Effects of Different Nitrogen Application Rates on Yield, Nutrient Uptake and Nitrogen Utilization of Cotton in Southern Xinjiang

【Objective】 To study the effects of different nitrogen application rates on yield, nutrient uptake and nitrogen utilization of cotton under the condition of film mulching drip irrigation in the hope of proving scientific evidence for reasonable nitrogen application in cotton production in Awati County, Xinjiang. 【Method】 The experiment was conducted in Awati County of Xinjiang from 2017 to 2019 and five different nitrogen application rates were set up under the same amount of phosphorus and potassium. Cotton samples were collected at the boll opening stage, and the yield, biomass, nutrient absorption and nitrogen utilization of cotton were determined. 【Result】 The cotton yield, biomass and output value increased significantly with the increase of nitrogen application rate when the rate was 0-220 kg/hm², and the absorption of nitrogen, phosphorus and potassium also increased significantly, but the effect was not significant when the nitrogen application rate was higher than 220 kg/hm². The nitrogen partial productivity and agronomic efficiency of cotton decreased significantly with the increase of nitrogen application rate. Nitrogen apparent utilization decreased significantly when the nitrogen application rate was more than 220 kg/hm², and the difference of nitrogen contribution rate was not significant. 【Conclusion】 The cotton yield, biomass and output value increased significantly with the increase of nitrogen application rate when the rate was 0-220 kg/hm², and the absorption of nitrogen, phosphorus and potassium also increased significantly, and nitrogen apparent utilization decreased significantly when the nitrogen application rate was more than 220 kg/hm². Therefore, considering yield, economic benefits, nutrient absorption and nitrogen utilization of cotton, the recommended nitrogen application rate of the selected cotton field is 220 kg/hm², and the amount of N, P₂O₅, K₂O absorbance by 100 kg cotton is 4.25 kg, 1.14 kg and 3.61 kg when nitrogen application rate was 220 kg/hm².