A rotation cycles nutrients by following nitrogen-fixing legumes with the crops that need the most nitrogen, then lighter feeders, and by alternating deep-rooted and shallow-rooted crops and returning residues to the soil. The nitrogen credit from a legume depends on whether its residue is returned: a bean crop harvested for its seed removes much of what it fixed.
Nutrient cycling through rotation is the ordering of crops so that what one leaves in the soil supports the next.
The Carrier’s Order, And What It Assumes
The carrier orders the four-bed cycle by fertility: legumes fix nitrogen and enrich the soil for the brassicas that follow; brassicas leave moderate fertility for solanaceae; solanaceae are moderate feeders, followed by light-feeding roots. The idea is sound: put the greediest crop where the soil is richest and the least demanding where it is poorest (Crop Rotation for Disease Break).
Two caveats. First, feeding classes differ by source: tomato is often classed as a heavy feeder, though the carrier calls solanaceae moderate. Judge by your yields and soil tests. Second, a legume’s nitrogen credit is real only if the residue goes back to the soil. Beans and peas grown for dry seed carry much of their nitrogen out in the seed. The Phase 2 guides give the nitrogen a legume fixes (Nitrogen Fixation, Cover Crops); a legume green manure, dug in before seed, returns the most.
Four Levers
| Lever | How a rotation uses it |
|---|---|
| Nitrogen | Legumes first; hungry crops next |
| Rooting depth | Alternate deep roots (some brassicas, carrots, corn) with shallow roots (lettuce, onion) so the whole soil profile is used and pulled up |
| Residue | Return straw, crop remains and compost; leaves on the bed feed the next crop |
| Soil cover | Follow a harvested bed with a cover crop rather than bare soil (Fallow Rotation and Soil Recovery) |
Method
Step 1: Class your crops as heavy, moderate or light feeders from your own observation: which crops fail when the soil is poor, and which don’t.
Step 2: Put compost or manure where the heavy feeders go. Add it to the bed before the heaviest crop, not after.
Step 3: Follow heavy feeders with moderate ones and then light ones, and end with a legume or a cover crop.
Step 4: Match the gap years to disease needs (Family-Based Rotation Schedules); fertility and disease can pull in different directions, and disease is usually the stricter limit.
Step 5: Record yields by bed. If a bed under a family yields poorly two years running, test its fertility and pH before blaming the weather.
Compost Moves Nutrients Between Beds
A rotation does not create nutrients; it spends what the soil, the legumes, the compost and the manure supply. Composting returns plant remains and household waste to the beds (Composting). Compost from diseased plants should not be spread on clean beds (Sanitation and Quarantine Protocols).
Common Mistakes
- Counting a legume’s nitrogen when you took the seed away.
- Following brassicas with brassicas to “use up” the fertility. It builds disease.
- Overfeeding. Too much nitrogen gives soft growth that pests and mildew prefer.
- Leaving beds bare after harvest. Nutrients wash out and weeds move in.
What’s Next
- Learn next: Nitrogen-Fixing Companions — more sources of nitrogen
- Combine with: Soil Fertility — the nutrients themselves