Source?
https://www.thespruce.com/how-many-vegetables-per-person-in-...
> To grow all the food for one person's needs for the whole year requires, for most people, at least 4,000 square feet—though some diet designs are possible that can use a smaller area.
https://permaculturism.com/how-much-land-does-it-take-to-fee...
> A 0.44 acre of land can produce enough vegetables and fruits to meet up with the daily calories needed for one person to feed for a year.
Food and Agriculture Organization of the United Nations, 1993:
> It is realistic to suppose that the absolute minimum of arable land to support one person is a mere 0.07 of a hectare–and this assumes a largely vegetarian diet, no land degradation or water shortages, virtually no post-harvest waste, and farmers who know precisely when and how to plant, fertilize, irrigate, etc.