Nitrate management in tile water is a big reason why this water control structure has slowly gained a foothold in the Corn Belt
Control water levels and nitrogen with tile systems
The practice that really has Charlie Schafer, manufacturer of the water control structure at Agri Drain in Adair, Iowa, revved up is drainage water management. An inline water control structure installed at the edge of a field intercepts a tile line, raising and lowering water levels in the soil as the crop needs it. Ahead of planting, all stop-logs are removed, completely draining the field. After planting, stop logs are reinserted to raise soil water levels as rainfall infiltrates the tile. The water and nitrates are then available to the crop during the growing season. If rains are exceptionally heavy, the stop logs can be removed to prevent ponding. Before harvest, the stop logs are removed again to dry out the soil. After harvest, they can be reinserted to capture winter moisture.
Adjustable riser boards or stop logs of a water control structure back water into tile lines to raise the water table and saturate the soil upstream. When the stop logs are removed, water flows out.
Illustration: NRCS
