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

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 Microb...

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Bibliographic Details
Published in:Environmental pollution (1987) 2019-04, Vol.247, p.812
Main Authors: Bhanja, Soumendra N, Wang, Junye, Shrestha, Narayan K, Zhang, Xiaokun
Format: Article
Language:English
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
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Summary: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.
ISSN:1873-6424