Water stability and labile humic substances of typical chernozems under different land uses

Abstract

The water stability of typical chernozems was studied, as well as the content and composition of the labile humic substances (LHSs) in the structural units of perennial experiment treatments: C_org was 4.68% on an unmown steppe (fallow), 3.55% under continuous winter wheat without fertilizers, and 2.92 and 2.78% in two treatments of permanent black fallow. It was shown that the water stability of the chernozem’s structure depended on the land use; it deteriorated in the following series: fallow > winter wheat > permanent fallow. No clear relationship was found between the content of C_org in the aggregates obtained by dry sieving and the size of these aggregates. At the same time, the content of C_org in the water-stable aggregates was shown to increase with their size. A positive correlation between the size of the water-stable aggregates and their content of LHSs was found for the unmown steppe and continuous winter wheat treatments.