Recent estimates show that up to 35% of the US Corn Belt has lost its carbon-rich topsoil, with mechanical tillage promoting erosion.
PHOTO: GRANT HEILMAN PHOTOGRAPHY/ALAMY STOCK PHOTO
The current era of major loss of agriculturally productive soils has gained relatively little public attention. It seems intuitively unnecessary to spell out what will happen to food production, hydrology, carbon sequestration, and ecological services if we allow soil erosion to proceed at current rates. However, it is difficult to quantify soil loss and to translate that into agricultural loss. Thaler et al. focused on the US Corn Belt and used remote sensing to map areas in fields that have no carbon-rich (i.e., A-horizon) soils remaining. Previous attempts to quantify soil loss suggested that little damage had occurred. By contrast, the new estimate indicates that ∼35% of an area of ∼400,000 square kilometers (a third of the Corn Belt area) has lost its A-horizon soil (∼1.4 petagrams), especially on hillslopes. The authors suggest that mechanically working the land (tillage) has been responsible for most soil loss in this region. This degree of erosion translates into a 6% reduction in overall crop yield and ∼$3 billion in economic loss.
Proc. Natl. Acad. Sci. U.S.A. 118, e1922375118 (2021).
