摘要
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．
Permanent negative charge capacities of soils in central and southern China were measured by using effective cation exchange capacity (CEC) method, salt titraion-potential titration (STPT) method, Mehlich method and pH0 method respectively, which were compared with CEC determined by NH4OAc (pH7.0) displacement method. Results showed that : 1) The value of CEC was higher than that of permanent negative chafge, due to the veriable negative charge produced by the higher pH(7.0) or the NH4OAc System. 2) The four methods gave large differences in permanent negntive charge values which followed the order of ECEC>8p>CECK>CECk. 3)To some extent, the different values of permanent negative charge by different methods renected the adsorptive characteristics of soils. 4)The effective CEC method was recommended for permanent negative charge measurement for the examined soils.
基金
国家自然科学基金!49301013
欧共体International Scientific Cooperation资助!CI1-CT94-0048
关键词
土壤
永久负电荷量
测定方法
中南地区
soils
permanent negative charge capacities
measurement methods
