Mineral nitrogen content in the 60-90 cm layer of grassland soils relative to other fodder crops, way of managing agricultural lands and farming intensity

layer. The lowest nitrogen content was shown in grassland mineral soils, whereas the cultivation of both maize and mixed cereals promoted greater accumulation of this nutrient in the soil profile at the depth of 60-90 cm. Mineral nitrogen content also depended on the use of grassland ecosystems. In mineral soils, the highest amounts of Nmin were found in hay grasslands, whereas in organic soils in hay and pasture grasslands. The lowest amounts of nitrogen in the investigated soil layer were observed in alternate grasslands. It was also revealed that strong significant correlations exist between livestock density and the content of mineral nitrogen in the 60-90 cm soil layer. Calculated regression equation describing those relationships can help the farmer to plan sustainable fertilisation depending on livestock density of his farm. K e y w o r d s: nitrogen losses, land use, mixed cereals, maize, grasslands, farming intensity * This study has been partly financed from the funds of the Polish National Centre for Research and Development in the framework of the project: BIO-FERTIL, contract number: BIOSTRATEG3/347464/5/ NCBR/2017. A. WATROS et al. 344