U.S. Midwest Lost 57.6 Trillion Tons Of Soil Due To Plowing, Experts Claim

A new study in the journal Earth's Future led by the University of Massachusetts Amherst shows that, since Euro-American settlement approximately 160 years ago, agricultural fields in midwestern US have lost, on average, two millimeters of soil per year. This is nearly double the rate of erosion that the US Department of Agriculture (USDA) considers sustainable, ScienceDaily reported.

Photo Insert: The Midwest has lost 57.6 trillion metric tons of topsoil since farmers began tilling the soil.

Furthermore, USDA estimates of erosion are between three and eight times lower than the figures reported in the study.

The study's authors conclude that plowing, rather than the work of wind and water, is the major culprit. Isaac Larsen, professor of geosciences at UMass Amherst and one of the paper's co-authors, initiated the study after finding out that the surface of the fields was a few feet lower than the surface of the never-tilled areas in the region.

Larsen, along with the paper's co-lead authors, Evan Thaler, who completed the research as part of his Ph.D. at UMass Amherst, and Jeffrey Kwang, a postdoctoral researcher at UMass Amherst at the time of the study, found himself standing in central Iowa on the "escarpment," or drop-off, separating a native prairie from a field of soybeans.

Thaler had worked extensively with the Iowa Natural Heritage Foundation and other organizations to pinpoint the few remaining pockets of original, never-farmed prairie. He then reached out to the farmers whose land abutted the prairies, asking them for permission to survey their fields.

Thaler wound up with 20 sites, the majority of them in central Iowa, with a few in Illinois, Minnesota, South Dakota, Kansas, and Nebraska.

Once Thaler had secured the landowner's permission, the team went to work. Using an extraordinarily sensitive GPS unit that looks more like a floor lamp than a hand-held device, the team walked dozens of transects, or perpendicular routes across the escarpment, from the untouched prairie to the eroded farm field, stopping every few inches to measure the change in altitude.

They did this throughout the summers of 2017, 2018, and 2019. Using historical land-use records and computer models to reconstruct erosion rates in the Midwest, they discovered that Midwestern topsoil is eroding at an average rate of 1.9 millimeters per year.

The authors estimate that the Midwest has lost 57.6 trillion metric tons of topsoil since farmers began tilling the soil. This was despite conservation practices put in place in the wake of the Dust Bowl in the 1930s. The team suggests that more sustainable practice, like no-till farming and soil regeneration, "will likely be required to reduce soil erosion rates in the Midwest to levels that can sustain soil productivity, ecosystem services, and long-term prosperity."

WEEKLY FEATURE : MVP Group Keeps Lights On During Pandemic