|Smith Jr, Sammie|
Submitted to: American Society of Agricultural Engineers Meetings Papers
Publication Type: Proceedings
Publication Acceptance Date: December 1, 2001
Publication Date: March 11, 2002
Citation: SMITH JR, S., DABNEY, S.M., COOPER, C.M. VEGETATIVE BARRIERS AFFECT SURFACE WATER QUALITY LEAVING EDGE-OF-FIELD DRAINAGE PIPES IN THE MISSISSIPPI DELTA. AMERICAN SOCIETY OF AGRICULTURAL ENGINEERS TOTAL MAXIMUM DAILY LOAD ENVIRONMENTAL REGULATIONS PROCEEDINGS. 2002. P. 454-465. Interpretive Summary: Modified field drainage pipes [slotted-board riser (SBR) pipes and slotted-inlet (SI) pipes] in the Beasley Lake watershed within the Mississippi Delta MSEA (Management Systems Evaluation Area) project are being compared for their effectiveness in improving edge-of-field water quality. The SBR pipes have boards installed to pond water during the winter. Pipes are instrumented for automatic collection of field runoff based on a flow. Instrumentation is relatively simple and compact, and involves an area-velocity flow logger and a scaled-down automated composite runoff sampler. This is significantly less costly and less labor intensive than the traditional instrumentation involving a flume, larger instrument shelter, flow-measuring device (a stage recorder), and full-size sampler. Runoff is being analyzed for pesticides, nutrients, and sediment concentrations. Discharge from pipes with and without an upslope grass hedge and with and without a tile drain are being compared from fields planted with no-tillage to Roundup-Ready® Bt cotton. As this research is only recently underway, the purpose of the paper is to describe in detail the instrumentation, site setup, and treatments, as well as to present some early findings. The results of this research are expected to help the development of new tools, which may offer alternatives for runoff remediation and improve TMDL development accuracy.
Technical Abstract: Three slotted-board riser (SBR) pipes and 3 slotted-inlet (SI) pipes in the Beasley Lake watershed were instrumented to measure water quality and quantity of runoff from their respective cropped areas. One SBR and one SI is a control. Two SBR and 2 SI pipes have a vegetative barrier (VB)planted upslope. Of these, a subsurface tile drain was installed under one SBR and one SI. In 2001, adjacent fields were planted with no-tillage to Roundup-Ready® Bt cotton (Gossypium hirsutum L.) and the sites were instrumented to automatically collect runoff on a flow proportional basis. Water quality measurements included pesticides, nutrients, TOC, and sediment concentration. There are no apparent differences in pesticide concentrations within treatment for both types of pipe sites. This is primarily the result of the fact that the VBs are newly-established and not providing any significant sorption surfaces for the more water soluble pesticides or any sediment trapping efficiency for those pesticides transported attached to sediment. Results for nutrient and TOC concentrations are similar. Sediment concentrations are lower from the SI pipes than from the SBR pipes. Once the VBs become well-established, we will observe and be able to quantify significant improvements in water quality from pipes that have VBs. We expect to see improvements in water quality from SBR pipes versus SI pipes.