Inspired by Al Gore, House & Garden's garden guy Tom Christopher has written an eye-opener about "the cost in fossil fuels of the synthetic nitrogen fertilizers we apply so lavishly to our yards and gardens":
"After a bit of research and doing the math, I have found that [Gore] is right. The raw material for all synthetic nitrogen fertilizers is anhydrous (water free) ammonia, which is manufactured by combining hydrogen from natural gas with atmospheric nitrogen. This is an extravagant process: to produce one ton of anhydrous ammonia requires the consumption of 33.5 million British Thermal Units (BTU's) of natural gas. According to a 2001 U.S. government estimate, that's almost exactly half the quantity of gas needed to heat the average home in one of our northeastern states for a whole year.
"A farmer may need the fertilizer (though synthetic nitrogens are a relatively inefficient source of this nutrient because so much of what is applied simply leaches away through the soil to pollute groundwater and streams); what I can longer justify as a home gardener is my consumption of this costly stuff. Currently, I'm putting in a lawn as a fire-break and tick-free zone around our house in the country. If I were to plant a half acre of Kentucky bluegrass and fertilize according to the recommendations on the fertilizer bags, I'd apply a total of as much as 85 lbs. of synthetic nitrogen annually – consuming in that way more than 1.4 million BTU's of natural gas."
Obviously, nitrogen is necessary for plant development; we just need to be a little more thoughtful about how we use it and where we source it. Nitrogen-fixing cover crops, "grasscycling" with a mulching mower, and dressing the soil with well-composted manure can all increase your nitrogen delivery organically, and in fact counter some of the damage done by the production, and application, of synthetic fertilizers.