Effects Of Nitrogen Application On Technical Parameters Of Precision Nitrogen Fertilization In Rapeseed

The effect of nitrogen application on nitrogen absorption , amount of nitrogen to produce one hundred kilogram seeds and nitrogen fertilizer use efficiency were studied through measuring dry matter and nitrogen content of each organ at different growing stages in rapeseed. The main results were as follows:1. The N content of the whole plant of rapeseed descended gradually with the development process and increased a little at maturing stage. The content of N of the whole plant all increased with the increasing of N fertilizer application at each stage. As the increasing of the proportion of basal and seeding fertilizer to bolting fertilizer when applying the same amount of N fertilizer, the N content of whole plant increased at the bolting stage, but decreased at the beginning of flower and ending of flower stage.2. The amount of N in rapeseed increased with the development of growth process. The nitrogen accumulated most from bolting stage to the beginning of flower stage, and the increasing range of nitrogen accumulation in this stage was also the highest. The amount of N accumulatd increased with the increasing of N fertilizer application. The difference of the amount of nitrogen accumulation between basal and seeding fertilizer and bolting fertilizer was less. The amount of N accumulation that fertilizer used as basal and seeding fertilizer was much bigger than that of bolting fertilizer. 3. The relationship between the amount of N fertilizer application and the nitrogen use efficiency could be expressed as cubic curve function. When the amount of nitrogen used as basal and seeding fertilizer and bolting fertilizer were 107.4 kg /hm2 and 78.14 kg /hm2 respectively, the N use efficiency was the highest,which were 63.36% and 46.60% respectively. The N use efficiency was the highest when the proportion of basal and seeding fertilizer to bolting fertilizer was 7:3, and the lowest when 5:5. The N use efficiency of basal and seeding fertilize was much higher than that of bolting fertilizer at the same amount of fertilizer application.4. The relationship between the amount of N produced one hundred kilogram seeds and the amount of N fertilizer application was positive linear correlation. When the amount of N fertilizer used as basal and seeding fertilizer and bolting fertilizer increased 100 kg /hm2 , the amount of N produced one hundred kilogram seeds increased by 0.39kg and 0.66kg respectively. The ratio of basal and seeding fertilizer to bolting fertilizer had less effect on the amount of N produced one hundred kilogram seeds at the same amount of nitrogen fertilizer application.5. Decrepit leaves of rapeseed may affect identifying technical parameters in precision application of N fertilizer.