Not to mention crop monoculture is terrible for the quality of the soil, forcing farmers to use (literally) tons of synthetic phosphorous, nitrogen, and potassium just to get acceptable yields. It results in lower quality crops than those that result from polyculture, as well.

A comment in the top thread mentioned The Omnivore's Dilemma by Michael Pollan as a good introduction to this issue and I'll second that. A fun read, too. He investigates hunting and amateur mycology as well.