Effect of application amount of nitrogen fertilizer(~(15)N) on nitrogen absorption and utilization in sugarcane

Under low(available N 68.85 mg/kg) nitrogen of soil,three treatments were desiged with 2.5 g,5.0 g and 7.5 g 15N-labeled urea/pot respectively,to study the effects of different application amount of nitrogen fertilizer on nitrogen absorption and utilization in sugarcane varieties ROC22.The results were as follows: dry matter accumulation,nitrogen accumulation,the proportion of N from nitrogen fertilizer in sugarcane and available nitrogen content in soil increased with the amount increase of nitrogen fertilizer,while nitrogen utilization rate in sugarcane decreased significantly.The nitrogen fertilizer application had obviously influence on dry matter distribution,nitrogen distribution,nitrogen utilization rate in sugarcane organ and nitrogen distribution in soil.The nitrogen of sugarcane uptaked was most from the soil of 20~40 cm depth.The appropriate amount and soil depth of nitrogen fertilizer application should be considered to increase nitrogen utilization efficiency in sugarcane.