Abstract: Based on the long??term fertilizat ion experiment of Loess Plateau, the effect of longterm P fertilization onwinter wheat yield was sudied under certain amount of N fertilier( 90 kg/ ha). The results showed that the yield of wheatwith P fert ilization is still increased obviously in the field with long??term P fert ilization. The wheat yield increased by1 393.75- 2 121.00 kg/ ha and 48.41% - 73.67% higher compared to the control treatment.The wheat yield reachedthe highest value 5 000 kg/ ha in the P treatment of 39??6 kg/ ha,which was consist with the value of P fertilization whenthe spike number was highest. The relationship between yield and the amount of P fertilizer application f it the regressionequation Y= - 0.866 7X2+ 82??641X + 3 008??4( R2= 0.92) well, P fertilizer mainly influenced the yield of wheat by changing spike number per ha, however, its?? impact on both of grains per spike and 1 000 grains yield was not obvious.The P fertilization can also promoted the absorption and utilization of N, P,K in wheat, and improved fertilizer efficiencyand fertilizer use efficiency.Too little P fertilizer can not meet the demand of crops and thewheat yield was low, the wheatyield will not contiue to raise with the increasing of amount of P fertilizer when excessive amount of P fertilizer was used,on the contrary, certain decrese happened.

Key words: Loess Plateau, Winter wheat, Effect of P fert ilization

CLC Number: 

• S143.2