Generalizing Microbial Parameters in Soil Biogeochemical Models: Insights From a Multi-Site Incubation Experiment

Incorporating microbial processes into soil biogeochemical models has received growing interest. However, determining the parameters that govern microbially driven biogeochemical processes typically requires case-specific model calibration in various soil and ecosystem types. Here each case refers to an independent and individual experimental unit subjected to repeated measurements. Using the Microbial-ENzyme Decomposition model, this study aimed to test whether a common set of microbially-relevant parameters (i.e., generalized parameters) could be obtained across multiple cases based on a two-year incubation experiment in which soil samples of four distinct soil series (i.e., Coland, Kesswick, Westmoreland, and Etowah) collected from forest and grassland were subjected to cellulose or no cellulose amendment. Results showed that a common set of parameters controlling microbial growth and maintenance as well as extracellular enzyme production and turnover could be generalized at the soil series level but not land cover type. This indicates that microbial model developments need to prioritize soil series type over plant functional types when implemented across various sites. This study also suggests that, in addition to heterotrophic respiration and microbial biomass data, extracellular enzyme data sets are needed to achieve reliable microbial-relevant parameters for large-scale soil model projections. Incorporating soil microbial processes can improve soil model projections, and achieving a common set of microbial parameters across sites remains less studied. Based on a two-year soil incubation data set, this study showed that key microbial parameters could be generalized at the soil series level (four distinct soil series) but not land cover type (forest vs. grassland). The common set of parameters includes those processes controlling microbial growth and maintenance as well as extracellular enzyme production and turnover. This study informs that future microbial model developments prioritize soil series type over plant functional types when implemented across various sites. Besides the heterotrophic respiration and microbial biomass data, soil extracellular enzyme data sets are particularly needed to achieve reliable microbial-relevant parameters for large-scale soil model projections. Generalizing microbial relevant parameters in soil biogeochemical models were achieved at soil series level but not plant type The common set of parameters includes processes of microbial growth and maintenance as well as extracellular enzyme production and turnover Soil heterotrophic respiration, microbial biomass data, and extracellular enzyme data sets are needed for large-scale soil model projections