Study on Phosphorus Threshold of Winter Wheat in Rain Fed Agricultural Region of Loessal Soil

Experiment is carried out to study the effects of different phosphorus application and different phosphorus application combined with manure on the yield of winter wheat in rain fed agricultural region of loessal soil under the same nitrogen level.The result showes that under the same nitrogen application,the grain number、ear weight and thousand-grain weight of phosphorus application(150 kg/hm2)combined with manure(7 500 kg/hm2)treatment are higher than that of other treatments,the yield is also the highest which is 5 317.60 kg/hm2,it is increased by 52.71% compared with the treatment without phosphorus and manure.It could be used as the phosphorus application threshold of winter wheat in Tianshui and the surrounding area.