A new accounting of nitrogen pollution in the Mississippi-Atchafalaya River Basin (MARB) reveals a significant decline in recent decades, suggesting positive momentum for water quality goals in local watersheds and the Gulf. Surprisingly, the University of Illinois Urbana-Champaign-led study doesn’t credit the change to reduced fertilizer application, but instead to cleaner air and more efficient nitrogen uptake by modern corn hybrids.
“Between 2000 and 2020, we saw major increases in crop yields, as well as reductions in nitrogen oxide emissions from smokestacks and vehicles as part of the Clean Air Act. Reduced nitrogen oxide emissions result in less biologically available nitrogen coming into soil and water from the atmosphere,” said the study’s lead author, Greg McIsaac, associate professor emeritus in the Department of Natural Resources and Environmental Sciences, part of the College of Agricultural, Consumer and Environmental Sciences at Illinois. “It’s great to see trends moving in the right direction.”
Less nitrogen moving through the MARB should mean a smaller or shorter-lived “dead zone” in the Gulf, an area of oxygen-depleted water that can’t support fish or other marine life. For two decades, the Gulf Hypoxia Task Force and a dozen states bordering the Mississippi River have set goals and incentives to reduce nitrogen flows by 45%.
“Progress toward that goal has been slow, but over the last decade, we have finally started to see nitrogen flows in the Mississippi River decrease,” said study co-author Robert Howarth, Atkinson Professor of Ecology & Environmental Biology in the College of Agriculture and Life Sciences at Cornell University. Howarth led a committee of the National Academy of Sciences in the late 1990s that recommended significant reductions in nutrient flows to all coastal waters.
Read the full article from College of ACES.
University of Illinois Extension develops educational programs, extends knowledge, and builds partnerships to support people, communities, and their environments as part of the state's land-grant institution. Extension serves as the leading public outreach effort for University of Illinois Urbana-Champaign and the College of Agricultural, Consumer and Environmental Sciences in all 102 Illinois counties through a network of 27 multi-county units and over 500 staff statewide. Extension’s mission is responsive to eight strategic priorities — community, economy, environment, food and agriculture, health, partnerships, technology and discovery, and workforce excellence — that are served through five program areas — 4-H youth development, agriculture and agribusiness, community and economic development, health and community wellness, and natural resources, environment, and energy.