The soy is used for cattle feed.
Also interesting, te USDA permits more pesticides to be sprayed on crops destined for livestock feed than that destined for human consumption. I'm no biologist, but doesn't alot of that end up concentrated in the fat of the animal which is then consumed as part of my hamburger? Not to mention all the steriods and antibiotics they pump into these cows to beef them up and protect from disease due to the fact they are raised in brutal, overcrowded conditions.
Also, raising livestock creates alot of pollution in the form of liquid waste that gets dumped into lakes, rivers and groundwater.
Wanna make a difference in global warming, pollution, your personal health and animal welfare all at the same time? Eat two vegetarian meals per week.