The sand and dirt that form soil contain more carbon than Earth’s vegetation and atmosphere. That’s why even a small change in soil carbon has significant implications for the planet’s climate. Soils also play a crucial role in keeping the planet cool by absorbing and storing heat and blocking its transfer to deeper layers of the atmosphere.
A new study investigates how to stop soil carbon from evaporating and trapping heat in the air. The research, published Aug. 6 in the Proceedings of the National Academy of Sciences, is part of a broader effort to find ways to reduce global warming by capturing carbon dioxide from the air and transferring it into soils.
Scientists are focused on two main kinds of soil: cropland and permafrost. Farmland occupies about 10% of the world’s land and is a significant source of carbon emissions contributing to climate change. Scientists have found that planting perennial plants, which don’t die every year, and “cover crops” such as beans and peas planted after the crop has been harvested can help agricultural soils take in more carbon. Farmers can also improve the structure of their soil by tilling less. Tilling breaks up the soil structure, allowing carbon to escape into the air. Instead, scientists recommend that farmers use no-till farming methods like conservation tillage.
In permafrost soil, which forms in cold climates, carbon is stored permanently in organic matter—bits and pieces of dead plants and other organisms, sloughed-off cells and tissues of soil organisms, and substances from plant roots and microbes. The amount of carbon in permafrost soil is sensitive to environmental changes since it can melt and release methane—another greenhouse gas—into the air.
Scientists are studying whether adding fine mineral particles to the soil, called histosols, will prevent carbon from escaping into the air and turning into the greenhouse gas carbon dioxide. Histosols comprise only about 1.3 percent of the Earth’s surface but store 23 percent of its carbon.
The University of Central Florida is working on a project to use soils to cool the atmosphere. Funded by a nearly $750,000 grant from the USDA National Institute of Food and Agriculture, the research will examine how to prevent soil carbon from evaporating and turning into the greenhouse gas carbon dioxide, which warms the globe by retaining heat as it builds up in the atmosphere.
Scientists plan to conduct their work at the Everglades Agricultural Area south of Lake Okeechobee in Florida. The land is a former sugarcane field restored by potentially responsible parties (PRPs). The PRPs expanded the wetlands habitat, created wildflower and native grass meadows, placed bat boxes and other bird nesting structures, and planted habitat brush piles on the upland areas of the site. Currently, the site houses commercial and industrial businesses and municipal parking lots. It is home to the SunRail commuter rail line and is scheduled for mixed-use redevelopment in the future.
