Microbial kinetics and thermodynamic (MKT) processes for soil organic matter decomposition and dynamic oxidation-reduction potential: Model descriptions and applications to soil N 2 O emissions

• Published in: Environmental pollution (1987) Vol. 247; p. 812
• Main Authors: Bhanja, Soumendra N, Wang, Junye, Shrestha, Narayan K, Zhang, Xiaokun
• Format: Journal Article
• Language: English
• Published: England 01.04.2019
• Subjects: Air Pollutants - analysis; Biodegradation, Environmental; Carbon; Environment; Environmental Monitoring; Kinetics; Nitrogen Dioxide - analysis; Nitrous Oxide - analysis; Oxidation-Reduction; Saskatchewan; Soil - chemistry; Soil Microbiology; Thermodynamics; Water; Saskatchewan; Soil biogeochemical cycle modelling; Soil oxidation-reduction potential dynamics; Soil organic matter decomposition modelling; Soil NO emission; Soil greenhouse gas emission modelling
• ISSN: 1873-6424

A conversion of the global terrestrial carbon sink to a source is critically dependent on the microbially mediated decomposition of soil organic matter (SOM). We have developed a detailed, process-based, mechanistic model for simulating SOM decomposition and its associated processes, based on Microbial Kinetics and Thermodynamics, called the MKT model. We formulated the sequential oxidation-reduction potential (ORP) and chemical reactions undergoing at the soil-water zone using dual Michaelis-Menten kinetics. Soil environmental variables, as required in the MKT model, are simulated using one of the most widely used watershed-scale models - the soil water assessment tool (SWAT). The MKT model was calibrated and validated using field-scale data of soil temperature, soil moisture, and N O emissions from three locations in the province of Saskatchewan, Canada. The model evaluation statistics show good performance of the MKT model for daily soil N O simulations. The results show that the proposed MKT model can perform better than the more widely used process-based and SWAT-based models for soil N O simulations. This is because the multiple processes of microbial activities and environmental constraints, which govern the availability of substrates to enzymes were explicitly represented. Most importantly, the MKT model represents a step forward from conceptual carbon pools at varying rates.