Sorption of labile humus substances by structural-aggregate fractions of eroded chernozems

Abstract

Erosion processes are the main cause of degradation of chernozems, which occurs mainly as a result of the loss of soil organic matter and deterioration of the structural and aggregate state. The main part of organic carbon (Corg.) is concentrated in macroaggregates, therefore the destruction of macroaggregate fractions is the main cause of loss of Corg. during the development of erosion processes. The ability of soils to maintain a water-resistant structure is due to the sorption of humus substances, which have amphiphilic properties in them. To the greatest extent, such properties are possessed by young fractions of labile humus substances (LHS), present in an adsorbed state in microaggregates. Consequently, the quantitative content of LHS in structural-aggregate fractions is a reliable indicator of their anti-erosion resistance. The goal of the research was the evaluation of the role of adsorbed LHS in the structural-aggregate fractions of chernozems in relation to their anti-erosion resistance. Objectives: conduct field research of eroded chernozems; to select soil samples and conduct a series of laboratory studies of these samples for identification of the sorption properties of structural-aggregate fractions in relation to Corg. and LHS; to prove that the sorption of LHS by structural-aggregate fractions plays a significant role in maintaining the water-resistant structure of chernozems. It has been established that in eroded chernozems there is a degradation of the structural-aggregate state, accompanied by deterioration of microstructure, a decrease in the number of mesoaggregates and the coefficient of structure, as well as the loss of a water-resistant structure. It has been shown that the sorption of LHS by structural-aggregate fractions plays a significant role in maintaining the water-stable structure of chernozems. It was established that the main role in the sorption of Corg. belongs to mesoaggregates with the size of 5-1 mm, which quickly lost by the soil during the development of erosion processes.