Soybeans produce at least two times as much usable protein per acre than any other major vegetable or grain crop, except for hemp which can produce up to 293 lbs of usable protein per acre 33 g/m². They produce 5 to 10 times more protein per acre than land set aside for grazing animals to make milk, and up to 15 times more protein per acre than land set aside for meat production.[1]

via Edible protein per unit area of land – Wikipedia, the free encyclopedia.