500 bushels/acre is probably not scalable. For corn, if you get 150 bushels/acre, you are doing well. I think the grand champion of caloric yield per unit are

500 bushels/acre is probably not scalable. For corn, if you get 150 bushels/acre, you are doing well. I think the grand champion of caloric yield per unit area is actually the sweet potato. But potato is second place, has more protein, and a better sale price. Also, sweet potato contains raffinose, meaning that it will give you gas. Browse fao.org for a bit for more information on the nutritional yields of various crops. Though last time I checked, there was no comparison with perennial tree crops like oil palm, neem, and jackfruit.