Soil contains about twice as much carbon as the atmosphere and plants combined. It is a major carbon sink, capable of absorbing more carbon dioxide from the atmosphere than it releases. Management of soil carbon is key in efforts to mitigate climate change, in addition to being vital to soil health and agricultural productivity. Measuring soil carbon, however, is a painstaking, expensive process. Samples must be dug from the ground and sent to a lab for analysis, making upscaling measurements on a large spatial scale challenging. Now environmental scientists have combined field-level data with machine-learning techniques to estimate soil organic carbon at the U.S. continental scale. The Journal of Geophysical Research -- Biogeosciences published the new soil organic carbon estimate, which improves the overall estimate for the United States and gives new insights into the effects of environmental variables on soil organic carbon. "There is growing recognition that soil organic carbon is important and that we should invest in building it up through sustainable land management practices," says Debjani Sihi, senior author of the study and assistant professor of environmental sciences at Emory University. "Our estimate is more accurate than existing estimates and provides a better benchmark to guide policymakers and land managers in adopting climate-smart practices." Land is far more efficient than the ocean at retaining carbon, Sihi notes, and offers one possible nature-based solution to help mitigate climate change. "We could potentially create conditions," she explains, "that are favorable for soil to capture carbon dioxide from the atmosphere and lock it there for a really long time -- over millennia." Sihi is a biogeochemist who studies environmental and sustainability issues at the nexus of soil and climate. First author of the current paper is Zhuonan Wang, a former postdoctoral fellow in Sihi's lab who is now at... |