Application of a mobile electromagnetic sensing system (MESS) to assess cause and management of soil salinization in an irrigated cotton-growing field

Abstract. Generally, traditional soil surveys do not adequately account for the spatial variability of soil properties. Maps that are derived using these cursory soil data are likely to contain errors and thus make interpretation and soil management difficult. On the other hand quantitative methods of soil inventory at the field scale involve the design and adoption of sampling regimes and laboratory analysis that are time consuming and costly. In the latter case new technologies are required to efficiently sample and observe the soil in the field. This is particularly the case where soil salinization is prevalent, and detailed quantitative information for determining its cause is required. In this paper, a Mobile Electromagnetic Sensing System (MESS) is described and its application in an irrigated-cotton field, located in the lower Namoi valley in New South Wales, Australia. Results from the EM38 instrument were found to be correlated with the effective cation exchange capacity ( r ²= 0.81). This was related to variability in soil mineralogy across the field. In addition, differences in soil chemical and textural variables, measured along a transect and adjacent to water storage, were used to identify seepage areas near a water reservoir where soil salinization was evident.