Modeling the electrical conductivity relationship between saturated paste extract and 1:2.5 dilution in different soil textural classes
Moh’d M. Omar, Mawazo J. Shitindi, Boniface H. J. Massawe, Ole Pedersen, Joel Meliyo, Kadeghe G. Fue
Abstract
Regression models were developed to estimate the electrical conductivity of saturated paste extract (ECe) from the electrical conductivity of soil-water ratio (EC 1:2.5 ) for different soil textural classes. ECe is a crucial parameter used to indicate the presence, type, and distribution of salinity in soils. However, determining ECe is demanding, time-consuming, requires considerable skill to accurately identify the correct soil saturation point, and is not routinely performed by soil testing laboratories. Many laboratories, instead, commonly measure the electrical conductivity of soil-water extracts at various dilutions, such as EC 1:1 , EC 1:2.5 , or EC 1:5 . In this study, 706 soil samples were collected from depths of 0 - 30 cm across three rice irrigation schemes to determine EC 1:2.5 , with 50% analyzed for ECe. ECe values were grouped based on soil textural classes. The results showed a strong linear relationship between EC 1:2.5 and ECe values, with a high coefficient of determination (R² > 0.95). The Root Mean Square Error values were low (1.4 < RMSE), and the Mean Absolute Error values were similarly low (0.85 < MAE). Therefore, the regression models developed provide a practical means of estimating ECe for various soil textural classes, thereby enhancing soil salinity assessment and management strategies.