Corn monocropping emits higher levels of nitrous oxide, a greenhouse gas which traps heat in the atmosphere more than 300 times as effectively as carbon dioxide. Simple interventions could drastically reduce emissions, experts say.
Year after year, the same 15 million acres across Illinois, Iowa, Minnesota and Wisconsin are planted with corn.
Each August, the fibrous green leaves in those fields reach eye level. And each November, the dusty stalks are razed to stumps.
“Continuous corn,” as the growing strategy is called, allows farmers to profit from a steady demand for corn from the ethanol and livestock industries. The approach is also a major source of a potent and little-discussed greenhouse gas: nitrous oxide.
Agricultural nitrous oxide makes up only 6 percent of U.S. greenhouse gas emissions, but it traps heat in the atmosphere over 300 times as effectively as carbon dioxide and persists in the atmosphere for 120 years, compared to methane’s 8 to 12 years.
“This is something that’s not really being talked about enough, compared to methane and carbon dioxide from ag,” said Anne Schechinger, midwest director for the Environmental Working Group (EWG).
Establishing forest buffers and planting trees, shrubs, hedgerows or windbreaks on or bordering continuous corn fields could significantly reduce nitrous oxide emissions, a new report from EWG, co-authored by Schechinger, finds.
Adopting one of these four practices on just 4 percent of continuous corn acres would have an emissions reduction effect equivalent to getting more than 850,000 gas-powered cars off the road, according to the report.
“Nitrous oxide is powerful. It lasts a long time. But it’s also something that these types of conservation practices can really have an impact on reducing,” said Schechinger.
Analyzing U.S. Department of Agriculture Census of Agriculture data, EWG determined that 20 percent of cropland across Illinois, Iowa, Minnesota and Wisconsin has been used to grow corn for at least three consecutive years between 2016 and 2024.