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Open tile intakes in Midwest farm fields, “is a practice that should be ended,” says Gary Feyereisen, a USDA drainage expert in Minnesota.
He notes that open tile intakes allow debris, sediment and pollutants, such as nitrogen and phosphorus, to enter surface waterways and block underground pipes.
Most farmers would love to get rid of open surface tile intakes, adds Gary Sands, University of Minnesota Extension ag engineer, “provided they can maintain adequate drainage flow. Alternatives to open inlets, such as inlet risers, rock inlets, or intensive tiling, are “a win-win” for both farmers and the environment.”
More inlet versions
Ag Solutions’ Quick Drain is one of several new tile inlet alternatives to open surface intakes. These innovations are designed to be convenient for farmers and safer for the environment, while still maintaining drainage capacity.
Standard perforated risers, such as the familiar orange Hickenbottom, slow water discharge, allowing some soil particles and pollutants to settle out, says Richard Cooke, a drainage engineer at the University of Illinois, who is testing the performance of several new tile intake designs.
Like any inlet, they can become blocked with debris, and farmers dislike working around them, says Phil Algreen, technical support manager for AgriDrain, a drainage equipment company in Adair, Iowa. “With today’s big implements, it can be difficult for farmers to maneuver equipment around the inlets.”
AgriDrain recently introduced an inlet that farmers don’t have to plant around. The Water Quality Inlet consists of bundles of 5/8-in. slotted polyethylene tubes, or wicks, that snap into single-wall, corrugated plastic pipe, Hickenbottom or Precision underground sections. Drainage velocity is slower than with standard perforated risers, says Algreen, which “gives sediment more time to settle out.” The inlets can also be deployed underground.
Drainage contractor Charles Adams, A.J. Adams and Sons, Kansas, Ill., has installed AgriDrain’s Water Quality Inlets both above and below ground. Placed above ground, the flexible inlets take less maintenance than coated-steel “bird cage” inlets, he says, and they don’t snag field equipment.
For rock or blind inlets, Adams inserts a 36-in.-tall bundle of wicks vertically into the tile line T, then covers the inlet with about 3 ft. of 1-in. gravel. “No-tillers love them,” he says. “They don’t have to farm around the drain and it absorbs water faster than a regular field drain because the intake is closer to the surface and there’s a larger area for water to enter.”
In tilled fields, drainage contractor Doug Wulf, Wulf Tiling, Morris, Minn., suggests replacing open tile intakes with bird-seed sand French drains, another variation of a rock inlet. The T is laid horizontally in a 30-ft. trench, which is filled with about 18 yards of washed, 1/8-1/4-in. aggregate. The trench is mounded so soil doesn’t fan over the drain when the planter or disk ripper goes through.
Surface water flows easily through the birdseed sand, and the smaller aggregate is less likely to get plugged with soil particles than larger gravel or rocks, which extends the life of the drain, notes Wulf. “It works best with pattern tiling, providing the same drainage capacity as a 6-in. open drain, with fewer environmental hazards. We’re really excited about these drains.”