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Posted 4 October 2016. PMN Crop News.

Controlling Drainage Flow Traps Water, Helps Crops

Source: South Dakota State University Press Release.

Brookings, South Dakota (September 7, 2016)--When it comes to moisture, most farmers will admit, it’s usually feast or famine. However, a U.S Department of Agriculture project aims to use controlled drainage systems to make more water available for growing crops.


“We’re improving subsurface drainage practices,” said assistant professor Laurent Ahiablame, a hydrologist in the South Dakota State University Department of Agricultural and Biosystems Engineering. He is the South Dakota lead for a five-year, $5 million project, which involves USDA Agricultural Research Service and researchers from eight states. Professor Jane Frankenberger of Purdue University directs the project.

“Our goal is to secure water for crop growth,” Ahiablame said. “At the same time, we want to be able to maintain appropriate drainage when conditions are wet. In addition, we are mindful of the environmental consequences and seek to limit nutrient losses in drainage water.”

Subsurface tiling helps drain excess water from fields. The National Institute of Food and Agriculture project looks at three main practices: a comparison of conventional drainage flow versus controlled drainage flow, strips of grass called buffers to capture nitrates from drainage water, and on-farm ponds to capture surface and subsurface drainage water and use it to irrigate crops.

Test sites are scattered across the Corn Belt from southeastern South and North Dakota to Ohio, as well as North Carolina. More information on these projects is available at

Ahiablame and three graduate students will present their work at the 10th International Symposium Drainage Symposium Sept. 6-9 in Minneapolis. Other project collaborators will also participate in the symposium.

For the USDA project, Ahiablame is working with two approximately 4-acre plots at the SDSU Southeast Research Center near Beresford. From one plot, the water flows freely from the drain tile outlet, while the other has a control system that regulates the amount of water that drains from the field.

“We control the amount of water in the soil profile,” Ahiablame explained. In winter and early spring, riser boards in the control system close off the outlet to keep water and nutrients in the field. Before planting, the water is released—early April for corn and mid-April for soybeans.

After planting, the level of the riser boards is adjusted so the plants can utilize the moisture during the growing season, according to Ahiablame. However, he cautioned, “We don’t want plant roots to stay in excess water.”

Before harvest, the boards are removed so the soil can dry. “Once we finish harvesting, we will replace the riser boards to keep the water in the field,” he explained. “The logic of controlled drainage is to hold water in the root zone when crops need it and release it when it is not needed, and, thereby, to protect the environment.”

Through the control structure, the researchers calculate the amount of water draining out of the field and collect samples for water quality analysis. This is the first of two years in which data will be collected for the project. “As researchers, we want to come up with better ways to optimize drainage practices for crop production,” he added.

Laurent Ahiablame