[bin_bash]

If it’s not arable then the cow’s food has to come from arable land somewhere else. You can’t just put a cow on a rock and expect it to produce milk.

[Symmetry]

Between land that gets enough rain for intensive cultivation without draining aquifers and land that's a barren desert there's a wide range and you can still graze cows on most of it, though it takes more land per cow in drier areas.