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Comment by sytelus | Hacker News Reader

Article says that gurus think you need 4000 sq ft per person but then article changes tunes and, without citation, it says you need only 200 sq ft per person.

Let’s calculate ourselves. Currently 50M km^2 of land is used for agriculture. Divide that by world population and we get 76000 sq ft per person.

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You don't cite your source for how much land is used for agriculture (and what definition of agriculture you're using). Are you sure this doesn't include land used for growing specifically feed crops and crops to make food oils, wheat, etc.?

I am willing to bet that there are a lot of variables that math doesn't calculate for, such as mass farming inefficiencies that can be accommodated for by small-family farming, monoculture crop dominance, space for heavy machinery and food storage, and what agriculture we're talking about (as, for instance, the corn grown for conversion into ethanol or high fructose corn syrup isn't always the same kind of corn grown for human consumption, or hay and other grains grown to feed cattle, sheep, pigs, and chickens).

There are also extra inefficiencies due to greenhouses, orchards and the like that take up a lot of space for little resultant plant matter, and I don't know if you checked but if that figure accounts for cattle grazing that in addition to needing land for food to be grown for them also requires land for them to occupy and live in until they are slaughtered.

I'm not saying you're wrong, just more that your figure puts a minimal upper bound on the amount of land needed to feed a human rather than placing a minimal lower bound on it.

8 bushels (400 lbs) of corn/maize per human year for pure calories.

200 bu/acre yield for corn/maize nowadays, so

25 people supported by an acre of industrial agriculture.

43560 sq ft in an acre.

Intensive dirt farming would require 2000 sq ft/person, at a minimum, fudging up for protein and nutrients. Looks like a decimal error on their part.

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