The rich, black topsoil is 3 ft. deep on Karl Retzlaff’s farm in western Minnesota — but only on the lowlands. The buff-colored hilltops have been rubbed almost bare. A century of cultivation has pushed 18 in. of fertile topsoil down the hillsides, depleting the upper slopes and exposing the clay subsoil.

For the past four years, Retzlaff has tested a simple approach for restoring productivity to these eroded knobs: he moved the good earth back where it came from.

Using his own scraper, Retzlaff removed 6 in. of accumulated topsoil from the basins and added it to the hills above. Corn yields on the rehabilitated ground have jumped as much as 70%.

This method for reversing erosion, called soil-landscape rehabilitation, is being tested in Minnesota and other northern regions by the USDA Agricultural Research Service and South Dakota State University. It’s the latest precision-agriculture technique for tailoring management to soil variations within fields.

All tillage sends soil downslope, says soil scientist Sharon Papiernik, research leader of the North Central Agricultural Research Laboratory in Brookings, S.D. “Reducing the number and intensity of tillage operations decreases tillage erosion. However, some recent research suggests that secondary tillage and seeding can result in surprisingly high soil movement.”