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Title: Implementation of Drainage Water Management in Open Ditch Drainage Systems of the Mississippi Alluvial Valley

Author
item Appelboom, Timothy
item Fouss, James

Submitted to: Nature Conservancy
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/1/2006
Publication Date: 12/10/2006
Citation: Appelboom, T.W. and J.L. Fouss. Implementation of Drainage Water Management in Open Ditch Drainage Systems of the Lower Mississippi River Basin. 2006. In: Proceedings, Innovations in Reducing Non-Point Source Pollution: Methods, Policies, Programs, and Measurement Meeting, Indianapolis, Indiana, November 28-30, 2006. Ed. Dennis Wichelns. Rivers Institute at Hanover College. PP. 177 - 189. (ARIS #202537) (Lecture and Paper).

Interpretive Summary: Increased riverine nutrients linked to agricultural activities in the Mississippi River Basin have contributed to degraded surface waters within the basin as well as to the hypoxic zone along the Louisiana Gulf coast. In the Mississippi Alluvial Valley (MAV), these nutrients are transported from agricultural fields in drainage waters through improved surface and subsurface drainage using open field ditches and collector canals. Studies have shown that annually an average of 5.6% of nitrate applied to agricultural fields in the MAV is transported in drainage water to receiving surface waters. Drainage water management (the holding back of drainage water within the soil profile and drainage network) can be implemented in the MAV open ditch drainage networks by the installation of a water control structure at a drainage outlet. The water control structure can be placed in a field ditch to control drainage from a single field or placed in a collector canal to control drainage from a number of fields. A typical management schedule would be the same as that found in the Midwest; the outlet elevation would be lowered to or near the bottom of the drainage ditch at the outlet (free drainage) during planting and harvesting operations, elevated to just below the root zone during the growing season and elevated to a shallow depth (e.g., 8 inches) below the soil surface during the non-growing season. Studies conducted in the Midwest have shown that this schedule can reduce nitrate losses with drainage water up to 50%. Elevating the drainage outlet to just below the root zone during the growing season may prove to be important in the MAV as previous research has shown that a majority of nitrate losses (62% to 95%) occur during this time. Raising the outlet to a shallow depth during the non-growing season and an elevated drainage outlet during the growing season may reduce the current 5.6% nitrate loss to 2.8%.

Technical Abstract: Increased riverine nutrients linked to agricultural activities in the Mississippi River Basin have contributed to degraded surface waters within the basin as well as to the hypoxic zone along the Louisiana Gulf coast. In the Mississippi Alluvial Valley (MAV), these nutrients are transported from agricultural fields in drainage waters via improved surface and subsurface drainage; primarily using open field ditches and collector canals. Studies have shown that annually an average of 5.6% of nitrate applied to agricultural fields in the MAV is transported in drainage water to receiving surface waters. Drainage water management can be implemented in the MAV open ditch drainage networks by the installation of a water control structure at a drainage outlet. The water control structure can be placed in a field ditch to control drainage from a single field or placed in a collector canal to control drainage from a number of fields. A typical management schedule would be the same as that found in the Midwest; the outlet elevation would be lowered to or near the bottom of the drainage ditch at the outlet (free drainage) during planting and harvesting operations, elevated to just below the root zone during the growing season and elevated to a shallow depth (e.g., 20 cm) below the soil surface during the non-growing season. Studies conducted in the Midwest have shown that this schedule can reduce nitrate losses with drainage water up to 50%. Elevating the drainage outlet to just below the root zone during the growing season may prove to be important in the MAV as previous research has shown that a majority of nitrate losses (62% to 95%) occur during this time. The implementation of a shallow drainage outlet during the non-growing season and an elevated drainage outlet during the growing season may reduce the current 5.6% nitrate loss to 2.8%.