为了测定土壤不同形态的磷,目前应用的有各种提取方法。以水直接提取土壤所测得的磷量被认为是对植物直接有效的。通常低肥力的土壤和森林土壤,水中有效性磷的浓度每毫升只有几个微克,而在用水提取后,浓度一般要降低到0.5ppm 以下。低浓 In order to determine the different forms of soil phosphorus, there are a variety of extraction methods currently used. The direct determination of the phosphorus content of soils by water is considered to be directly effective for the plant. In generally low-fertility soils and forest soils, the concentration of available phosphorus in the water is only a few micrograms per milliliter, whereas the concentration after water extraction is generally reduced below 0.5 ppm. Low concentration