VISIT JOHN VRIEZE’S EMERALD DAIRY in northwestern Wisconsin and you’ll be struck by what’s missing: It doesn’t stink. That ripe, rich aroma of rotting manure that so often wafts from the barns and lagoons of dairy operations is absent. On most days the air carries only a hint of silage or fermenting fodder. And Vrieze works hard to keep it that way. “If I’m having a beer on my deck at 10 o’clock at night,” says the 56-year-old farmer, whose family has been dairying for more than 100 years, “the last thing I want is to sit out and smell my manure. So why would I expect my neighbors to want to put up with that?”
That Vrieze can breathe in the fresh air around Emerald is no small feat. Cows are prodigious animals when it comes to poop, excreting between 85 and 120 pounds of the stuff every 24 hours. This works out to a good-sized German Shepherd of waste created by every cow, every day. So for a farm like Emerald-which houses 1,650 dairy cows-that means some 150,000 pounds of manure on any given afternoon. Seventy-five tons of dung. Fifty thousand gallons of waste. If it’s not fouling up the air, where is it all going?
The answer is that Vrieze’s manure is hard at work. It’s coursing underground through 36-inch PVC pipes, fractionating into useful components and nourishing a surprising list of living things. Through a combination of expensive technology and innovative design, Vrieze squeezes his cows’ patties for every last drop of utility. Instead of managing manure as a problem, he sees it as an opportunity.
“The goal is in two years to have as much net income off the back end of the farm as from the dairy,” says Vrieze, who also owns the nearby, 1,050-cow Baldwin Dairy.
Dairy farmers have long held a love-hate relationship with manure. On one hand, it’s full of carbon-rich fibers and nutrients, especially nitrogen, phosphorus and potassium, which act as natural fertilizers and help condition the soil for planting. On the other, manure smells awful and often contains viruses and bacteria such as E. coli that can pose serious threats to human health if ingested. In 2006, spinach tainted with manure-borne bacteria on a California farm killed three people and sickened more than 200.
Soils only accept a limited amount of manure’s nutrients before shedding them into runoff water, leading to algal blooms and other far-reaching environmental problems. Farmers can help prevent runoff by spreading manure over wider swaths of land, but that too has drawbacks. For one thing, it means owning (or renting) a hefty parcel of land. And manure is not the easiest substance to move around, either. At 75 to 92 percent water, it’s heavy and expensive to ship or store.
Farmers also have to pay attention to another part of manure they can’t see-the gases. A recent United Nations report says the livestock sector is currently responsible for a significant share of human-related greenhouse gases: 9 percent of carbon dioxide, more than 37 percent of methane and more than 65 percent of nitrous oxide. While many farmers have doubts about global climate change and their potential to affect it, most acknowledge that these data are likely to lead to new restrictions and regulations on emissions in the years to come, which is why Vrieze agreed to serve on Governor Jim Doyle’s Climate Change Task Force last year.
“I’ve been trying to tell my industry it doesn’t matter if you’re talking about believing global warming or don’t believe in global warming or whether you do or don’t think man has an impact on climate change,” says Vrieze. “I drive around my dairy almost every day thinking of another way we can reduce our carbon footprint because someday I think we’ll get regulated.”
Vrieze started revamping his farms’ manure management practices piece by piece in 1999, the same year Emerald Dairy was constructed. A member of the CALS Board of Visitors, he pulsed dairy and engineering experts for new ideas, but Doug Reinemann BS’80 MS’83, a professor of biological systems engineering, recalls that he was clearly ahead of the curve.
“John was sort of the catalyst of a group that got together from the UW, the (Wisconsin) Department of Ag and the Department of Natural Resources to look at this issue of greenhouse gas production and carbon sequestration on dairy farms,” says Reinemann. That group secured funding from Wisconsin’s Focus on Energy program to evaluate how dairy farms can play a larger role in the growing market for green agriculture. With Vrieze’s help, they are also trying to quantify how much carbon dairy farms might be able to trap and store-which may help pave the way for cow-powered carbon trading.
But it is Vrieze’s own operations that may offer the most intriguing model of where dairy in Wisconsin might be headed. The systems in place on his two dairies resemble something out of a Willy Wonka movie, combining off-the-shelf technology and improvisations of Vrieze’s own design. Together, they create an integrated loop that helps turn one of dairy’s biggest headaches into a surprisingly versatile player in its economic and environmental future.
It all starts in the barn. Three times a day tractors outfitted with rubber scrapers shovel mounds of manure through grates and into the gravity-driven pipes that whisk it all away. Then the magic begins. At Emerald Dairy, the pipes lead into a patented mix-plug-flow anaerobic digester, designed by GHD, Inc., which looks like a giant, underground shoe box. The manure spends three weeks inside the oxygen-free shell, slowly being decomposed by specialized bacteria that break down its carbohydrate structure and convert its sugars into gases. The ultimate prize is methane, which can be used as an on-farm power source or sold to power utilities. The process also kills off pathogenic bacteria, creating contaminant-free byproducts that can be used in other ways around the farm.
Currently, 22 anaerobic digesters operate in Wisconsin, and at least nine more are under construction. The net effect is to turn energy-consuming operations into energy producers. At the Crave Brothers Farm in Waterloo, Wis., for example, anaerobic digestion enables the 800-cow farm to produce 230 kilowatt hours of energy, enough to power the dairy, an on-farm cheese factory and 150 homes.
The downside is the cost. Digesters can easily run close to a million dollars to purchase and install-a price tag that puts them out of reach for many small- and mid-sized dairies. And selling energy isn’t all that profitable. Wisconsin farmers are helped by the state’s renewable energy portfolio standard, which requires investor utilities to get a specified amount of their power from cleaner sources and guarantees those green-energy suppliers a subsidized rate of eight cents per kilowatt hour. “It’s that eight cents that really makes it practical for people to do it,” says Reinemann. “It’s still not a money-making proposition, but at least it becomes possible to do it financially.”
Alternatively, farms can contract with third-party companies like Clear Horizons, an organic-waste management operation that owns the digestion equipment at the Crave farm. Clear Horizons footed the up-front costs and manages the maintenance of the facility in exchange for rights to sell the energy captured by the digester. “The farm gets what’s more of a soft benefit,” says Karl Crave BS’06, son of one of the Crave dairy’s co-owners and project manager at Clear Horizons. “Basically they get a system without paying for it, so they get their manure processed essentially for free. And they also get things that go along with it, like odor reduction, greenhouse gas reduction and better nutrient management with their manure.”
Because Vrieze’s utility doesn’t offer the green rate, he bypasses the grid altogether and converts his methane into compressed natural gas, which he sells to the Northern Natural Gas Company. Specialized trucks arrive twice a day to collect the gas and inject it directly into the pipeline. But he’s found additional benefits to digesters, as well. At his Baldwin dairy, he rigged the technology to suit the soon-to-be-built 27,000 square foot aquaponics system which will grow tilapia fish and leafy greens using water fed by leftover digester heat and nutrients.
And back at Emerald, he’s fashioned a bioreactor to take advantage of the excess heat there. The digester warms water that runs through a tall rack of tubes filled with two strains of algae. To help the algae grow, he adds some of the super-concentrated nutrients leftover from the digester. Under the fluorescent lights, the tubes glow an eerie green.
Vrieze is not sure what to do with his algae yet. Initially he planned to press it for oil to make the biodiesel that fuels several of his farm machines. Now he thinks the green stuff might have a higher-value use. He’s considered feeding it to his cows as an Omega 3-rich supplement or even incorporating it into dairy products as a nutraceutical. He says he needs more research to figure out the best application. Last fall he dropped an algae-filled bucket on the desk of CALS associate dean Ben Miller with a plea to find someone who could probe its potential.
“When I showed up,” Vrieze laughs, “I said, ‘Here it is. Now do something with it.'”
That pretty much sums up the challenge offered by manure: Here it is, and it’s here to stay. So what do we do with it? At the USDA Forest Products Laboratory, a fedeÏral facility housed on UW-Madison’s campus, that quest drives a team of researchers who are studying biosolids-the odorless, sawdust-like powder left over from the digestion process. One intriguing idea is to use this material, which is full of fiber that isn’t fully digested by microbes, to make fiberboard.
At FPL, Jerry Winandy has led efforts to experiment with recycled materials such as wood chips, sawdust, reclaimed cardboard and paper waste for years. Adding manure to that mix only makes sense, he says. “If our real goal is to develop a sustainable economy in the long run, the only way to do it is to use the whole myriad of biological materials that right now we use or we throw away or we don’t even think of using-all of them.”
In 2006, Winandy teamed up with Tim Zauche, a UW-Platteville chemistry professor with big dreams of developing value-added manure products, on a project to make composite boards using manure fibers. With a $30,000 grant from the Wisconsin Department of Agriculture, Trade and Consumer Protection, they built a bench made from manure fibers, which they took to last year’s World Dairy Expo. There were a few predictable jokes about its origins, but Zauche wasn’t fazed. “We have this solid-we have to do something with it,” he says.
Now manure-based composite boards may be closing in on commercial reality. John Hunt, an FPL research engineer with a specialty in recycled products, has refined the process for making the boards, molding them into a honeycomb-like structure similar to the inner core of I-beams. The resulting boards are one-fifth the weight of traditional composite boards but just as strong. And thanks to Hunt’s design tweaking, unlike regular boards, these composites require no additional resins such as formaldehyde, which could be a plus for some chemical-conscious consumers. A California company, ECOR-Noble Environmental Technologies, plans to market the boards later this year.
Despite what people may think, the boards don’t smell. The panels look and perform just like any other composite board, says Hunt. The fibers from manure are superheated twice during the processing of the boards, and by the time they’re ready for paneling, he says, they bear no resemblance to their bovine origins.
“Really, we’re not using manure. We’re using cellulosic material,” he says.
While it remains to be seen if consumers feel the same way, there are signs that the market for manure-based products is expanding. One company in Connecticut is selling biodegradable, manure-based flower pots, which are placed directly into the ground, where they feed nutrients to plants while they degrade. And the Elephant Conservation Center in northern Thailand is peddling products like paper, cards and fans made from the fibers of elephant dung to support the plight of pachyderms in the region.
And if consumers are ready to accept this “cellulosic material” in their bookshelves and note cards, what about their shopping bags and Pepsi bottles? That, too, could one day be possible, says Kerem Gungor, a researcher in CALS’ biological systems engineering department who is studying bioplastics, which are alternative forms of plastic made from organic material.
Currently, the most prevalent technique for making bioplastics involves using pure materials such as glucose, often from corn, as a substrate for microbes that produce PHA, a biodegradable polymer that has similar properties to petroleum-derived plastics like polypropelene and polyethylene. But corn is not the only organic material capable of harboring PHA-producing microbes. Manure can, too, but because so much of its fibers are comprised of tough, hard-to-digest lignin, it hasn’t really been considered a good alternative for producing PHA. But fresh off a research project centered on phosphorus removal-one of the chief problems associated with too much manure-Gungor felt motivated to give it a try. Although he’s a long way from any commercial application, Gungor thinks the idea of poo-based plastic is compelling enough to keep working at it.
So that takes care of the solids, but what about the water? As they turn manure into powder, anaerobic digesters suck out thousands of gallons of cocoa-colored, nutrient-filled liquid. To deal with this output, Vrieze once again turns to specialized technology-a customized wastewater treatment system that creates two separate liquid byproducts. The first is a nitrogen-rich fluid that Vrieze pumps onto 2,100 acres of cropland using a drag hose system-a contraption that resembles a hefty fire hose attached to claw-like cultivators. Using this, Vrieze injects the liquid six inches deep into his soil.
The other end product is clean water. That’s right, clean water from cow manure.
Using reverse osmosis and filtration, Vrieze’s equipment purifies water to the point that it’s essentially potable. (Vrieze claims it’s on par with distilled water sold in stores.) So far, Emerald is the only dairy in Wisconsin-and maybe in the country-to use this technology, says Liz Grinager, project manager of ISS, the company who built Vrieze’s system. Vrieze plans to discharge this reclaimed water onto his fields, where it will infiltrate the soil and flow to a constructed wetland that will provide drinking water for his cows. He’s undergone an extensive vetting process with both the Environmental Protection Agency and the state DNR and is awaiting final approval.
All told, it’s a far cry from the old days. Vrieze remembers when fertilizer was cheap and when farmers sometimes piled manure by the side of the road for the taking.
“It used to be, 20 years ago, my nutrient management plan was based on how cold it was,” he says. “If it was 20 degrees below zero, the manure got about 50 feet away from the barn and the spreader went out. If you were busy, it got to the first field behind the barn.”
The trouble with those methods is now pretty evident. The old conventional wisdom was that the land could serve as a phosphorus bank, building up a nutrient reserve as insurance for lean growing seasons. Farmers bought up phosphorus fertilizer and added supplements to their dairy cows’ diets, making their manure piles rich in the nutrient. We know now that it’s less like a bank and more like a curve of diminishing response. Once the optimal level of soil phosphorus is exceeded, it does little for the crops-and it becomes more likely to wash away with the rains.
Wisconsin’s soils run phosphorus-rich, which is why the state’s nutrient management plans are based on soil phosphorus instead of nitrogen. This means farmers have to first know the existing phosphorus levels in their soils and then take into account how much of that nutrient their crops will take up before they plan their applications.
But calculating the precise prescription of needed nutrients is a complex matter. Crops usually require nitrogen to phosphorus ratios of 6:1 to 8:1, but the ratio in manure is usually around 4:1 to 5:1. So it’s easy to heap too much phosphorus onto the land while trying to meet the crops’ needs for nitrogen.
That’s one reason alternative uses for manure make sense. But not everyone is sold on the idea. Many farmers are still leery of the costs. And many advocates of small-scale farming worry that systems like Vrieze’s encourage even larger confinement operations, both because of the large capital investments involved and the fact that dealing with manure now represents one of the largest barriers to increasing herd size.
Doug Reinemann expects that the technology won’t please everyone. “It depends on what shade of green you’re talking about when you talk to environmentalists,” he says. For people who think there should be no animal agriculture, wide adoption of anaerobic digesters might seem like a turn in the wrong direction. But if you accept that animal agriculture is a relatively fixed part of the portfolio, at least for now, Reinemann says, “then it comes down to a question of producing animal products in the most environmentally sensitive way that we can. And that’s exactly, in my view, what John’s looking at.”
But the ultimate irony is that Vrieze is no tree-hugging environmentalist. His interest in trapping greenhouse gases on his farm is driven largely by economics.
At a recent dairy conference, Vrieze spoke with an official from Wal-Mart-a retail chain known for its bottom-line thinking-about the company’s current efforts to encourage its dairy suppliers to reduce their carbon footprints. To Vrieze that speaks volumes about what mainstream consumers want.
“We started asking the question, ‘What do you, Mr. Wal-Mart, think the carbon footprint is on a gallon of milk?’ Well, it happens to be 10.4 pounds of carbon,” he says. “If I can say my carbon footprint is 3 (pounds), and if greenhouse gas emissions and global warming is really high on your list as a consumer, maybe you’ll choose to buy my milk instead of somebody else’s.”This article was posted in Agriculture, Features, Spring 2009 and tagged Bioenergy, Carbon sequestration, Dairy, Farming, Nutrient management.