DISCRETE SIMULATION MODEL TO STUDY HETEROTROPHIC MICROBIAL ACTIVITY IN SOIL

摘要

The soil heterotrophic microorganisms have been modelled using a discrete simulation methodology that stands on individual-based models. INDISIM-SOM is a simulator that deals with soil microbial activity in terms of its microscopic components. It has been specifically used to study the mineralisation and immobilisation of C and N that takes place in short-term dynamics of soil organic matter, considering that the microorganisms have a key role. The simulation domain is divided into square cells. Amounts of different types of organic compounds identified by polymerised organic C and N, labile organic C and N, and mineral compounds such as NH_4, CO_2 and O_2 are controlled in each spatial cell. The microorganisms are controlled at each time step, using a set of time dependent variables for each biotic element and specific rules for their motion, uptake, metabolism, reproduction, viability and lyses. Different sources of C and N can be used by the microbial elements are identified. The simulation model is calibrated using experimental data from laboratory incubations. The microbial activity is used in order to perform the sensitivity analysis for the soil parameter: the ratio microbial biomass carbon to soil organic carbon.