Turning farmland into wetland may lower flood risk, but it’s a difficult choice in Iowa
When Laura Krouse ripped out four acres of corn on her Mount Vernon, Iowa, farm, to put in a wetland, the neighbors noticed.
“It was a bit of a stretch for the neighbors to see me taking this perfectly good field out of production,” Krause said. “They had a lot of questions. A lot of cars going by slowed down real slow when they looked to see what we were doing.”
What they were doing was thinking ahead.
With the upper Midwest experiencing heavier rainstorms and rising rivers each year, scientists say it’s only a matter of time before the area is hit by another major flood. Communities in Iowa, in particular, are still recovering from flooding disasters in 2008 and 2010.
Environmentalists want to lower the risk of flooding by convincing farmers to turn some farmland into wetland, which would slow runoff. But as market demand for corn and soybeans increases, that’s proving to be a tough sell.
Krause is a believer, though. Her new wetland sits on just about 4 percent of her 72 acres of farmland but absorbs nearly all the water that used to run right off it.
“And so even if we get a really big rain event, some of it is going to get stored before it starts to release to the stream below,” she said.
A wet outlook
And really big rain events are exactly what’s in store, said Richard Cruse, an agronomist at Iowa State University.
He noted that from the 1970 to 2005 the frequency of very intense rainstorms increased 30 percent.
“When you couple the intensive row crop production with these really heavy rainstorms, it is a really ugly picture,” Cruse said.
Cruse is part of an increasingly vocal group of scientists who say the homogenization of Iowa's landscape is the second-biggest contributor to its flood risk. The first, of course, is the heavier precipitation.
They point to the dominance of corn and soybeans, which has vastly reduced Iowa’s absorbent prairie grass, wetlands, and forests. Cruse said restoring even some of that diversity would significantly reduce flood risk.
“We’ve shown that you could take 10 percent of the land that’s currently in row crop and reduce those erosion losses by way more than 50 percent,” he said. “It doesn’t make sense to farm areas that are flooding every other, every third, even every fourth year. Those areas could be put into perennials and probably not lose much economic return.”
But the demand for corn and soybeans is intensifying – prices continue to rise for both. And traders say Iowa will need to grow 500,000 more acres of corn than it did last year if the nation’s going to prevent price spikes or even rationing.
With land at a premium, conservation isn’t cheap.
Krause said most of her neighbors would put in a wetland if the state would raise its conservation incentives to reflect current land prices.
“It’s partly cultural too. We take out trees and fence lines and drain places and make more ground. We don’t put prairie and wet soggy places back on the landscape,” she said. “And so for $100 an acre, a farmer probably wouldn’t be willing to give up this land. But for $200 an acre – it’s awfully cheap, actually, compared to $5.4 billion worth of loss from Cedar Rapids from the flood.”
But Cruse isn’t optimistic that flood risk can trump farm interests.
“The way you make money with high land prices and high commodity prices is to farm everything you can. Everything is under tillage. It’s under intensive row crop production,” he said. “No one likes to see soil sediment in their second floor bedroom from the farm fields. But the risk of that happening is increasing.”