Effect of diversified fertilization with mineral nitrogen on changes in phosphorus content in soil and plant

Results of investigations carried out to evaluate changes in concentrations of total phosphorus in red clover and in soil fertilized with diversified doses of mineral nitrogen applied as ammonium nitrate (N-0 - 0, N-1 - 30, N-2 - 60, N-3 - 90 kg N ha(-1) have been presented. In total 170 kg N were introduced to soil as mineral fertilizers to the objects over a single rotation period. Soil and plant samples were taken twice (in June and September) in 2004. Fertilization with mineral nitrogen in the N2 dose caused the highest increase of total nitrogen concentration both in the soil and red clover under study, while the N3 dose triggered lowering of the soil pH, a decrease of phosphorus in soil and the plant, lower and higher activities of alkaline and acid phosphatases in soil, respectively.