Soil organic carbon for different depths in a sequence of disturbance and reference sites

Abstract

Soil organic carbon (SOC) at depth can be destabilized by various climatic or anthropogenic factors, so it is necessary to characterize it properly. The modeling of the vertical distribution of the SOC has generally been approximated using empirical approaches to mathematical model adjustments. This scheme is used to characterize the SOC at depth in different land uses and it is analyzed, but with an incremental approach of introducing constraints in the experimental adjustment, by nonlinear regression. The boundary conditions introduced (for zero and infinity depth) allow parameterizing models with physicochemical and biological sense. The best models selected in the progressive adjustment process were reviewed to analyze the congruence of their parameters, arguing that their bases are not clear to characterize the dynamics of the SOC. As an alternative, a reaction kinetics of variable order n was introduced in the experimental settings, obtaining good results (R2 > 0.99) and clear patterns in the relationships between order n and the kn reaction rate of the alternative model.