Research by Northeastern University indicates soil on organic farms contains more of a key component for sequestering carbon than soils on other farms, said the Organic Trade Association. The trade group said the study, which compared samples of soil from across the country, “provides a significant proof point that organic agricultural practices build healthy soils and can be part of the solution in the fight on global warming.”
Organic farms have 44-percent higher levels of humic acid — the component that sequesters carbon over the long term — than soils not managed organically,” said the OTA. Jessica Shade, director of science programs at The Organic Center, a research nonprofit affiliated with OTA, said the study was “truly groundbreaking. We don’t just look at total soil organic carbon, but also the components of soil that have stable pools of carbon — humic substances, which gives us a much more accurate and precise view of the stable, long-term storage of carbon in the soils.”
Geoffrey Davies, one of the leaders of the National Soil Project at Northeastern, said the results of the project will be useful to farmers and policymakers. “We were focused on developing and adopting reliable methods of soil analyses for this national project. It was a huge, cooperative effort involving hundreds of sample donors.” The study is to appear in the October issue of the journal Advances in Agronomy.
Conventional and organic farmers have debated for decades over their methods of production. Conventional agriculture often claims higher yields per acre from highly mechanized, large-scale operations that use synthetic fertilizers and weedkillers. Organic farms rely on more intensive management and crop rotations while shunning chemical inputs. Organic food sales, mostly in produce and dairy, are a rapidly growing segment of grocery sales.
Soils rich in organic matter can maintain carbon for long periods of time, said the OTA. Organic matter comes from plant and animal material in the dirt. “The study shows that the components of humic substances — fluvic acid and humic acid — were consistently higher in organic than in conventional soils.” The Northeastern study said soils from organic farms on average contained more organic matter, more fulvic and humic acid, and greater potential for long-term carbon storage.
For the study, 659 soil samples were collected from organic farms in 39 states and compared to 728 samples from conventional farms in the contiguous 48 states.