磷素是作物生长发育不可缺少的养分之一。农作物吸收各种营养元素,是按一定比例的,如水稻吸收氮、磷、钾的比例大体是1∶0.5∶1.5。上海郊区低洼地区的青紫泥和沿海地区的盐碱土,有不少田块不同程度地存在着缺乏速效磷素,水稻生长发育不良,产量不高。及时地测出土壤速效磷的含量,可以使目前为数不多的过磷酸钙,施在磷素最缺 Phosphorus is one of the essential nutrients for crop growth and development. Crops absorb a variety of nutrients, according to a certain percentage, such as rice absorption of nitrogen, phosphorus and potassium ratio is generally 1: 0.5: 1.5. There are many plots of lime green mud in the low-lying areas of Shanghai suburbs and saline-alkali soil in the coastal areas. To some extent, there is a lack of readily available phosphorus in varying degrees. The growth and development of rice are poor and the yield is not high. Timely measure the content of available phosphorus in the soil, can make the current few superphosphate, applied in the most phosphorus deficiency