When the United States Department of Agriculture (USDA) set out to study greenhouse gas and air quality emissions from dairy farms nationwide, they needed instrumentation that could deliver laboratory-quality results in rough, real-world field conditions — across dozens of farm sites, repeatedly. They chose Cerex FTIR analyzers. The results exceeded expectations.

The Challenge

Dairy operations are complex emission sources. Barns, lagoons, feed areas, and land application sites each produce different combinations of gases — methane, ammonia, hydrogen sulfide, nitrous oxide, volatile organic compounds, and more. Measuring these accurately in a farm environment requires:

  • Sensitivity down to parts-per-billion or better for trace gases
  • Simultaneous multi-gas measurement (a single instrument needed to capture many compounds at once)
  • Durability in outdoor environments with dust, humidity, and temperature extremes
  • Minimal maintenance burden across many remote sites
  • Data quality sufficient for scientific publication and policy guidance

Conventional single-gas sensors couldn’t meet all of these criteria. The USDA needed a spectrometric solution.

The Solution: Cerex Air Sentry FTIR

The USDA selected Cerex Air Sentry FTIR open path analyzers for their on-farm monitoring campaigns. The Air Sentry FTIR uses Fourier-Transform Infrared Spectroscopy to simultaneously identify and quantify hundreds of gases in real time, archiving raw spectral data every 5–30 seconds.

Key advantages for this application included:

  • Open path measurement: The Air Sentry’s transmitter-receiver configuration allowed the USDA to monitor emissions across entire barn cross-sections or lagoon surfaces — capturing a true integrated picture rather than a single point sample.
  • Multi-gas capability: One instrument simultaneously tracked methane, ammonia, carbon dioxide, nitrous oxide, and other target gases — eliminating the need for multiple sensor systems at each site.
  • Archived spectra: Because raw spectrographic data is stored, the research team could go back and re-analyze historical data for compounds of interest that emerged during the study — a capability unique to full-spectrum FTIR systems.

The Results

The USDA’s research team generated what they describe as the most comprehensive on-farm air emissions dataset in the United States. In the words of April L., USDA researcher, May 2025:

“We have been able to do some amazing work for the dairy industry with your FTIRs. I would say we have the most on farm data in the US for sure… We have learned a lot of things that we were not expecting which has been helpful to guide the industry on how to target and solve their problems. So huge thanks to you and your team, we couldn’t have done it without you!!”

Key outcomes from the project included:

  • A dataset spanning multiple farm types, regions, and operational practices — enabling statistically meaningful comparisons
  • Discovery of unexpected emission patterns that are now informing industry best practices and mitigation strategies
  • Data quality sufficient to underpin peer-reviewed research and USDA policy guidance for the dairy sector

Why This Matters for Other Research and Government Applications

This project demonstrates that Cerex FTIR analyzers are not only industrial compliance tools — they are research-grade instruments capable of generating publishable, policy-relevant data in demanding field environments. The same properties that made them ideal for this USDA project apply across a wide range of government and research applications:

  • Air quality research and baseline monitoring
  • Agricultural emissions inventory programs
  • Environmental impact assessments
  • Industrial fence-line and community air monitoring

If you’re planning a monitoring campaign that requires multi-gas, research-grade data from the field, contact our application engineers to discuss how Cerex instruments can support your project.