How organic farming fights cloimate change

How Stuff Works - Agriculture is one of the more significant contributors to global warming. Nitrogen-based fertilizers and farm animals generate greenhouse gases, including methane and nitrous oxide. Conventional farming depletes soil of carbon, while planting and managing forests can help offset carbon emissions.

But a new study shows that organic farming fights climate change by trapping temperature-raising carbon in soil, keeping it from contributing to the greenhouse effect. Organic farming can also help offset carbon by storing it in soil. The study is published in the Oct. 1 issue of the journal Advances in Agronomy.

The research was conducted by scientists at Northeastern University's National Soil Project, in partnership with The Organic Center. They gathered more than 650 topsoil samples from organic farmers in 39 U.S. states and compared those samples with more than 725 conventional soil samples from the continental U.S. The results showed soil from organic farms is 26 percent better at retaining carbon — and retaining it for longer periods of time — than soil that's farmed with conventional methods and synthetic fertilizers.

Here's why: The matter that organic farmers use, such as compost, green manure, animal matter and others — as well as the living things in healthy soil, such as microorganisms, earthworms and other components — gives soil humic acids. "It's all these plus the presence of marvelous, long-lived natural organic compounds in soils called humic substances (HS). Humic substances are responsible for the colors of soils," Elham Ghabbour, Ph.D., a co-leader of the National Soil Project, said in an email.