Very rough calculations... Please check
If you go by the standards of Ireland circa 1845, you can get about 6 tons of potatoes per acre (say 15 tons per hectare). That's UK tons - which is 'nearly' 1000kg
The average person needs 2.5 kg of food per day (very approximately). So let's assume that each hectare gives 6000 man-days of food.
To feed 40 000 for 1 year, you need 40 000 x 365 man-days of food = 14.6 million man-days
Therefore, you need 2 500 hectares = 25 square kilometres = You need a fertile space about 5 kilometres by 5 kilometres
Central Park is 3.4 km2
edited - hectares bigger than acres
If you go by the standards of Ireland circa 1845, you can get about 6 tons of potatoes per acre (say 15 tons per hectare). That's UK tons - which is 'nearly' 1000kg
The average person needs 2.5 kg of food per day (very approximately). So let's assume that each hectare gives 6000 man-days of food.
To feed 40 000 for 1 year, you need 40 000 x 365 man-days of food = 14.6 million man-days
Therefore, you need 2 500 hectares = 25 square kilometres = You need a fertile space about 5 kilometres by 5 kilometres
Central Park is 3.4 km2
edited - hectares bigger than acres
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