Influence of water erosion on the structure and content of labile humic substances in the structural-aggregate fractions of leached chernozems of the Central Chernozem region

The structural-aggregate composition of leached chernozems (Voronic Chernozems Pachic according to WRB-2014), the distribution of organic compounds Corg and labile humic substances (LHS) in the structural-aggregate fractions of carbon in the conditions of a slope type of terrain during the development of erosion were studied. The work was carried out in the northern part of the Voronezh region on the catena, which included a section of the watershed, smoothly turning into a southwestern slope about 1500 m long and 5˚ steep. The soils of the following sections of the catena were studied: 1) the watershed part; 2) the upper part of the slope; 3) the middle part of the slope. It was shown that degradation of the structural-aggregate state occurs in eroded chernozems, accompanied by a deterioration in microstructurality, a decrease in the number of mesoaggregates and a structural coefficient, as well as a loss of a water-resistant structure. According to the results, LHS play a very important role in maintaining the water-stable structure of chernozems. The most significant contribution to the content of Corg contribute mesoaggregates 5-1 mm in size, which are actively lost during the development of erosion.