Incorporating electromagnetic induction methods into regional soil salinity survey of irrigation districts

Many land use decisions are made without the aid of soil maps in countries without National soil surveys. The purpose of this research was to create a soil survey delineating salinity phases at a regional scale that could serve as the basis for improved decision making, or highlight areas for further investigation. Soil salinity survey at a regional scale remains a challenge. We demonstrate a survey methodology suited to small fields, often found in Europe and developing countries, and present a streamlined survey methodology making this typically labor-intensive process more efficient. A regional soil survey was conducted at a scale of 1:25 000, mapping consociations and complexes of soil series. The soil survey information was then used to guide an electromagnetic induction (EMI) survey of the soils with observed salinity, to delineate phases. A calibration method for estimating the electrical conductivity of the extract of the saturated paste (ECe) from the EMI measurements was devised. After testing several statistical methods, a single calibration of the EMI data was found to be suitable using a nonparametric regression. The use of the EMI method reduced operation costs, where time, personnel, analysis time, and budget are limitations.