Madeline HeimMilwaukee Journal Sentinel
Solar panels, carbon storage and alternative fuel sources are all key elements of the U.S. transition to cleaner forms of energy, reducing the country's reliance on climate change-causing fossil fuels. But space for them seems to come at a premium.
Transforming productive farmland for renewable energy projects has caused tension in some communities, as has pursuing such projects on lands valued for their natural resources.
Now, research out of UW-Madison offers a potential middle ground.
A team of scientists from the UW-led Great Lakes Bioenergy Research Center mapped millions of acres of abandoned farmland across the U.S. over several decades in a study published in the journal Environmental Research Letters. Knowing where this abandoned land is could help people evaluate it for different uses, including climate solutions, the team theorized.
"These areas, for one reason or another, aren't cultivated anymore, so they're not prime agricultural lands," said Tyler Lark, a scientist at UW-Madison's Center for Sustainability and the Global Environment and an author of the study. "We also know they're not pristine native ecosystems, because they've been plowed up. That can make them really attractive locations for a lot of different applications around energy development."
Here's what to know about the recent study's findings.
It's the most detailed map of abandoned farmland
There have been previous efforts to map the country's abandoned cropland by county or region, Lark said, but none that have been able to pinpoint it in such fine detail.
Technological advances allowed the team to go through a large amount of satellite images of U.S. cropland between 1986 and 2018, identifying down to the acre which lands were no longer in production. That approach also allowed them to say with relative certainty when the lands had been taken out of production, Lark said.
More: Wisconsin lost 10% of farms, 30% of dairies in 5 years, U.S. agriculture census shows
About half of the abandoned farmland changed to grassland and pasture, about 19% to shrubland and forest, about 8% to wetlands and about 5% to non-vegetated lands, the study found. The researchers excluded urbanization of former cropland because those lands are unlikely to be returned to their pre-developed state.
The data is publicly available, and Lark said he hopes it will be helpful to municipalities that are evaluating land use and to researchers looking into other questions about renewable energy.
Great Plains, lower Mississippi River valley had the most abandoned cropland
The areas with the most abandoned farmland include the Great Plains over the troubled Ogallala Aquifer and the lower Mississippi River valley, as well as the Atlantic Coast, North Dakota, northern Montana, and eastern Washington state.
Lark said he isn't sure yet what made these regions most susceptible to farmland loss, but suspects that declining water availability could have played a role across the Great Plains.
The Mississippi River has lost many of its floodplain forests, Lark noted, and the abandoned lands along it could be sites for restoring them.
More: What to know about floodplain forests, a struggling ecosystem on the Mississippi River
Most abandoned lands weren't part of protective conservation programs
Some farmers and landowners choose to take cropland out of production and enroll it in federal programs that pay them to let it rest, such as the Conservation Reserve Program through the U.S. Department of Agriculture. The program is meant to improve the health of environmentally sensitive lands and increase wildlife habitat, meaning those lands can't be disturbed by renewable energy projects.
Because previous estimates of abandoned cropland were more general, it couldn't be determined how much of it was enrolled in programs like that, Lark said.
More: Federal conservation programs help farmers, but funding is so tight that 'frustration and anger is pretty real'
This more detailed analysis found that less than 20% of the abandoned cropland was enrolled in the Conservation Reserve Program, leaving the rest open to other uses.
"The assumption was, a lot of abandoned land was in a formal conservation program," Lark said. "What this means is perhaps there's more land available that fits the characteristics of abandoned production than we previously thought."
Future research will explore why these lands were abandoned
This study focused just on mapping abandoned farmland, not figuring out why the land was abandoned. That will be the subject of future research, Lark said.
Most of the land is privately owned, and figuring out why its owners ceased production will help inform what it might be used for.
More: Interested in purchasing solar panels? Nonprofit group offers education, group buy options
For example, if a farmer abandoned a few fields that weren't performing well but maintained the rest of the farm, that could mean the land is in good shape to grow sustainable crops for biofuels, Lark said. Leasing land for a solar or wind project can also be an economic boon for farmers struggling with tight profit margins. On the other hand, if the farm was abandoned completely, the land might be more suitable for a natural habitat restoration project.
The study isn't 'an endorsem*nt of recultivating,' author says
Because of the tensions that can spring up when claiming land for energy production, these abandoned lands could provide a "sweet spot," Lark said.
Solar panels don't have to stand alone on farmland. "Agrivoltaics" projects, where active farming and solar happen in the same place instead of separately, offer a dual-use approach.
More: Can solar power and farming coexist? This partnership between UW, Alliant aims to find a way
Bioenergy crops are another use of farmland that can reduce dependence on fossil fuels, but right now, the U.S. mainly grows them in the form of corn for ethanol, Lark said. Corn requires large amounts of fertilizer to grow and some farmers who grow it leave the soil bare after harvesting, risking soil loss and nutrient runoff. There's growing interest in using different bioenergy crops like switchgrass, Lark said, a perennial grass that could store more carbon in its roots while also being harvested for energy.
But he said the study shouldn't be interpreted as "an endorsem*nt of recultivating" the land.
It's instead meant to help answer questions about the characteristics of the land, namely where it's located, so that others can make more informed decisions about what to do with it.
"The goal of the study is not to identify all this land so someone can go out and plow it all back up," Lark said. "At the same time ... we know we need to grow food, produce energy — we just want to make sure we use our landscapes in the best manner possible."
Madeline Heim is aReport for Americacorps reporter who writes about environmental issues in the Mississippi River watershed and across Wisconsin. Contact her at (920) 996-7266 ormheim@gannett.com.
