completely eats the difference.
As a life member of PETA (People Eating Tasty Animals) I wish your argument worked. But it doesn't, because the amount of resources (land, water, energy, chemicals) it takes to produce X calories of beef is far higher than the amount of resources it takes to produce X calories of most kinds of edible vegitation. Even taking into account the fertilizer that cows produce.
It doesn't take evil technology to make eating plants less damaging than eating cows. At pretty much any technological level, carnivores do more damage. Except perhaps in terms of making an economy run. Farmers can produce more edible calories without expanding the fields or resorting to exotic biotech, simply by reducing the number of cows. Fertilizer might be a challenge without any cows, but the number of cows could be reduced quite a bit before a fertilizer shortage would occur. Except for those exotic biotechs, which tend to require fancy chemicals instead of dung.
No, I'm not some kind of vegitarian activist - I buy my dead cows by the quarter cow, and there is a chunk of dead cow ready for my lunch right now. Also some rice. I recognize that I am consuming more resources than I really need to. So be it. I do not aspire to be harmless.