A groundbreaking multi-year study from the University of Illinois has produced the most comprehensive dataset to date on greenhouse gas emissions from agricultural soils, offering new insights into how farming practices influence climate impact.
A gas analyzer measures carbon dioxide and nitrous oxide from fields. Image Credit: University of Illinois Urbana-Champaign
Farmers apply nitrogen fertilizers to crops to boost yields and feed both people and livestock. But when plants can't absorb all the fertilizer, some of the excess can turn into gases—most notably nitrous oxide, a potent greenhouse gas that traps nearly 300 times more heat in the atmosphere than carbon dioxide. Agriculture is responsible for about 70 % of human-generated nitrous oxide, making it essential to identify strategies to reduce those emissions.
Before scientists can recommend effective mitigation practices, they first need to understand when and where these gases are released. The challenge is that measuring emissions from soil is time-consuming and costly. As a result, most studies have been limited in scope, often lacking the spatial and temporal detail needed for accurate estimates.
A new study from the University of Illinois Urbana-Champaign set out to change that. Researchers rigorously measured nitrous oxide and carbon dioxide emissions in commercial corn and soybean fields, under realistic management practices, across multiple years. The goal was to generate a dataset robust enough to inform both emission reduction strategies and climate models used to forecast future global scenarios.
Mitigating agricultural soil greenhouse gas emissions can help us meet global climate goals. High spatial and temporal resolution, large-scale, and multi-year data are necessary to establish well-informed mitigation strategies. Before our study, these datasets just did not exist.
Chunhwa Jang, Study Co-Author and Research Scientist, University of Illinois Urbana-Champaign
Led by Kaiyu Guan from the Agroecosystem Sustainability Center, the team used funding from the US Department of Energy’s ARPA-E SMARTFARM program to build the most comprehensive on-farm emissions dataset to date. They established an expansive network of gas-sampling sites across corn and soybean fields managed using conventional, conservation, and no-till practices.
Picture a field outfitted with small, ground-level devices—like miniature smokestacks—capturing gases released from the soil. The research team visited these sites weekly or biweekly over two growing seasons to measure gas concentrations. Some locations regularly emitted high levels and were designated “hot spots.” Events like rainfall or fertilizer application often triggered “hot moments,” when emissions surged across much of the field.
Jang added, “We found carbon dioxide flux was similar across individual fields, sites, and years, or even between corn and soybean systems. These results tell us that carbon dioxide emissions are consistent and that high spatial resolution sampling is likely sufficient to estimate field-wide flux.”
Nitrous oxide, however, proved far less predictable. Emissions at individual sites could spike one day and drop the next, and hot spots shifted unpredictably across the field.
Jang added, “Spatially and temporally, nitrous oxide was very variable. One day, point A would be having a hot moment, and then at the next measurement, we would find hot moments at points B and C. The hot spots were just moving around.”
This variability matters. If prior studies only sampled a few spots or days, they may have dramatically misjudged total nitrous oxide emissions—skewing the climate models built on that data. And since those models help determine how close we are to climate tipping points, getting the numbers right is critical.
This project enabled us to capture spatio-temporal and management variation to provide gold standard data and a platform for validating field-level greenhouse gas emissions. This is necessary for sustainable practices to secure both food and bioenergy demand and minimize emissions to the atmosphere.
DoKyoung Lee, Study Co-Author and Professor, Department of Crop Sciences, University of Illinois Urbana-Champaign
The study also highlighted how farming practices affect emissions. Carbon dioxide levels were similar for corn and soybeans and between conservation and no-till systems. But emissions were higher with conventional chisel tillage and continuous corn cropping.
As for nitrous oxide, levels were significantly higher in corn than soybeans under conservation and no-till systems—and nearly off the charts in continuous corn fields managed with chisel tillage.
Jang further added, “We may not be able to predict where and when nitrous oxide will spike, but we do know management makes a difference. In continuous corn, farmers have to apply high amounts of nitrogen fertilizer, which converts into nitrous oxide. And conventional tillage interrupts the soil surface and releases gas. We know what to do to mitigate it.”
Nakian Kim, Chunhwa Jang, Wendy Yang, Kaiyu Guan, Evan DeLucia, and DoKyoung Lee are the co-authors.
Journal Reference:
Kim, N., et al. (2025) Spatial variability of agricultural soil carbon dioxide and nitrous oxide fluxes: Characterization and recommendations from spatially high-resolution, multi-year dataset. Agriculture, Ecosystems & Environment. doi.org/10.1016/j.agee.2025.109636.