Abstract: The key of the different amount of fertilizers applied in various soils lies in how to determine the level of the soil fertility.According to field fertilizer experiments made by us in many years and sites on the basis of unified design,we belive that,the content of available phosphorous in soil nutritions is well correlated with the yield:y=8.25+62.46logp r=0.8618**(y:the percent of the yield,P:the measurement value of the available phosphorous in the soil)So,it is practical to use the content of the available soil phosphorous as one of the indexes of the soil fertility in this province.According to the relationship between the available soil phosphorous and the yield percent,the level of available phosphourous of the soil can he divided into three grades:below 10ppm,between 10 and 20 ppm,and above 20ppm.The corresponding yield percents of these grades are:below 70,between 70 and 90,and above 90.According to different levels of availabl soil phosphorous,three different equations of fertilizer effects are made up,and the best economical fertilizer application amount and the proportion of nitrogen and phosphorous can be calculated and the yield range can be predicted.The suitable application amount of fertilizers in the main production areas of winter wheat in the province can be recommended according to the level of available phosphorous of the soils,the effection equation of phosphate fertilizer,and nitrogenous and phosphate fertilizers.The yield and net profit can also be prodicted.The experimental result indicates the fertilizer fomula applicable for winter wheat in the province macroscopically.It is of universal significance in instructing fertilization scientifically in wheat.In the meanwhile,it provides scientific basis for the country to arrange production and allocate fertilizers.

Key words: Soil phosphorous, Winter wheat, Fertilizer application