Nitrous oxide emissions erupt from farms in unpredictable bursts

The world’s ability to feed itself depends heavily on farms. Nitrogen fertilizers are used on farms to grow more crops, ensuring food for people and feed for livestock. But while fertilizers power growth, they also carry an environmental cost that often goes unseen.

When plants can’t absorb all the nitrogen, part of it escapes into the atmosphere as nitrous oxide (N₂O) – a greenhouse gas with staggering potency. It traps nearly 300 times more heat than carbon dioxide (CO₂), warming the Earth far more efficiently.

Despite its low profile, nitrous oxide is a major player in the climate crisis. About 70% of all human-caused nitrous oxide emissions come from agricultural soils.

Yet unlike carbon dioxide, which follows predictable patterns, nitrous oxide behaves more like a phantom – appearing without warning and vanishing just as fast. Understanding when and where these gases emerge is crucial, not only for scientific models but also for practical solutions that reduce emissions.

Precision matters in soil science

Until now, most studies on soil greenhouse gases have relied on small sample sizes, limited sampling dates, or simplified assumptions. This makes it difficult to fully understand how much gas escapes from a given field over time.

Conventional methods are often too narrow in scope to capture short-lived or scattered emission events, especially those from nitrous oxide.

A research team from the University of Illinois Urbana-Champaign set out to overcome these limitations. Their goal was ambitious: to capture the full spatial and temporal complexity of CO₂ and nitrous oxide emissions across real farms, over multiple years, and under typical farming conditions.

The study focused on commercial corn and soybean fields using three tillage practices: conventional, conservation, and no-till.

“Mitigating agricultural soil greenhouse gas emissions can help us meet global climate goals,” said study co-author Chunhwa Jang. The team noted that only a large-scale, high-frequency dataset could paint a reliable picture of what’s happening beneath our feet.

Nitrous oxide emissions from farms

To monitor soil emissions, the researchers deployed a network of gas sampling points across three large farms in central Illinois.

Picture these points as tiny smokestacks embedded in the earth. Machines were brought in every week or two to measure gas levels, capturing both CO₂ and N₂O over the full growing seasons of 2021 and 2022.

The experts found that CO₂ emissions were consistent across fields, crops, and years – a reassuring result. It meant scientists could confidently monitor carbon dioxide using lower sampling densities without losing accuracy.

“We found carbon dioxide flux was similar across individual fields, sites, and years, or even between corn and soybean systems,” Jang noted.

Nitrous oxide, however, defied predictability. Its emissions fluctuated wildly, creating what researchers called “hot moments” and “hot spots.”

One day, a particular point might spike in emissions; the next day, it might go quiet while another area lit up. These chaotic shifts meant that even dense sampling grids sometimes missed key events.

Nitrous oxide spikes unpredictability

Unlike CO₂, which was evenly distributed, N₂O hotspots packed a disproportionate punch. Though they occupied just 12–13% of a field, they could account for up to 54% of total emissions.

At the Villa Grove site – managed with conventional tillage and planted with continuous corn – the numbers were most extreme.

Data showed that emissions from this site were more than four times higher than those from conservation-managed fields. The combination of heavy nitrogen use and deep tillage likely triggered this spike.

These methods disturb the soil, release trapped gases, and increase microbial activity – all of which drive nitrous oxide production.

“We may not be able to predict where and when nitrous oxide will spike, but we do know management makes a difference,” said Jang. Fields with continuous corn and traditional tillage saw much higher emissions than those under rotation or conservation practices.

Nitrous oxide hotspots on farms

The researchers observed that the timing and method of fertilizer application had major impacts. For example, fields receiving side-dressed nitrogen along crop rows were more predictable than those with broadcast applications.

Yet even then, randomness crept in. Sometimes, emissions seemed tied to where the fertilizer landed in relation to the gas sampling collar, adding uncertainty to the readings.

To make matters more complex, nitrous oxide hotspots rarely stayed in the same place from one year to the next. In most cases, the spatial patterns changed so much that it was hard to determine whether observed hotspots were real or artifacts of shifting management practices.

The team conducted a detailed analysis of flux consistency across years. They found that only a few sampling points behaved reliably. At many locations, N₂O emissions fluctuated by tenfold or more between years.

“Spatially and temporally, nitrous oxide was very variable,” Jang reiterated. This variability challenges the way scientists currently model soil gas emissions.

Smarter monitoring for N₂O emissions

The unpredictability of nitrous oxide means traditional monitoring methods fall short.

Static chambers and small sample sizes are likely to miss the true scale of emissions. If models are based on these limited datasets, they may under- or overestimate field-scale emissions, distorting climate forecasts.

“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,” said co-author DoKyoung Lee.

The team’s findings suggest that higher sampling density is essential – especially for nitrous oxide.

Through simulation, the researchers found that to estimate N₂O emissions with less than 25% error, fields need at least 5.6 sampling points per hectare. For CO₂, only 1.6 points are needed. This shows how much more sensitive nitrous oxide emissions are to spatial resolution.

Farming practices shape nitrous oxide emissions

One of the study’s key takeaways is the role of management in emission control. Fields under conservation and no-till practices showed both lower emissions and less variability.

In contrast, conventional systems that disrupt soil and apply nitrogen heavily had not only higher emissions but also larger uncertainties.

In particular, the Villa Grove site stood out. Managed with deep chisel tillage and continuous corn, it produced up to 785 mg/m² of nitrous oxide – nearly nine times the levels observed in rotated soybean systems. This finding aligns with earlier studies and confirms that farming practices strongly shape emission profiles.

Though it’s hard to predict where hotspots will form, choosing crop rotations and reduced tillage can help shrink the overall size of the problem. That gives farmers a way to contribute to climate solutions without sacrificing yields.

Climate models need better data

Accurate field data is the foundation of every global climate model. If the field data is wrong or incomplete, then the predictions those models generate may misguide policies.

The University of Illinois study provides one of the most robust datasets yet for calibrating climate models with real-world agricultural emissions.

It also points to a broader issue: the tradeoff between scale and control. Gathering high-resolution, multi-year data across large farms is incredibly labor-intensive.

The researchers suggest that small, well-managed field experiments may be a better way to understand the biological mechanisms behind N₂O emissions. For large-scale estimates, however, grid-based sampling with enough points per hectare seems to be the best path forward.

Each gas needs a unique strategy

This research reveals how differently CO₂ and N₂O behave in agricultural soils. While CO₂ flows steadily, nitrous oxide erupts in bursts, influenced by everything from rainfall to fertilizer timing. That difference demands tailored strategies for each gas.

Reducing agricultural emissions isn’t just about cutting fertilizer or changing crops. It’s about understanding the invisible patterns in the soil and designing systems that can track and respond to them.

With the right data, tools, and practices, farmers can keep growing food while also shrinking their carbon – and nitrogen – footprint.

This work serves as a reminder that not all gases are created equal, and neither are the ways they move through the soil. Precision, patience, and smarter farming can help us stay grounded – even as we try to cool the skies.

The study is published in the journal Agriculture Ecosystems & Environment.

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