Wednesday, November 18, 2009

Carbon Footprint of Fruits and Veggies

Once upon a time I thought that simply purchasing anything and everything organic was the greenest option. I went about my merry way in the organic produce section and slept well at night. But last year I took a closer look after realizing that the organic apple in my hand had traveled to Maryland all the way from New Zealand. I remember looking around at the bananas, pineapples and watermelon and thinking to myself, "I have never even seen a banana on a tree. Do pineapples grow on trees or in the ground? Surely the ground, right? Oh man...there is no way eating watermelon in the middle of winter is sustainable!"

Yes, fertilizer is the enemy of the oceans but there is a lot more to keeping the carbon footprint of the crops you consume at a minimum. Brendan Borrell for Slate's Green Lantern, addressed this very dilemma in Tuesday's post Sustainable Salads:

"...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.

As it turns out, it's not hard to find digestible data on the use of fertilizers. The United Nations Food and Agriculture Organization offers a handy list of various crops and their associated fertilizer loads. Bananas consume the most by a very large margin, requiring a whopping 427 pounds of nitrogen, phosphate, and potash fertilizer per acre of cultivation. Sugar beets and citrus crops are next, followed by vegetables, tubers, and grains. Peas and beans require just 35 pounds per acre, in part because they have capacity to absorb nitrogen from the air. In short, eat more beans.

...What does all this fancy number-crunching mean? Considering that about one-third of greenhouse gases (PDF) emitted from agriculture in the United States come from fertilizers and pesticides, identifying low-impact crops can be at least as important as sourcing your foods locally. For instance, switching from strawberries to oranges in your fruit salad cuts pesticide use by half and fertilizer use by a factor of 10. For those who can't do without their berries, your best bet may be to buy from a truly sustainable source that avoids the worst pesticides, sticks to manure and other organic fertilizers, and prevents excess nutrients from flowing into waterways. Major organic growers like Cascadian Farms and others provide limited information about their agricultural practices on their Web sites.

What about organic versus conventional produce? When it comes to dietary staples like corn, wheat, and rice, the choice isn't so clear. David Pimentel of Cornell has estimated that it takes about 30 percent less energy to grow organic soy and corn than it does to grow the conventional kind. On the other hand, organic doubters, including the father of the Green Revolution, Norman Borlaug, have suggested that the spread of fertilizer and pesticide-free agriculture would result in more land being cleared for crops to match today's conventional yields, a view that has been supported by a British government report. The USDA has just started surveying some organic crops, and we'll have to wait until all the data is in to issue a final verdict on that front. As for fruits and vegetables, going organic is the eco-friendly choice. The switch will reduce your impact on the soil and water and won't require a vast expansion of the agricultural footprint.

For all this, one of the simplest ways to ballpark the impact of a conventionally grown fruit or vegetable is to glance at its price. The trick doesn't always work, but, in general, the cheaper one probably required less fertilizer, pesticide, land, and energy."

As always, I fall back to the same advice: Buy local, in season produce *when possible. This is going to be a long winter, huh?

*** I emphasize "when possible" because everything here on JustSaying is a suggestion - encouragement in an eco-conscious direction only. Nothing changes overnight and not even yours truly can live here in America without giving in to the convenient option now and then. Just remember: a little bit goes a long way and do the best you can for yourself, your family and your environment and know that any effort whatsoever makes a difference.

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