A crop’s calorie yield per acre is its yield in pounds per acre multiplied by its calories per pound, and on hand-worked land potatoes and corn deliver about 2.5-5.25 million kcal per acre while wheat, oats and dry beans deliver roughly 0.9-2.3 million. A community of 100 needs 102.2 million kcal a year, so the choice of crop changes the land it needs by a factor of two or more.
Part of Caloric Budget for a Community
Crop calorie yield is the food energy a crop produces from one acre in a season, found by multiplying harvested weight by the energy in each unit of weight.
Calories Per Acre Is The Number That Turns A Diet Into Land
The caloric guide tabulates realistic, non-industrial yields: hand labour or animal-powered cultivation, saved seed, no synthetic fertilizer and moderate soil. The calories per pound are food-composition values; the guide gives them for its nine crops.
| Crop | Yield (lb/acre) | kcal per lb | kcal per acre (million) |
|---|---|---|---|
| Potatoes | 8,000-15,000 | 350 | 2.8-5.25 |
| Sweet potatoes | 6,000-12,000 | 390 | 2.3-4.7 |
| Corn (grain) | 1,500-3,000 | 1,650 | 2.5-5.0 |
| Wheat | 800-1,500 | 1,520 | 1.2-2.3 |
| Oats | 700-1,200 | 1,740 | 1.2-2.1 |
| Dry beans | 600-1,200 | 1,520 | 0.9-1.8 |
| Sunflower (oil) | 500-1,000 | 2,620 | 1.3-2.6 |
| Cabbage | 10,000-20,000 | 110 | 1.1-2.2 |
| Winter squash | 5,000-12,000 | 180 | 0.9-2.2 |
Check one row: potatoes 8,000 lb × 350 = 2,800,000 kcal and 15,000 × 350 = 5,250,000, which matches the 2.8-5.25 million.
Worked Example: Acres To Feed 100 People On One Crop Alone
The community need is 100 × 2,800 × 365 = 102.2 million kcal a year. Dividing by each crop’s calories per acre:
- Potatoes: 102.2 ÷ 5.25 = 19.5 acres to 102.2 ÷ 2.8 = 36.5 acres.
- Corn: 102.2 ÷ 5.0 = 20.4 to 102.2 ÷ 2.5 = 40.9 acres.
- Wheat: 102.2 ÷ 2.3 = 44.4 to 102.2 ÷ 1.2 = 85.2 acres.
- Dry beans: 102.2 ÷ 1.8 = 56.8 to 102.2 ÷ 0.9 = 113.6 acres.
These are energy-only figures: they ignore storage loss, seed, fallow, failure and animal feed, and no one eats a single crop. They show the scale: the staple choice moves the cropland from about 20 acres to over 100. The land plan that follows from this is in Land Allocation Planning.
What You Need
- Your own yield figures, from your own soil and seed; the parent’s table is a guide, and it says to track actual yields each year
- A weighing method at harvest
- A food-composition source for calories per pound of the crops you grow
- A rotation plan (Crop Rotation)
Method: Compute Your Own Table
Step 1: Record the weight harvested from each plot and its area in acres. Step 2: Convert to pounds per acre. Step 3: Multiply by the crop’s calories per pound. Step 4: Divide the community’s annual need by the result to get the acres that crop alone would require. Step 5: Combine crops in a mix; the guide uses an average of 2.5 million kcal per acre for a diversified plan.
Common Mistakes
- Comparing a fresh-weight root with a dry grain by pounds. Potatoes are mostly water, so their weight per acre is large and their calories per pound small.
- Planning from the top of the range. Use the middle and keep a margin (Buffer for Crop Failure and Pests).
- Counting calories as nutrition. A crop can supply energy and still leave a protein or vitamin gap.
What’s Next
- Learn next: Staple Grains: Wheat, Corn, Rice, Oats — the grain rows in detail
- Combine with: Root Crops — the two high-yield rows