Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: October 21, 2001
Publication Date: N/A
Technical Abstract: Soil water is one of the major factors controlling hydrologic processes. Ground truth data is required to test adequately the applicability of various approaches of representing temporal and spatial variability of soil water from the application of geostatistical technique to deterministic representations. We collected soil water data over three years, beginning in February 1998, at 12 locations in an 8-ha bermuda grass pasture near Watkinsville, GA, in the Southern Piedmont. We used a TDR-based instrument (ESI, Victoria, British Columbia, Canada) that measures average soil water in the 0-15, 15-30, 30-60, 60-90 and 90-120 cm depth. Six sites were located on mid-slopes and the other six at slope bottom on the flatter part of the bowl-shaped watershed. The soil is a Cecil sandy loam (clayey, kaolinitic, thermic Typic Kanhapludults). The late fall and winter months were times of recharge, while the spring and summer months were periods of drying. The soil profile was highly responsive to wet and dry conditions, especially in the top 60-cm. Mean soil water varied between 10 and 35% in the 0-15, 16 and 32% in the 15-30, 20 and 35% in the 30-60, 25 and 38% in the 60-90, and 30 to 40% in the 90-120 cm depths. The profile was wettest in January and February. It was driest in summer except when recharge occurred following precipitation then the profile quickly dried out. Considering most drying periods, there was between 10 and 48 % more total loss (mm of soil water) from mid-slope than bottom-slope locations in all but the bottom profile. Such soil water dynamics has implications for hydrologic processes such as infiltration and runoff.