Submitted to: American Society of Agronomy Meetings
Publication Type: Abstract Only
Publication Acceptance Date: July 18, 2001
Publication Date: N/A
Fundamental watershed-scale hydrologic processes governing chemical transport through soil to neighboring ecosystems are so poorly understood that strategies for mitigating chemical contamination cannot be accurately formulated. The major limitation to quantifying chemical transport at the field and watershed scale is an accurate characterization of the subsurface eflow processes, including preferential flow. Ground-penetrating radar data was used to identify the subsurface convergent flow pathways on four small watersheds, USDA-ARS, BARC. The spatial distribution of corn grain yields, remote sensing, real-time soil moisture monitoring, and surface soil cores were used to evaluate and confirm the location of the GPR-identified flow pathways. Soil moisture observations near the GPR-identified flow pathways support the existence of funnel flow. Under water-limiting conditions high corn grain producing regions were poorly correlated with surface soil texture, organic matter, P and K spatial concentration distributions. However, superimposition of the subsurface convergent flow pathways with the high yielding corn regions on a CIR image suggest that funnel flow processes do influence yield. As a result, a sampling strategy based primarily on ground-penetrating radar may be useful in identifying subsurface convergent flow pathways.