We instead grow large amounts of crops that go to animal feed. It takes a lot less cropland for plant-based diets because we don't have to grow feed to another creature (who then will use up a large amount of that energy)
The research suggests that it’s possible to feed everyone in the world a nutritious diet on existing croplands, but only if we saw a widespread shift towards plant-based diets.
If we would shift towards a more plant-based diet we don’t only need less agricultural land overall, we also need less cropland.
In the hypothetical scenario in which the entire world adopted a vegan diet the researchers estimate that our total agricultural land use would shrink from 4.1 billion hectares to 1 billion hectares. A reduction of 75%. That’s equal to an area the size of North America and Brazil combined.