Rest 25-33% of the land each year, ideally under a cover crop or legume rather than bare, and plan the crop acres on the remaining 67-75%. For a community of 100 that needs 41 acres of crops, resting a quarter to a third means holding 55-61 acres of arable land, since only the productive share bears the harvest.
Part of Caloric Budget for a Community
Fallow rotation is the practice of resting part of a community’s cropland each year, usually under cover plants, so that soil fertility and structure recover between crops.
Rest Costs Land That Has To Be Counted
The caloric guide lists fallow rotation among the reasons its crop acreage must be doubled: 25-33% of land resting each year. Its sample plan holds 15-20 acres in fallow and rotation out of 91-128 acres in total.
Worked Example: The Land Cost Of Fallow
- For a community of 100, if a fraction f of arable land rests, the productive share is 1 − f. A quarter resting leaves 0.75 (75%); a third leaves 0.667 (the three-field system in Three-Field Calendar raises productive land from 50 to 67 percent).
- To grow 41 acres of crops (102.2 million kcal ÷ 2.5 million per acre = 40.9): 40.9 ÷ 0.75 = 54.5 acres of arable land, or 40.9 ÷ 0.667 = 61.4 acres. That is 55-61 acres.
- Check against the plan: its crop rows total 51-68 acres, and 25% to 33% of that is 12.8 to 22.4 acres (51 × 0.25 = 12.75; 68 × 0.33 = 22.4), which brackets the plan’s 15-20 acres of fallow.
- The cost: fallow adds 33% (1 ÷ 0.75 = 1.33) to 50% (1 ÷ 0.667 = 1.5) to the land for the same crop acres.
What Recovery Needs
True fallow means no harvestable crop at all, not just bare soil; with cover crops and timed cultivation it restores soil instead of just resting it (Fallow Management). A green fallow replaces bare soil with an actively growing cover crop, often the single most cost-effective soil improvement, needing only seed (Green Fallow, Cover Crops). Legumes fix 50-200 kg of nitrogen per hectare through their root nodules, according to the crop-rotation guide (Crop Rotation), so a legume year replaces some of what grain years remove. Manure and compost also restore fertility (Animal Manure).
What You Need
- A plot map and the number of plots equal to the years in your cycle (Field Division for Rotation)
- Cover crop or legume seed
- Grazing or mowing control for the resting plots
- Records of which plot was in what, for each year
Method: Run A Rotation
Step 1: Divide the arable land into as many plots as the cycle has years. Step 2: Put one plot to fallow, planted to a cover crop or legume, each year. Step 3: Move crops so that no plot hosts the same crop family in consecutive years (Crop Families and Rotation Logic). Step 4: Count the land cost with the formula above before you fix the plot sizes. Step 5: Measure yields on each plot to see whether fertility is holding.
Common Mistakes
- Fallow as idleness. Bare soil loses topsoil and nutrients.
- Forgetting the land cost in the plan. A 41-acre crop plan is a 55-61-acre arable plan.
- Putting the same crop family back too soon. Pests and diseases build up.
What’s Next
- Learn next: Buffer for Crop Failure and Pests — the next claim on the land
- Combine with: Land Allocation Planning — where fallow sits in the plan