IMPACT OF LIME AND MINERAL FERTILIZERS ON CONTENT AND FRACTIONAL COMPOSITION OF HUMUS BALANCE IN SODDY-PODZOLIC SOILS OF THE EURO-NORTH-EAST
In long-term stationary field experiment on sod-podzolic low-cultured soil it was conducted the research on the effect of lime (aftereffect 1983) and the annual application of mineral fertilizers calculated for planned removal of NPK by the crops of perennial grasses, to modify the properties of soil, including humus. As a result of research the influence of the residual effect of lime and mineral fertilizers on content of organic matter in the soil, as well as group and fractional composition of humus was revealed. It was determined that fertilizers and ameliorant had a significant impact on the change in the balance of humus and group and fractional composition. Our research showed that the reserves of humus in the soil of experimental plot were 44.2-46.8 t/ha. Volume of soil explosives residues according to variants of experiment was 3.9-5.3 t/ha, the greatest number obtained in case of use of NPK in the soil limed - 5.0-5.3 t/ha and productivity of perennial grasses in these options was the highest (4.5 to 4.8 t/ha of dry matter). In the process of humification and mineralization of organic matter residues corresponding the number of newly formed humus was 0.7-0.95 t/ha, its greatest number was also in the variants NPK and ameliorants (0.90-0.95 t/ha). The greatest balance of humus was also in the above mentioned variants. The use of lime and fertilizer increased in the composition of humus amount of humic acids from 21.8 to 27.7 %, in the variant without fertilizers it was 19.3 %. Especially increased (from 2.3 to 7.9 %) the fraction of GC-2, associated with calcium and magnesium. The most aggressive fraction of fulvic acids FC-1A (from 4.2 to 1.6 %) dropped significantly. These changes in labile part of humus is allowed to change the type of humus from fulvatic type (SGK:SFK 0.5), humate-fulvatic - SGK:SFK>0.5, which improved the soil structure and plant nutrition.