N、P、K是植物营养的三大要素,因此在土壤及农作物分析中,一般是首先要分析这三种元素.过去,三元素的测定大多是分别进行的,测N:用开氏法消煮,并加入不同的催化剂:测磷:在马福炉中进行半干灰化;为了减少磷的挥发,增加醋酸镁,或在混合浓酸中进行;测钾,则多用干灰化,在热水或热稀盐酸溶提,也有用1N浓度的冷HCI来浸提. N, P, K are the three major elements of plant nutrition, so in soil and crop analysis, it is generally the first to analyze these three elements.In the past, the determination of the three elements are mostly carried out, measured N: Digestion and boiling, and add a different catalyst: Phosphorus: In the muffle furnace for semi-dry ashes; In order to reduce the volatilization of phosphorus, increase the magnesium acetate, or in the mixed concentrated acid; Potassium, the more dry ashing, hot Water or hot dilute hydrochloric acid leaching, but also useful 1N cold HCI concentration to leach.