大家知道,为了在农业上取得更好的收成,每年都要将成千上万吨的化肥运到农村去。而这些肥料是氮、鉀、磷、鈣等化学元素的化合物。难道土壤中就沒有这些化学元素吗?不,土壤中是含有植物所需的上述元素的。可惜的是,这些元素往往都以不能被植物直接吸收利用的化合物在土壤中出現。而氮的无机化合物,植物非常需要它,但是土壤中的含量却太少,而 Everyone knows that in order to achieve a better harvest in agriculture, tens of thousands of tons of chemical fertilizer will be transported to rural areas every year. These fertilizers are compounds of chemical elements such as nitrogen, potassium, phosphorus, and calcium. Is there no such chemical element in the soil? No, the soil contains the above elements needed for the plant. Unfortunately, these elements often appear in the soil as compounds that cannot be absorbed directly by plants. The inorganic compounds of nitrogen, the plants are in great need of it, but the content in the soil is too little, and