Use of ground penetrating radar to map soil features that influence water content

Vadose zone studies are being conducted in the loessial soils at Ames Plantation, which is located near Memphis, Tennessee. The vadose zone beneath two agricultural production fields at this site (one a tilled field and the other a no-tilled field) is heterogeneous. The soil profile consists of two or more parent materials, varying soil textures, and lamella formations. These nonhomogeneous soils can govern solute migration throughout the vadose zone, having an impact on the offsite transport of agrochemicals.

To assist the ongoing vadose zone monitoring studies at Ames Plantation, an interdisciplinary team of scientists from The University of Tennessee is developing innovative applications of Ground Penetrating Radar (GPR) technology. Studies have shown that GPR can provide an accurate and nonintrusive method for mapping and studying nonhomogeneous soil profiles. Research focused on the development of near-surface survey methodologies for identifying and mapping subsurface hydrogeological features. Subsurface features of primary interest include loess/alluvium interfaces, perched water tables, and preferential water flow paths. Successful identification of such features include (1) a shallow water table, (2) coastal plain sediments, and (3) fragipans.

At Ames Plantation newly devised methodologies for data acquisition and GPR settings were incorporated. These new methodologies allowed researchers to map the loess/alluvium interface, giving insight to the offsite transport of agrochemicals from a no till site and a tillage site. Other subsurface features successfully mapped by GPR at Ames Plantation were a fragipan and increases in soil moisture content.