우리나라 서남해안 간척지 토양의 염도 측정시 1:5 추출법 EC를 이용한 포화 침출액 EC 환산법

Measurement of electrical conductivity of saturated soil paste (ECe) which is the best indicator of soil salinity is time-consuming when the number of sample is huge or frequent monitoring is required. Thus, conversion of electrical conductivity of 1:5 soil-water extract (EC1:5) to ECe using a dilution factor is necessary. In South Korea, a wide range (5.49-9.94) of dilution factor for EC1:5 has been reported, but no relevant study has been conducted for new reclaimed tideland (RTL) constructed since 2000s. Therefore, this study was conducted to find the dilution factor to estimate ECe from EC1:5 using the relationship between EC1:5 and ECe for the new RTL soils. Soil samples (n=40) were collected from four RTLs, and analyzed for EC1:5 and cation compositions of 1:5 soil-water extract and ECe of extracts of saturated soil paste. The dilution factor (8.70) was estimated by fitting simple linear regression between EC1:5 and ECe, and the obtained dilution factor was validated by applying to an independent data set (n=96) of RTL soils. The ECe measured and predicted for independent data set was strongly correlated (r2=0.74, P<0.001), but ECe was overestimated by 16% particularly for the soils with high clay content and low sodium adsorption ratio (SAR). Therefore, this study suggests that conversion of EC1:5 to ECe using a dilution factor is feasible method to monitor changes in the soils salinity of the study RTL. However, when monitoring the salinity of the soils with high clay content and low SAR, overestimation of ECe should be cautioned.