COMPOSITION OF PHOSPHORUS FRACTIONS IN ER OSIVE DENUDATIONS IN RELATION TO AGROCHEMICAL TREATMENTS IN A CATCHMENT-AREA

Erosive denudations contain no available phosphorus (P-a) and have low er levels of organic phosphorus (P-org). The soils from the sites test ed have been 30 and 50% P-org from P-tot, while this proportion in the eroded particles is between 20 and 40%. Contents of P-R2O3 fraction a re very high and surpass 50%. The composition of phosphorus fractions in the erosive denudations changes with improving soil tending, such a s liming, organic fertilization and other treatments. Proportion of P- Ca fraction increases, while those of P-org fraction and especially P- R2O3, fraction decrease. In spite of fluctuating levels in the individ ual plots in a catchment area the analysis of the erosive denudations provides the comprehensive view over the soil tending in the whole cat chment area.