We also grow plants to burn in F150s. OTOH you also cannot convert all the pastoral land into agricultural land. In fact its probably pastoral land in the first place because the land is not that possible to farm on otherwise (e.g. hilly/narrow/rock laden pastures which are quite common across hilly areas like appalachia).
The fact is there are good ways to grow animals and plants, and bad ways, and we should just focus on eliminating the bad ways and allowing the market to set prices on what the good practices are. It honestly wound't be too expensive; grassfed pastured beef isn't too much of a premium, neither is soybean that came from an ohio field instead of a Brazilian rainforest. If subsidizes were eliminated for the mass market operations that damage the environment, and introduced for these sustainable operations, you'd see a lot of self correction in the market to fit these more sustainable practices.