Identification of areas within Australia with thepotential to enhance soil carbon content

Soil Sciences not elsewhere classified

Baldock, Jeff ; Grundy, Mike ; Wilson, Peter ; Jacquier, David ; Griffin, Ted ; Chapman, Greg ; Hall, James ; Maschmedt, David ; Crawford, Doug ; Hill, Jason ; Kidd, Darren

Department of Agriculture, Fisheries and Forestry

RP-ID  :  EP121592

学科分类：地球科学(综合)

澳大利亚|英语

来源: CSIRO Research Publications Repository

【 摘 要 】

Much interest exists in defining the content of organic carbon in Australian agricultural soils and the capacity to increase soil carbon through altered agricultural management strategies. This interest arises because of the important contributions that organic matter, and thus organic carbon and its associated elements, make to both productivity and the potential for mitigating greenhouse gas emissions. The objective of this reportwas to develop an objective spatial assessment of the potential of Australian agricultural soils to capture and retain additional organic carbon using existing environmental, soil and land-use data. The organic carbon content of a soil is defined by the balance of inputs and losses. Soils with the greatest potential to capture additional organic carbon will be those that meet the following criteria:• a significant loss of carbon occurred on initiation of agriculture,• the capacity exists to support additional plant biomass production and thusenhance inputs of carbon to the soil, and• a capability exists to protect added carbon against decomposition.Three separate indices, one for each of the identified criteria, were created. The indices were labelled respectively as: a Capacity Index, a Carbon Gains Index and a Carbon Losses Index. The three indices were combined to provide an overall Potential Capability Index that defined the relative potential of a soil to capture additional organic carbon beyond that which it currently contains. The assessment was completed by combining spatial data layers of key variables within the Multi-Criteria Analysis Shell (MCAS) produced by the Bureau of Rural Sciences (http://adl.brs.gov.au/mcass/index.html).The Capacity Index provided an assessment of how much organic carbon had been lost from the soil since agriculture was initiated. The index incorporated time since clearing, the nature of the agricultural system employed (cropping versus pasture), and the soil clay content. The Carbon Gains Index assessed the potential for increasing the input of organic carbon to the soil. It used data for the amount and distribution of annual rainfall, soil erosivity to provide an indicator of the usefulness of rain in creating plant biomass, and grazing intensity to assess the potential return of plant residues to soils. The Carbon Losses Index was used to assess the ability of a soil to protect added carbon against loss principally through biological decomposition. The Carbon Losses Index used data layers for soil clay content, previous land use, annual temperature and the Prescott Index.All data were input into MCAS as classified spatial data layers and then added or multiplied together to produce the three initial indices. The final Potential Capability Index was created by multiplying the Capacity Index by 2 (to reflect its greater importance than the other two indices) and adding it to the sum of the Carbon Gains and Carbon Losses Indices. In general, soils with a long history of agricultural production (particularly cropproduction), significant clay contents and high amounts of low intensity rainfall have received higher rankings for their potential to increase soil organic carbon content. Sandy soils cleared recently and used predominantly for pasture production in regions with low rainfall have received lower rankings.