“People think if you just put on enough fertilizer, you can compensate for erosion and loss of topsoil,” says Thomas Schumacher, professor of soil biophysics at South Dakota State University. “But that’s not true. Soil is more than a nutrient warehouse.” It also holds moisture, oxygen, organic matter and beneficial microbes essential for plant growth.

Research across the north-central states in the 1980s and 1990s quantified yield losses from erosion, Schumacher says. “On average, we saw 15-20% yield loss, and as high as 30-40%, depending on the soil.” This is “long-term loss that you can’t compensate for.”

The USDA estimates that erosion costs Midwest growers more than $100/sq. mile annual yield losses, Papiernik says. Finding an affordable way to restore that lost productivity would be a great benefit to farmers, she says.

About a third of Karl Retzlaff’s acreage near Cyrus, MN, is highly erodible, characterized by long ridges that slope up to 25%. For years, he raised strips of alfalfa along the contours to curb soil movement from chisel plowing. “Then I got too old to throw bales!”

Retzlaff’s farm is well tiled, so a few years ago, he eliminated tillage for soybeans; his corn ground gets a fall application of anhydrous ammonia and a light field cultivation ahead of the planter. “With my erodible land, no-till has been a real boon.”

These measures have nearly halted erosion, he says, but sharp yield differences still persist from the top to the bottom of slopes as a result of past management practices. Papiernik saw “a good opportunity to bump up productivity on his worst-performing land” by replacing the topsoil.

She set up replicated plot trials on Retzlaff’s farm and another hilly site near Sisseton, S.D., to compare corn and soybean yields on eroded and rehabilitated land. The trials are being repeated in Manitoba, Canada on wheat ground.