Mapping Soil Salinity of the Northern Region of Yazd-Ardakan Plain Using EM38 Instrument and ESAP Modeling Software

Increasing aridity caused by the drought phenomenon in recent years has led to a decrease in the threshold wind speed for removing dust particles from the soil surface of arid areas. The accumulation of salts on the surface of the soil, due to low precipitation and high evaporation, causes disintegration of the aggregates. Salt particles along with the soil particles are removed by wind and they fall over a distance. If the target area is agricultural land, dust containing salt results in the transfer of salt to the affected area, which leads to a decrease in the yield of the crops. In this research, EM38 electromagnetic induction instrument was used in horizontal orientation in order to provide a cheap and fast map for surface soil salinity (0-30 cm) in the area that are sensitive to wind erosion in northern Yazd-Ardakan plain. The ESAP-95 2.35R Software package was also used to determine the number and location of soil samples in order to determine the regression model and to prepare a map of the salinity pattern in the area. With the transfer of EM38 data to the ESAP-RSSD program, the standard number and soil sampling points for 12 sites were identified. Subsequently, a Multiple Linear Regression model (MLR) was developed using ESAP-Calibrate and using Electrical Conductivity data of the saturated extract (ECe), saturation percentage (SP) and percentage of water content (WC). The results showed that the proposed regression model could model the soil surface salinity from EM38 readings with a determination coefficient (R2) of 0.37 and Root Mean Square Error (RMSE) of 80.55. The results of using the ESAP-SaltMapper program for mapping soil surface salinity showed that the southeast of the study area had higher salinity and the possibility of harvesting salt by the wind was much higher. The results also showed that the use of the EM38 device should be made in areas with homogeneous and standardized moisture at field capacity level and ESAP software can be used to map soil salinity.