|Huang, Chi Hua|
Submitted to: Soil Science Society of America Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 11/5/2000
Publication Date: N/A
Technical Abstract: Phosphorous (P) and nitrogen (N) in runoff from agricultural fields is key issue in water quality and extensive efforts have been made to determine conditions that contribute to P/N losses. However, one factor, artesian seepage, which may contribute significant P/N movement on the landscape, has not yet been quantified. Recent studies showed increased soil erosion under seepage conditions. The enhanced chemical dissolution at moisture saturation, combined with the increased sediment production may accelerate P/N losses. A laboratory study was designed to evaluate surface hydrologic effects on P and N losses in surface runoff under simulated rainfall. Hydrologic conditions included: free drainage (DR) saturation (SA), seep flow alone (SP), and seep flow with rain (SP+R). Results showed that artesian seepage condition has a great effect on runoff water quality. Comparing to DR condition, nitrate concentrations in runoff were 30, 4000 and 700 times greater and dissolved P in runoff were 5, 8 and 7 times greater under SA, SP and SP+R conditions for a nominal fertilization rate of 100 kg/ha N and 40 kg/ha P. These results confirm that seepage condition significantly affects water quality and efforts need to be focused on identifying conditions that trigger hillslope seepage and methodologies to minimize the seepage effects.