This time last year I gave a talk in Clonakilty on How much space we need to grow enough food for ourselves. I meant to put these diagrams up before now but didn't quite get around to it. they are based on some fairly sketchy research mostly from the internet and are probably not very accurate. The first one shows the yield per ha of some basic foods grown without artificial manure. The beef figures are based on a grass only diet.
This next one shows the amount of each food type needed to give 2700cals or enough food for a person for a day. Its a lot of cabbage.
This one shows the price per kg of the same foods.
This one shows the price of a million calories of each which is the number of calories an adult would need per year.
And finally the number of sq meters needed to grow a years supply of food for one person eating a diet of 40% cereals, 5% pulses, 30% fruit and veg, 20% nuts, meat and dairy, and 5% oil.