Exploring Atypical Stabilization Pathways Using Pool-Based Modeling

Abstract

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.