Effect of landscape position on soil water distribution and solute transport

Topography affects hydrology and results in variability in soil water distribution, crop production, and solute transport at different landscape positions. Our objectives were to evaluate the effect of landscape position on soil water status, corn (Zea mays L.) silage production, and Br{dollar}sp-{dollar} transport. Two transects that included a footslope, linearslope, and interfluve were selected in a farmer-managed field. KBr was surface applied and vertical and lateral Br{dollar}sp-{dollar} transport was determined on soil cores collected after 140, 560, and 1460 mm of rainfall. Soil water content and soil water pressure were monitored using neutron attenuation and tensiometers. Plant available water was calculated to be in situ soil water content minus water content at {dollar}-{dollar}1500 kPa. Total soil water content, plant available water, soil water pressure, and silage yield varied with landscape position. Total soil water content increased from the footslope to the interfluve and was negatively correlated with silage yield. Soil water pressure was significantly higher at the footslope and was correlated with silage yield. The footslope had the lowest total water content, but also had more plant available water for plant uptake. Both vertical and lateral Br{dollar}sp-{dollar} transport varied with landscape position being greatest at the footslope. After 140 mm of rainfall, most of the Br{dollar}sp-{dollar} remained in the upper 30 cm of the soil profile, but measurable lateral Br{dollar}sp-{dollar} transport occurred at all landscape positions. After 560 mm rainfall, the maximum Br{dollar}sp-{dollar} concentration occurred above 60 cm, but Br{dollar}sp-{dollar} was detected as deep as 150 cm at the footslope and interfluve. Lateral Br{dollar}sp-{dollar} transport as far as 150 cm occurred at the foot and linear slopes. After 1460 mm rainfall, most Br{dollar}sp-{dollar} disappeared from the footslope. Lateral transport of Br{dollar}sp-{dollar} as much as 225 cm downslope occurred at all positions. Net soil water recharge and loss varied with landscape position and the patterns depended on the antecedent moisture content. The footslope had the highest recharge and the lowest water loss. Accumulation of Mn at the footslope indicated that a strong lateral component is associated with water flow in Piedmont landscapes.