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不含碳酸盐土壤的代换性盐基测定,一般用盖德洛以茨法,可说很少遇有困难;但是含碳酸盐土壤,不仅代换性Ca~(++)与Mg~(++),直到目前尚无法正确测定,而且吸收容量(即代换性阳离子总量,或称盐基代换量)的测定,也经常遇到困难。其原因是含碳酸盐土壤中的碳酸盐类(CaCO_3及MgCO_3)在中性盐溶液中被溶解,而与代换性Ca与Mg相混淆。同时这种土壤常伴含有可溶性碳酸盐类(Na_2CO_3,NaHCO_3,Ca(HCO_3)_2,Mg(HCO_3)_2及CaSO_4
Substitution of carbonate-free soils for salt-based determination of the general use of Gaddeau-Root method, can be said to be rare encounter difficulties; but carbonate-containing soil, not only substitutional Ca ~ (++) and Mg ~ (++), until it has not been determined correctly until now, and the determination of absorption capacity (ie, total amount of exchangeable cations, or salt base substitution) is also often encountered with difficulties. The reason for this is that the carbonate (CaCO 3 and MgCO 3) in carbonate-containing soils is dissolved in neutral salt solution and is confused with substitutional Ca and Mg. At the same time, this soil often contains soluble carbonates (Na_2CO_3, NaHCO_3, Ca (HCO_3) _2, Mg (HCO_3) _2 and CaSO_4