Lettuce sprouts amid rows of plastic covering the ground at One Straw Farm, an organic operation north of Baltimore. Although conventional farmers also use plastic mulch, organic produce farms like One Straw rely on the material even more because they must avoid chemical weed killers, which are banned in organic farming. Lisa Elaine Held/NPR hide caption Lettuce sprouts amid rows of plastic covering the ground at One Straw Farm, an organic operation north of Baltimore. Although conventional farmers also use plastic mulch, organic produce farms like One Straw rely on the material even more because they must avoid chemical weed killers, which are banned in organic farming. Drew and Joan Norman have been producing organic vegetables on 60 acres just north of Baltimore since 1983. On a recent spring day, signs of another new season at One Straw Farm were everywhere: seedlings in the greenhouse waiting to be transplanted, asparagus ready to be picked, tiny leaves of red- and green-leaf lettuce sprouting out of the ground — and rows and rows of plastic covering the ground on each field. Plastic is under attack these days for the environmental problems it causes. But sustainability-min...