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Two major opportunities for agricultural soils to contribute toward South Australia’s low carbon economy are:
(1) soil organic carbon (SOC) sequestration; and,
(2) enhanced nitrogen fertiliser use efficiency.
Assessment of the carbon sequestration opportunity for all South Australian agricultural soils was undertaken using data from DEW’s State Soil and Land Information Framework and the sites currently being formatted for inclusion in the Australian Soil Resource Information System (ASRIS). Soils that have been modified through the addition of subsoil clay to sandy topsoil have been identified as having a large carbon sequestration opportunity, potentially just over 1,000,000 t CO2-e / yr for 25 years. Furthermore, recent field data suggests there are significant opportunities to improve Nitrogen (N) fertiliser efficiency through clay modification and in long-term no-till cropping systems, with a potential abatement of 80,000 t CO2-e/year.
This project undertook a desktop analysis to: (1) collate, reanalyse and conceptualise existing carbon and nitrogen data for clay modified soils; and (2) identify gaps in current knowledge, identify available models, and assess their ’fitness’ for clay modified soils.
A road-map to support the opportunity for carbon sequestration and N2O reduction was developed to improve the knowledge base required to inform agricultural carbon offset policy and landholder adoption. Next steps will be identified providing the basis for a number of potential ‘follow-on’ projects including the soil modification component of CRC for High Performance Soils, and modifiying existing or developing a new soil carbon methodology under the Emissions Reduction Fund.
