Conversion Factors for Electrical Conductivity of 1:5 Soil-Water Extracts to Saturated Paste of Reclaimed Tideland Soils are Affected by Sand Contents

Abstract

Electrical conductivity (EC) of saturated soil paste extracts (ECe) is a standard measure for soil salinity assessment. However, due to the difficulty of ECe measurement, EC of the extracts of 1:5 soil:water ratio (EC1:5) is widely used, and thus conversion of EC1:5 to ECe is often required. However, the conversion factor varies widely being affected by many soil factors including soil texture though such variation has rarely been investigated. This study was conducted to explore the effect of soil texture (particularly sand content) on the EC conversion factor using soil samples (n = 628) from 19 reclaimed tidelands (RTLs) located in the coastal areas of Korea. The conversion factors ranged from 4.6 to 9.9 (average 7.5) and the conversion factors were positively correlated with the average sand content of the RTL (r2 = 0.48, P < 0.001) except for three RTLs which have extremely low sand contents. The increased EC conversion factors for soils with higher sand contents should be ascribed to decreased saturated water contents for ECe. Our results demonstrate the critical influence of sand content on the EC conversion factor by highlighting the necessity of consideration of sand content for EC conversion factor.Correlation between EC1:5 and ECe of soils collected from reclaimed tideland. The slope (7.5) indicates that the conversion factor from EC1:5 to ECe is 7.5.