A buffer zone provides, well, a buffer.
Once a field is eligible to produce a crop sold as organic, it has to follow organic regulations, which include no pesticides and chemicals. A farmer can follow the guidelines all day long, but if a neighboring farm does not follow organic regulations and some of these chemicals end up in the organic farm, the product cannot be sold as organic.
Which leads to the creation of the buffer zone.
The buffer zone is a strip of vegetation around an organic farm that keeps out any non-organic substances used by a neighboring farm. These zones are actually required under regulations if there is any risk of contamination from non-organic approved substances. (National Sustainable Agriculture Coalition)
What are buffer zones made of?
There is really no limit to what a farmer can plant as a buffer. Grass, shrubs, trees, and a variety of crops for harvest can be used. The only distinction is that, even though the farmer will tend to these products grown in the buffer as organic, they must be sold as conventional.
Buffers have also been made by digging ditches to prevent water runoff or contamination. Mounds of dirt have been used as buffers and serve as windbreaks, to prevent air-borne pesticides from contaminating organic crops. (ATTRA Sustainable Agriculture)
What are other ways buffer zones can be used?
A unique use is in Belize where cacao bean production is in high demand. Instead of cutting down rainforests to grow cacao, sustainable farmers have been establishing their cacao crops just outside the rainforest’s edge, creating a buffer with their entire farm. This protects the rainforest flora and fauna from human encroachment, while providing the world with the cacao beans we just can’t get enough of. (Belize Organic Cacao)
For more information, check out International Agriculture Center’s approach to creating and managing buffer zones.