A task force has been dedicated to updating the nation's aging drainage systems. It's called ADMS — Agricultural Drainage Management Systems.
Starting with the Midwest, the ADMS task force seeks to reduce fertilizer loss and increase crop yields.
Soil scientist Norm Fausey, who heads research at the Agricultural Research Service (ARS) Soil Drainage Research Unit in Columbus, OH, says the historical practice of allowing water to flow from the drains year-round is being changed based on research.
Drainage innovations can allow 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 water can run from the drainage tiles.
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. NRCS recommends draining fields in the spring only enough to allow a tractor to drive on them for tilling and planting.
The task force issued a report on controlled drainage based largely on research in Illinois, North Carolina and Ohio that showed reductions in flow of nitrate and water off fields. Fausey and ARS agricultural engineers Kevin King and Barry Allred are now in the sixth year of doing studies in northwest Ohio along with Ohio State University-Columbus (OSU) scientists Larry Brown and Andy Ward.
”We're finding that controlled drainage can reduce nitrate losses by 45% and drain 40% less water. The results are similar in the other Midwest studies and earlier studies in North Carolina,” Fausey says.
In Illinois, Donald Pitts, the state water quality specialist and NRCS agricultural engineer; Richard Cooke with the University of Illinois; and Paul Terio, a U.S. Geological Survey water quality specialist, used an ARS-supported computer model called DRAINMOD to show that nitrate loads could be reduced 35% if farmers controlled drainage level at one foot below the soil surface during the off-season.
The ADMS taskforce includes the ARS, the U.S. Department of Agriculture's Natural Resources Conservation Service (NRCS) and Cooperative State Research, Education, and Extension Service; the U.S. Geological Survey; state universities and departments of agriculture; local soil and water conservation districts and drainage districts and farmers.