Losses of nitrogen,phosphorus and potassium from agricultural watersheds of minor rivers in the Oka Valley

The losses of nitrogen (NH₄, NO₃, N_org), phosphorus (P_ortho, P_poly, P_org) and potassium (K⁺) from watershed areas of minor rivers, draining regions of different agricultural land use in the Oka Valley, U.S.S.R., were investigated. No N, P, and K pollution was shown in these watersheds, even though the rate of losses was found to be highly correlated with the amounts of mineral fertilizers and FYM applied. The losses were also determined by the natural soil fertility, erosion processes and soil texture under the similar level of fertilization.