[The nitrogen fixing activity of actinomycetes in the dark chestnut soil of Northern Kazakhstan].

About 250 strains of actinomycetes have been isolated from dark chestnut soil of the Northern Kazakhstan in crop rotation. Nitrogen fixing actinomycetes constituted 12% of the total number. Their productivity was rather low: from 0.11 o 1.77 mgN2/g of assimilated sucrose. But since their number is high, these microorganisms may play an important role in fixation of molecular nitrogen and maintenance of nitrogen equilibrium in soil during crop rotation.