ИСТИНА

The results of investigations which were obtained during a ten year period in stationary field experiments on weakly and moderately leached grey forest soil (Middle-Russian Elevation), have shown that water storage in snow was changed from 63.6 mm on ploughed plot to 96.6 mm on grasses in the first year of use. The values of melted water discharge were minimum on the variants with ploughing (19.3 mm) and maximum on grasses in the second year of use (53.7 mm). Water flow increases by 3.3 mm with the increase of gradient of slope from 0.0525 to 0.105. Erosion was absent on grasses during all years of observations. The erosion on winter crops was, in average, 0.34-0.39 t/ha, on stubble-mulch tillage 0.41-0.45 t/ha and on ploughing 0.65-0.71 t/ha. The generation of water discharge and soil erosion results in removal of chemical elements with products of erosion and violating of natural biogeochemical cycles. The observations on the reception of chemical elements with atmospheric precipitations (snow), reveal their changes in the snow cover taking place as a result of freezing-thawing processes. Analysis of ion composition of runoff from thawed water were carried out for the following parameters: NH4+, NO3-, K2O, Р2O5, Na+ Ca+, Mg2+, Сl, HCO3-, S042-, pH of precipitations. The results of investigations showed that the catchment area receives the precipitations with the concentration of above-mentioned elements from 0.03 to 6.24 mg/l. It gives 0.1-20.5 kg/ha. It is determined that the migration of chemical elements in the soil-snow system take place as a result of temperature gradients. It results in die change of their concentration in snow (0.11-4.51 mg/l) and the content of elements in it fluctuates from 0.07 to 30.5 kg/ha before the beginning of snow melting. The concentration of chemical elements in flowing water is changed from 0.11 to 15.67 mg/l and their removal to the water catchment area depends on the kind of element and conservation treatment and changes from 0.14 to 5.90 kg/ha.