By Dick Sloan
Market and societal forces have led farmers to become more specialized and individual farms less diverse. We have converted from small fields with long rotations of corn, small grains and alfalfa fed to livestock into farming systems featuring only two row crops grown largely with commercial inputs.
Many now realize how these changes have altered the way water moves through our landscape. With pasture and Conservation Reserve Program lands being converted to row crops and fewer perennials in our fields, rains in excess of 1.5 inches per day will run off quickly, leading to potential erosion, pollution and spoiling of national resources.
But farmers who want to protect the environment and their communities’ future do have opportunities to refine their conservation plans and integrate several new techniques.
By adopting the Natural Resources Conservation Services’ soil health management plan, farmers agree to add plant diversity, intensity (growing plants year-round), and limiting physical disturbance (no-till and strip-till) to enhance crop production and soil function while improving air and water quality and energy efficiency.
Farmers are learning how excessive tillage destroys soil structure, leading to lower water infiltration rates and greater runoff. When farmers begin to think more about the biology of healthy soils, they develop a longer view of all the factors related to soil health.
As organic matter increases in three to 10 years, more water and nutrients are held on the farm. A 1 percent increase in organic matter in the top 6 inches of soil would hold an additional 1 inch of rainfall.
Another in-field tool to slow water runoff is establishing contoured prairie strips in fields such as those being studied at Neal Smith National Wildlife Refuge. The 30-foot wide strips to the east of my farmstead were planted in 2012 to a mix of more than 20 species of native grasses and forbs. Many of these plants have stiff stems and large root systems so that when downpours of rain occur, they remain upright, catching residue and absorbing water into the soil. The strategic placement of diverse perennials in my fields will reduce erosion and runoff as well as provide habitat for game, native birds and pollinators.
While farmland drainage has been pointed to as a flooding contributor, remember that tile systems are designed to remove only up to one-half inch per day of surplus water from the soil profile. This is just enough to allow for timely field operations and to ensure deep rooting and healthy plants for high yields and sustainable production.
Newer systems can incorporate drainage water management, where the outlets are controlled allowing farmers to fill the soil profile with water during appropriate times, reducing water and soluble nitrate transport from the land. Another new approach involving ag drainage is saturated buffers, where tile outlets to streams are tapped to spread the water along a wooded streamside buffer between the cropland and the stream.
But there is probably nothing we need more to secure Iowa’s future than additional wetlands: areas where water can spread, slow down and infiltrate. Where silt and solids can settle, and biological processes can reduce nutrient loads to streams. Places where water can run to when Mother Nature sends us a rain train.
Planning tools are being developed to identify small areas best suited to wetland development. Farmers will then have the ability to restore a significant portion of Iowa’s historic water storage capacity by using only a fraction of its land.
Applying innovations such as these on individual farms could assure Iowans that the valuable natural resources that we enjoy will continue to be available in a resilient future.
Dick Sloan is a farmer from Rowley. Comments: firstname.lastname@example.org