One of my favorite quotes is by an anonymous writer: “Despite all our accomplishments, we owe our existence to a 6-inch layer of topsoil and the fact that it rains.”
It’s not often that we think about what happens to the soil in the field. To be honest, that topsoil is probably the component that is most taken for granted in a cropping system of any kind. So, what happens when we lose any of that precious soil to wind or water erosion?
During this season of extra water, in the form of rain or snow, we often forget that although moisture is critical for growing crops next season, rain and snow can also move soil. Rainfall splatter is a very real thing in your fields and can cause soil to be displaced.
However, cover crops are the not-so-secret ingredient to keeping soil where it needs to be, as the roots hold it in place and penetrate soil layers to help reduce soil compaction and improve water infiltration.
Topside cover crop growth protects the soil from erosion caused by brisk winter winds, while helping trap nutrients so nutrients do not runoff or leach out of the soil. Once spring arrives, those covers can assist in suppressing spring annual weeds.
The type of cover crop can also be a factor in how well soil is sheltered from erosion. Michigan State University Extension created a chart listing multiple cover crop species and ranking them based on how well they help hold the soil.
NRCS recommends that growers keep in mind existing weed, disease, nematodes and other soil problems when choosing a cover crop species to plant. Cornell University also has a cover crop selection tool to aid growers in deciding which cover crop species will work best in their operation.
According to the USDA’s Sustainable Agriculture Research and Education program, studies show decreases in soil loss from fields planted with different species of covers.
Cover crops including cereal rye, annual ryegrass, triticale, barley and wheat reduced soil loss by 31-100% compared to fields with no covers. On conventionally tilled fields, cover crops reduced sediment losses from erosion by 20.8 tons per acre; 6.5 tons per acre on reduced tillage fields; and 1.2 tons per acre on no-till fields.
Cover crop species such as red clover, crimson clover, lentil and peas reduced soil loss by 38-69% compared to fields with no covers. Mustard reduced soil loss by up to 82%.
With repeated cover crop use soils builds organic matter, which also helps improve water infiltration. That upgraded soil structure and stability means that soil can better withstand heavy farm equipment, so soil compaction is less likely to return.
Don’t take that 6 inches of topsoil for granted anymore. Cover crops can help keep that topsoil around for many growing seasons to come.