High Stakes Operations
"Farmers are the biggest gamblers in the world," my dad, once a farmer, used to say. So many forces come into play—the weather, the marketplace, the government’s policies, and the land itself—as farmers make their best bets on how to turn a profit this year.
Ultimately, farmers bet their living on the land. More than most of us, they can see the link between economy and environment every day. In this issue Brian DeVore’s story, "Manure Matters," takes up livestock farmers’ number one environmental issue—manure.
Manure, like any asset, requires management. The best management practices, DeVore explains, balance the number of farm animals with the land’s capacity to recycle nutrient-rich manure. With bigger and bigger farms, the balance becomes harder to maintain; and manure can turn into a liability, polluting air and water.
So what’s a farmer to do? DeVore reports on large and small alternatives to today’s conventional livestock operations. Ingenious and imaginative, these new approaches to using manure should be heartening to any conservationist.
In fact, some innovations have precedents elsewhere. For instance, DeVore notes a Minnesota dairy farm that began operating a manure digester in 1999. Starting with liquid manure, the 400,000-gallon digester uses bacteria to produce methane, which goes into a generator that converts it to electricity which powers the entire operation and then some. The end product is a nearly odorless, liquid fertilizer. Several hundred farms in Europe run similar digesters. For decades perhaps a million small digesters have been operating in China and India.
If manure can be treated as a commodity, so can other natural resources. Likewise, natural processes can be viewed as valuable services, as the city of Rochester, Minn., discovered.
In the 1950s, wells in the Rochester area stopped drawing water from the upper aquifer because of nitrate and bacterial pollution from agriculture. Instead, the farms, homes, and businesses tapped into lower aquifers. A 40-foot-thick layer of shale separated the upper and lower aquifers. Nearly impervious, the shale bedrock apparently kept pollution from leaching into groundwater below.
In the late 1980s, scientists found otherwise: Groundwater from the polluted upper aquifer actually was spilling over the shale edges and flowing downhill into the lower aquifers. About half of Rochester’s drinking water was being replenished in this way. Worried city and county managers launched a large research project to uncover pollution of wells in the city, suburbs, and surrounding farmland. After two years of testing, they had found few problems. How had the lower aquifers escaped contamination?
Nearly a decade later, researchers have learned that "cleaning services" are being routinely provided by a natural filtration system—wooded hills surrounding the city. As water spills over the shale and runs down the hillsides, soils and vegetation filter out contaminants before they reach the lower aquifers. A University of Minnesota study calculated an annual cost of $5 million to mechanically filter nitrate from this water supply. The natural buffer zone serves as a low-cost alternative.
But the story doesn’t end here. The hills, once deemed too steep and wet to develop, are facing the same growing pressure as the rest of the valley. Now, managers are trying to quickly figure out how to guide development and to protect this natural system that supplies clean water. With Legislative Commission on Minnesota Resources funding, they initiated a project to inventory groundwater management areas and create models of how land-use changes might impact water resources.
The consequences of land-use changes are complex. Models are examining, for instance, what happens when houses replace farms. One might suppose fewer nitrates would flow into the aquifer. But that will depend on housing density and how much fertilizer homeowners use.
Nearby cities with similar geology also rely on groundwater and have a keen interest in what Rochester’s research shows. In reality, we all have a big stake in understanding the interplay of natural processes and human activity.
Kathleen Weflen, editor