Heterotrophic nitrification in soils

The contribution of heterotrophic microorganisms to nitrification processes in soils of different types under natural vegetation and in agrocenoses wa s estimated. The intensity of heterotrophic nitrification was higher in soi ls of native biocenoses than in croplands. In cultivated soils, the populat ion of autotrophic nitrifying bacteria increased. They had a dominant role in the production of nitrates (84 to 99%). The heterotrophic nitrification was more active in soddy-podzolic soil of the wood sorrel spruce forest (Pi netum oxalidosum). In the gray forest soil of the birch forest and in the v irgin dark chestnut soil, heterotrophic microorganisms were responsible for the production of 33-46% of nitrates. In leached brunizems of the pine and oak forests and in soils of different-aged laylands in the forb-grass prai rie, the participation of heterotrophic microorganisms in nitrification was estimated at 25%. The additional application of nitrogen fertilizers 2-5 t imes decreased the activity of heterotrophic organisms.