Physicochemical nature of soil structure stability in gray forest soils of Vladimirskoe Opol'e

摘要

A decrease in the stability of soil structure and an increase in clay peptization in the Ap horizon of gray forest soils (Vladimirskoe Opol'e) are explained by the insufficient concentration of Ca2+ and Ma(+) ions in the liquid fraction and the presence of mixed-layerd smectite minerals in the clay fraction. Under these conditions, the main structuring agent-mobile humic acids-do not coagulate and, thus, do not perform their structuring function. In the transitional (A2B) and illuvial horizons, mineral and organo-mineral substances are coagulated by positively charged Fe and Al hydroxides under increasing Ca and Mg concentrations in the soil solution. The coagulation of these substances by Fe and Al hydroxides is accompanied by the acidification of the A2B and B horizons.