Abstract: A computer model of chemical and microbiological production processes of plant biomass, soil microorganisms, and nutrients in the rhizosphere—a complex heterogeneous polydisperse multifactor natural system—has been developed, which makes it possible to determine the growth of the biomass of agricultural crops and the rhizosphere productivity. Parametric identification and the adequacy verification of the developed mathematical model have been carried out using the available experimental data sample on the growth of Krasnoufimskaya-100 spring wheat. Computational experiments have been carried out to determine the safe life of agricultural lands when fertilizers with varying degrees of heavy metal content are applied. © 2020, Pleiades Publishing, Ltd.