I am hunting for it right now, but I recently read about how soy production has equalled or is getting really close environmental impact of beef.
> Soybean meal is the largest source of protein feed in the world, and is generally used in animal feed. Therefore, most of the world's soybeans are consumed indirectly by humans through products like meat (chicken, pork and beef), dairy, eggs and farmed fish.
http://wwf.panda.org/our_work/food/agriculture/soy/consumers...