The Interaction of Nitrogen and Phosphorus on Cotton Fields in Medium Fertility Sandy Loam in Arid Region

【Objective】This study researched the effects of the optimal proportion of Nitrogen,Phosphorus and Potassium to cotton yield under the same irrigation condition in arid area.【Method】The experiment adopted orthogonal saturated designs,design of different N,P fertilization level and their combination treatment,and the total experimental plots were 27.【Result】According to the experiment results,the polynomial regression was established,that is,the cotton(ginned cotton) yield(Y) and nitrogen(N) and phosphorus(P) quantity of regression equation:Y=206.58+3.21XN+9.83 XP-0.003 5 XN2 + 0.029 XP2-0.011XNXP.The optimum formulation of fertilizer was: nitrogen fertilizer was 260.74 kg/hm2;phosphorus fertilizer was 120.07 kg/hm2.At this time cotton(ginned cotton) can get the highest yield:Y=1 214.98 kg/hm2.【Conclusion】Different levels of nitrogen and phosphorous fertilizers decide different cotton yields. Interaction between Nitrogen and Phosphorus is very significant.