Restoring our Prairielands: Cleaner Water, Better Soil, Reduced Flooding
Written by Rudi Roeslein
‘Recording-breaking’ floods seem to be happening far too frequently. Einstein said the definition of insanity is doing the same thing over and over but expecting different results. It is time to recognize that development in flood plains, wetlands, and riparian buffers are causing these catastrophes. It is also time to recognize that nature has provided the only solution that is practical, cost-effective, and scalable.
We can soak up water before it floods.
A strategic re-introduction of native grasslands on just 10 percent of the Mississippi River watershed’s tributary landscape would significantly reduce flood levels. The potential positive impact is enormous with simultaneous benefits for the environment, wildlife, and renewable energy.
Missouri receives more than 138-million-acre feet of rainwater annually; eight times more than the flow through the Colorado river basin. We need to store that water by absorption, infiltration, and transpiration instead of diverting it to creeks, streams, and rivers. Roughly one-third of Missouri was once covered by tallgrass prairie, with root systems capable of absorbing water deep in the soil and underground aquifers. Native prairie can soak up eight-inch rainfalls using high concentrations of soil organic matter that hang on to water and nutrients. It is equally clear from hydrology research on major U.S. rivers, including studies involving ecologist Steve Apfelbaum of AES Inc., that the absence of native vegetation coincides with a dramatic increase in flooding. Along Illinois’ Des Plaines River, low and median flood levels are 200-400 times greater than historically; high flow floods are three to five times greater. The increases coincided with the original plowing and drainage of prairies and wetlands followed by the development of impervious landscapes in towns and cities.
We are documenting the benefits of native grasses at my Northern Missouri farm. Dr. Ranjith Udawatta and Dr. Shibu Jose at the University of Missouri are comparing soil and water conditions of constructed prairie on highly erodible land with adjacent land planted in row crops. Initial results show far less water run-off from the prairie tract. And the water is much cleaner. We are also implementing the innovative Iowa State University STRIPS program which calls for planting native grassland species in strategic locations within row crops to protect soil and water quality.
More than five million acres of grassland, wetland and fragile land were converted to corn and soybean production between 2006 and 2012; a period of high commodity prices and generous government crop insurance programs. With lower commodity prices, owners of highly erodible acres should be open to returning these assets to their natural intended use. One private market incentive to accomplish this conversion is to sustainably harvest and sell a portion of the grass as feedstock for renewable energy production. A broad cross-section of stakeholders at the Midwest Conservation Biomass Alliance is working to determine the optimum mixture of native plantings to sustain energy production, the environment and wildlife habitat.
Another step involves the increasingly popular use of cover crops on commodity agriculture land. Corn and soybean production provides food, feed, and fiber for a growing world population. But their production systems reduce water infiltration and storage. Planting cover crops after harvest facilitates water absorption, enhances soil health, prevents erosion, and reduces soil compaction while providing wildlife and pollinator habitat.
The floodplain closest to waterway channels needs restoration to take strain off free-flowing streams and rivers modified by dams and levees. Continuous riparian corridors containing natural vegetation retain flood water and prevent property damage. However, riparian corridors are frequently disrupted by development that replaces native vegetation.
The main point is that catastrophic flooding is avoidable. Restoring native grasslands, promoting cover crops, and fortifying riparian corridors deliver a natural water accumulation system to reduce the environmental impact of major floods. It creates new habitats where wildlife and pollinators can thrive. Renewable energy production makes the concept economically viable.
The elimination of most native prairie over the past two centuries happened for reasons commensurate with the time. But this is a new and different time. We are obligated to change land management practices because of our collective responsibility to sustain our planet. A vast amount of good can come about as a result.
If we cannot learn from our mistakes, then why bother recording history? The great Dust Bowl was created when people on the semiarid plains mistakenly believed ‘if we plant wheat it will rain’. Documentary producer Ken Burns called it “…the worst man-made ecological disaster in American history; when the irresistible promise of easy money and the heedless actions of thousands of individuals, encouraged by the government, resulted in a collective tragedy that nearly swept away the breadbasket of the nation.”
Sadly, we are again trying to make land do something it cannot do. Today’s misconception is that millions of hilly acres unsuitable for farming can be terraced to permit corn and soybean production. But when it rains, most of the water runs off the hills or is quickly carried into creeks by drain tiles. H. Howard Finnell, a soil scientist from Oklahoma A&M who had the daunting task of saving the soils of the Dust Bowl in the 1930s, concluded that “nearly 80 percent of a year’s rainfall never soaked deeply enough into the subsoil to benefit crops.” The Meramec River basin has nearly four thousand square miles (or 2.56 million acres) feeding it. When it rains 12 inches, 840 billion gallons of water must go somewhere. So, if 80 percent runs off, more than 672 billion gallons of water goes into the Meramec River basin without the benefit of accumulation of its prior flood plains, riparian areas, and the accumulation created by prairies and wetlands.
This is a problem that can be turned into an opportunity to store water, preserve soil, and prevent this continuous cycle of flooding and misery. Restore our prairies, and our flood plains, and change our agricultural practices. Then we can solve this ever-worsening man-made calamity. Mr. Finnell’s conclusion after the Dust Bowl rings true about recent historic flooding: “Our efforts to manipulate the forces of nature to fit our own convenience are wrong. Instead, we should attempt to harmonize our farming operations to fit conditions as they are, rather than as we hope they will be.”