INFLUENCE OF BIOMASS AND FERTILIZERS PLOWED IN THE SOIL ON THE DYNAMICS OF NUTRIENTS IN SOWN GRASS STANDS
The dynamics of plant nutrients in the aboveground part of sown grasses at the application of potassium-nitrogen fertilizers and the natural fertility of soddy-podzolic soil of a forested 8-year-old fallow used more than 40 years ago in field crop rotations, is shown. It has been established that the most optimal conditions for the absorption of nitrogen by grasses, both within the years and on the average for 4 years, are created with the embedding of aspen wood, and the least favorable with the embedding of birches. Against the backdrop of NK fertilizers, the greatest nitrogen uptake was noted with the embedding of willow seedlings, and potassium with the embedding of aspen wood. Absorption of phosphorus by the grass stand is noticeably reduced with the years of research. In the sixth to seventh years of herbs (2013-2014), when the soil is rapidly depleted of mobile P<sub>2</sub>O<sub>5</sub>, it is necessary to apply phosphorus fertilizers (even if it is temporarily over-abundant in the soil).