Effect of nitrogen fertilizer rates on utilization efficiency and fate of fertilizer nitrogen at elongating stage of sugarcane

In the present study,the sugarcane cultivar ROC22 was used,and three nitrogen rates treatments were conducted by pot planting in grennhouse to investigat the effects of nitrogen application rates on nitrogen utilization and fate at elongating stage.Results showed that almost 15%~27% of total N was supplied by fertilizer,and 73%~85% came from soil and seed-stem.The efficiency of fertilizer was 21.78%~26.75%,N-fertilizer residue ratio was 61.24%~69.85%,and N-fertilizer loss was 8.37%~12.02%.In addition,with the enhancment of nitrogen application rates,the accumulation of dry matter and nitrogen as well as the proportion of N from N-fertilizer in sugarcane increased obviously.The uptake,residue and loss amount as well as residue ratio of N-fertilizer were also increased significantly,while uptake ratio and loss ratio of N-fertilizer decreased significantly,the distribution of nitrogen and dry matter in stalk displayed a dropping trend.The results also indicated that the N-fertilizer distribution in soil layer of 0~20 cm increased significantly when the nitrogen application rates was increased,but which in soil layer of 20~40 cm decreased significantly.