[Nonsymbiotic nitrogen fixation in the podzolic soils of the Kola Peninsula]

Non-symbiotic nitrogen fixation was studied in virgin and cultivated podzol soils of the Kola Peninsula by the acetylene and isotope techniques. The activity of nitrogen fixation varied sharply in cultivated soils due to degradation of plant residues and the action of plant root secretion. No significant changes were observed in the activity of nitrogen fixation within the vegetative period in virgin soils. Less than 1 kg of nitrogen per hectare was accumulated in soils as a result of its non-symbiotic fixation during the vegetative periods of 1976--1977.