In The High Frontier Gerard O’Neil states that to feed one person we need 65 square meters of agricultural land. Also he argues in the same book that people need 45 square meters of living space per person to live comfortably. These numbers are important for designing space settlements and here we will assume these numbers to be true.
Around 1900 Ebenezer Howard presented his influential Garden City concept. In his urban design Howard took 6,000 acres of land, 1,000 acres to be allocated for buildings and 5,000 for farms. He foresaw a population of 32,000 people.
One acre is approximately 4,000 square meters. One thousand acres will be 4 million square meters. If we divide this number by O’Neil’s 45 square meters of living space, we will see that a thousand acres allow a population of about 89,000 people. Or nearly three times as much as Howard planned.
How much agricultural land would 32,000 people need? Using O’Neil’s estimate, we will obtain a figure of 2,080,000 square meters or 520 acres. Or only ten percent of the land reserved by Howard for farming. 89,000 people would need about 1450 acres of farm land.
It should be noted that O’Neil based his figure of 65 square meter of agricultural land on the assumption that certain agricultural methods would enable four harvests per year. Polyculture, i.e. planting different crops among each other, is an essential feature of these methods.