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Black snow evidence of soil erosion

Black snow, shown in eastern South Dakota, is a sign of soil erosion, most often from tillage for crops. (SDSU Extension photo)

BROOKINGS -- Have you noticed the black snow in eastern South Dakota? According to Anthony Bly, SDSU Extension soils field specialist, this year there is more soil on top of the melting snow drifts than in previous years.

He explains that although black snow is not common in South Dakota, black snow is a regular occurrence in central Iowa along interstate 35 and other areas where snow piles up in drifts because of their widespread use of intensive fall tillage.

"This evidence of soil erosion by wind, is created by lack of soil cover. In South Dakota it could be caused by the fact that planting dates have been moved up. As a result more intensive fall tillage has been used to promote early drying of surface soil in the spring," Bly said.

He added that the eroded soil, which is now in ditches and fence lines, is the most productive soil from our fields.

"This lost soil is generally higher in organic matter and nutrients. Of course, unless wind erosion is extreme, like in the Dirty Thirties, the effects of what happened last winter probably will go unnoticed," he said. "However, over time these smaller, annual soil erosion losses add up and can have a significant impact on sustainable soil productivity."

Farming practices to prevent soil erosion

Currently, Bly said there is an increased emphasis on soil health and/or quality. Allowing the soil to be unprotected greatly increases the breakdown of stable soil aggregates (clumps of sand, silt and clay). He explained these aggregates help the soil take in water, hold nutrients and promote oxygen exchange for carbon dioxide thus providing a healthy root environment.

"Maintaining maximum soil cover with crop residues or cover crops protects the soil from aggregate breakdown, increases organic matter and carbon levels that promote further soil aggregation and structure that improves water, nutrient and air movement within the soil that leads to increased crop productivity," Bly said.

Bly said the best method to increase soil cover and build beneficial soil properties is the use of no-till, diverse crop rotations and cover crops.

"I realize that not everyone is going to choose no-till, there are other farming practices that can also lead to improved soil surface protection such as: strip-tillage, chisel plows fitted with straight shanks and not twisted, maintaining surface roughness by leaving stalks intact and not using stalk choppers or chopping heads, not baling and removing crop residues, and not tilling after low residue crops such as soybeans," Bly said.

For more information on soil conservation and soil health, please visit or the Natural Resources Conservation Service website,