Nothing said here refutes the parent comment. It turns out that a lot of land is really shitty for growing stuff that isn't a weed (without adding a ton of chemicals to the environment), and humans don't eat weeds. Cows, sheep, pigs, and chicken do.
I doubt that 86% of that 77% is truly unsuitable for farming human food, but I wouldn't be surprised if 30-50% of it was.
I doubt that 86% of that 77% is truly unsuitable for farming human food, but I wouldn't be surprised if 30-50% of it was.