EFFECT OF NITROGEN FERTILIZATION AND APPLICATION OF SOIL PROPERTIES IMPROVING MICROBIAL PREPARATIONS ON THE CONTENT OF MINERAL NITROGEN IN SOIL AFTER SPRING WHEAT HARVESTING

The effect of nitrogen dose and application of soil properties improving microbial preparations on the content of mineral nitrogen in soil after spring wheat harvesting were evaluated in a three-year field experiment. The investigations were conducted under conditions of Luvic Chernozem. Diverse nitrogen fertilization (0, 40, 80, 120 and 180 kg. ha-1) was applied and microbial preparations: Proplantan AM, Effective Microorganisms EM and UGmax Soil Fertilizer. The content on Nmin in the soil after wheat harvesting, particularly in the upper layers of the soil profile was growing with increasing nitrogen fertilization level. The amount of nitrate nitrogen in the soil after harvest plants was below the average content of N-NO3 for this category of agronomic soil in Poland. Bigger quantity of mineral nitrogen in soil after plant harvesting than before their sowing was registered only on the obejcts receiving 160 kg N.ha-1 in the years characterized by a similar to multiannual average amount and distribution of rainfall during the period from April to June. Microbial preparations Proplantan AM and Effective Microorganisms EM caused a significant decrease in nitrate and ammonium nitrogen in the 0-30 and 30-60 cm soil layers.