Cash crops such as soy that are a mainstay in vegan diets? What do you think most of the cows eat before they're slaughtered for your lunch? A five year Oxford University study done on 38,700 farms showed that if everyone in the world switched to a plant based diet, we would be able to reduce agricultural land by 76% [1].

[1] https://pubmed.ncbi.nlm.nih.gov/29853680/