Soil salinity and sodicity appraisal by electromagnetic induction in soils irrigated to grow cotton

• Published in: Land degradation & development 2014-05, Vol.25 (3), p.228-235
• Main Authors: Ganjegunte, G. K, Sheng, Z, Clark, J. A
• Format: Article
• Language: English
• Subjects: adsorption; apparent electrical conductivity; clay; cotton; crop yield; Electrical conductivity; Electrical resistivity; Electromagnetic induction; electromagnetic induction technique; equations; farm profitability; irrigated soils; irrigation; linear models; Mathematical models; prediction; Resistivity; river water; saline soils; Salinity; salinity management; sodicity; sodium; sodium adsorption ratio; Soil (material); soil salinity; soil sodicity; Synthetic aperture radar; USA
• ISSN: 1085-3278; 1099-145X
• DOI: 10.1002/ldr.1162

In the Far West Texas region in the USA, long‐term irrigation of fine‐textured valley soils with saline Rio Grande River water has led to soil salinity and sodicity problems. Soil salinity [measured by saturated paste electrical conductivity (ECₑ)] and sodicity [measured by sodium adsorption ratio (SAR)] in the irrigated areas have resulted in poor growing conditions, reduced crop yields, and declining farm profitability. Understanding the spatial distribution of ECₑ and SAR within the affected areas is necessary for developing management practices. Conventional methods of assessing ECₑ and SAR distribution at a high spatial resolution are expensive and time consuming. This study evaluated the accuracy of electromagnetic induction (EMI), which measures apparent electrical conductivity (ECₐ), to delineate ECₑ and SAR distribution in two cotton fields located in the Hudspeth and El Paso Counties of Texas, USA. Calibration equations for converting ECₐ into ECₑ and SAR were derived using the multiple linear regression (MLR) model included in the ECₑ Sampling Assessment and Prediction program package developed by the US Salinity Laboratory. Correlations between ECₐ and soil variables (clay content, ECₑ, SAR) were highly significant (p ≤ 0·05). This was further confirmed by significant (p ≤ 0·05) MLRs used for estimating ECₑ and SAR. The ECₑ and SAR determined by ECₐ closely matched the measured ECₑ and SAR values of the study site soils, which ranged from 0·47 to 9·87 dS m⁻¹ and 2·27 to 27·4 mmol¹/² L⁻¹/², respectively. High R² values between estimated and measured soil ECₑ and SAR values validated the MLR model results. Results of this study indicated that the EMI method can be used for rapid and accurate delineation of salinity and sodicity distribution within the affected area. Copyright © 2012 John Wiley & Sons, Ltd.