Diversified Crop Rotations Key to Preventing Erosion
Rick Cruse is on a mission to save Iowa’s most valuable resource: its soil.
Cruse, an agronomy professor at Iowa State University, has conducted erosion studies across the state and is spreading the word about soil-conservation practices. He says there are three keys to keeping soil in place.
“Incorporating a systems approach that includes crop rotation, grass waterways and reduced tillage (no-till in ideal scenarios) is the best way to prevent erosion,” Cruse says. “You’re not going to be able to get it done by growing corn and soybean alone – not even with no-till.”
Crop rotation
Adding small grains; perennials, such as alfalfa; and cover crops to a crop rotation can do wonders to protect and enrich soil. Cruse says these types of rotations work best for farmers who’ve integrated livestock into their operations. Planting a variety of crops with differing root systems improves organic matter and its distribution throughout the soil.
“If you have the right mix of crops, you can not only keep your soils in place, but you can improve its structure, the amount of organic matter within it and its water-holding capacity,” Cruse says.
Cruse notes it’s important to remember farm fields are living biosystems.
“Biology does better with diversity than simplicity,” he explains. “The biological diversity you get from crop rotation increases yield, provides for different means of controlling pests, minimizes the risk of resistant weeds and builds healthier soils.”
Grass waterways
When rains wash nutrient-rich topsoil from a field, it’s not just dirt that’s lost. Erosion impacts crop yield, which eats into farmer’s profits. Studies have shown that soybeans grown on severely eroded soils yield 14 percent to 29 percent lower those grown on slightly eroded soils.1
The U.S. Department of Agriculture pegs the average loss of topsoil from erosion at a little more than five tons per acre annually. That’s like losing the equivalent of a 12-foot moving truck full of soil. However, those estimates do not include losses from ephemeral gullies, the temporary washouts that appear in fields after heavy rainfall, which Cruse says could account for an additional 30 percent of erosion.
To prevent the formation of ephemeral gullies, Cruse recommends the installation of grass waterways to slow water flows and protect the soil surface from erosion.
“Ephemeral gullies wash away topsoil and farmers typically repair them by dragging additional topsoil into the gullies,” Cruse says. “Guess what happens when the next big rain event comes? The gullies wash out again and the cycle continues. The vegetative cover in grass waterway slows the flow of runoff water enough to prevent gully formation.”
Reduced tillage
Conservation-tillage systems are great ways to reduce erosion by as much as 90 percent depending on the method.
Cruse says no-till is preferred, but any reduction in tillage will make soil less susceptible to the erosive forces of wind and water. Farmers who opt for a no-till approach will benefit from improved soil tilth, greater soil-moisture conservation and reductions in fuel and labor expenses. Incorporating cover crops capable of suppressing herbicide-resistant weeds can reduce the need for tillage as a weed-control option.
Click here to see more...