Evaluation of mineral nitrogen content (Nmin) was performed for the 60-90 cm layer of grassland soils relative to other selected agricultural fodder crops.Soil samples were collected two times per year, in spring and autumn, over the period 2010-2012from fixed locations scattered across whole Polandterritory.Additionally,particle-size distributionwasassessedinthe tested soil samples, which allowed to assign soil agronomic categoriesto them and assess the relationship between Nmincontent and assigned categories. Regardless of sampling date and land use, agronomic category had a significant effect on Nmincontent. Generally the relationships between the percentage of particles with dimensions below 0.02 mm and Nmincontent were characterized by a negative correlations, but in maize crops they were found to be positively correlated. Based on the obtained correlations, linear regression equations were developed. Calculatedrelations were less pronounced in spring, before fertilization,thanin the autumn, after harvest. These equations can be very important from the practical point of view, as they maybe used by farmer to plan a rational and sustainable fertilization based on forecasting of losses of mineral nitrogen content in the soil depending on the percentage of fine particles (agronomic category) of cultivated soil.