土壤是植物营养之本。但并不是在各地的植物都能在土壤中找到其需要量的所有必需的营养元素。植物不易获得土壤中营养元素的基本部分,其内容卽所谓游离的和在土壤中不比一般含量的百分比多很多的并易于植物接受的营养物質。营养元素转化为植物易于接受的状态主要是由于土壤微生物生命活动的結果。 Soil is the root of plant nutrition. But not all the essential nutrients that the plants everywhere can find in their soil are what they need. It is not easy for plants to obtain essential elements of nutrients in soils, the content of which is so-called and not so much in the soil as a percentage of their content in general and readily accepted by the plant. The conversion of nutrients into plants that are easily accepted is mainly the result of life activities of soil microbes.