Comparing three geophysical tools for locating sand blows in alluvial soils of southeast Missouri

ABSTRACT:

The level, moderately fine and fine-textured, poorly and very poorly drained alluvial soils of the southern Mississippi River Valley are well suited to rice production. However, in many areas, small inclusions of more rapidly permeable, coarse-textured soils occur as sand blows. Because of their more rapid permeability, these included soils are considered marginal for rice production. In this study, an EM38 meter, a GEM300 sensor, and a Veris 3100 soil EC mapping system were compared and used to assess clay content and to locate sand blows in southeastern Missouri. All three tools produced similar gross spatial patterns of apparent conductivity that corresponded to mapped soil delineations and changes in clay content. However, spatial patterns of apparent conductivity are more intricate than major soil patterns and indicate soil map unit inclusions. Moderate correlations (r = 0.39 to 0.71) were found between apparent conductivity and average clay content of the o to 25 cm layer. Correlations improved (r = 0.63 to 0.90) as the clay content was averaged over the o to 75 cm and the o to 100 cm depth intervals. As spatial patterns reflect differences in clay content, these tools can be used to help locate small, included areas of coarse-textured soils that might otherwise be overlooked.