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More Than One-Third of Corn Belt Farmland Has
Completely Lost Its Carbon-Rich Topsoil
TOPICS:AgricultureGeographyGeologyPopularUniversity
Of Massachusetts Amherst
By UNIVERSITY OF MASSACHUSETTS
AMHERST MARCH 14, 2021
UMass Amherst researchers used remote sensing to quantify the
previously underestimated erosion.
More than one-third of the Corn Belt in the Midwest – nearly 30
million acres – has completely lost its carbon-rich topsoil, according
to University of Massachusetts Amherst research that indicates the
U.S. Department of Agriculture has significantly underestimated the
true magnitude of farmland erosion.
In a new paper published in the Proceedings of the National Academy of
Sciences, research conducted by UMass Amherst graduate student Evan
Thaler, along with professors Isaac Larsen and Qian Yu in the
department of geosciences, developed a method using satellite imagery
to map areas in agricultural fields in the Corn Belt of the Midwestern
U.S. that have no remaining A-horizon soil. The A-horizon is the upper
portion of the soil that is rich in organic matter, which is critical
for plant growth because of its water and nutrient retention
properties. The researchers then used high-resolution elevation data
to extrapolate the satellite measurements across the Corn Belt and the
true magnitude of erosion.
Productive agricultural soils are vital for producing food for a
growing global population and for sustaining rural economies. However,
degradation of soil quality by erosion reduces crop yields. Thaler and
his colleagues estimate that erosion of the A-horizon has reduced corn
and soybean yields by about 6%, leading to nearly $3 billion in annual
economic losses for farmers across the Midwest.
The A-horizon has primarily been lost on hilltops and ridgelines,
which indicates that tillage erosion – downslope movement of soil by
repeated plowing – is a major driver of soil loss in the Midwest.
Notably, tillage erosion is not included in national assessments of
soil loss and the research highlights the urgent need to include
tillage erosion in the soil erosion models that are used in the U.S.
and to incentivize adoption of no-till farming methods.
Further, their
research suggests erosion has removed nearly 1.5 pentagrams of carbon
from hill slopes. Restoration of organic carbon to the degraded soils
by switching from intensive conventional agricultural practices to
soil-regenerative practices, has potential to sequester carbon dioxide
from the atmosphere while restoring soil productivity.
Reference: “The extent of soil loss across the US Corn Belt” by Evan
A. Thaler, Isaac J. Larsen and Qian Yu, 23 February 2021, Proceedings
of the National Academy of Sciences.
DOI: 10.1073/pnas.1922375118
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