Transformation of soil organic matter in agricultural and natural ecosystems

Abstract

The results of a long-term stationary study of the transformation of the group and fractional composition of humus in typical chernozem under the influence of anthropogenic (fertilization systems) and natural (fallback) factors are described. The object of the study is typical medium-humus chernozem (Haplic Chernozem [Profundihumic]) heavy loam at two locations. The first location is a multi-year stationary experiment with different fertilization systems (organic, organo-mineral and without fertilizers, but with the leaving of plant residues), The second is a separate fallow plot bordering the experiment, on the territory of the Poltava State Agricultural Experiment Station named after M. I. Vavilov, in the village of Stepne, in the central part of the Eastern Forest-Steppe of Ukraine. It was found that in areas where manure and manure with mineral fertilizers were applied for a long time, the total carbon content in the soil was 3–9% higher compared to areas where only plant residues were left (control). Having analyzed the effect of different fertilization systems and natural vegetation on the fallow, we concluded that their versatile influence the dynamics of humus content in the soil, the degree of humification and the type of humus. It was shown that the long-term use of different fertilization systems, regardless of the doses and ratio of the amount of organic and mineral fertilizers applied, changed the degree of humification to "very high" from "high", which was determined where only plant residues were left (control) and on the fallow. The type of humus in the experimental variants fertilized with manure and mineral fertilizers was determined as "humate", and in the control and fallow – as "fulvate-humate". It was found that the quality of humus, which was determined by the indicators of its group and fractional composition, is related to the fertilization system and the type of land use. According to the ratio of humic and fulvic acids, the optimal option for fertilization was considered to be the application of manure together with plant residues. According to the total content of humic acids in the soil, the leaving of plant residues, destructor and mineral fertilizers; according to the proportion of the fraction of humic acids HA-2 (calcium humates), the optimal option was found to be fallow.