USDA recommends the average no. calories per person per day is 2,500 calories (2,000 for women and 3,000 for men), of which about 50% is from carbohydrates, 22.5% from proteins, and 27.5% from fats.
This means the source of calories for a person per day is:
1,250 calories is from carbohydrates
562.5 calories is from proteins
687.5 calories is from fats
The agriculture yield per day per m2 is:
Grains (source of carbohydrates) = 1.5 calories
Meats (source of proteins) = 0.3 calories
Oils and dairy products (source of fats) = 0.4 calories
Hence, the land area needed per person per day is:
1,250 / 1.5 = 833 m2 for carbohydrates
562.5 / 0.3 = 1,875 m2 for proteins
687.5 / 0.4 = 1,718.75 m2 for fats
Total land area for producing the needed carbohydrates, proteins, and fats for one person is then 833 + 1,875 + 1,718.75 = 4,426.75 m2.
Answer: about 4,500 sq. m (or 1.11 acres) of land area needed per person.