Draining problem: Book ties row crops to flooding problems
By Matthew Wilde
CEDAR FALLS – Major floods statistically have little chance of occurring in the Cedar Valley. But they do – twice in 15 years.
The Cedar River and other Northeast Iowa waterways inundated residential neighborhoods and farm fields in historic fashion in 2008 and 1993. With local rivers and streams just returning to their banks this year, conditions – saturated ground and a thick snow cover that recently melted – are ripe for another hydrologic disaster.
A book released earlier this month by University of Iowa Press explores the dynamics of the flood two years ago. “A Watershed Year: Anatomy of the Iowa Floods of 2008,” in part, looks at the state’s history to explain why severe flooding is occurring more frequently. According to the book, grain production is a primary reason.
Experts said the 2008 catastrophe, which caused billions of dollars in property damage and threatened to submerge downtown Cedar Falls, was called a 500-year flood because it had a 1 in 500 chance of occurring in any year, or .2 percent.
Subsequently, a 100-year flood, like what happened in many areas in 1993, has a 1 in 100 chance of taking place.
Cornelia Mutel, editor of “A Watershed Year” is an ecologist at the University of Iowa. Mutel said the change from water-absorbing prairies to intensive crop production and tiled farmland is one of the main reasons behind intense floods.
“The public needs to understand what’s going on,” Mutel said. “People need to understand their actions have consequences and affects the environment.”
People that depend on the land for a living have a different view. Farmers say Iowa has some of the richest soils in the world and the ground is needed to food, which big bluestem and butterfly milkweed that used to dominate the landscape won’t do.
Producers say they are good stewards of the land. Drainage tile is needed to make it more productive and absorb water.
“I won’t deny there’s been a change in agriculture from the 1940s. But if you look at major flooding, it’s more Mother Nature’s whims, not how subsurface drainage impacts it,” said Tim Recker, a farmer and land contractor from rural Arlington.
Who’s to blame?
“A Watershed Year” provides a comprehensive look at the cause and effect of flooding statewide. A recurring theme is a change in the state’s landscape.
The book contains 25 chapters written by different experts – all with past or present ties to the state – ranging from hydrology and conservation to economics and public works.
Laura Jackson, a biology professor at the University of Northern Iowa, co-authored Chapter 24 detailing how perennial farming systems can resist flooding. She believes modern crop production and farm policy are the leading reasons behind flooding problems.
“We are blaming corn and soybeans, but not farmers. There is a difference,” Jackson said. “Farmers are just going with the flow.”
Iowa used to be 80 percent prairie in the early 1800s. Jackson said the tall grasses with deep root systems acted like a sponge, soaking up water when the ground wasn’t froze. Though flooding occurred before row crops (corn and soybeans) dominated the landscape, some experts say it wasn’t as severe or frequent.
To feed a growing nation and the world, the prairies were eventually plowed under to farm. U.S. farm policy, supported by taxpayer subsidies, encourages corn and soybean production. Grain is primarily used for food, livestock feed and biofuels. As a result, hay and oat acres drastically dwindled, which help soak up water, Jackson said.
Iowa is the top corn and soybean producer in nation, totalling 2.44 billion bushels and 486 million bushels, respectively, last year. According to government statistics, slightly more than 30 million acres in Iowa is devoted to farming.
To produce food, Jackson said the prairies had to go.
“It’s a blessing and a curse,” Jackson said.
Instead of perennial grasses that soak up water nine months out of the year, Jackson said Iowa is dominated by annual row crops that don’t absorb or hold back water as well. Plus, many fields are artificially drained and are worked by heavy equipment compressing the soil.
“The sponge is less spongy. It’s going to a cookie sheet,” Jackson said.
If a rain drop falls in northern Iowa, the U.S. National Agricultural Statistics Service indicates it has a 88 percent chance of landing on a row-crop field.
To increase production, farmers tile fields to eliminate wet spots and to help plants use water more efficiently. Allen Bradley, a hydrologist at the University of Iowa who authored two chapters in the book, said Iowa’s altered landscape has played a significant role increasing the severity flooding.
“All of it produces more run-off and water running off faster,” Bradley said.
Northeast Iowa farmers and drainage contractors feel it’s unfair they’re often blamed for severe flooding problems. Matt Helmers, an agriculture engineer and drainage expert at Iowa State University, agrees.
While there’s no doubt crop production and farm tile has increased water run-off into rivers and streams, he said there would have been record flooding in 2008 and 1993 even if the landscape was mostly prairie.
Saturated soil from previous fall rains and late-winter snow melt, along with storms that produced 7-10 inches of rain in a short amount time like in June of 2008, are the real culprit when it comes to major floods.
“There’s no place for water to go. There’s only so much capacity to hold water,” said Helmers, noting most soil in Iowa can hold anywhere from 6-9 inches of water.
Dan Rasmussen, executive director of the Iowa Land Improvement Association, said tiling is good for the environment, and in some ways, helps control flooding. He also works for Rasmussen Drainage Service in Independence, which he used to co-own with his brother, Tim.
On Monday, the Rasmussens tiled a 15-acre portion of a field 4 miles east of Brandon. Four-inch corrugated plastic tiles were buried 4 feet deep and 50 to 65 feet apart. Small slits allow water to enter the tile, which will drain into a nearby creek that eventually dumps into the Cedar River.
Rasmussen, a former state legislator who’s running for office again, said he’s heard the public blame farmers for flooding problems.
“I can understand why people think that way; they’re looking for an answer. There’s a lot of misinformation out there,” Rasmussen said.
The drainage expert said tile merely drains away excess water crops aren’t going to use. Too much water can stunt plant growth, delay planting and harvesting and not allow proper use of fertilizer and other nutrients. In other words, wet fields waste time and money.
Rasmussen said it takes 24 to 48 hours for rain to infiltrate the ground and reach tile. Draining excess water, he said, increases the ground’s ability to hold water and reduces erosion.
The weather is the primary reason for flooding, in Rasmussen’s point of view, and urban sprawl – towns encroaching on farmland and concrete that doesn’t allow water to soak in – also plays a role.
“(Flooding) really comes down to the amount of rain, topography and duration. To blame drainage is wrong,” he said.
It costs about $500 an acre to install tile, Rasmussen said. To Mark Toale, who farms the ground tiled on Monday, the investment is worth it. He and his landlord split the cost.
Farmers said tiled land typically increases corn yields by 10 to 40 bushels per acre and boosts soybean production by 5 to 10 bushels per acre. ISU Extension estimates a little more than 9 million acres of row crops are tiled in the state. In 2009, 23.3 million acres of corn and soybeans were planted.
“We’re a big believer in (tiling). It’s better for the ground,” Toale said.
Farmland is Iowa’s No. 1 resource. Economic experts say agriculture helped build the state and it remains a primary industry.
Those studying Iowa’s flooding problem agree prairies will never dominate the landscape again. It’s also unlikely agriculture will revert to 1950, when nearly 35 million acres were farmed, but only 35 percent of the ground was devoted to corn and soybeans. Today, 77 percent is in row crops.
“Farmers just need more options. They have to grow corn and beans,” Jackson said.
Two possible solutions that are attainable, according to Jackson, is to change farm policy so raising hay, oats and grass pastures are financially equitable again. The year-round cover grass provides will slow water run-off and limit soil erosion.
Jackson also said a ISU study involving 10-foot-wide strips of prairie grass on contours shows promise to intercept water and nutrients. Raising more perennial crops with long root systems instead of annuals would help.
Helmers also rattled off a laundry list of ways to control flooding.
More grass waterways.
Buffer strips near waterways planted with prairie grass.
Reduced tillage or no-till farming.
Cover crops, like winter wheat or rye grass.
The solution starts with “watershed management from top to bottom,” Helmers said. “There are a lot of practices to reduce overall volume.”