植物生长需要氮、磷、钾、钙、镁、硫、硼、钼等营养元素,其中氮、磷、钾尤为重要,常称为三要素。在农业生产水平低,施肥较少和土壤比较贫瘠的情况下,单施氮亦可以提高作物产量,但是,当施肥量达到较高水平后,氮、磷、钾肥必须符合一定的施肥比例,才能最经济地获得最大的增 Plant growth needs nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, boron, molybdenum and other nutrients, of which nitrogen, phosphorus and potassium are particularly important, often called the three elements. In the case of low levels of agricultural production, less fertilization and poor soil conditions, single application of nitrogen can also increase crop yields, however, nitrogen, phosphorus and potassium fertilizers must meet certain fertilization rates when fertilization rates reach a high level The most economical gain the biggest increase