The effect of biologically mediated decay rates on modelling soil carbon sequestration in agricultural settings

Microbial biomass carbon is the most active component of the soil organic carbon that regulates bio-geochemical processes in terrestrial ecosystems. We might expect that the carbon decomposition rate should be related to the microbial population activity whereas some studies in the literature ignore this effect. We explore it on the accuracy of modelling soil carbon (SC) sequestration by developing and comparing two SC models that consider a carrying capacity, maximum microbe population size sustained by available resources in an environment, and limit the growth of the microbial biomass pool. We select the best model in terms of having the best predictive performance through two model selection methods. Our analysis shows that our simpler model outperforms the commonly used complex SC model (RothC), resulting in more accurate predictions. Also, considering microbial population growth improves model accuracy in the presence of a large dataset.