Exploring Atypical Stabilization Pathways Using Pool-Based Modeling.
Saran Sohi, Rothamsted Research, Harpenden, AL5 2JQ, United Kingdom
Simulation models that explicitly account for the impact and interaction of soil and environmental variables can assist in predicting the accumulation of C and its rate of turnover. Relevant, verifiable (i.e. measurable) pools of Soil Organic Matter (SOM) provide the most robust basis for elucidating the underlying mechanisms. We have developed a model based around three measurable pools of SOM which can be measured using a density-based fractionation procedure, and verified by extensive chemical characterization. The model has been optimized against measurements of C and N and isotope-tracers in several soils amended with isotope-labeled organic matter. According to recent estimates black C is a much larger component of Soil Organic Carbon (SOC) in typical agricultural soils than previously assumed. Since black C may also be the most stable form of organic C in the soil, the amount of black C in the soil must impact both on the bulk rate of soil C mineralization (turnover) and the extent to which a particular management intervention can alter SOC. Until now our simulations have not accounted explicitly for the effect of black C on the dynamics of each pool. We are now examining how black C is characterized by physical location within the soil matrix, and in order to account for the influence of black C using this model affects C mineralization, and the distribution of charcoal between each of the measured fractions.