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四、各种离子的提取能力及各种提取剂 现在我们再看看各种提取剂中具有作用力的离子是怎样去作用于各类土壤磷化合物的。目前已被提出的土壤速效磷提取剂虽然种类繁多,但它们所含有的具有提取能力的离子则不外下列各种: 1.H离子 它可作用于各种Ca—P.土壤中有些ca—P的溶解度很低,但它们在酸性条件下也能够逐渐溶解。其原理正如磷矿石加H_2SO_4制成过磷酸钙一样。H离子也可以相当缓慢地作用于A1—P,并以更缓慢的程度作用于Fe—P,故H离子的总的提取力顺序为:Ca—P>Al—P>Fe—P。 2.OH离子 它的作用能力正好与H离子相反,它能溶解各种Fe—P,并以稍低的程度作用于A1—P.OH离子几乎不能作用于Ca—P.故OH离子的总的提取力顺序为:Fe—P>Al—P>Ca—P.此外,OH离子
Fourth, a variety of ion extraction ability and a variety of extractants Now we look at a variety of extractants in the role of ions is how to go to various types of soil phosphorus compounds. Although there are many kinds of soil available phosphorus extractants that have been proposed so far, they contain the following kinds of extractable ions: 1. H ions can act on various Ca-P soils Some ca- The solubility of P is low, but they also dissolve gradually under acidic conditions. The principle is the same as phosphate rock plus H_2SO_4 made of superphosphate. H ions can also act on A1-P quite slowly and act on Fe-P to a much slower extent. Therefore, the total extraction order of H ions is Ca-P> Al-P> Fe-P. 2.OH ion its ability to act just opposite H ion, it can dissolve a variety of Fe-P, and to a lesser extent the role of A1-P.OH almost no role in Ca-P. So the total OH ion The order of extraction power is: Fe-P> Al-P> Ca-P. In addition, OH ions