Quantity and Quality of Surface and Subsurface Runoff from an Eroded Loess Slope Used for Agricultural Purposes

The purpose of the work was to determine the surface and subsurface water runoff and selected constituents of the matter contained and carried out from the eroded loess slope used as arable land. The research was carried out in 2008–2011 on the Lublin Upland. The quantity of water flowing out of the slope was measured and samples were collected in order to determine the concentration of the soil suspension of nitrogen and its forms as well as phosphorus and potassium. Soil tests were also carried out and the rainfall amount and intensity was monitored. The research results show that the amount of precipitation was significantly statistically correlated with the quantity of surface and subsurface water runoff and with the precipitation and surface runoff erosion indicator EI30 (correlations at the level of r = 0.75–0.78). In addition, the mass of eroded soil was strongly correlated with the erosion indicator of rain and surface runoff EI30 (r = 0.86). The annual soil losses were from 21.1 to 173.1 Mg ha−1. The concentration of chemical components dissolved in the surface and subsurface runoff water in most cases proved to be negatively statistically correlated with the amount of precipitation and indicator EI30. The correlation coefficients (r) were at levels from −0.32 to −0.52. The annual loss of nutrients caused by chemical erosion was: nitrogen 7.210–29.949 kg ha−1, phosphorus 0.846–5.279 kg ha−1 and potassium 7.065–21.660 kg ha−1. The highest intensity of water erosion was recorded in 2010, when root crops were grown in the field.