S. Todorova, N. Simeonova, K. Trendafilov, V. Valcheva Abstract. Our work is aimed at studying the natural potential of the soil to provide assimilated forms of nitrogen and phosphorus for plants, after cessation of 45-year mineral and organic-mineral fertilization. The object of our

S. Todorova, N. Simeonova, K. Trendafilov, V. Valcheva Abstract. In our research we are studying changes of some common chemical properties (pH, salt concentration, total carbonates, and humus content) during long-term organic-mineral fertilization and after its cessation. The object