Microbial growth in soil and nitrogen turnover: Model calibration with laboratory data

A model of soil microorganisms growth limited by carbon and nitrogen sources was calibrated with data from a laboratory incubation experiment (14 d). Microbial C and N, CO2 evolution, mineral N and soluble C were measured in a soil amended (i) with glucose, (ii) with glucose and 15N-labelled ammonium sulphate and iii) in an unamended soil. Predictions of the model agreed well with experimental data on microbial growth in the different conditions. The fraction of total variation explained by the model (R2) was in the range 0.92–0.985 for the different variants of the experiment. Sensitivity analysis of the set of optimized model parameters showed satisfactory variability of their values if experimental data were changed within 10%. Efficiency of substrate uptake by microorganisms (Ys), and efficiency of microbial biosynthesis and maintenance (Ym) were the most sensitive characteristics. Parameter values are discussed in comparison with published ones for similar models of microbial growth in soil.