Effect of nitrogen application rate on yield and nitrogen fertilization efficiency in rapeseed.

Field experiments were carried out to study the effects of nitrogen ( N ) application rate on rapeseed yield and N fertilizer use efficiency in Hubei Province during 2007 to 2008. Compared to no N application, the yield of N treatments ( as 75, 150 and 225kg/hm²) increased 41.9%, 70.3% and 66.2% respectively. N content increased 9.1%, 14.2% and 13.1%, and total N absorbed by above ground parts increased 59.6%, 111.6% and 108.0% respectively. The results demonstrated that N application significant promoted growth, yield and N accumulation. With increased N application rate, N requirement for 100kg -seeds was increased, while N agronomic use efficiency (AUE), partial factor productivity (PFP) and apparent recovery efficiency (ARE) of rapeseed decreased significantly. Based on rapeseed yield and N use efficiency, the optimum N fertilizer application rate was 150kg/hm² in Hubei Province. [ABSTRACT FROM AUTHOR]