Diversity, diversity, diversity! But I don't have any animals on my farm. Don't worry build it and they will come. The neighbors cows, horses and pigs regularly find holes in their fences and come where the food is.
They have 20 acres and 5 cows cant find enough to eat. They range over to whole area eating what they like and leaving what they don't like. Naturally then what grows there is what they don't like.
Watch this and se how to gradually learn to manage production instead of mining the soil. It is possible to increas soil and production concurently.