Mineral nitrogen content in soils depending on land use and agronomic category

Abstract

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 2010-2012 from fixed locations scattered across whole Poland territory. Additionally, particle-size distribution was assessed in the tested soil samples, which allowed to assign soil agronomic categories to them and assess the relationship between Nmin content and assigned categories. Regardless of sampling date and land use, agronomic category had a significant effect on Nmin content. Generally the relationships between the percentage of particles with dimensions below 0.02 mm and Nmin content 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. Calculated relations were less pronounced in spring, before fertilization, than in the autumn, after harvest. These equations can be very important from the practical point of view, as they may be 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.