Which fruits, vegetables, and other crops have the smallest environmental footprints?

from Slate:
We've already been over the environmental benefits of choosing poultry over beef and anchovies over haddock. But you're right to suggest that the same sort of logic can apply to picking vegetarian foodstuffs. Certain crops require loads of phosphate fertilizer, for example, which is mined from the ground and can eventually cause stream-choking algal growth. Other fruits and veggies are grown with heavy doses of pesticides, fungicides, and other chemicals that can pollute waterways and cause reproductive problems in animals. So how do you know which crops are best to eat? Here's the Lantern's rule of thumb: Try to keep your more extravagant fruit cravings in check, but don't sweat the low-impact calories that come with your carbs.