INFLUENCE OF MAIN TILLAGE TECHNIQUES AND MINERAL FERTILIZATION ON YIELD AND GRAIN QUALITY OF CORN HYBRIDS
The article shows that the mineral fertilizers application at the rates of N<sub>30</sub>P<sub>30</sub>K<sub>30</sub>, N<sub>45</sub>P<sub>45</sub>K<sub>45</sub>, N<sub>60</sub>P<sub>60</sub>K<sub>60</sub> kg/ha (the planned yield level of 6-7-8 t/ha) resulted in the grain yield of 6.63-7.52-7.80 t/ha with moldboard plowing, and 7.08-7.67-8.01 t/ha with Paraplau subsurface loosening. When applying N<sub>60</sub>P<sub>60</sub>K<sub>60</sub>, on average, the highest increase in grain yield of 3.54 and 3.49 t/ha was recorded both with plowing and subsurface loosening. The kernels of the hybrid Delitop, grown in the experimental variants with various tillage techniques, did not have large differences in the content of crude protein, fat, fiber, ash, nitrogen-free extractives. In the variants with N<sub>60</sub>P<sub>60</sub>K<sub>60</sub> the content of crude protein, nitrogen-free extractives, crude fat, crude fiber and ash in kernels slightly increased as compared to the variant with N<sub>30</sub>P<sub>30</sub>K<sub>30</sub>. The content of total nitrogen and phosphorus in comparison with the control significantly rised in the variants with an increase in the rates of mineral fertilizers applied, while the potassium content did not change and was at the same level in all experimental variants. The content of nitrates (N-N0<sub>3</sub>) in kernels in the phase of full ripeness was determined by the level of mineral nutrition of plants and varied in small amounts from 26.4 to 43.9 mg/kg with plowing and from 25.8 to 43.0 mg/kg with subsurface loosening, being significantly lower than the maximum allowable concentration level. In the variants without mineral fertilizers, the nitrate content was low and did not exceed 25.5-25.8 mg/kg.