Topsoil in the U.S. Corn Belt is disappearing fast — and cover crops are one way to keep more topsoil in place.
According to a new study published by scientists at the University of Massachusetts-Amherst in the journal Proceedings of the National Academy of Sciences, more than a third of farmland in the U.S. Corn Belt has completely lost its carbon-rich topsoil to erosion.
That loss of topsoil has reduced corn and soybean yields by 6%, costing growers $3 billion a year — not to mention the increased sediment runoff and nutrients, which depletes water quality.
The study found that the greatest loss of topsoil was on hilltops and ridgelines, which is no surprise. The erosion has removed nearly 1.5 petagrams (1 petagram = 1 billion metric tons) of carbon since the U.S. Corn Belt has been farmed.
How can growers reverse this trend? By using cover crops and either no-till or strip-till.
A study published in November 2020 in the Journal of Environmental Management stated that if growers shifted entirely to no-till practices, it would reduce soil erosion by more than 70%. Currently, only 21% of U.S. agricultural land is continuously farmed with either no-till or strip-till.
A recent report conducted by USDA’s Economic Research Service found that 15.4 million acres of cover crops were planted in 2017, a 50% increase compared to the 10.3 million acres planted in 2012. Cover crop adoption was highest on fields that include corn silage in the rotation, and lowest on wheat fields.
One way for growers to utilize cover crops is by taking advantage of federal, state and private funding available for cover crop use. A variety of incentive programs administered in at least 22 states supported more than 1 million cover crop acres in 2018.
The USDA report showed that only 1/3 of acres planted with covers in 2018 received financial assistance, which aligns with the results of the second annual Cover Crop Strategies Benchmark Study.