Restore wetlands, shift to prairie for energy cropsBy ANDREW HUG
June 29, 2008–Des Moines Register
After yet another series of tragic floods in Iowa, citizens and local and state governments are evaluating how to mitigate them in the future. Experts are proposing higher, stronger levees, restrictions on construction in flood plains, buyouts of properties that flood regularly and more.
The menu of remedies should include two land-use changes – restoration of wetlands and, when cellulosic biofuel production becomes feasible, conversion of corn and soybean fields to deep-rooted perennials.
This year, with strong bipartisan support, the Iowa Legislature took the first step toward passing a constitutional amendment to create a fund for water quality, parks and outdoor recreation, part of which could be used to assist farmers in converting some of their land into wetlands. The process requires that the General Assembly pass the legislation again, and then the citizens of Iowa would get to vote on this fund in November 2010.
Farmers have lined up to enter land into voluntary wetland-creation programs, but most are turned away for lack of funding. These wetlands benefit society by providing wildlife habitat and cleaning the water in addition to flood control. One acre of wetland can prevent 1 million to 1.5 million gallons of water from entering a flooded waterway. Wetlands act like a sponge – absorbing and then slowly releasing water. In some areas, wetlands are the most economical way to reduce flooding. Depending on landscape conditions, one acre of wetland placed at the outlet of a farmer’s tile lines can also filter out most of the nitrogen and sediment from up to 100 acres of adjacent cropland.
The flood-control benefits of new wetlands must be balanced against needs for food, feed and fuel, but they can be one component of Iowa’s effort to reduce flooding.
Another component: new cropping patterns enabled by cellulosic biofuel production. Organisms that create biofuels by devouring cellulose, or plant fibers, are equal-opportunity feeders. For the most part, they do not care what species of plant they consume, so farmers can choose among a wide variety of energy crops. Some energy crops, such as switchgrass, will soak up more water and hold more soil in place than corn or soybeans do. Even better: a perennial mix of native prairie species.
Prairie covers the soil surface year-round and anchors the soil with an extensive root system, enabling it to soak up tremendous amounts of water and release it slowly. Since prairie requires no annual tillage, farmers should be able to break or seal tile lines, even further reducing rapid flows into streams.
With prairie holding the soil in place, stream flow would not be impaired by tons of new sediment. The water would carry far less nitrogen and phosphorus, which kills aquatic life from Iowa’s Great Lakes to the Gulf of Mexico’s Dead Zone.
Cleaner, more stable streams benefit society in other ways as well. With more prairie, streams that now dry up and die in the dry season are more likely to continue flowing. More game fish would repopulate Iowa’s streams, and migratory waterfowl could head north out of Iowa healthy rather than malnourished. Our waterways would be more pleasant and safer for swimming, canoeing and water skiing. Prairie would also provide habitat for species of plants, birds, butterflies and other animals that are now rare or endangered.
Flooding is a problem of small impacts spread over many acres; therefore, flood-control solutions can be small changes spread over many acres. Shifting significant acreage of corn and beans to prairie energy crops would dramatically reduce the amount of floodwater flowing off our farmlands.
In pursuing flood control, Iowa’s leaders should support options for agriculture that will help both the farmer and the city dweller. Iowa needs to finish the path the Legislature has begun and pass this new environmental fund. In addition, Iowa needs to promote policies that drive the source of cellulose-based biofuels toward prairie as opposed to crops that don’t significantly help control and clean our waters.