Labile organic matter and fertility of chernozems

Soil organic matter can be divided into stable and labile, with the latter directly supporting plant growth and development during the growing season. To restore soil fertility and ensure high productivity of agrocenoses, a certain ratio between the labile and stable parts of humus must be maintained. The purpose of this study was to determine the content of labile organic matter under different tillage and fertilisation options and to establish the optimal ratio between their content and the content of total carbon, based on which to develop measures to restore and improve the fertility of chernozem soils. In stationary experiments, the study investigated the impact of the intensity of chernozem use, its cultivation and fertilisation systems on the humus state of the amount of labile organic matter and its ratio to humus carbon. Field research, laboratory method of soil sample analysis, systematisation, analysis, and generalisation were used in the study. The soil samples were analysed for humus content according to DSTU 4289:2004 and labile organic matter content according to DSTU 4732:2007. When chernozems are ploughed up, labile organic matter is mineralised the most and their share in humus decreases, while when arable land is converted to fallow land, it is restored the fastest. Minimising tillage systems and applying organic and mineral fertilisers increases the amount of labile organic matter in the humus of chernozems. The use of no-till for sixteen years resulted in a 0.13% increase in humus content, and a 0.53% increase over forty-two years compared to ploughing. The application of organo-mineral fertiliser increased the ratio of labile organic matter carbon content to total carbon content compared to the unfertilised variants. A strong correlation was found between the content of labile organic matter in chernozems and the yield of winter wheat and maize. The practical significance of the research results is to minimise the fertiliser rate and the C:N ratio to ensure gross crop yields and restore soil fertility