Wednesday, June 27, 2007

Go organic to fight global warming!

Need another reason to buy organic food?

According to findings from the ongoing Farming Systems Trial at The Rodale Institute, organic grain farming, including low- or no-till soil preparation and cover cropping, actually increases carbon sequestration in the soil by 15% - 28% compared with conventional farming techniques. Translation: 15% - 28% percent less carbon dioxide goes into the atmosphere because it's bound up in the soil. This is in addition to reduced carbon dioxide emissions from farm equipment on organic farms (no-till means fewer passes over the field with a gas-guzzling tractor and about one-third less carbon emissions), and from the production of petroleum-based fertilizers. Add to that buying local AND organic, and you eliminate still more greenhouse gas production from food transport. Wow!

So what does carbon sequestration mean, and why do organic farms have more of it? Well, the folks at Rodale have a couple explanations:

One is that organic cultivation focuses on building up carbon-based organic matter, or humus, in the soil. Humus refines soil texture and holds nutrients and water. Soil rich in humus is more naturally fertile, and holds a more consistent level of moisture, even in the face of heavy rains or drought. Plus, humus is made of carbon! On a conventional farm, application of nitrogen-rich chemical fertilizer stimulates soil organisms to break down any humus in the soil very quickly, and when they do, they release carbon dioxide into the atmosphere. On an organic farm, humus is added to the soil and breaks down very slowly, so it feeds the plants over a long period of time, AND releases much less carbon dioxide.

Another reason has to do with mychorrhizae - microbial fungi that are naturally present in organic soil. These mychorrhizae actually work symbiotically with plant roots, helping them to take up more water and nutrients from the soil in exchange for a 12% share of the (carbon-based) energy that the plants make using photosynthesis. This means that plants working together with mychorrhizae are doing more photosynthesis and fixing more carbon dioxide from the atmosphere into the soil, in addition to being healthier and more disease resistant. Synthetic fertilizers and pesticides used in a conventional farming system actually kill off some of the mychorrhizae and stop this symbiotic carbon sequestration from occurring.

But how much greenhouse gas are we talking here? Is this enough to put a real dent in global warming? Here are some numbers to put this into perspective:

If all 160 million acres of corn and soy grown in the US were transitioned to organic, they'd be sequestering about 580 billion extra pounds of carbon dioxide per year. That's like taking 58.7 million cars off the road, or about 25% of the cars in the US. Yow! If ALL American cropland went organic, it'd be like taking more than half the cars in the US off the road.

Check out this video (starring Percy Schmeiser) about the Rodale findings, and be sure to add "eat organic food" to your list to-dos for reducing your carbon footprint, right up there next to compact flourescent lightbulbs, carpooling, or riding your bike!

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