Fractional and group humus composition of the sod-podzolic soils under different land use

Abstract

In a long-term stationary experiment in Perm region the change in the quality of humus in sod-podzolic soil under long-term (40 years) land-use (continuous bare fallow, permanent barley and winter rye, crop rotation with various percent of leguminous grasses - 0; 28.6 and 42.9 % lea ) was studied. It was found that the long-term bare fallow causes a decrease in the total content of humic acids, mainly the most mobile fraction of HA-1, and the accumulation of fulvic acids (CHA : CFA = 0.55). When permanently cultivating crops in crop rotation, the content of humic acids increases due to the accumulation of fractions of HA-1 and HA-2 and the displacement of the type of humus formation from fulvate to humate-fulvate, with an increase in the ratio of CHA: CFA to 0.70-0.79. The use of manure makes it possible to fertilize the soil with fractions of humic acids, both easily mobile (HA-1) and calcium-bound (HA-2), thereby increasing the "maturity" of humus and resistance to mineralization. The introduction of or ganic and mineral fertilizers under monocultures and in crop rotations with a different proportion of legumes leads to the accumulation of calcium humates (HA-2) to 0.14-0.25 % of the soil mass. Transformation of arable soil into the fallow soil promotes the accumulation of valuable for agriculture fractions of humus - humic acids and reduction of fulvic acids, ŒA: CTA. = 0.96.