土壤电导率原位测定的直流四极法

Determination of Soil Conductance "in situ"with DC Four Electrode's Method

简要地讨论了用直流四极法测定土壤电导的原理,较详细地描述了作者设计的一种测定天然水和土壤浸出液的直流四极电导池的结构。在内电极的端部覆盖一层离子交换树脂膜和动物胶膜的情况下,在10^(-1)～10^(-4)mol/L的NaCl标准溶液中,电导池的电导与盐的浓度呈现良好的线性关系。在上述浓度范围内,用直流四极法和交流二极法所得结果的相关系数为0.998。讨论了土壤含水量对测定结果的影响。达到稳定响应的时间约为5分钟。本方法已用于原位测定了种植棉花和绿肥的表土以及盐碱荒地的表土的电导。

The principle of measuring the conductance of natural water and extracted solution of soil with the DC four electrode's method is briefly discussed. A special structure of DC conductance measuring cell is detailly described. When the tip of the inner electrode is covered with a layer of ion-exchange resin membrane or of animal colloidal membrane, a good correlation between the conductivity of DC conductace cell and the salt concentration of soil is found in the range of 10-1-10-4mol/L NaCl solution. The correlative coefficient between the results obtained respectively with DC four electrode 's method and AC two electrode 's method is of 0. 998. The effect of water content of soil on determined results is discussed. The time attaining to stable response is about 5 min. This method has been used to determine the conductance in earth surface where the cotton and the green manue have been planted, and to that in saline-sodic uncropped location 'in situ'.