Nutritional value of soybeans and the yield of protein and fat depending on the cultivar and nitrogen application

A field experiment was carried out in 2015-2016 on a private farm in the District of Zamość, Poland. The experimental field was located on soil with the textural composition of clayey silt, having slightly acid reaction, moderate organic matter content (19.4 g kg-1) and moderate content of available phosphorus, potassium and magnesium. The following factors were analysed: I) soybean cultivar: Amandine and Merlin; II) nitrogen fertilisation (kg ha-1): 1) N – 0; 2) N – 30 before sowing; 3) N – 30 at BBCH 73-75; 4) N – 60 (30 before sowing and 30 at BBCH 73-75). The aim of the study was to determine the influence of a cultivar and the level of nitrogen application on the content of basic nutrients in soybeans, and the yield of seeds, proteins and fat per ha of the crop. The research indicates that the soybean varieties Amandine and Merlin grown in the conditions of south-eastern Poland not only produce soybeans with high nutritional value, but also ensure high yields of seeds, protein and fat per ha. The Amandine soybeans had a significantly higher content of crude ash, crude protein and crude fibre than the Merlin cultivar. The highest level of crude protein was noted in the soybeans fertilised with nitrogen at a dose of 30 kg ha-1 at BBCH stage 73-75. This level of nitrogen application also resulted in the highest content of crude fat in the soybeans. The crude fat content was 202.3 g kg-1 in the Amandine soybeans and 217.2 g kg-1 in the seeds of the Merlin cultivar. The smallest proportion of monounsaturated fatty acid and the highest proportion of polyunsaturated fatty acid were noted in the seeds of the Amandine cultivar. The level of nitrogen fertilisation did not affect the fatty acid composition of the soybeans.