Apparent soil electrical conductivity mapping as an agricultural management tool in arid zone soils

Electromagnetic induction (EM) is a commonly used tool for non-invasive mapping of apparent soil electrical conductivity (ECa). In this paper, we examine three applications of EM surveying used in arid southwestern US agriculture: repetitive salinity mapping, soil texture mapping, and locating buried tile lines. The basic statistical modeling techniques associated with each application are described and then demonstrated using data from three different field survey projects. In the first study, pre- and post-EM surveys are used to quantify the degree of salt removal from a field leaching event. These survey results demonstrate that the degree of salt removal was spatially variable and that the leaching process was not successful in sub-areas of the field that exhibited high pre-survey salinity concentration levels. The second study demonstrates the use of EM survey data for precision soil texture mapping under non-saline conditions, and illustrates how texture prediction maps can be generated from EM survey data. The final study represents an example of how EM survey data can be used to precisely locate the positions of buried tile lines. In this latter study, two different EM survey data sets that were collected 1 year apart produced estimates of tile line positions within 1 m of each other, validating the reliability and repeatability of the proposed tile line identification strategy. These projects demonstrate three applications of ECa surveying techniques used to derive spatial information that aids in the effective management of agricultural fields.