Indiana University Purdue University Indianapolis

Digging in the “Dirt”, Researcher Studies How Farming Practices Impact the Environment

Pierre-Andre Jacinthe, Ph.D.
Assistant Professor, Department of Earth Sciences

Enter the laboratory of Pierre-André Jacinthe, School of Science at IUPUI associate professor of earth sciences, and you may see several student researchers working at a central table, a state-of-the-art gas chromatograph, boxes of seemingly empty — but air-filled — glass bottles of varying size, and a large refrigerator with glass doors revealing hundreds or perhaps thousands of baggies of soil.

Jacinthe, a biogeochemist, has been interested in soil and water since his childhood in rural Haiti, a country with some of the world’s most degraded farmland. More recently his research has focused on the U.S. Midwest, which possesses some of the world’s richest farmland.

Since 2009, with U.S. Department of Agriculture funding, he has been investigating the exchange of carbon dioxide, methane, nitrous oxide and other greenhouse gases between land surface and the atmosphere. He also studies water in the region’s streams and rivers looking for agricultural contaminants that may ultimately wind up in reservoirs serving cities and towns.

“Intensive plowing leaves the soil bare and unprotected, exposing it to erosion,” Jacinthe said. “Farmers know this is bad. Our studies show that, in addition to decreasing erosion and maintaining soil health, less plowing — or not tilling the land at all — can also lessen the transfer of greenhouse gases from the land to the atmosphere, and even increase the capacity of surface soil to consume atmospheric methane.

“While farmers don’t want to waste tillable land, when they plant up to the field edge, fertilizer and pesticides will wind up in nearby streams. Our research indicates that creating land areas, called buffers, along streams or rivers and keeping them in a natural forest-like state makes a difference because a buffer of only a few yards can prevent a significant amount of noxious chemicals from entering streams. Contaminated water is expensive to treat, and some municipalities do not have the facilities to remove key contaminants, especially pesticides.”

However, Jacinthe says that buffers may not be a universal panacea. In a 2011 study, he and colleagues determined that buffer areas are hot spots of nitrous oxide, and more so after short periods of flooding than following long-term flooding. “So we need to be aware of these trade-offs,” he said.

Other research by Jacinthe in 2011 looked at the impact of organic farming, which eschews chemical fertilizers and pesticides, in arid climates. He and colleagues found, rather unexpectedly, that soil quality in New Mexico did not improve with nine years of organic farming.

“This shouldn’t discourage farmers from going or remaining organic,” Jacinthe said. “It may be that organic farmers are plowing down more frequently to control weeds rather than using artificial herbicides. Technically, this can be solved.”

Out in the fertile fields of Indiana and Ohio, Jacinthe and his students collect soil, water and air samples to take back to the lab and analyze. Back in the lab, their findings may positively impact the quality of the soil, water and air for generations to come.