Transfer of C and N from the Surface Litter into the Mineral Soil Using Isotopically Labelled Plant Residues in Tracer Studies, South East Queensland Peri-Urban Supersite, Samford, 2013

The conceptual link between surface C inputs and soil C stocks is clear: more inputs leads to more soil C. But our understanding of surface C and N movement into the soil is actually very limited. Surface C moves into the soil through leaching and mixing processes, but it is less certain what proportion of surface C remains in the soil (versus what is lost to the atmosphere as CO2) and for how long and in what pools it resides. Due to the lack of quantitative information on the fate of above-ground C inputs, the current suite of crop-soil models poorly represents the movement of C and N into the soil and their stabilisation within soil fractions. This major gap in our understanding limits our ability to accurately forecast how changes in management practices will affect C sequestration. The research will address this knowledge gap through site-based experimentation, representing a unique and practical opportunity to further our understanding of SOM dynamics, improve modelling capabilities, whilst better understanding how climate and management drive changes in soil C stocks. Experiments will be carried out at the following sites: Samford Ecological Research Station Facility (SERF); Kidman Springs, NT; Brigalow Research Station, QLD; Tamworth (Colorado Farm); Crow's Nest Farm; Kingsthorpe; Longreach Research Station; Belmont Research Station; and Boulia.