Tyler Cowen cites a passage (from Voting with your trolley) against organic farming:
Perhaps the most eminent critic of organic farming is Norman Borlaug, the father of the “green revolution”, winner of the Nobel peace prize and an outspoken advocate of the use of synthetic fertilisers to increase crop yields. He claims the idea that organic farming is better for the environment is “ridiculous” because organic farming produces lower yields and therefore requires more land under cultivation to produce the same amount of food. Thanks to synthetic fertilisers, Mr Borlaug points out, global cereal production tripled between 1950 and 2000, but the amount of land used increased by only 10%. Using traditional techniques such as crop rotation, compost and manure to supply the soil with nitrogen and other minerals would have required a tripling of the area under cultivation. The more intensively you farm, Mr Borlaug contends, the more room you have left for rainforest.
You should also question the environmental benefits of local food production:
The DEFRA report, which analysed the supply of food in Britain, contained several counterintuitive findings. It turns out to be better for the environment to truck in tomatoes from Spain during the winter, for example, than to grow them in heated greenhouses in Britain. And it transpires that half the food-vehicle miles associated with British food are travelled by cars driving to and from the shops. Each trip is short, but there are millions of them every day. Another surprising finding was that a shift towards a local food system, and away from a supermarket-based food system, with its central distribution depots, lean supply chains and big, full trucks, might actually increase the number of food-vehicle miles being travelled locally, because things would move around in a larger number of smaller, less efficiently packed vehicles.Research carried out at Lincoln University in New Zealand found that producing dairy products, lamb, apples and onions in that country and shipping them to Britain used less energy overall than producing them in Britain. (Farming and processing in New Zealand is much less energy intensive.)