ARS | Publication request: HOW NEAR-SURFACE MOISTURE GRADIENT AFFECT PHOSPHORUS TRANSPORT?

Submitted to: American Society of Agronomy Meetings
Publication Type: Abstract Only
Publication Acceptance Date: October 21, 2001
Publication Date: October 21, 2001
Citation: Zheng, F., Huang, C., Norton, L.D. How near-surface moisture gradient affect phosphorus transport? CD-ROM. Charlotte, NC: American Society of Agronomy Meetings. 2001.

Technical Abstract: Accelerated phosphorus (P) loss with runoff and eroded sediment from intensively managed agricultural lands can contribute to eutrophication of fresh water body. Numerous studies have been conducted to determine the source factors and site conditions contributing to P loss with runoff and eroded sediment. However, there is little information relating surface hydrologic condition, specifically under saturation and artesian seepage conditions, to P transport on the landscape. A laboratory study was conduct to quantify the near-surface moisture gradient effects on P transport under simulated rainfall. Hydrologic conditions studied included: free drainage (Fd), saturation (Sa), and artesian seepage (Sp). Results showed that near-surface moisture gradients have a significant effect on P transport in runoff and sediment. Under a normal fertilizer application rate of 40 kg ha-1 P, average P concentrations in runoff under Sa and Sp were 4 and 7 times greater than P measured under Fd. After accounting for the total runoff and sediment discharge, the total P loading from runoff were 6 and 10 times and from sediment 4 to 8 times under Sa and Sp conditions as compa to the Fd condition. These results show the importance of considering the surface hydrologic condition as a factor in evaluating runoff water quality impacts.