Perennial bioenergy grasses begin rebuilding Midwest soil carbon lost to maize
Nearly two centuries of maize-based agriculture in the U.S. Midwest has halved soil organic carbon (SOC) stocks compared with tallgrass prairies native to the region. Replacing annual maize/soy cropping with perennial bioenergy grasses may partially reverse these resulting SOC deficits.
For nearly two centuries, the U.S. Midwest's soil has suffered a loss of half its original organic carbon (SOC) stocks, due to centuries of maize-based agriculture that replaced the region's native tallgrass prairies. In a study conducted by the Center for Advanced Bioenergy and Bioproducts Innovation (CABBI), researchers explored whether perennial bioenergy grasses, such as miscanthus and switchgrass, could help restore the region's soil carbon deficit by comparing soil organic carbon (SOC) levels in native prairie, maize cropping systems, and seven established perennial bioenergy cropping systems.
The study, published in the journal Geoderma, reveals that perennial bioenergy crops have the potential to rebuild SOC over time, even with annual harvesting. After five years, mature miscanthus and switchgrass demonstrated higher 0-1 m SOC stocks compared to maize, although they still fell short of native prairie levels. Notably, SOC increased in the first five years under mature bioenergy crops at four of the seven sites, with carbon isotopes (δ13C) confirming that the gains originated from the perennial crops.
This discovery indicates that perennial bioenergy grasses could potentially rebuild soil carbon depleted by annual maize cultivation, offering a promising solution to address the SOC deficit caused by traditional annual farming practices.
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