Agricultural Practices That Caused Dust Bowl Continue To Impact Nation's Soil Quality, Researchers Say

Are farming practices similar to those that led to the Dust Bowl –- the decade-long drought and agricultural-production declines that occurred during the 1930s and plagued the Plains states – still negatively impacting our U.S. soil? A recent study, conducted by researchers from the University of Tennessee at Knoxville, is shedding new light on how farming practices have altered soil health since that devastating period.

"We took a novel approach of merging a watershed erosion model with an organic matter cycling model to build a better understanding of how sediment and nutrients are transported differently depending on topography," Thanos Papanicolaou, a professor in the Department of Civil and Environmental Engineering at the University of Tennessee at Knoxville, explained in a news release. "We also addressed a few major challenges such as soil texture, bulk density and the organic carbon in soil."

For their study, researchers collected soil cores in order to better understand how soil carbon and soil health on farms since 1930 have been affected by different farming practices. After recording soil sample data, they modeled carbon budgets in agricultural areas. Additionally, researchers accounted for variations in properties such as soil type, landscape slope or land management.

A carbon budget is defined as a the amount of greenhouse gas emissions that a specific area can tolerate over a certain period of time. Using these measurements, researchers concluded that human interaction has reduced the productivity of agricultural areas, compared to grasslands or forests.

"We set out not to go over data that had already been collected but to make new findings," Papanicolaou added in the release. "We wanted to understand what happened to carbon levels over time, and hopefully develop some new directions for soil use out of that."

Researchers also discovered that soils upslope were continually depleted of rich organic matter long after the end of the Dust Bowl. This stems from agricultural practices and the erosion they cause. Subsequently, the nutrients traveling from high areas generated healthier soils downslope. Most models neglect this environmental factor, Papinicolaou noted.

However, researchers suggest things are turning around. Although levels of organic material in upslope soils hit rock bottom in the late 1980s, organic matter has improved to about half the level it was in the 1930s.

"Our study brought together hydrology, biology, geochemistry, engineering and mathematics in a way not previously done," Papanicolaou added. "We were able to show that, yes, soils are improving, but the methods of farming from 1935 to 1987 have taken their toll."

The study will be published soon in the Journal of Geophysical Research: Biogeosciences.

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