And not a drop more

Monitoring sump at demo farm gives view of drainage

If ever there were a place in need of drainage, it was the flat cropland on a southeast Iowa research farm last week. After about six inches of rain in 36 hours, you could get a sense of why Midwest farmers see drainage as an essential, high payback production practice.

All the moving water was also a reminder of why ag is in the spotlight for its contribution of “nutrient-enhanced” flows into streams, rivers and the Gulf of Mexico.

You had to jump over a ditch and wade through mud and ankle deep water in field borders to get a look at the experimental drainage structures presented at the demonstration.

Lifting the steel cap off a monitoring sump, Iowa State University ag engineer Matt Helmers explained how the new drainage technology can be used to reduce nitrate flows into waterways, manage cropland water tables, and potentially raise crop yields.

So far the conservation benefits are fairly clear in the Iowa work. If you retrofitted your fields with this equipment, you could be pretty sure to cut nitrate flows leaving your farm—by as much as 50 percent.

Managed properly, the control structures would enable you to drain the root zone for field work and planting in the spring and to conserve soil moisture for crop use in the summer.

The yield impacts are less vivid. In Illinois last year, one 160-acre field in a project produced a 20% increase in corn yield. Long-term studies in North Carolina show a 5% increase in a corn-wheat-soybean rotation, 9% in corn alone. But that’s North Carolina, not the Midwest, where the Agricultural Drainage Management Coalition is attempting to change drainage practices. “That doesn’t happen every time [in the Midwest],” said Leonard Binstock, the coalition’s executive director. “But we think the potential is there.”

Binstock presented a calculation, assuming a 5% yield boost, that showed a net payback of $21.95 per acre for installing a full conservation drainage system with new tile lines and control structures. Cost-sharing and low-interest loans are available for the practices, too, he pointed out.

The golden rule of drainage, Binstock says, is to drain only what’s necessary to get your equipment in the field and to produce a crop—and to drain "not a drop more.”

That “not a drop more” is a big drop--one that could have a major impact on how agriculture manages one its most fundamental practices.

View video: Matt Helmers discusses conservation drainage benefits

See slideshow: Testing out conservation drainage