Water erosion in the agricultural loess catchment with a periodical water outflow in Wielkopole (Lublin Upland) in the years 2008-2011

The research was carried out in the years 2008–2011 in the loess catchment area in Wielkopole in the Lublin Upland. The purpose of the work was to determine the intensity of water soils erosion and the size of the outflow beyond the water catchment and the selected constituents of matter contained in it. After surface water runoff, quantitative and qualitative inventory of erosion damage was carried out. The quantity of waters from the catchment was also measured, from which samples were taken in order to determine the concentration of soil suspension of nitrogen and its forms as well as phosphorus and potassium. The height and intensity of precipitation as well as the thickness of the snow cover were also monitored and observations of its melting were carried out. The research results prove that the condition of the plant cover determines the amount of erosive damage. Spring crops and root crops poorly protect the soil from erosion, while winter cereals, grassland and forests protect good. The average annual erosive damage in the catchment was: rills – 189 m3·km-2, surface runoff – 153 m3·km-2, deposits – 128 m3·km-2, and soil washout – 0.335 mm. The outflow of water outside the catchment is on average correlated with the amount of precipitation (correlation coefficient r = 49). On the other hand, a very high correlation (r = 0.85) was found between the outflow of water and soil from the catchment. On average, during the year outflow from the catchment were: 7.1 mm of water, 44.85 Mg·km-2 of the soil, 127.2 kg·km-2 N-Nog, 18.2 kg·km-2 P and 145.6 kg·km-2 K.