Now, farmers are discovering that the FDA's proposed rules would curtail many techniques that are common among organic growers, including spreading house-made fertilizers, tilling cropland with grazing animals, and irrigating from open creeks. Suddenly, from small family operations nestled in the foothills of Appalachia to the sophisticated organic-grower networks that serve Los Angeles and San Francisco, the farms that celebrity chefs and food-conscious consumers jostle to buy from are facing an unexpected adversary. They're fighting back. Even though full enforcement of the rules is still years away, they are warning customers that some farms would have to close. "They are...