Nitrogen Uptake from Different Sources by Soybean Grown at Different Sowing Densities

Abstract

The objective of the research reported here was to determine the amount of nitrogen fixed from the atmosphere and taken up from mineral fertilizer and soil reserves by soybean cv. Abelina grown at three densities (per 1 m2) under central European conditions. Moreover, an attempt was made to determine what amount of nitrogen taken up from the individual sources was removed from the field with seed yield and was introduced to the soil with post-harvest residues and that will be the source of this macronutrient for the following plants. The following densities were used: A1–50 seeds, A2—70 seeds and A3—90 seeds per 1 m2. The share of nitrogen derived from the atmosphere, soil reserves and mineral fertilizer and taken up by the total plant biomass was 46.28, 45.52 and 8.2%, respectively. The whole biomass accumulated 58.51, 52.85 and 9.71 kg N∙ha−1 from the respective sources. An average of 95.24 kg N∙ha−1 was removed from the field with seeds, it being 46.17, 42.20 and 6.68 kg N∙ha−1 for an uptake from the atmosphere, soil reserves and mineral fertilizer, respectively. An incorporation into soil of residues and roots provided over 25.82 kg N∙kg−1 associated with all the sources.