By Gabriella Sotelo for Sentient.
Broadcast version by Judith Ruiz-Branch for Illinois News Connection reporting for the Sentient-Public News Service Collaboration
Nitrous oxide (N2O) emissions from agriculture are not only coming from soil. They’re also flowing through the streams that run alongside farms, a recent study finds. Researchers at the University of Minnesota and University of Illinois discovered more than one-third of regional nitrous oxide emissions were measured from streams.
While often overshadowed by the more widely known greenhouse gases like carbon dioxide and methane, nitrous oxide is the third-largest contributor to greenhouse gas emissions. Nitrous oxide also has an EPA-rated “Global Warming Potential” 273 times that of carbon dioxide (over a 100-year timescale), and is a significant contributor to ozone depletion. This means that even small amounts of nitrous oxide emissions can have a disproportionately large impact on global warming. And the flip side is also true: taking some action, including better manure management and eating less meat, can have a big climate impact for the better.
The discovery highlights a previously overlooked pathway for nitrous oxide to enter the atmosphere: as agricultural soils undergo the process of nitrification and produce nitrous oxide, the gas is transported via runoff into nearby streams. During the nitrification process, bacteria in soils break down ammonia — in this case from fertilizers — into nitrates that can produce nitrous oxide gas. While this gas may be released immediately from the soil, it can also become trapped in the soil or dissolve in water, only to be carried into streams during rainfall or snowmelt.
“What we basically found is there [are] other pathways, and this stream emission could be important,” Zhongjie Yu, hydrologist and researcher in the study, tells Sentient.
Traditionally, when researchers consider nitrous oxide emissions from agriculture, they focus on soil. Excess nitrogen from fertilizers accumulates in agricultural soil, where it can be transformed into nitrous oxide, and released directly into the atmosphere. However, this new study suggests that emissions from streams — carrying runoff from agricultural fields — can be just as important, if not more so, in certain regions. Factory farms can be a major driver of this issue, as these operations produce large amounts of waste, composed partly of nitrogen.
When researchers consider initial nitrous oxide emissions, it’s often in the context of fertilizer input to soil. This excess nitrogen accumulates in agricultural soil, and can then lead to the direct release of nitrous oxide into the atmosphere.
Though the study used only the University of Minnesota’s Tall Tower Trace Gas Observator to sample air emissions, Yu and his research team are confident about the data.
“We found that N2O is emitted from streams, but we believe it’s originally from fertilizer nitrogen. It is just carried by water, and gets emitted from those aquatic systems. It’s not saying it’s a natural source, but it’s still related to fertilizer nitrogen. But it just provides another pathway that N2O gets lost from some land to the atmosphere.”
Yu also emphasized that agriculture is the dominant source of human-caused nitrous oxide emissions. This study not only challenges the conventional understanding of agricultural emissions, but also underscores a broader issue: agricultural runoff is not just a water quality problem — it is also a major contributor to climate change.
Nitrous Oxide: the Lesser Known Climate Threat
Human activities are significant contributors to nitrous oxide emissions. While other natural sources, such as the ocean, also release nitrous oxide, agricultural practices — particularly fertilizer application — are by far the largest contributor of anthropogenic emissions.
This gas is primarily produced when nitrogen-based fertilizers and manure are applied to agricultural soils. Microbes in the soil convert this nitrogen into nitrous oxide through processes such as nitrification and denitrification. The situation is made worse by the practices of industrial farming, which rely heavily on the use of synthetic fertilizers and animal waste.
Around 12 million tons of nitrogen are applied to crops each year in the United States. An EPA report found that agricultural soil management — like fertilizer use and other practices that boost nitrogen levels in the soil — accounts for nearly 75 percent of the United States’ nitrous oxide emissions. Within the agricultural sector itself, it makes up almost half of all emissions.
These soil management practices are primarily intended to optimize crop production, but much of the land is used for growing farm animal feed and biofuel crops. In 2020, only a small fraction of corn grown in the U.S. — less than two percent — was used for direct human food. Around 31 percent was dedicated to biofuels such as ethanol, while the majority, around 35 percent, went toward feeding livestock. With global meat consumption steadily rising, the demand for animal feed is expected to increase, further driving the need for feed crops like corn — along with higher fertilizer use and a corresponding rise in nitrous oxide emissions.
And now, the source of these emissions isn’t just the soil. Stream emissions can contribute to a much larger portion of annual nitrous oxide emissions than researchers previously thought.
“The high contribution of stream emissions suggests that soil emissions may have been overestimated in current regional nitrous oxide budgets,” Yu writes.
Yu points out that the link between agricultural runoff and stream emissions has often been overlooked in past research. Traditional methods use soil chambers to measure nitrous oxide emissions, a method that places a closed chamber over the soil, in order to capture any gases emitted from it. This approach primarily measures how much nitrous oxide is released directly from the soil, but misses the nitrogen that leaches out of the soil and flows into water systems, where it can then be converted into nitrous oxide and emitted to streams.
The Bottom Line
The source of nitrous oxide emissions from agriculture is more complex than scientists once thought. While traditional efforts to reduce nitrous oxide emissions have focused mainly on fertilizer management and improving soil efficiency, this new discovery emphasizes the importance of looking at the entire agricultural system, including runoff into streams. If the number of factory farms continue to rise, there is likely to be a rise in nitrous oxide pollution, particularly in streams, due to greater fertilizer use and runoff.
Yu mentions that improving water and nutrient management not only benefits water quality, but can also be a crucial tool in reducing greenhouse gas emissions. Fertilizer and manure runoff, especially from factory farms, can carry large quantities of nitrogen into waterways, which may then be converted into nitrous oxide — further complicating efforts to mitigate emissions from agriculture.
“We need to be a little bit careful here, because that water gets leached from surface soil and can end up in streams and rivers, carrying a lot of that greenhouse gas to those systems and having an impact there,” Yu says.
Gabriella Sotelo wrote this article for Sentient.
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New Mexico farmers finding it more difficult to grow historic crops are taking up conservation techniques to meet the challenge.
Drought, water scarcity, and extreme weather events combine to require growers to adopt new methods and modern tools.
John Idowu, extension agronomist specialist at New Mexico State University, shows farmers how to improve soil health and help control wind erosion. For long term success, he said they need to focus on sustainable, regenerative practices.
"How can I optimize my system and make it more resilient to climate change, to weather changes?" Idowu explained. "Once we have all those things worked out, farmers will tend to stay in business for longer."
Earlier this year, a NOAA satellite captured an image of winds lifting vast amounts of dust and dirt from New Mexico's dry farmlands. Some forecasters compared it to images last seen in the 1930s Dust Bowl.
Plowing agricultural fields annually was a common practice until the Dust Bowl period but in recent decades no-till or low-till farming operations have gained traction.
Bonnie Hopkins Byers, program director for the San Juan County Extension Service, encouraged New Mexico farmers to get a soil analysis and consider adopting the less aggressive approach. She said it could mean they do not need to till every year.
"One of the biggest problems is that people do something because that's the way they've always done it, or because it's the way their parents have done it, or their grandparents," Hopkins Byers acknowledged. "My philosophy has always been if you're going to till something over, till something in."
Intense dust storms known as "haboobs" were originally thought to be confined to Africa's Sudan but are becoming more common in other arid regions such as the Southwest.
Idowu stressed it makes the adoption of regenerative practices more urgent, as topsoil on New Mexico farmland disappears due to drought, land use changes and wind, which he noted has been particularly strong this year.
"The wind has been a major force, especially in the spring, so many days where you couldn't do anything outside because of the wind," Idowu observed. "You have a lot of dust and that means a lot of erosion and that is exactly what you don't like when it comes to crop production."
The New Mexico Healthy Soil Working Group formed to help farmers improve their land and livelihoods.
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By Carolyn Beans for Lancaster Farming.
Broadcast version by Mark Richardson for Keystone State News Connection reporting for the Lancaster Farming-MIT Climate Change Engagement Program-Public News Service Collaboration
At Mountain View Holsteins in Bethel, Pennsylvania, owner Jeremy Martin is always working to make his dairy more efficient.
Currently, he has his sights set on a manure solid-liquid separator. He'd like to use the solid portion of his manure as bedding for his 140 cows and the liquid as fertilizer.
But the project is pricey - he expects the equipment alone will run around $100,000. So Martin hopes to defray the cost through grant funding for dairy projects that reduce greenhouse gas emissions. Removing much of the solids from manure reduces the feed for the methane-producing microbes that thrive in the anaerobic conditions of liquid manure.
The approach is just one of many dairy practices now considered "climate-smart" because they could cut production of climate-warming gases.
For Martin, a manure separator wouldn't be possible without a grant.
"Once it's in place and going, I think some of these practices will pay for themselves, but the upfront cost is more than I can justify," he says. "If there's money out there to pay that upfront cost to get started, it makes sense to me to do it."
Across Pennsylvania, dairy farmers are learning more about climate-smart practices and funding opportunities, and weighing whether these changes are really sustainable for their businesses as well as the environment.
The Latest Buzzword
USDA has defined climate-smart agriculture as an approach that reduces or removes greenhouse gas emissions, builds resilience to the changing climate, and sustainably increases incomes and agricultural productivity.
"Before climate-smart was a thing, we called it conservation. We called it stewardship," says Jackie Klippenstein, a senior vice president at Dairy Farmers of America.
Indeed, long before the Food and Agriculture Organization of the United Nations coined the term "climate-smart agriculture" in 2010, Pennsylvania dairy farmers had adopted many of the practices that now fall under the label.
For dairy, climate-smart practices largely include strategies that reduce greenhouse gases emitted from cows, manure or fields. Tried and true conservation practices like cover cropping and reduced tillage count.
So do newer practices like using the feed additive Bovaer to reduce methane production in a cow's rumen, or precision nitrogen management to reduce nitrous oxide emissions from fields.
Paying for Climate-Smart
"Margins are very tight on the dairy farm," says Jayne Sebright, the executive director of the Center for Dairy Excellence, a public-private partnership to strengthen Pennsylvania's dairy industry. "Some of these (climate-smart practices) are good for the climate, but they don't make good economic sense until they're subsidized."
In 2022, the center joined a Penn State-run program called "Climate-smart Agriculture that is profitable, Regenerative, Actionable and Trustworthy" to provide dairy farmers with funds for switching to climate-smart practices.
CARAT was launched with a $25 million USDA Partnerships for Climate-Smart Commodities grant, but the future of the Pennsylvania project is in doubt. In April, USDA canceled the partnership program, suggesting that recipients reapply to a new USDA initiative called Advancing Markets for Producers.
Over 60 dairy farmers across Pennsylvania, including Martin, had already applied and been accepted into the first phase of CARAT. This initial phase was intended to help farmers identify the best climate-smart practices for their operations. In the second phase, farmers would have applied for funding to implement those practices. One farmer was already paid for his project before the USDA canceled the partnership program.
"There are fewer funding sources for climate-smart projects than in the last administration. However, private organizations and other entities are funding climate-smart projects," Sebright says. "Depending on what the practice is, (climate-smart) could also be conservation projects. It could be water quality projects."
Sebright suggests that dairy farmers also look for support through state-level funding, such as Pennsylvania's Resource Enhancement and Protection program, which offers tax credits for implementing practices that benefit farms and protect water quality.
Pennsylvania dairy farmers can also contact their county conservation districts to ask about funding opportunities for climate-smart projects, says Amy Welker, a project manager and grant writer for Pennsylvania-based Jones Harvesting, which operates Maystone Dairy in Newville and Molly Pitcher Milk in Shippensburg.
In the next year, Jones Harvesting plans to install a methane digester and solid-liquid separator at a site near Maystone Dairy. The digester is funded with an Agricultural Innovation Grant from the state and an Environmental Quality Incentives Program grant from USDA, along with private funds.
There's money out there for farmers who implement climate-smart practices, says Welker. But "you can't just look at one source."
Long-Term Payoffs
Ultimately, for climate-smart projects to make economic sense, they must continue paying for themselves long after the initial investment. One major goal of the USDA's Partnerships for Climate-Smart Commodities program was to develop markets where farmers adopting these practices could earn a premium.
Some dairy farmers might see that return in the carbon market. National checkoff organization Dairy Management Inc. and its partners have pledged to shrink the industry's net greenhouse gas production to zero by 2050. There are growing opportunities for companies working toward that goal in the dairy supply chain to pay farmers for their contributions.
Early last year, Texas dairy farmer Jasper DeVos became the first to earn credits through the livestock carbon insetting marketplace. DeVos earned carbon credits by reducing methane emissions with a feed protocol that included the feed additive Rumensin. Dairy Farmers of America then purchased those credits through Athian, a carbon marketplace for the livestock industry.
Increased Efficiency
Even without direct monetary payoff, many farmers who adopt climate-smart practices reap rewards in improved efficiency and productivity.
"When you look at climate-smart, you also have to look at what's farm smart," Sebright says. She suggests that farmers choose practices that benefit their farms, not just the climate.
A farmer might decide to put a cover and flare system on a manure pit, not only because it reduces methane emissions but also because it keeps rainwater out of the pit and reduces the number of times each year the pit must be emptied.
Andy Bollinger of Meadow Spring Farm in Lancaster County has been running a manure separator since 2009. The liquid fertilizes his fields, and a portion of the solids becomes bedding for his cows.
He estimates the system saves him at least $20,000 a year in bedding costs.
"We put a fresh coating of it onto the stalls that our cows lay in every day and scrape the old stuff out," says Bollinger, who is also the vice president of the Professional Dairy Managers of Pennsylvania. "It seems to work quite well, and it saves us from buying other bedding products."
No-till farming is also a cost saver because it reduces field passes with equipment, says James Thiele of Thiele Dairy Farm in Cabot, which has been 100% no-till for at least six years. The practice saves him money on fuel and herbicides.
"You're saving your environment, and you're also saving green," he says.
But Thiele questions whether some other climate-smart practices like methane digesters would be practical for his farm, which has 75 to 80 cows.
"I don't know if it'd be worth it for somebody as small as I am," he says.
"I think over the next few years, we'll rapidly see (climate-smart) tools become more available, and we'll see more organizations like DFA talking to our small to mid-sized farmers to make sure they understand they've got a place in this, they can benefit from it, and the practices and tools are affordable to them as well," Klippenstein says.
Weighing Climate-Smart
Many dairy farmers wonder whether some of the practices championed as climate-smart will really support their businesses.
Donny Bartch of Merrimart Farms in Loysville has adopted environmental practices from cover cropping to a manure management plan.
"I want to protect the environment. I want to keep my nutrients here on the farm and be sustainable for another five generations," Bartch says. "But we have to make sure that we're making the right decisions to keep the business going. And to do some of these (climate-smart) practices, the only way they pencil out is to have those subsidies."
There is also frustration with a system that rewards climate-smart improvements made today without acknowledging the contributions of farmers who were climate-smart before anyone put a name on it.
"You come around and want to start rewarding people for doing these things. You really need to start with the ones that have been doing it for a long time, but that's really not what happens," says Jim Harbach of Schrack Farms in Loganton, whose farm has been no-till for 50 years.
Climate-smart grant money and carbon credits are typically awarded for the implementation of new practices.
"It's just the unfortunate way that all of the policies and regulations were written," Sebright says. "What I would say is, if you do a climate-smart plan, maybe there are practices or things you can do to enhance or support or take what you're doing a step further."
Scientific Measurements on Real Farms
Some dairy farmers also want to know more about how climate-smart practices will affect their farms before jumping in.
Steve Paxton remembers participating in a government program to improve timber over 50 years ago on his family dairy, Irishtown Acres in Grove City. His family members were paid to climb up into their white pines and saw off many of the bottom branches.
The goal was to create a cleaner log. Instead, more sunlight shown through, which caused grape vines to climb up and topple the trees.
"The bottom line is, there was research done, it looked good, but it hadn't had enough time to follow through and see just really what the end results would be," Paxton says.
When Paxton sees estimates of how some practices might reduce greenhouse gases emitted from cows, he wonders how much of that research has been tested on actual dairies.
"I think some of it now is just kind of a textbook estimate of what's happening," he says.
More meaningful data is needed to show how climate-smart practices reduce greenhouse gases on individual dairies, Sebright says.
As part of the CARAT program, Penn State researchers planned to place greenhouse gas sensors on a dozen dairies and test how much greenhouse gas production falls as farmers experiment with different practices. The researchers intended to then use that data to build models that predict how those practices may affect emissions on other farms. They will still measure emissions this spring on one farm that is experimenting with a new approach for spreading manure in fields of feed crops.
"The real goal of (CARAT) is to have research that says, if you put a cover and flare (manure storage system) on a 500-cow dairy, this is how greenhouse gas emissions will change," Sebright says. "Or if you use Bovaer on a 90-cow herd, here's how this will affect greenhouse gas emissions."
Martin of Mountain View Holsteins has his own personal beliefs about where a dairy farmer's responsibilities to the planet begin and end. But from a business perspective, he feels compelled to adopt climate-smart practices because he expects the industry will eventually require them.
"Climate concerns are coming whether I'd like it or not," he says. "So my thought is, I might as well get started on it while there's funding to do it."
Carolyn Beans wrote this article for Lancaster Farming.
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Oregon's new state budget cuts funding for programs intended to protect residents from extreme weather and make renewable energy more accessible.
Climate justice advocates said it is a major setback after years of progressive climate policies.
Ben Brint, senior climate program director for the Oregon Environmental Council, is disappointed to lose funding for the Community Renewable Energy Grant Program, which supports a variety of projects tailored to communities, including microgrids and solar storage.
"We felt legislators didn't fund climate resilience programs while fires are raging, people's houses are burning down and the state has already experienced record heat waves in June," Brint pointed out. "Legislators don't see we are in an actual climate emergency and chose inaction."
Brint said the grant program aimed to help low-income, rural and communities of color, those most impacted by climate disasters. Lawmakers attributed the cuts to budget shortfalls and uncertainty over federal funding.
Joel Iboa, executive director of the Oregon Just Transition Alliance, said the Community Resilience Hub program, which creates networks as well as physical places to protect people from extreme cold, heat and smoke also lost funding this session. He argued the hubs are effective because communities design them to meet their unique needs.
"Whether it be a place to plug in your phone or a place to go get diapers or get an air conditioner or whatever your community may need," Iboa outlined. "Depending on what's going on."
A heat pump program for rental housing, aimed at making energy-efficient heating and cooling more affordable, was also cut this session.
Brint added he realizes legislators have to make tough decisions about how to fund health care and housing but emphasized climate change is connected to those issues.
"When we're talking about heat pumps or the C-REP program, we're talking about people's health and livelihoods and saving lives in the face of climate fueled disaster," Brint stressed.
Brint added since climate change is not going away, the movement to push for climate resilience will not either.
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