Effects of Nitrogen Fertilizer Levels on Nitrogen Utilization and Residue in Sugarcane-planted soil

The study was conducted to research the effects of nitrogen fertilizer levels on nitrogen utilization and nitrogen residual by sugarcane cultivar ROC22.There were three treatments 15N-labeled urea 2.5 g pot-1,5.0 g pot-1 and 7.5 g pot-1 respectively.The results thowed that dry matter accumulation,nitrogen accumulation and the proportion of N from nitrogen fertilizer in sugarcane increased with the levels of nitrogen fertilizer increment.The alkali hydrolytic N content,NO3--N content,nitrogen residual amount and nitrogen residual ratio of soil were also increased significantly,while nitrogen utilization ratio in sugarcane decreased significantly.The nitrogen fertilizer application had obviously influence on dry matter distribution,nitrogen distribution,nitrogen utilization ratio in sugarcane organ and nitrogen distribution in soil.In the present study,the suitable amount and location of nitrogen fertilizer applied were 5.0 g urea pot-1 and 20 cm soil depth.