September 11, 2017
Intensive agriculture is one of the main sources of greenhouse gases (GHGs), releasing huge amounts of carbon into the atmosphere through the disruption of soil.
Current efforts to reverse this trend of increasing carbon emissions and help mitigate climate change are centered on improving farming practices and boosting sequestration, the long-term storage of carbon in soils.
Now, a new study shows that organic farms have 26 percent more greater potential for long-term carbon storage, and 13 percent higher soil organic matter, than conventional farms.
The new study was conducted by researchers with the National Soil Project at Boston's Northeastern University in collaboration with The Organic Center (TOC), a nonprofit educational and research group managed by the Washington, D.C.-based Organic Trade Association (OTA).
TOC said the study is the first to provide an "accurate picture of the long-term soil carbon storage on organic versus conventional farms throughout the U.S."
“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," said Jessica Shade, TOC's director of science programs.
Humic substances resist degradation and can remain in the soil for hundreds and sometimes thousands of years. The more humic substances in a soil, the longer that healthy soil is trapping and keeping carbon out of the atmosphere.
"These results highlight the potential of organic agriculture to increase the amount of carbon sequestration in the soil, and by doing so, help decrease a major cause of climate change," Shade said.
The study, which measured 659 organic soil samples from 39 states and 728 conventional soil samples from the 48 contiguous states, found that the components of humic substances - fulvic acid and humic acid - were 150 percent and 44 percent higher, respectively, in organic than in conventional soils.
The study, "National Comparison of the Total and Sequestered Organic Matter Contents of Conventional and Organic Farm Soils," will be published in the Oct. 1 issue of the journal Advances in Agronomy.