America’s Corn Belt wouldn’t be a Corn Belt without underground drainage. These unseen drains, which lie about 3 to 5 feet under more than a third of the Midwest’s farmland, are the reason crops can grow well and people can live there.

Many parts of the Corn Belt, have poorly drained soils—former swamps—that leave fields too cool and wet for planting in early spring. Drainage is essential to economical farming in the Corn Belt region, and it can help reduce flood threats and benefit the environment as well. The Red River Valley is a highly productive area and drainage is as important here as in the corn producing areas, however very few acres are tile drained in NW MN and ND.

The Agricultural Research Service is part of a task force dedicated to updating the nation’s aging drainage systems. American farmers began laying underground drains with pipes in 1878—digging trenches by hand and laying clay pipes one foot at a time. After 1900, manufacturers also sold concrete pipes. Then, in the late 1960s, farmers switched to the perforated, corrugated plastic pipes that homeowners often use to carry rainwater away from their downspouts. Now, contractors come in with a heavy-duty machine that digs a trench and simultaneously lays 4-inch-diameter plastic pipe—from a big roll—as one continuous piece across a field. More recently, some farmers have begun using a lighter duty machine pulled by their own tractors so they can lay pipe themselves, although not as deep as the more powerful machines can.

Today, the Midwest is crisscrossed by a network of underground pipes—clay, concrete, and plastic—and the surface or roadside ditches they drain into. The water they carry eventually funnels into streams, lakes, and oceans. However a major innovation allows farmers to control when—and at what water level—water will flow through the drainage pipes. Contractors attach an adjustable, in-line control structure to the drainage pipes in one or more parts of a field. These structures allow the farmer to periodically adjust the height the water table must reach in the soil profile before triggering drainage. Commercially available structures offer either stacked flashboard risers or floats to adjust this water level. Water level is set high during winter and at other times when no crops are growing; low during planting and harvesting periods; and at intermediate levels during the growing season, depending on the crop, its growth stage, and amount of precipitation that occurs.

Farmers can raise and lower the drainage control height in the structure, depending on what farm operations they are doing and what season it is, being careful to not overdrain or underdrain their fields. It is recommended to drain fields in the spring only enough to allow a tractor to drive on them for tilling and planting and regulated the water flow during the summer. This controlled drainage system is very well suited for the relatively flat areas of the Red River Valley. Managing the water table will reduce production risk and increase crop yields. It will also make field operations easier to manage.

A decade of experience with harvester-mounted yield monitors has shown farmers in the Corn Belt how much their yields drop in the wet areas between widely spaced drainage pipes. So farmers are adding more pipes all the time—placing them closer together and running them under entire fields, sometimes at shallower depths.

For more information about tile drainage see the Extension Service web site at:

 http://d-outlet.coafes.umn.edu/