Soils pay key role in keeping the planet cool: Study

ORLANDO: The study looked at a way to prevent soil carbon from evaporating and retaining heat in the atmosphere. A new initiative from the University of Central Florida seeks to chill the atmosphere by using soils.

The project, which will be supported by a roughly $750,000 USDA National Institute of Food and Agriculture grant, will look at a way to prevent carbon from escaping soils and turning into the greenhouse gas carbon dioxide. Carbon dioxide warms the Earth by trapping heat as it builds up in the atmosphere. The study is crucial since, according to NASA, this summer has witnessed some of the planet's warmest temperatures ever recorded. “When we talk about climate change, a lot of people have the misperception that most of the Earth’s carbon is stored in the atmosphere,” said Lisa Chambers, the project’s principal investigator and an associate professor in UCF’s Department of Biology. “But the atmospheric carbon pool is actually quite small, relative to the pool of carbon in the soil.” The research will focus on histosols, or organic-rich soils, in the Everglades Agricultural Area located south of Lake Okeechobee in Florida. 

Histosols comprise only about 1.3 per cent of Earth’s land surface but store approximately 23 per cent of its carbon. The nutrient-rich soils are perfect for agriculture, but their drainage and cultivation lead to increased carbon dioxide in the atmosphere. The research team, which includes Jehangir Bhadha from the University of Florida and Jing Hu from Mississippi State University, will examine adding fine minerals — such as silt and clays — to the histosols to prevent carbon from escaping.

Research has found that mineral-associated organic matter releases less carbon into the atmosphere because it is less susceptible to decomposition by microbes. “It’s been shown through carbon-14 dating that the carbon that’s associated with these fine silts and clays has remained in the soil the longest,” Chambers said. “Whereas unassociated, loose organic matter only dates back tens to hundreds of years old and is easily decomposed by microbes into CO2, the mineral-associated organic matter has been aged to be millennia.”

She says the Everglades Agricultural Area is the perfect place to perform the research because not only could the work help with climate change, but it could also improve agricultural production and sustainability in the area. Soil subsidence due to decomposing histosols has become a major problem in the Everglades Agricultural Area, where in some locations soil elevation has dropped as much as six feet over the past 100 years.

“The cas been so unprotected and oxidizing so fast, that there are places where the soils are almost completely gone, turned back into carbon dioxide in the atmosphere, and they're almost down to bedrock,” she said. “So, it's kind of a precarious situation.”