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Abstract

In all solonetzes under the study, the ammonifying microflora predominated over the amylolytic one. On the solonetz of fine chestnut, the maximum number of ammonifying microorganisms was observed in horizon A (16.0×106 CFU/g), the number of ammonifying microorganisms decreased sharply to the lower horizon. Cellulose-depleting actinomycetes in the upper horizons prevailed 2-21.5 times over cellulose-destroying fungi, this is explained by the fact that plant residues are decomposed mainly by actinomycetes on poor soils. On solonetz medium-chestnut, the maximum abundance of microorganisms was observed in the humusaccumulative horizon (2.5×106 CFU/g). The number of amylolytic bacteria was maximal in horizon B (2×106 CFU/g). Only cellulose-destroying fungi were observed of cellulose-destroying microorganisms, the number of which does not vary with depth. On the dark chestnut incomplete, dark chestnut shallow and darkchestnut medium-thick carbonate soils, the maximum number of amylolytic microorganisms is observed in the humus accumulative horizon. The number of these microorganisms decreased with depth. They were followed by heterotrophic bacteria whose maximum abundance was observed in the horizon B. Of cellulosedecomposing microorganisms on dark chestnut incomplete and dark chestnut shallow soils, actinomycetes predominated over fungi 2-3 times in horizon A, in the underlying horizons cellulose-disrupting actinomycetes were not observed, however, the number of fungi with depth did not change (10×103 CFU/g). The investigated soils of Northern Kazakhstan (solonchaks, solonetzes, dark chestnut, chestnut soils and chernozems) differed in the number and composition of microbial groups. When analyzing on various nutrient media, there is a tendency where the maximum number of microorganisms is concentrated in the upper humus-accumulative horizon. With depth, the number of microorganisms reduces, which is believed to be because of the lack of organic substances and oxygen.