Energetic limitations on the microbial growth act as additional constraints to the decomposition of soil organic matter (SOM). The coupling of Gibbs energy in anabolic (biosynthesis) and catabolic biochemical reactions form a basis for the energy requirements of microorganisms growth. In aerobic decomposition processes, metabolic products as a results of oxidative substrate are CO2 and H2O, furthermore, the substrate act as the carbon as well as the energy source. The global growth reaction is often associated with negative enthalpy change which result in the heat release from the system. This heat can be measured using micro-Calorimeter. In this study, we formulate a mass-energy balance model for SOM decomposition to explain the observed heat released. We also synthesize the thermodynamic based efficiency measures in the context of SOM decomposition and provide a general theoretical base for estimating biomass yield from routine thermodynamic measurement.
Decomposition model: Substrate added is glucose (\({C_6H_{12}O_6}\)) and average formula for biomass is \(CH_{1.8}O_{0.5}N_{0.2}\); \(\mu\), \(m_s\), and \(k_d\) are the specific growth rate, the maintenance rate, and the mortality of the microorganisms respectively.