Of Cows and Climate

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.

Coping with the Climate

It’s late May, weeks before southern Wisconsin would be locked into a scorching drought, and Kirk Leach BS’78 is worrying about the weather. The grass around his house is already brittle and yellow. A hose snakes across the driveway, trickling moisture over some sad and thirsty new aspens.

But it’s the corn planted just on the other side of his kitchen garden that troubles him. There are patches—hand-high daggers of green—but there is not enough height, not enough uniformity and just plain not enough of it coming up. “This is the last corn I planted, two weeks ago tomorrow,“ he says. “You’d expect a little more growth than that.” He squats above an empty row, probing through three inches of crumbling earth until he unearths a seed, hard and polished as if just spilled from the bag.

Every farmer has an opinion about the weather. Leach remembers when he was young and everything germinated, even seed just thrown on the ground. But in Leach’s mind it’s these little mini droughts—two or three weeks in a row without rain—that have his attention. “Whether that’s significant enough or evidence of climate change I don’t know,” he muses. “Is it because I was a young, carefree 20-year-old like my sons that I didn’t think about it? Whereas now all the responsibility is mine, and so I’m worrying about every time the next rain is going to come?”

That’s the kind of conundrum that climate change presents to Wisconsin farmers as they’re forced to adapt to wild swings in the weather. Some trust the science, but many have questions, too. They’re all practical scientists with their own, very personal sets of data and research concerns.

The reality is that they’re already adapting to climate change, just as they’ve adjusted to so many other challenges. They’re planting earlier. Schedules for vegetable canneries and cranberry harvest have shifted later to reflect consistently warmer autumns. Even the USDA plant hardiness zone map was updated this year, showing Wisconsin a half-zone warmer than in 1990.

But the forecast calls for a whole lot more, in the way of both opportunity and challenges. The simplest take is that slowly warming temperatures may help boost agricultural production by extending the growing season. But higher temperatures could also reduce corn and soy yields and lead to more pest problems. Higher annual rainfall and more intense storms could mean more soil erosion.

Those broad-brush projections are statistical abstractions for any given farmer. Wherever the weather compass spins, the challenge is to craft a livelihood from sunshine, dirt and water.

The silver lining: a generation of stress in the farm economy has left a population of survivors, farmers who are hungry for information and who are lean and agile enough to act on it. If you have the skill and luck to bring a harvest to market, prices have been good. But with input costs soaring ever higher, extreme climate events can make farming seem more like placing a bet than following a business plan.

The growing season in Wisconsin has lengthened by two to three weeks over the last half-century—a big change over a short time. But because spring can be cold and late one year and early the next, some people tend to chalk it up to variability.

Agronomy professor Chris Kucharik BS’92, PhD’97 has no doubt that it’s climate change. Simply put, the earth is like a giant car, and increasing the amount of carbon dioxide is like rolling up the car windows on a sunny day. But under the hood is a series of massive mathematical models that attempt to mimic and forecast such fundamental earth forces as wind, temperature, evaporation and photosynthesis.

Early in his career Kucharik spent a few years in the far northern boreal forests of Canada helping to fine-tune these climate models. When he grew dissatisfied with the abstraction, he decided to try something closer to home: fit agriculture into the models. Honing in on local, Midwestern problems, he became one of the state’s foremost experts on climate and agriculture, with a joint appointment in the CALS agronomy department and the Nelson Institute for Environmental Studies.

Kucharik knows better than most how dense the science can get, but he is adamant that evidence for climate change is clear and overwhelming. In fact, he can even show how it’s helped agricultural productivity in some locations in Wisconsin over the last few decades. It’s not easy to tease out, because crop genetics and management practices have significantly improved over the same period. But trends in precipitation and temperature during the growing season from 1976 to 2006 explain more than a third of the variability in corn and soybean yield trends, he says.

The bad news is that this productivity trend might be hurt by continued warming without adaptive measures. Indeed, for each additional Celsius degree of future warming, corn and soybean yields could potentially decrease. With luck, modest increases in summer precipitation could offset this. Unless, of course, it fails to rain at all.