Оptimization of fertilizer and foliar feeding winter rape (Brassica napus L.) in the Western Polissia

Topicality. Significant changes in market conditions and disruptions in the sown area structure in Ukraine require to search for optimal and cost-effective systems of fertilisation and crop management for modern varieties and hybrids of winter rape. The application of sulphur fertilisers, ammonium nitrate in early spring fertilisation and foliar feeding with growth stimulants and microfertilisers improves winter rape growth and development, yield structure and productivity. Purpose. To develop innovative agrotechnical practices involving the compound fertilizers, microfertilizers, growth stimulants, aimed to realize the high yield potential of winter rape in the Western Polissia. Methods. The research was carried out at the Institute of Agriculture of Western Polissia on a typical low-humus light loamy chernozem. General scientific methods and analyses were used to compare the factors under study: field method was used to determine the fertiliser efficiency; visual, measuring and weighing method; laboratory method; comparative and calculation method; statistical method. The results. It was found that on winter rape crops, the best degree of overwintering was 85.5–88.8 % and 83.0–86.0 % for fertilisation with N35P90K120 + N85S40 + N30 and N35S60K90 + N85, compared to N35P60K90 + N85, where these indicators are within 77.3–77.7 %. The highest survivability of plants during the growing season was 98.4–98.6 %, when N35P90K120 + N85S40 + N30 was applied together with foliar feeding (Huliver Stymul + Avanhard Silicon Bio (1.0 + 1.0 l/ha) and Huliver Stymul + Avanhard P Phosphorus + Potassium (1.0 + 0.6 l/ha) in the rosette phase and the beginning of budding. The largest number of pods per plant is 121.5–124.0 pcs, the number of seeds per pod is 24.1–24.7 pcs, the thousand seed weight – 4.54–4.56 g was observed for fertilisation with N35P90K120 + N85S40 + N30 with two foliar feeding with Huliver Stymul + Avanhard Silicon Bio (1.0 + 1.0 l/ha) and Huliver Stymul + Avanhard P Phosphorus + Potassium (1.0 + 0.6 l/ha). The maximum yield of 4.45 t/ha was obtained with fertiliser of N35P90K120 + N85S40 + N30 and foliar feeding with Huliver Stymul + Avanhard P Phosphorus + Potassium (1.0 + 0.6 l/ha). Conclusions. It was found that early spring application of ammonium sulphate N35S40 and ammonium nitrate N50–85 kg/ha was an effective method to increase the winter rape yield to 4.45 t/ha, the increase in yield due to fertilisation varied within 5.1–15 %. When foliar feeding with a growth stimulator and microfertilisers was applied two times in the spring rosette and flower budding stage, the yield increase ranged from 2.8 to 16.5 %. Key words: winter rape, fertilization system, foliar feeding, productivity