Ecology, Environment and Conservation Paper

MAPPING OF SOIL SALINITY USING ELECTROMAGNETIC INDUCTIVE METHOD AT THE AGRICULTURAL RESEARCH STATION OF KFU, AL HASSA, KSA

Ahmed S. El Mahmoudi, Adel A. Hussein and Yousf A. Al-Molhem

Abstract

The agricultural research station of King Faisal University, KSA is a key field of scientific studies conducted by faculty members and graduates of King Faisal University. The soil and water are of the most important factors that determine the success of agricultural activity in any location and based on their characteristics, the type of plants, as well as their productivity are determined. Soil salinity is considered to be of a dominant problem affecting the agricultural activities in this agricultural research station. To contribute to solution of this problem: irrigation water samples were collected from the operating six water wells, which are the source of irrigation water at this research station and electromagnetic induction implemented in this study. EM38-MK2 conductivity meter, as an inexpensive, rapid and effective modern technique for evaluating soil salinity of soil, used in vertical mode to measure the electrical conductivity (ECe) at depths of 75 and 150 cm at about 700 sites along the study area. Moreover, about 157 soil samples using a hand auger were collected at depth intervals of 10-20 cm and 30-40 cm for the same site. The electrical conductivity for the collected soil samples measured at the lab to correlate with the EM38-Mk2 data. The analysis of collected ground water samples showed that ECiw ranged from 1.37 to 1.83 dS/m. The calculated sodium absorption ratio (SAR) hazard value of the collected ground water samples is relatively low in comparing with the critical level of sodium hazard. Based on the criteria used for interpreting water quality for irrigation purpose, the used groundwater from the operating six water wells in the area of study is consideto be acceptable for agricultural purposes while the most domaint problems is potential salinity. The collected ECe using the data of the EM38-MK2 was processed & analyzed and two salinity maps constructed at 75 & 15 cm. In addition, two salinity maps constructed from the ECe data of the collected soil samples at depth intervals of 10-20 cm and 30-40 cm. Both of salinity maps of EM38 are in good match with the salinity maps of lab measurements. The salinity variation was found to change laterally and vertically due to change in soil type/texture and soil moisture and mainly due to the existing of the hardpan layer at shallow depths at the area of study which in turn leas to formation of sabkha in the study area.