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用有效阳离子交换量法、盐滴定-电位滴定法（STPT）、Mehlich法和pfo原理法测定了中南地区几种土壤的永久负电荷量．并与醋酸铵法测定的CEC进行了比较．结果表明：（1）由于醋酸铵法浸提了土壤的部分可变负电荷．它测出的CEC值使其它方法测得的永久负电荷量高．（2）不同方法测得的土壤永久负电荷量差异较大，且用上述四种方法测得的值依次减小．即ECEC＞δP＞CECp＞CECk，这与测定方法和指示离子的本性有关．但都能反映土壤永久负电荷容量的相对大小．（3）不同方法测得的不同的永久负电荷量值．在一定程度上反映着土壤的吸附特性，但有效阳离子交换量法能较好地反映土壤永久负电行量．
The permanent negative charge of several soils in central and southern China was determined by the method of effective cation exchange, salt titration - potentiometric titration (STPT), Mehlich method and pfo method. The results were compared with CEC measured by ammonium acetate method. The results showed that: (1) Partially variable negative charge of soil was extracted by ammonium acetate method. It measured the CEC value of other methods to measure the permanent negative charge high. (2) The difference of soil permanent negative charge measured by different methods is larger, and the values measured by the above four methods decrease in turn. Ie ECEC> δP> CECp> CECk, which is related to the nature of the assay and the indicated ion. But all reflect the relative size of soil permanent negative charge capacity. (3) Different permanent negative charge values measured by different methods. To a certain extent, reflect the adsorption characteristics of soil, but the effective cation exchange capacity method can better reflect the soil permanent negative electrical capacity.