The most common form of subsurface watertable management used in the Midwest is conventional farm drainage. A system of plastic drainage pipes which outlet into a ditch or stream acts to lower the watertable level equal to the drain depth. However, the method of using watertable control structures to create controlled drainage is gaining popularity.
With controlled drainage the traditional drainage pipe system is intercepted by a water control structure. This allows the drainage system outlet to be artificially set at any level between the ground surface and the drains. Gates, or stoplogs, are added or removed to adjust the watertable level based on the time of year and needed field operations.
Raising the outlet after planting helps keep water available for plant use longer than uncontrolled subsurface drainage. This practice can also be used to recharge the watertable between growing seasons. Research conducted in North Carolina indicates that controlled drainage may provide some reduction in nitrate (N) losses over conventional drained cropland.
Watertable Control Structures
- Rugged 1/2″PVC structure
- Plastic lockable lid
- Stainless steel screws and custom anodized aluminum corner extrusions are used for strength and durability
- 5″& 7″ stoplogs for adjustability
- Flexible couplers allow PVC, plastic pipe, or other materials to be easily attached
- 5-year warranty on all standard structures
With subirrigation, one system provides both the drainage and irrigation requirements for the crop. The watertable level in the field is regulated through the subsurface drainage system using control structures. The subsurface drain spacing for subirrigation is usually 30 to 50 percent denser than that used for conventional subsurface drainage. Irrigation occurs below the ground surface, thus raising and maintaining the watertable at an appropriate depth in the crop root zone.
To order a watertable control structure, contact your local Timewell sales manager.