YIELD AND MINERAL COMPOSITION OF SEEDS OF LEGUMINOUS PLANTS AND GRAIN OF SPRING WHEAT AS WELL AS THEIR RESIDUAL EFFECT ON THE YIELD AND CHEMICAL COMPOSITION OF WINTER OILSEED RAPE SEEDS

A controlled field experiment was carried out in 2011-2014 in order to determine yields and chemical composition of selected genotypes of leguminous plants and spring wheat, as well as their value as a preceding crop (crop volume, mineral composition of seeds) for winter oilseed rape grown in Northern Poland. Chemical analysis of the content of macronutrients and micronutrients in seeds and grain was conducted using standard methods after mineralisation in H2SO4 with H2O2 as an oxidant (macronutrients), or in a mixture of the acids HNO3+HCl+HClO4 (micronutrients). It was proven that among the examined species and seasonal types of legumes, the highest total seed and protein yield volume was obtained from both field bean forms, traditional and determinate one. The lowest yield was achieved from blue lupine. The yield of winter wheat grain oscillated around 5.6 t ha(-1). Blue lupine seeds were characterised by the highest total protein content. Seeds of both field bean forms were distinguished by the highest content of potassium, phosphorus, copper and zinc, while blue lupine seeds had the highest content of calcium, magnesium and manganese. The research showed a clear tendency towards a higher winter oilseed rape yield in a field after determinate field bean and seed pea. Spring wheat proved to be the worst previous crop for winter oilseed rape. The tendency for greater accumulation of nitrogen, phosphorus, calcium, copper, iron and zinc in winter oilseed rape seeds was observed in a field after determinate field bean. The lowest content of macronutrients and micronutrients was characteristic for seeds of winter oilseed rape grown after spring wheat. Winter oilseed rape seeds in a field after determinate field bean and blue lupine were rich in manganese. The research proved a positive relationship between the total nitrogen content in soil after harvest of pre-crop plants and winter oilseed rape seeds yield (r = 0.864).