CONTENT OF MACRONUTRIENTS IN WINTER WHEAT GRAIN DEPENDING ON THE SOWING DATE AND LEVEL OF NPK FERTILIZATION

The mineral composition of cereal grains has a direct impact on the health of people and farm animals. This consideration encourages making constant efforts to improve both productivity of cereal crops and quality of their grains, including an increased grain content of minerals. The research objective has been to determine the effect of sowing date and level of NPK ferti-lization on the yield and content of macronutrients (N, P, K, Mg, Ca) in grain of the winter wheat cultivar Arkadia. The first factor consisted of the time of sowing (4 dates): from mid-September to the end of October. The second factor consisted of NPK fertilization levels (kg ha(-1)): 1 NPK (310 kg ha(-1)), composed of 140 N, 70 P and 100 K, and 1.5 NPK (465 kg ha(-1)), composed of 210 N, 105 P and 150 K. The wheat grain content of macronutrients (N, P, K, Mg, Ca) was analyzed according to well-established methods. The sowing date winter wheat did not have any distinct, annually repeatable effect on changes in the content of the determined macronutrients in wheat grain. The NPK fertilization levels had an unequivocal effect on the content of nitrogen, which accumulated the most in the grain of wheat supplied the higher NPK dose. Neither a delay in the sowing date nor the applied NPK fertilization caused an unambiguous decrease in the content of macronutrients, nor did they depress the quality of wheat grain as a potential ingredient in food for people or in concentrated feeds for animals. Overall, concentrations of the analyzed macronutrients in winter wheat grain varied between the years of the experiment.