Study on the Fertilization Effect and Nutrient Management for Direct Seeding Rapeseed in China

This project was implemented by Huazhong Agricultural University. A total of 17 on-farm trials on winter rapeseed fertilization were conducted in seven provinces along the Yangtze River basin in 2012. Nitrogen fertilization trials were located at 10 sites, while P and K fertilization trials were conducted at the other seven sites. Five N fertilization rates were evaluated along with applications of 90 kg P₂O₅, 120 K₂O and 15 kg/ha borax. Four P fertilization rates were evaluated along with applications of 180 kg N, 120 kg K₂O and 15 kg/ha borax, while four K fertilization rates evaluated along with applications of 180 kg N, 90 kg P₂O₅ and 15 kg/ha of borax.

For N, results showed that N application in winter rapeseed increased seed yield and economic benefit with the highest values (2.8 t/ha and US$ 2,213/ha, respectively) obtained with 360 kg N/ha application. Compared to the treatment without N fertilization, the average rapeseed yields increased by 608 (49%), 1,148 (100%), 1,356 (115%), and 1,398 (125%) kg/ha when 90, 180, 270, and 360 kg N/ha were applied, while the average economic benefit values increased by $482, $911, $1,076, and $1,110/ha, respectively. However, seed yields did not differ significantly when N application rate exceeded 270 kg N/ha.

For P, results showed that P application also increased seed yield and economic benefit of winter rapeseed with the highest values (2.4 t/ha and $1,894/ha, respectively) obtained with 180 kg P₂O₅/ha application. With P₂O₅ applications of 45, 90 and 180 kg/ha, average yields increased by 575 (45%), 728 (57%) and 794 (65%) kg/ha and average economic benefit values increased by $456, $578 and $630/ha, respectively, over the no P treatment.

For K, results showed that seed yield and economic benefit of winter rapeseed increased with K application rates, with the highest values (2.3 t/ha and $1,859/ha) obtained with 240 kg K₂O/ha application. With K₂O applications of 60, 120 and 240 kg/ha, average yields increased by 13, 21 and 22% and average economic benefit values increased by $186, $298 and $316/ha, respectively, over the no P treatment. The response of winter rapeseed to K application was lower than that to the application of either N or P. Hubei-39