Dmitry Vyacheslavovich Dubovik

The humus state of gray forest soil formed on loess-like loams on the slopes of the northern and southern exposures at slopes of 1, 3, 5° was studied. Soil samples were taken in sections laid in the middle part of the horizon (Apax, A1, A1A2, B), in three-fold repetition. The determination of organic carbon and the fractional group composition of humus was carried out according to the scheme of I.V. Tyurin, modified by V.V. Ponomareva and T.A. Plotnikova. The content of mobile humic substances was studied in 0,1n NaOH extraction from soil without decalcification in the modification of the V.V. Dokuchaev Soil Institute with preliminary composting.
Gross nitrogen was determined by the Ginzburg wet salting method with ammonia distillation according to Kjeldahl. It was found that the content of organic carbon in gray forest soil was higher on the northern slope than on the south- ern one. At the same time, the process of mineralization of organic matter occurs faster in the soil of the southern slope, which is due to a narrower ratio of C:N compared to the soil of the northern slope. It was revealed that for gray forest soil, the degree of mobility of humic substances depends more on the exposure of the slope than on its steepness. At the same time, the ratio of organic matter components in the studied soils is determined by agroeco- logical conditions, therefore, the regulation of the qualitative and quantitative composition of organic matter must be carried out taking them into account.