FERTILIZATION SYSTEM AS A FACTOR OF TRANSFORMING THE HUMUS STATE OF THE SOIL

Aim. To establish the effect of different fertilization systems in short field crop rotation on the change in the state of humus in the dark gray podzolic soils in Western Forest-Steppe of Ukraine. Methods. Field studies were carried out in a stationary experiment of the Department of Soil Science and Agricultural Chemistry of the L'viv National Agrarian University; determination of humus content - according to DSTU 4289: 2004, and that of its labile forms - in accordance with DSTU 4732: 2007, fraction-group composition - by Ponomareva-Plotnikova's method, according to the measurement procedure 31-497058-008-2002. Results. The use of organo-mineral fertilizer system in short field crop rotation with the saturation of organic fertilizers of 15 t/ha of crop rotation contributes to the humus content increase by 0.7% after the third rotation in 0-40 cm layer of dark gray podzolic soil, the increase in the share of stable forms of humic compounds up to 57-59% and the increase in the ratio of R-HA:R-FA to 1.3-1.4. The study demonstrated very high dependence of amount of gross energy reserves in the humus on the R-HA:R-FA ratio. Conclusions. The combined application of organic fertilizers in the form of manure, non-market of the crop (straw) and siderate, along with mineral fertilizers is recommended in short field crop rotations of Western Forest-Steppe of Ukraine toensure expanded reproduction of fertility of dark gray podzolic soil, improvement of its humus status, increase in gross energy reserves and the share of the stable forms and humic acids in the humus.