Australian net (1950s–1990) soil organic carbon erosion: implications for CO2 emission and land–atmosphere modelling

A. Chappell, N. P. Webb, R. A. Viscarra Rossel, E. Bui
2014 Biogeosciences Discussions  
The debate about soil erosion substantially offsetting fossil fuel emissions and acting as an important source or sink of CO<sub>2</sub> remains unresolved. There is little historical land use and management context to this debate which is central to Australia's recent past of European settlement, agricultural expansion and agriculturally-induced soil erosion. We use "catchment" scale (&sim;25 km<sup>2</sup>) estimates of <sup>137</sup>Cs-derived net (1950s–1990) soil redistribution of all
more » ... sses (wind, water and tillage) to calculate the net soil organic carbon (SOC) redistribution across Australia. We approximate the selective removal of SOC at net eroding locations and SOC enrichment of transported sediment and net depositional locations. We map net (1950s–1990) SOC redistribtion across Australia and estimate erosion by all processes &sim;4 Tg SOC yr<sup>−1</sup> which represents a~loss of &sim;2% of the total carbon stock (0–10 cm) of Australia. Assuming this net SOC loss is mineralised, the flux (&sim;15 Tg CO<sub>2</sub>-e yr<sup>−1</sup>) represents an omitted 12% of CO<sub>2</sub>-e emissions from all carbon pools in Australia. Although a small source of uncertainty in the Australian carbon budget, the mass flux interacts with energy and water fluxes and its omission from land surface models likely creates more uncertainty than has been previously recognised.
doi:10.5194/bgd-11-6793-2014 fatcat:nqejmfp2e5cgrjh5jebteedckm