He had been reading about controlled drainage and thought it might fit the bill. The method uses outlet controls installed in tile lines to raise and lower the field's water table. Water can be held back in the winter and released before planting and harvesting. During the growing season the water table can be raised and lowered according to crop needs. The practice reduces nitrate losses and also conserves water during dry spells.

Hicks connected with Jeff Strock and Gary Sands, University of Minnesota researchers who are doing drainage water design and management research throughout Minnesota. Strock says Hicks' field was ideal for controlled drainage. It has very productive but poorly drained soil and little slope. The drainage water ends up in the Cottonwood River, classified as an impaired waterway by the Minnesota Pollution Control Agency.

Hicks pattern-tiled the 100-acre field in late 2005, with laterals on 50-ft. spacings and two main lines: one 15-in. and one 10-in. In the course of tiling, “we discovered a good streak of sand about 3 ft. down,” which explained the low-yielding area. “The soil wasn't able to hold the moisture.”

Hicks paid for the tiling. The field has two outlet control structures, which each manage the water table in a 45-acre zone of the field. The cost of the two water control structures — about $3,000 — was shared with the Redwood Cottonwood River Control Area, a conservation group.

For the last three years, Hicks has raised the tile outlet after fall tillage and lowered it the first week of April. Within seven or eight days, the water table drops enough for fieldwork, Hicks says. This fall, he applied 4,000 gal./acre of hog manure and then raised the outlet again, bringing the water table up to about 6 in. from the surface.

It's not much different from how he manages another low-lying field, which has a pumped tile outlet. In the spring, after planting and spraying, he shuts off the pump and lets the water table rise. “Why send that water to the river?” he says. “So we've been thinking about managing our drainage water for a long time.”

Now, Hicks is cooperating with Strock and Sands on side-by-side comparisons of controlled and free-flowing drainage. The multi-year trials will look at how drainage water management affects corn and soybean yields, tile flow and discharges of nitrates, pesticides and other pollutants. Researchers will also be tracking fecal coliform in the drainage water, and even greenhouse gas emissions from denitrification in the soil.

Similar drainage management systems are being tested on farms throughout the Midwest. Demonstrations like this are important for agriculture, Hicks says. “We, as farmers, need to be proactive in telling our story and showing that what we're doing isn't detrimental to the environment.”

WHERE DOES THE RETAINED WATER GO?

What happens to water that is held back in the field through drainage water management?

Good question, says Matt Helmers, an Iowa State University agricultural engineer. Researchers don't yet have a clear picture.

Besides subsurface drains, water leaves the field along several pathways. It can return to the air through evaporation and transpiration by plants. It can run off the surface, percolate down into the aquifer or flow laterally below the tile depth. But these movements are very hard to measure, Helmers says.

Still, “It is generally thought that these pathways tend to have water lower in nitrate concentration than tile flow water,” says Don Pitts, a water quality and drainage expert at the Illinois Natural Resource Conservation Service. That helps explain why curbing tile flow also reduces nitrate losses.