Optimization of Spring Rapeseed Nutrition

An on-farm experiment with spring-seeded rapeseed was conducted in 2015 in Buinsk District, Tatarstan Republic. The site's leached chernozem soil (0 to 20 cm depth) had a heavy texture, high organic matter content (5.3%), low pH (5.6), very high Olsen P concentration (33 ppm), higher than medium exchangeable K (140 ppm), and low available S (3 ppm). The five fertilizer treatments (N, P₂O₅, K₂O, and S) were: 1) 29-46-30 kg/ha, 2) 90-46-30, 3) 90-46-30-14, 4) 120-46-30, 5) 120-46-30-21. A complex NPК fertilizer was applied at planting (2.5 cm x 0 cm spacing from the seed row) that provided 24 kg/ha of each N, P₂O₅ and K₂O. The remaining nutrients were provide with other fertilizers (i.e, monoammonium phosphate, ammonium nitrate, potassium chloride, and ammonium sulfate nitrate) applied in spring before planting.

The 2015 season suffered drought conditions from mid May till July, which negatively affected crop production. There was a strong response to N fertilizer application and a noticeable response to S fertilizer use. Seed yields for the five treatments (14% moisture content) were: 1) 1.12, 2) 1.51, 3) 1.62, 4) 1.76, 5) 1.84 t/ha. Crop yield response to S fertilizer application was statistically significant with the addition of 14 kg S/ha. A higher S application rate (21 kg S/ha) had no additional impact on seed yield. There was a trend towards higher seed protein content in treatments receiving S fertilizer.