Tens of Millions of Acres of Cropland Lie Abandoned, Study Shows

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June 11, 2024

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by Erin Blakemore (Washington Post) The biggest changes took place around the Ogallala Aquifer, whose groundwater irrigates parts of numerous states, including Colorado, Texas and Wyoming. -- About 30 million acres of U.S. cropland have been abandoned since the 1980s, a new analysis suggests. The study, published in Environmental Research Letters, offers a detailed look at land with immense environmental and economic potential — land that, researchers write, was abandoned at a rate of over a million acres a year between 1986 and 2018.

The analysis used satellite data and cropland information from the U.S. Agriculture Department to map the locations of abandoned cropland and how long it had been out of use. The researchers conclude that during the study period about 12.3 million hectares — or 30.39 million acres — of cropland went unused in the contiguous United States.

The biggest changes took place around the Ogallala Aquifer, whose groundwater irrigates parts of Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas and Wyoming, and which has been drying out because of excessive pumping and droughts. Other abandonment hot spots were located around Mississippi, the Atlantic Coast, North Dakota, northern Montana and eastern Washington state.

The fate of the former cropland varied. About half (53 percent) changed to grassland and pasture, while 18.6 percent became shrub land and forest. Other abandoned cropland became wetlands (8.4 percent) and non-vegetated lands (4.6 percent), while some of the rest was recultivated or could not be classified. The land was abandoned at an average of 0.51 million hectares — 1.26 million acres — a year.

The study did not focus on the reasons farmers stopped using the cropland. But the researchers reported that less than 20 percent of the abandoned land was enrolled in the USDA Conservation Reserve Program, which pays farmers to take out of agricultural production environmentally sensitive land that’s at risk of soil erosion, habitat loss or reductions in water quality.

That surprised researchers. “A lot of the assumptions were that this former cropland had a lot of overlap with formal conservation programs,” Tyler Lark, an assistant scientist at the University of Wisconsin-Madison’s Center for Sustainability and the Global Environment who co-authored the study, said in a news release. “But we saw that they’re almost entirely distinct pools.” READ MORE

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Abandoned farmlands could play a role in fighting climate change. A new study shows exactly where they are. (University of Wisconsin-Madison)
Cropland abandonment between 1986 and 2018 across the United States: spatiotemporal patterns and current land uses (IOP Science Environmental Research Letters)
Changing Their Minds on “Land Use Change”? (Renewable Fuels Association)

Excerpt from University of Wisconsin-Madison: Farmland is often a battleground in the fight against climate change.

Solar panels and energy crops are pitted against food production, while well-intended policy choices can create incentives for farmers to till up new lands, releasing even more heat-trapping gas into the atmosphere.

That’s why strategies for sustainable plant-based fuels focus on marginal lands — fields that are too hard to cultivate or don’t produce good enough yields to be considered profitable.

A new tool developed by scientists at the University of Wisconsin–Madison could help relieve that tension.

Led by Yanhua Xie and Tyler Lark, researchers with the Great Lakes Bioenergy Research Center, the team used machine learning to map nearly 30 million acres of United States cropland abandoned since the 1980s, creating a tool that could guide decisions about how to balance production of energy and food.

Their findings, published in the journal Environmental Research Letters, include the most detailed mapping of previously cultivated land in the U.S. to date. They provide field-level resolution of abandoned farmland that could be used to grow crops like switchgrass or sorghum, which can trap carbon in the soil and serve as feedstocks for biofuels and replacements for petrochemicals.

“If we can understand where these lands are and what the characteristics are, we can really understand their true potential for things like climate mitigation,” says Lark, a scientist at UW–Madison’s Center for Sustainability and the Global Environment.

Lark, who studies land use change and its impacts on land and water resources, says that understanding could be used to direct clean energy investments where they have the least competition with other beneficial uses.

“That’s a key application of this,” Lark says. “Whether it’s for solar photovoltaic, or agrivoltaics, or cellulosic bioenergy development, or just restoration of natural ecosystems: These sites could be great candidates for a lot of those applications.”

A map is shown, with an inset showing a close-up of part of it.

Screenshot of the GLBRC Atlas of Marginal Lands, which allows users to explore and download spatial datasets (A), and a zoomed-in example of the abandoned cropland dataset in a 1.5km2 section of southern Michigan (B). Field color in (B) indicates the earliest year in which land was no longer cultivated.

The study was a collaboration between researchers at UW–Madison and Michigan State University and was funded by the U.S. Department of Energy. The resulting data are publicly available in the GLBRC’s interactive atlas of U.S. cropland, which also maps trends in farmland expansion and irrigation.

Researchers have traditionally relied on datasets like the USDA’s Census of Agriculture, which provides county-level estimates of farmland at five-year intervals and can be used to estimate how much land has been taken out of production.

But until now there was no way of knowing exactly where that land was or when it was abandoned.

“Most of these estimates have all been at the county level,” Lark says. “This is really the highest resolution analysis available, looking right on the landscape — field by field, acre by acre — of where these crop lands are.”

While satellite imagery has been around for decades, without recent advances in cloud computing, Lark says it was impossible to classify the nearly 2 billion acres of land in the coterminous U.S.

To construct the team’s analyses, Xie, now a professor at the University of Oklahoma, used existing land cover data to train a computer to read those images and recognize patterns of cultivation. The researchers then had that algorithm analyze satellite data from 1986 through 2018 and categorize each pixel to determine whether it was cultivated.

The results accurately predict the precise location of abandoned croplands nine times out of 10 and can even pinpoint the year they were abandoned with about 65% accuracy.

The team found that more than 30 million acres of cropland were abandoned over those 32 years. Most abandoned land was concentrated in the Great Plains and along the Mississippi River between southern Illinois and the Gulf of Mexico.

Those 30 million acres don’t include urbanized land, which Lark says is unlikely to ever return to cultivation.

Of that abandoned cropland, more than half changed to pasture or grassland and about a third was either shrubland, forest, wetland, or bare.

Lark was surprised to discover that less than a fifth of abandoned land was enrolled in a formal conservation program, such as USDA’s Conservation Reserve Program, which pays farmers to take environmentally sensitive lands out of production. That means more land than previously thought could potentially be used to grow bioenergy crops.

“A lot of the assumptions were that this former cropland had a lot of overlap with formal conservation programs,” Lark says. “But we saw that they’re almost entirely distinct pools.”

Researchers can now use the resulting data to model how much biomass could be grown on these lands as well as their potential to trap carbon dioxide from the atmosphere in the soil.

The study does not explain why the lands were abandoned.

“The next step is to figure out the drivers,” Lark says.

To do that, Lark says the team may pull in other information like socioeconomic data and tax records to get a better sense of what’s happening at the parcel level — for instance, whether a farmer took one field out of production or sold the entire farm — and use that to identify potential uses for the land.

“If they’re farming a bunch of hay, that’s probably more easily adaptable to cellulosic biofuel feedstock, because they might already have the equipment … and you could harvest something like switchgrass then too,” Lark says. “If it’s somewhere where there’s no agricultural production at all anymore, it might be harder to do that, but maybe more suited for a solar installment.” READ MORE

Excerpt from Renewable Fuels Association: The study was accompanied by a well-funded, well-orchestrated public relations blitz that resulted in dozens of news articles and editorials, widespread radio and TV coverage, and echo-chambering on blogs and social media channels. Even though the study’s methods and findings were roundly criticized and swiftly rebuked by the scientific community, the massive PR push behind the study unfortunately succeeded in spreading the “land use change” myth far and wide.

Two years later (March 2024), Lark published another study on land use change. Only this time there was no big publicity campaign. No interviews on NPR, no pithy feature story on Fox News or HBO talk shows, no social media blasts, no TIME magazine pieces, no National Wildlife Federation press conferences, no congressional staff briefings (those are all things that really happened after the 2022 study). In fact, the newest Lark study made about as much noise as a tree falling in the woods.

Why? What changed? How come there wasn’t a massive PR effort around the new land use study?

Put simply: the results of the new Lark paper don’t fit the doomsday narrative that was carefully crafted by media-savvy PR firms following the release of 2022 study. Indeed, the new Lark study actually contradicts and undermines his study that made headlines two years ago. That’s why they’re keeping it quiet. READ MORE