EFFECT OF NITROGEN FERTILIZATION ON MICROBIAL PROPERTIES OF MEADOW SOIL

The aim of this study was to determine the numerical depot of some micro-organisms colonizing grassland soil under the influence of varying nitrogen fertilization. The research has begun in 1993 on the gley soil created from strong clay and implemented the following combinations of fertilizer: "0", PK, PK + 55 kg N, PK + 110 kg N, PK + 220 kg N. Soil samples for quantitative microbiological tests were taken during the growing season 2006 i.e.: spring (III decade of April), and after each regrowth harvest (III decade of May, and I decade of July and II decade of September). Samples were taken from a depth of 0-15 cm, from all combinations in an amount of about 0.5 kg. Then, after shaking 10g of soil samples were diluted in the range from 10(-1) to 10(-8). In order to know the number of selected microbial groups, inoculation was performed by standard methods. The most favorable for the development of the tested soil microorganisms was the sustainable grassland fertilization with phosphorus and potassium, and with a nitrogen dose of 110 kg N center dot ha(-1). The mineral fertilization of the permanent grassland reduced the number of bacteria and mould, and stimulated the growth of yeasts, which is a negative phenomenon for biological processes occurring in meadow soil.