三年来,经过我们在不同地区的不同地块试验和调查,土壤有效磷含量越低,增施磷肥的小麦增产量越高,反之,增产很少。据我们试验,土壤有效磷含量百万分之1.8—3.2,百万分之4.5,百万分之7—10和百万分之20,每亩增施磷肥30—40斤,每斤过磷酸钙增产小麦分别为8.8斤,4.4斤,1.2—3.4斤和不足一斤。在没有施过有机肥的严重缺 In the past three years, after we experimented and surveyed different plots in different regions, the lower the soil available P content, the higher the yield increase of wheat with P application, and the other hand, the less yield increase. According to our tests, available phosphorus content in soil is 1.8-3.2 parts per million, 4.5 parts per million, 7-10 parts per million and 20 parts per million by adding 30-40 pounds of phosphate fertilizer per acre, Calcium increased wheat were 8.8 pounds, 4.4 pounds, 1.2-3.4 pounds and less than a pound. In the absence of a serious shortage of organic fertilizer