Madison Reporter

A new study from the University of Wisconsin–Madison suggests that abandoned farmlands could play a significant role in combating climate change. Researchers have developed an interactive tool to map nearly 30 million acres of U.S. cropland abandoned since the 1980s, providing detailed insights into where these lands are located and their potential uses.

The study, led by Yanhua Xie and Tyler Lark from the Great Lakes Bioenergy Research Center, was published in Environmental Research Letters. It offers field-level resolution of previously cultivated land that could be repurposed for growing crops like switchgrass or sorghum, which can sequester carbon in the soil and serve as feedstocks for biofuels.

“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,” said Lark, a scientist at UW–Madison’s Center for Sustainability and the Global Environment.

Lark emphasized that this understanding could help direct clean energy investments to areas with minimal competition with other beneficial uses. “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,” he noted.

The research team used machine learning to analyze satellite data from 1986 through 2018, categorizing each pixel to determine whether it was cultivated. The results showed that more than 30 million acres of cropland were abandoned over those 32 years, primarily concentrated in the Great Plains and along the Mississippi River between southern Illinois and the Gulf of Mexico.

The study revealed that less than a fifth of this abandoned land was enrolled in formal conservation programs such as USDA’s Conservation Reserve Program. This indicates that 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 explained. “But we saw that they’re almost entirely distinct pools.”

The resulting data is publicly available in an interactive atlas created by GLBRC researchers. This atlas also maps trends in farmland expansion and irrigation.

While satellite imagery has been available for decades, recent advances in cloud computing enabled researchers to classify nearly 2 billion acres of land across the contiguous United States accurately. The algorithm used by Xie accurately predicts abandoned croplands nine times out of ten and can pinpoint the year they were abandoned with about 65% accuracy.

Researchers plan to further investigate why these lands were abandoned by incorporating additional information such as socioeconomic data and tax records. This will help identify potential uses for these lands based on their specific characteristics.

“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 said. “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.”