrogen for subsequent N₂O losses. Our findings indicate that improving the efficiency of the nitrification process by increasing soil pH through liming can decrease N₂O emissions from acidic, sandy soils after summer rainfall. Improved quantification of soil N₂O fluxes in this region has demonstrated that on-farm soil N₂O emissions are low from grain production on sandy soils.
Biography
Louise Barton an Associate Professor at The University of Western Australia, and has spent much of her professional career researching soil nitrogen cycling in various land-uses. Her research has focused on developing land-management strategies that minimise undesirable losses of nitrogen, such as nitrous oxide emissions and nitrate leaching, into the environment. Louise’s understanding of soil nitrogen cycling has been achieved by seeking to understand the interactions between soil biology, chemistry and physics on the fate of nitrogen in agriculture, forestry, and horticulture. Throughout her career Louise has enjoyed working collaboratively with Industry to ensure her research results in practical outcomes for all.
