Experiment in action: out at the U.S. Dairy Forage Research Center farm, researchers apply manure from cows that were fed three different diets over a three-month period. The manure will be tilled in and greenhouse gases measured every few hours for the first three days. The field will then be planted in corn for silage, and greenhouse gas measurements will be taken every week or two throughout the growing season Here, researchers take soil samples after manure application. Photos by Sevie Kenyon BS'80 MS'06

On a subzero February day, Mark Powell stops his vehicle on the road a few miles outside Prairie du Sac. He’s been explaining that cows actually enjoy the polar weather—and as if to prove it, a frisky group in the barnyard across the road turns toward us and rushes the fence.

As a USDA soil scientist and CALS professor of soil science, Powell is focused on the ground beneath their hooves. A few years ago he led a survey of manure handling on Wisconsin dairy farms. He and his colleagues knew how much cows left behind—about 17 gallons a day—but had only educated guesses about the ultimate environmental impact of barnyard design. In open yards like this, says Powell, they found that 40 to 60 percent of the manure ends up uncollected. “It just stays there,” he says. In the decade since his survey, the manure challenge has only grown, both in Wisconsin and nationwide. Water quality has been the major concern, but air quality and climate change are gaining.

A few minutes later we turn into the 2,006-acre U.S. Dairy Forage Research Center farm, and the talking points all turn to plumbing. There’s an experimental field fitted to track how well nutrients from manure bond to the soil. Parallel to one barn are nine small yards with different surfaces, each monitored to measure gasses emitted and what washes out with the rainwater.

The manure pit is frozen over, but circumnavigating the complex—shared by CALS and the U.S. Department of Agriculture—we arrive at the southern terminus of the barns. Uncharacteristic ventilation ducts adorn the walls and roofline. Inside are four unique stalls that can contain up to four cows each. The manure trough is lined with trays so that each cow’s waste can be set aside for further experiments. When the cows return from the milking parlor, airtight curtains will drop, isolating each chamber.

And in a nearby room, sensors sample the air leaving each stall, recording the release of moisture, carbon dioxide, ammonia, nitrous oxide and methane. This data is at the heart of a $10 million, five-year USDA grant to examine climate change and dairying in the Great Lakes region.

In 2009, the dairy industry became the first major segment in the U.S. economy to volunteer a significant cut in its greenhouse gas production, vowing to eliminate 25 percent by 2020. Now in its second year, the project brings together industry, four USDA labs, dozens of researchers from eight universities, and even Milwaukee’s Vincent High School. Funded through the USDA’s Coordinated Agricultural Projects program, the working nickname is Dairy CAP—pronounced as if it were one word.

To hit that target requires a deliberate look ahead. “What is the climate going to look like in the future?” asks Matt Ruark, a CALS/UW-Extension professor of soil science and leader of the Dairy CAP endeavor. “What is the dairy industry going to look like 10, 20, 50 years from now? And are those two in conflict with each other?”

Sustainable dairying is the ultimate goal, and Molly Jahn, a CALS professor of genetics and agronomy, gives the dairy industry high marks for targeting greenhouse gases. “One thing we know, if you look back over the last 50 years, is that the conditions under which we are dairying are becoming more extreme,” explains Jahn, a co-leader on the grant. “Dairying has many benefits to landscapes. As the industry continues to grow, we want to continue to innovate with respect to productivity and quality—and in harmony with our natural resource base.”

Dairy CAP will provide not only academic results, but also tools and management practices. “We intend to provide dairy farmers with the resources to make sure they are managing their operations for maximum short-term benefit and for long-term success and resilience,” Jahn says.

Living in Wisconsin, you can’t help but absorb a few things about dairy, beyond the calcium. You likely know that Wisconsin is America’s historic creamery. You also probably know that dairy farms are getting bigger, while other states are challenging Wisconsin’s historic primacy. And chances are you also have your own opinions about the advisability of wearing a large wedge of dimpled yellow foam on your head.

Soil science professor Mark Powell (right) and research associate Matias Aguerre pose with cows inside a research barn equipped to measure methane released from both ends of the cow.

But did you know that cows belch, and it’s a problem? Cows are ruminants, which means they regurgitate and re-chew their food. Combined with microbial action in multiple stomachs, they can break down fiber to get more nutrition out of plants. But these microbes also create methane, the primary component of natural gas.

In the last decade scientists have become increasingly concerned because methane has more than 20 times the global warming impact of carbon dioxide. New research suggests that livestock sources of methane have been undercounted by as much as half. Overall, agriculture creates 36 percent of human-related methane emissions, followed by natural gas systems (23 percent) and landfills (18 percent), according to a report, “Climate Action Plan: Strategy to Reduce Methane Emissions,” released by the White House in March.

Methane isn’t the only challenge. Another gas, nitrous oxide, is generated by nitrogen reactions in the soil and by the breakdown of manure. There is less of it, but nitrous oxide has 314 times the warming impact of carbon dioxide.

When this issue first surfaced around

A process made possible by encasing cows behind curtains that will lower to become airtight.

the turn of the century, the dairy industry was perplexed. Ruminants have been chewing their cud for millions of years, so wouldn’t their impact already have been rolled into natural systems? But as human population has grown, so has the cultivation of animals to feed them. Examining the initial evidence, rough calculations and trends, the dairy industry had to acknowledge that methane and nitrous oxide from agriculture was a real, if poorly quantified, threat.

The industry responded by taking environmental stock. They surveyed 540 farms across the country, scores of processors, and 20 percent of the milk transportation system. Overall, dairy was responsible for 2 percent of total U.S. greenhouse gas emissions. It wasn’t a massive number, but then that’s the challenge of greenhouse gases: because practically every human activity contributes to the problem, solutions need to be found everywhere.

Just taking stock led to some easy reductions. For example, if you design milk truck routes so that they are always turning right, you’ll avoid having those vehicles idling while they wait for traffic to clear. That kind of common sense can be easily implemented.

Methane and nitrous oxide are more intractable. Because this pollution is invisible, poorly understood and hard to measure, the first step is determining how much—and exactly where—it is being produced. Fortunately, the challenge ties deeply into husbandry. Ever since our ancestors milked the first cow, we’ve been tirelessly working to improve the yield. In part, that’s what helped establish Wisconsin as a dairy state: Our climatic sweet spot gave farmers an edge.

Modern dairying has taken productivity much further, drawing upon everything from nutritional advances and facility design to genetics. Most recently, dairies are shifting to thrice-daily milking to maximize production. Add up all of this tweaking, and you’ll find the carbon footprint of a gallon of milk has dropped 64 percent since 1946.

“That’s how we got to this 25 percent goal” for reducing greenhouse gas, says Erin Fitzgerald, the senior vice president for sustainability at the Innovation Center for U.S. Dairy in Chicago. “Sometimes where you’ve been is also an indicator of where you can go.”

From a business angle, there are about 20 major variables that dairy producers follow—everything from energy consumption and manure management to forage formulas and managing herds. These shape the bottom line, but many of them, particularly energy use, also drive greenhouse gas production.

But with so many variables, the problem was too big. “Sustainability is super complicated. If every single producer had to do its own carbon footprint, nobody would have done it,” Fitzgerald explains. Dairy CAP will distill that information for producers. “You’re working in an industry where there is an incredible ethos to do the right thing. If you can put that information in the right hands, what would they do?”

Marty Matlock’s job is to help read the climate crystal ball. A professor of biological and agricultural engineering at the University of Arkansas who’s also conducting research for Dairy CAP, he’s been thinking about agriculture and climate change since he heard NASA’s Sally Ride speak about it in 1996.

A lot of ink has been spilled since then, but the overall picture has not changed. “The evidence is clear that we are seeing more frequent and intense extremes,” Matlock explains. “Dryer dries, hotter hots, wetter wets, colder colds.”

Never mind the politics, farmers understand that they’ve never seen weather quite like this. “You have to be able to understand and manage for weather extremes, and be able to explain to your kids how to understand and manage for weather extremes,” he says. “And we have to be able to anticipate 20, 30, 50 years from now what our challenges in production are going to be.”

Drought and flooding have broadly affected feed price and availability in the last few years. The good news is, under every scenario available from climate modelers, the corn belt will be warmer and wetter, with a net increase in productivity. “What I can tell you is you’ll probably be planting your soybeans earlier and earlier,” says Matlock.

Researchers spread different types of manure on color-coded field testing sites (note the flags of different colors).

The bad news is increased intensity and frequency of extreme weather. “We under-predicted how fast change would occur. There was an assumption that the system was more buffered than it is. That’s frightening, because that means the rate of change is going to increase,” Matlock warns. “That translates to increased risks for the producer.”

Dairy CAP should help reduce dairy’s contribution to climate change, but Matlock says it will also help dairy farmers adapt. “This is not casting blame, this is improving efficiency. This is improving resiliency of dairy production,” he argues. “And our ultimate goal is to give farmers and policy makers the tools to make better policy, to make our dairy producers more profitable, so that we have a viable, profitable dairy industry in 50 years.”

Ignore climate change and we will undermine our dairy capacity, a process that may have already begun. “The risk of status quo is chaos, and chaos is bad for an industry that really is generational,” he says. It takes a decade or more to build a good herd, and the recent drought and high price of forage have already forced herd reduction. “That means we’re losing capacity, we’re losing resiliency. It could take a decade to build those herd genetics back up,” says Matlock.

“How can I prepare my farm? How can I stay in business given what’s likely to be unfolding in the climate?” By now, the wise dairy producer may be asking these questions—and not finding clear answers.

“Dairy production systems in 10 years, and certainly in 20 years, are going to look different than they do now because the climate is going to be different,” says Douglas Reinemann, a CALS/UW-Extension professor and chair of biological systems engineering.

This operational challenge is also an intellectual puzzle. Dairy CAP is tackling it through a detailed life cycle analysis—an accounting method that tries to account for the environmental impact of every input, process and emission, from producing the fertilizer to growing the crops to milking the cows and converting it to cheese.

The cow itself is part of the model, after cropping and before manure management. Each piece is connected—how we feed a cow influences the nutrients in the manure, and manure application affects the next generation of crops. “And of course, milk production is central to the whole thing,” Reinemann says.

Model building is a back-and-forth process: field scientists provide initial measurements and modelers build equations to explain the data. Equations that attempt to model reality are rarely perfect, but as the field scientists and the modelers pass information and questions back and forth, the models get better.

That’s where Dairy CAP picks up the torch. Agricultural scientists have been working with local models for decades. Problems develop when you calibrate a model for Wisconsin and then take it to Nebraska. Dairy CAP involves a massive validation effort that will refine and adapt it to different parts of the country.

Farmers need to know how they can adapt, what changes they may need to make to their infrastructure and how, ultimately, climate change might affect crop and milk production. “What are the choices we have to create our future?” asks Reinemann. “We’ll be able to give them much better advice than we can now.”

Manure is probably dairy’s single best opportunity for significant greenhouse gas reduction. When the industry made its reduction pledge, it had its eye on anaerobic digesters to harvest the manure methane, or biogas. It’s a double bonus, capturing methane that would otherwise enter the atmosphere, but also turning it into energy, preventing further emissions from burning coal or natural gas.

Researchers prepare manure for field application collected from cows fed different diets.

“It’s one of the largest tools we have to really limit emissions,” says Rebecca Larson, a CALS/UW-Extension biological systems engineering professor and bio-waste specialist who is leading the Dairy CAP manure team.

A visit to the Dane Community Digester in Waunakee, operated by Clear Horizons LLC, reveals this potential future. Tucked between three dairies in rolling landscape north of Madison, it operates at industrial scale. One steel tank accepts 100,000 gallons of liquid manure pumped daily from nearby farms. Waste from animal bedding goes into what the operator calls the “jacuzzi,” a massive liquefying tank, churning and steaming in the cold. A smaller tank stores food waste delivered by local food processors.All three waste types are mixed together and pumped into one of three 1.25 million-gallon digestion tanks where bacteria do the real work. The methane bubbles up, feeding two generators, each the size of a mobile home. At full capacity, the plant produces two megawatts of power, enough to power about 2,400 homes.

There’s more. Each day about one semi-load of spent fiber is filtered from the tanks and sold for use as livestock bedding or soil amendments. Liquid waste is returned to the farmers, who can then use it to fertilize their fields. This facility is also an emergency option for farmers. A local farmer whose retention pond was failing, for example, off-loaded 100,000 gallons in one weekend, averting disaster. And the operation is testing increasing phosphorus removal to help with local water-quality problems.

The whole thing may sound like science fiction, but—for the sake of comparison—Germany has more than 6,000 units like this installed, providing power for more than 4.3 million homes. The U.S. has just over 200 operating farm scale digesters, most installed in cooperation with the dairy industry. That should change as part of the new methane initiative announced by President Obama in March. This summer a partnership of USDA, EPA, the Department of Energy, and dairy will release a biogas roadmap, outlining strategies to increase adoption of digester technology and a range of other improvements.

Dairy CAP research will help guide this work, though for now, admits Larson, “It is a data-gathering nightmare.” Analyzing manure means knowing where the feed comes from, the inputs into the feed, where and how the manure is processed and land applied, and even how much energy one particular manure pump uses. “You have to understand all the inputs and outputs to the entire dairy system in order to assess impacts and make informed recommendations,” she says.

But such detail yields more precise ideas about how to reduce emissions by helping target areas with the greatest potential. Larson is already working on digester additives that might increase gas production and decrease the levels of corrosive sulphur.
Feeding electricity back into the grid is a big financial obstacle, but new technologies may cut that step altogether. For example, biogas can be cleaned and compressed for use as vehicle fuel. Biogas can also be used to make plastic; one company is exploring a system to manufacture plastic from digester methane.

BSE professor Rebecca Larson uses FTIR spectrometry (in wagon) to measure greenhouse gases being emitted inside the chamber (silver-covered apparatus on the ground). These measurements, along with soil samples, will be taken regularly throughout the growing season.

Larson calculates that if digesters processed waste from half of the 1.26 million dairy cows in Wisconsin, it would yield a 6 percent reduction in greenhouse gas from the agricultural sector. Other less capital-intensive processes could yield further reductions when combined with digestion.

“Although sometimes the numbers seem low, this is one piece of many that contribute to greenhouse gas emissions,” Larson says. “It will be critical as we move forward that we take advantages in all sectors to reduce our overall emissions.”

Working alongside climate scientists has opened her eyes to how critical it is to address climate change now—and how behind we really are. “Changes are coming,” she says. “We are on the verge of realizing significant impacts from climate change, if not past it.”

Back outside of the methane monitoring stalls at the U.S. Dairy Forage Research Center farm, Mark Powell is reviewing some of the many scientific questions moving forward.

Soil scientists, animal nutritionists and modelers are all looking ahead to the coming spring, planning experiments and anticipating equipment upgrades. Meanwhile, the manure of the future may be aging quietly in a row of blue barrels outside.

Dairy cows can’t be accused of leading very interesting lives, but this particular group has a new flavor note in their silage: dried tannins harvested from trees native to Argentina. And everyone is curious to know how this tannin-treated manure affects the nitrogen cycle.

Nitrogen in the soil, whether from manure or synthetic fertilizer or produced by microbes, has to go in one of three directions. The farmer wants it to be taken up by the plants, but when that doesn’t happen the nitrates either leach into the water or transform into nitrogen and nitrous oxide in the atmosphere.

Plants use the nitrogen to build protein, which the cows then transform into muscle and milk. Over the last 10 years, we’ve learned a lot about how feed affects milk production. Based on this research, feed mixtures in Wisconsin and beyond have cut crude protein from 18 or 19 percent down to 15.5 or 16 percent protein, lowering costs.

Measuring the efficiency of protein use allows farmers to finely tune feed mixtures and reduce the amount of nitrogen in the manure. “If we get farmers to reduce the crude protein in the diet, we can reduce on a statewide average ammonia emissions by 30 percent and nitrous oxide emissions by 8 percent,” explains Powell. The tannins may further bind up the nitrogen, yielding even greater reductions, but those experiments are just starting.

Other research will assess how dietary changes affect milk production, the manure in the digester and soil resiliency. How does long-term management and crop rotation affect soil properties such as water retention and carbon storage? It was all complicated enough before adding greenhouse gases to the equation.

“We only control a handful of variables in any one study,” explains Ruark. His specialty is nitrogen cycling, but he’s spent much of the last year learning to speak the many different languages of this transdisciplinary project.

“I was trying to get engineers to talk to dairy nutritionists, and getting physicists to talk to education specialists, getting these diverse people in the same room. We don’t necessarily understand each other completely, but we’re moving forward,” Ruark says happily. “Breaking down the silos, having that direct interaction. It’s a unique experience for everybody involved.”

Dairy CAP director and soil science professor Matt Ruark at the Arlington Agricultural Research Station, where some of the project’s soil measurement work takes place.

Dairy, as noted, accounts for only 2 percent of total U.S. greenhouse gas emissions, and it’s clear that getting reductions will be a challenge. It’s easy to look at that math and get discouraged. Therein lies the ultimate challenge of climate change.

“We know that developing modern solutions to a changing climate requires a doubling down on collaboration—between farmers, governments, researchers and industry,” Secretary of Agriculture Tom Vilsack said last year, soon after announcing the Dairy CAP grant. “We have got to think outside the box, work together and pool our resources to begin developing the next generation of climate solutions for agriculture. This is not a single, one-size-fits-all problem. We need a targeted approach geared to the particular challenge faced by each region.”

Over at the Innovation Center for U.S. Dairy, Erin Fitzgerald is upbeat about the challenge. “I really come at it from a business perspective. I’ll talk a lot about adaptation, preparedness, risk mitigation, long-range planning, looking for efficiencies,” she says. “I haven’t found a farmer who doesn’t understand it at a more granular definition.”

And if there is an underlying strength to Dairy CAP, it’s the buy-in from the dairy industry—its realization that not only was climate change a threat to business, it also was part of the problem, and thus part of the solution.

“If we can get the information in the hands of the people who are using it, we think that is what’s going to drive incremental improvement,” says Fitzgerald. “Stewardship, to me, is a value, it’s something that we aspire to. Sustainability is about making it work in your business model.”

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