NITROGEN IMMOBILIZATION AND REMINERALIZATION BY MICROORGANISMS AND NITROGEN UPTAKE BY PLANTS - INTERACTIONS AND RATE CALCULATIONS

The interactions between processes of the nitrogen cycle and nitrogen uptake by plants of winter wheat on an arable gray forest soil were examined. Nitrogen immobilized by microorganisms and inorganic nitrogen demonstrated opposite behavior: Microbial N increased while inorganic N decreased. Nitrogen uptake by plants was favored by mineralization of microbial nitrogen. To describe nitrogen immobilization by microorganisms, remineralization, gaseous losses, and nitrogen uptake by plants, a first-order model was used. In arable gray forest soil at least 70% of N-15 in the plant crop was derived from remineralized microbial nitrogen. Microbial biomass was found to be one of the main sources of nitrogen in plant nutrition and the important factor controlling nitrogen uptake by plants.