Mapping of Soil Salinity Using Electromagnetic Induction: A Case Study of East Nile Delta, Egypt

T he objective of this study is to map the spatial distribution of the soil salinity at field scale for site-specific management using the electromagnetic sensor (Geonics EM38). The salinity of an area of 67.2 ha cultivated wheat pivot field at East of Nile Delta, Egypt, was analyzed by reading the apparent soil electric conductivity (ECa) using the EM38 sensor at 432 locations within the pivot field. Twenty soil sampling sites were chosen according to spatial response surface sampling design (SRS). At those sites, soil core samples were taken at 0.3 m intervals to a depth of 0.9 m. Four soil variables were analyzed which are soil salinity (ECe), soil clay content (clay), soil water content (WC), and soil organic matter (OM). The multiple linear calibration model (MLC) was used to predict the depth-specific soil salinity ECe values at the remaining non-sampled locations. The MLC calibration model predicted ECe from EM38 signal readings with R2 ranging from 0.41 to 0.73 for the multiple-depth profile. Furthermore, the MLC model provided field range estimates of soil salinity. Ninety-one percent of the field had ECe values below 4 dS m-1. The obtained salinity maps were helpful to display the spatial patterns of soil salinity for site-specific management.