A new electrochemical cell with a back-inserted reference electrode was designed to study soil corrosion. It was proved that, with the new cell, the influence of IR drop between the reference and the electrodes could be effectively eliminated, and some real polarization information of a soil-corrosion system could be obtained. To determine the corrosion rate of Carbon Steel in various soil-corrosion systems, a low-polarization-curve-fitting technique was used to process the measured data. It was found that, for most of the specimens, the average corrosion rates obtained from polarization tests were higher than those calculated from the estimated weight losses, but there existed a good linear relationship between them. Therefore, with the electrochemical technique, the corrosivity of different types of soil toward Carbon Steel could be evaluated and investigated experimentally. The results also indicated that the soil moisture content, airpore content and total salt content deeply affected the corrosion behavior of Carbon Steel in soil. The maximum corrosion rate in soil usually occured at the moisture content between 30～60% of water holding capacity, and the moisture value for the maximum corrosion rate varied with the airpore content and the total salt content in the soil.
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