A technique of subsurface drainage of water from farm fields that is beginning to catch on in the Red River Valley merits study to understand both its benefits and environmental costs, experts said Thursday.
Drainage tiles, which collect water beneath the surface and use pipes to remove excess water from fields, are growing in popularity among farmers in the Red River Valley, but the method isn't yet in wide use, panelists at a workshop at North Dakota State University said.
One major concern: What effect would widespread tile drainage have on flood control?
"I would say tile is water management," said Hans Kandel, an extension agronomist at NDSU.
Because water must seep through the soil, where it is collected for drainage, it takes longer than surface drainage for removed water to reach streams and rivers, he said.
"There is a delay in release of water into the system," Kandel said. Also, he added, tile drainage produces crops with better-developed roots, allowing plants to remove more moisture from the soil.
"I think it is beneficial," he told an audience of farmers and others who gathered to learn more about the method. Kandel added that downstream runoff of certain nutrients, including phosphorus, is reduced.
The North Dakota State Water Commission has a record of about 200 drainage tile permits, all but a handful in the Red River Valley, hydrologist Bill Schuh said in an interview.
A mandated legislative study will determine whether drainage tiles deplete groundwater, he said. Subsurface drainage would not exacerbate a major flood, such as the devastating 1997 flood, Schuh said.
"When you get to that point, tile flow isn't adding to that," he said. "It's slowing it," often after the peak has subsided.
Still, agronomists and engineers agreed the effects of drainage tiles, because they are so new to the Red River Valley, aren't well understood.
"It really has the potential for sweeping changes," said Gary Sands, an agricultural engineer at the University of Minnesota, where researchers examined studies of tile drainage and its effects on the environment.
Although most drainage in the valley is surface removal, significant quantities of drainage tile have been installed throughout the basin over the past 20 years, Sands said.
The potential exists for some environmental benefits, he said, but the ongoing expansion of tile drainage has implications for water quality and ecosystems.
"We need more research," Sands said. "We need to understand these implications."