Study On The Fertilizer Utilization Rate And Optimal Nitrogen And Phosphorus Application Amount Of Cotton In Hami City

Cotton is regarded as one of the crucial cash crops in Xinjiang.Reasonable fertilization not only benefits the protection of agroecological environment,but also promotes the green and efficient cotton growth in Xinjiang.Accordingly,the urgent problem lies in determining the fertilizer utilization rate in season along with the optimal fertilization of nitrogen（N）and phosphorus（P）for cotton.In this study,Xinluzao 25 cotton was chosen as the research object to investigate the effects of elements deficiency and different N and P application rates on the growth,nutrient absorption,yield and economic benefits of cotton in Erbao Town,Hami City.The experiment consisted of elements deficiency test（NP,NK,PK,NPK）,N fertilizer gradient test（N₀,N₁,N₂,N₃）and P fertilizer gradient test（P₀,P₁,P₂,P₃）.The aims were to provide reference for formulating high-yielding fertilization measures and reduce the cost of cotton-growing.The experiment revealed that:（1）Through the analysis of cotton growth and production from element deficiency test,it was found that in comparison with the mean values of the deficiency treatments,the height and stem diameter of NPK plant increased by 11.6%,7.3%and 5.9%,5.3%respectively.As a matter of fact,NPK was discovered as the highest in both plots as for the dry matter quality in cotton.The N accumulation of single plant was significantly higher in NPK than PK treatment,and Potassium accumulation was remarkably higher in NPK treatment as well.Besides,per boll weight of NPK increased by 6.3%～8.6%compared to the mean value of each treatment,with yield reaching the highest,which showed no prominent difference from NP.But NP would reduce the AK content in soil.Therefore,NPK application not only accelerated cotton growth,nutrient absorption,dry matter quality and yield,but also maintained the available nutrients.The agronomic efficiency rates of N,P and K fertilizers in season for drip irrigation cotton in Hami City ranged from 30.17%～42.07%、6.33%～8.44%and 56.29%～58.43%,respectively.（2）Via comparing the effects of different N applications on drip irrigation cotton,it was found that moderate N fertilizer could bring the growth of cotton and vegetative organ to moderate levels and meanwhile promote growth to increase yield as well.N₀significantly reduced N accumulation in cotton at both A and B plots.Furthermore,the dry matter quality and the accumulation of Nitrogen,Phosphorus and Potassium in each organ by each treatment showed an“S”-type increasing trend.Cotton boll number,boll weight and yield indicated a trend of increasing to decreasing,all of which reached the highest at N₂with the net returns all present as N₂>N₁>N₃>N₀.To sum up,cotton plants under N₂performed best as for the accumulation of N,K and dry matter as well as yield.It can be inferred from the simulated equations that the N application for optimal yields of cotton seed were 229.77 kg·hm^-2and 211.27 kg·hm^-2for A and B plots,while 211.46kg·hm^-2and 201.37 kg·hm^-2for the highest profits.（3）The comparison of the impacts of diversified Phosphorus application on drip irrigation cotton suggested that the cotton plants presented the best performance in N,K content and accumulation,dry matter accumulation as well as yield under P₂(Phosphorus content at 126.97 kg·hm^-2)treatment.Actually,the dry matter quality and per boll weight of NP₃K were significantly lower in both plots,with P₂reaching the highest.The highest seed cotton yield of both plots was achieved in P₂treatment with 6374.25 kg·hm^-2and 6321.30 kg·hm^-2,with net yield presented as P₂>P₁>P₀>P₃.In fact,the simulated equations showed that the corresponding Phosphorus application for optimum yield in both plots were 152.41 kg·hm^-2and 187.49kg·hm^-2,while 137.66 kg·hm^-2and 170.52 kg·hm^-2for the highest profits.