Moving soil from non-cropped waterways to fields boosts yields.
Water drains off Mike Rolstad’s farmland along 25 acres of grass waterways. These buffers do more than curb erosion and runoff. Rolstad is also using them as a kind of “soil bank” to reverse tillage erosion.
Rolstad raises corn, soybeans and wheat on 650 acres of rolling terrain near the Little Minnesota River in Roberts County, S.D. Decades of tillage have carried more than 2 ft. of topsoil to low areas, while the uplands have almost no topsoil. Along old fence lines, there’s as much as 4 ft. of accumulated soil.
In 1997, Rolstad switched to minimum tillage, which has reduced soil movement. About the same time, he started regularly maintaining his grass waterways and also built some new ones. He pushed topsoil in the drainage ways back up the eroded slopes. “I cleaned one waterway three years in a row, because there was so much soil coming off my neighbor’s quarter.”
Restoring soil to cropped areas costs about three times as much as leaving the spoils near the waterway, Rolstad says. But the benefits are worth it, he says, for “improved soil fertility, soil moisture retention and water management.” In one field, for example, “I took a half acre of poor ground and turned it into great ground by moving soil and building a maintained grass waterway.”
Rolstad is working with soil scientists from South Dakota State University and the USDA-ARS
to measure the productivity effects of restoring topsoil. In areas where 6 in. of topsoil was added to eroded slopes, Rolstad’s soybean yields increased an average of 11%, and his wheat yields jumped 17%, says USDA-ARS soil scientist Sharon Papiernik.
In addition to farming, Rolstad also operates a gravel-mining and earth-work business, so he owns his own earth-moving equipment. He takes his Terex scraper to the fields for several days each fall, moving a couple of inches of topsoil at a time from non-cropped to cropped areas.
Owning his own scraper makes soil-landscape rehabilitation economically feasible for Rolstad, says Lorne Aadland of the Roberts County Natural Resources Conservation Service. There are no cost-share programs for soil restoration, he adds, so growers will need “some studies to show the cost payback.”
Thanks to cooperating farmers like Mike Rolstad, that data is coming, Papiernik says. Meanwhile, “If you are cleaning a drainage way or restoring a wetland — if you’re moving soil anyway — instead of just dumping it nearby, move it back to an eroded area.”