Possibility of using EM38 device to determine the extent and severity of soil salinity: a case study in the lower Seyhan plain, Turkey

Abstract

Salinity is an increasing problem in irrigated areas which causes important reductions in agricultural production. Distribution of soil salinity and its variability are required to set up measure-observation control in an irrigated area. The conventional methods to determine soil salinity in an irrigated area entail intensive land survey and laboratory analysis. However these take plenty of time and cost much. Instead of these conventional methods, lately, practical and simple techniques have become a current issue in salinity assessment. One of them is to use electromagnetic induction meter (Geonics-EM38) that measures apparent soil salinity, ECa. EM38 is a device which is designed to measure ECa horizontally and vertically, i.e., to a depth of 0-1 m and 0-2 m, respectively. In this research, we tried to investigate the effectiveness of EM38 device in identifying and mapping of soil salinity. The study was conducted in Yemi li Irrigation District (YID), covering an area of 7110 ha. YID is located in the Lower Seyhan Plain in the eastern part of the Mediterranean region, Adana, Turkey. The majority of farmers in YID use irrigation return flows of poor quality, diverted from main drainage canals. For this reason, the fields in YID are always under the risk of soil salinization. Therefore, soil salinity has to be monitored frequently in a quick and efficient way. Because of these characteristics, YID was chosen and 112 EM38 readings were done for salinity assessment. Concurrently, soil samples from 20 points, distributed randomly in the field, were taken from 1 m soil profile with 0.3 m intervals, summing up three totally. Extracts of soil saturation paste were obtained. Composite samples for 0-1 m depths were prepared by using extracts of each layer and salinities of composite samples were measured, ECe, to determine average ECe of 0-1 m depth. The relationship between ECe and ECa is determined. Then, ECe map was produced and salinity profile distribution was developed for the study area. The results showed that the electromagnetic induction meter (EM38) can be used very efficiently to determine soil salinity in areas prone to salinization like in YID. Additionally, spatial and temporal changes in soil salinity can be derived from EM38 readings, provided that the deterministic association between ECa and ECe is determined.