How do we get biomass from the land while preserving—or even benefiting—its living communities? Whichever course we take, researchers at the CALS-led Great Lakes Bioenergy Research Center are determined to put all pros and cons on the table.
By Madeline Fisher
THE CHILDREN’S SONG URGES HER TO FLY AWAY HOME, but the ladybug—or ladybeetle, as she’s properly called—is anything but a homebody. After feasting all summer on soybean aphids and other crop pests, the beetles take off from farm fields in search of snug overwintering spots, often winding up in people’s houses. Around Madison, this usually means a journey of five miles or more, says CALS entomology professor Claudio Gratton. But the insects can also fly much farther. In the Southwest, for example, they congregate on mountaintops. “You’ll come upon a bush just dripping with ladybeetles, and you know they probably had to travel 30 miles to get there,” says Tim Meehan, a research scientist working with Gratton who earned his doctorate in
Those wandering ways got Gratton and Meehan wondering a few years back if the beetles’ lives were touched not just by the soybean fields where they fed, but by the wider world as well. They soon discovered that, indeed, “What the landscape looks like actually makes a big difference,” says Gratton. In experiments across the Midwest, ladybeetles devoured more aphids in fields nestled within a patchwork of woods and grassy pastures than in those surrounded by soybeans and corn as far as a bug’s eye could see.
Although the two still aren’t sure why this is, it led them to ponder another possibility that has big implications for the sustainability of our farmlands. If the chance variation that exists in some farming areas already gives ladybeetles a boost, what if farmlands were purposely designed for diversity? Would the insects dispatch even more aphids? Might they even become tiny tools of sustainability, allowing farmers to spray fewer chemicals?
It takes a lot of imagination to picture such a landscape today, with two-thirds of the Midwest’s cropland blanketed in corn and soybeans. But there is a force that could re-stitch the Corn Belt into a crazy quilt—the push toward ethanol and other types of bioenergy. True, the ethanol blended into gasoline today still comes exclusively from corn kernels. And few “dedicated” bioenergy crops, such as grasses, have been sown so far for making cellulosic ethanol from stalks and stems, or burning in power plants instead of coal.
But bioenergy crops will almost certainly grow widely one day. The goal of the U.S. Department of Energy (DOE) is to replace 30 percent of gasoline and other U.S. transportation fuels with biofuels by 2030. And that, CALS scientists say, offers a chance to reshape our farmlands in an unprecedented way, so they yield not only food and fuel, but also things like ladybeetles and the benefits they provide.
In scientific parlance those benefits are called “ecosystem services”—natural processes we rely on but don’t usually pay for, Meehan says. Pest control by ladybeetles is one service; pollination by native bees, water cleansing, soil formation and even aesthetic beauty are others. Today’s simplified agricultural landscapes excel at producing corn, cotton and other vital commodities in massive amounts, but these may come at the price of water quality, erosion, loss of bird and insect habitat and increased pesticide use, as another study by Meehan and Gratton recently found. The question now is whether switchgrass, willow and other biofuel crops could cut those costs by sowing some plant diversity back into the system.
“The focus now is land use, not just food or fuel or a new crop. How do we use land sustainably?” says Chris Kucharik, a CALS professor of agronomy and environmental studies. “It just so happens that fuel has ignited the debate over sustainable land use right now.”
At the same time, strong forces are working to maintain the status quo. Skyrocketing commodity prices and rising demand for ethanol have led many farmers to put as much land in corn as possible. This year, 92.3 million acres were planted, according to the U.S. Department of Agriculture, four million above last year’s total and the second highest amount since World War II.