| name | prepare-soil |
| description | Assess and improve garden soil through testing, amendment, composting, and biodynamic preparations. Covers jar test, spade test, earthworm count, amendment by soil type (clay, sandy, depleted, compacted), composting methods (hot, cold, vermicomposting), no-till practices, cover cropping, and biodynamic preparations 500-508. Use when starting a new garden bed, when plants underperform despite adequate water and light, when transitioning to organic or biodynamic practice, when soil has become compacted or depleted, or when building a composting system.
|
| license | MIT |
| allowed-tools | Read |
| metadata | {"author":"Philipp Thoss","version":"1.0","domain":"gardening","complexity":"intermediate","language":"natural","tags":"gardening, soil, compost, biodynamic, amendment, no-till, cover-crop"} |
Prepare Soil
Assess soil condition and build healthy, living soil through amendment, composting, and biological activation.
When to Use
- You are starting a new garden bed and need to assess the existing soil
- Your plants are underperforming despite adequate water and light (soil is the likely cause)
- You want to transition from conventional to organic or biodynamic practice
- Soil has become compacted, depleted, or hydrophobic
- You need to build a composting system
- You want to apply biodynamic preparations (500-508)
Inputs
- Required: Access to the soil to be assessed (garden bed, field, or container)
- Optional: Current soil test results (pH, N-P-K, organic matter %)
- Optional: Garden history (previous crops, amendments applied, years cultivated)
- Optional: Target crops or plants to be grown
- Optional: Approach preference (organic, biodynamic, permaculture)
Procedure
Step 1: Assess the Soil
Three field tests that require no laboratory — do all three.
Test 1: Jar Test (Texture — Sand/Silt/Clay Ratio)
1. Fill a quart jar 1/3 full with soil from 15cm depth
2. Fill to top with water, add 1 tablespoon dish soap
3. Shake vigorously for 3 minutes, then set on level surface
4. Read layers after settling:
- Sand settles in 1 minute (bottom layer)
- Silt settles in 4-6 hours (middle layer)
- Clay settles in 24-48 hours (top layer)
5. Measure each layer as % of total soil depth
- Ideal garden soil: ~40% sand, ~40% silt, ~20% clay (loam)
Test 2: Spade Test (Structure and Compaction)
1. Push a spade into moist soil to full depth (25cm)
2. Lever up a block of soil and place on a board
3. Observe:
- Crumbles easily → good structure
- Breaks into angular blocks → compacted
- Smears or is sticky → too much clay or waterlogged
- Layers visible → hardpan or plough pan present
4. Smell the soil:
- Sweet, earthy → healthy aerobic biology
- Sour, sulphurous → anaerobic conditions (drainage problem)
Test 3: Earthworm Count (Biological Activity)
1. Dig a 30cm × 30cm × 30cm cube of soil
2. Place on a tarp or board
3. Gently break apart and count earthworms
- 0-5: Poor biology — needs organic matter
- 5-10: Fair — improving but not yet thriving
- 10-20: Good — healthy biological activity
- 20+: Excellent — this soil is alive
Expected: Clear picture of soil texture, structure, and biology. A jar test result, a structure rating, and a worm count.
On failure: If jar test layers are hard to distinguish, repeat with cleaner water and more vigorous shaking. If worm count is zero and soil smells sour, the soil may be anaerobic — drainage must be addressed before amendment.
Step 2: Diagnose and Plan Amendment
Match your assessment to an amendment plan.
Amendment by Soil Type:
┌────────────────┬─────────────────────────┬──────────────────────────────┐
│ Diagnosis │ Symptoms │ Amendment │
├────────────────┼─────────────────────────┼──────────────────────────────┤
│ Heavy clay │ Sticky, slow drainage, │ Gypsum (calcium sulfate) │
│ │ >40% clay in jar test │ 1 kg/m², worked into top │
│ │ │ 15cm. Add coarse compost. │
│ │ │ Plant daikon radish to break │
│ │ │ hardpan biologically. │
├────────────────┼─────────────────────────┼──────────────────────────────┤
│ Sandy │ Drains instantly, won't │ Compost 5-10cm thick, worked │
│ │ hold moisture, <20% │ into top 20cm. Add biochar │
│ │ silt+clay in jar test │ (pre-charged with compost │
│ │ │ tea) for moisture retention. │
├────────────────┼─────────────────────────┼──────────────────────────────┤
│ Depleted │ Pale colour, low worm │ 10cm compost top-dress. │
│ │ count, poor growth │ Cover crop (legume mix) for │
│ │ despite watering │ nitrogen fixation. Foliar │
│ │ │ seaweed spray monthly. │
├────────────────┼─────────────────────────┼──────────────────────────────┤
│ Compacted │ Angular blocks in spade │ Broadfork (not rototiller) │
│ │ test, surface pooling, │ to fracture without │
│ │ hard when dry │ inverting. Deep mulch (15cm │
│ │ │ wood chips on paths). Plant │
│ │ │ deep-rooted comfrey. │
├────────────────┼─────────────────────────┼──────────────────────────────┤
│ Acidic (pH<6) │ Blueberries thrive but │ Wood ash (light application) │
│ │ brassicas struggle │ or dolomite lime. Test pH │
│ │ │ before and after — adjust │
│ │ │ slowly over 2 seasons. │
├────────────────┼─────────────────────────┼──────────────────────────────┤
│ Alkaline (pH>7)│ Iron chlorosis (yellow │ Elemental sulphur or acidic │
│ │ leaves, green veins) │ compost (pine needles, oak │
│ │ │ leaves). Very slow to shift. │
└────────────────┴─────────────────────────┴──────────────────────────────┘
Expected: A specific amendment plan matched to the diagnosed soil condition.
On failure: If multiple conditions overlap (e.g., heavy clay AND depleted), address structure first (gypsum + broadfork), then biology (compost + cover crop). Trying to fix everything at once overwhelms the soil.
Step 3: Build Compost
Choose a method based on available space, materials, and timeline.
Composting Methods:
┌────────────────┬──────────────┬──────────────┬─────────────────────────┐
│ Method │ Time to │ Space Needed │ Best For │
│ │ Finished │ │ │
├────────────────┼──────────────┼──────────────┼─────────────────────────┤
│ Hot compost │ 4-8 weeks │ 1m³ minimum │ Large gardens, weed │
│ │ │ │ seed / disease kill │
├────────────────┼──────────────┼──────────────┼─────────────────────────┤
│ Cold compost │ 6-12 months │ Any size │ Low effort, small │
│ │ │ │ quantities │
├────────────────┼──────────────┼──────────────┼─────────────────────────┤
│ Vermicompost │ 3-6 months │ 0.5m² indoor │ Kitchen scraps, indoor │
│ │ │ │ / apartment gardens │
└────────────────┴──────────────┴──────────────┴─────────────────────────┘
Hot Compost Protocol:
1. Build pile in layers — 2 parts brown (carbon) to 1 part green (nitrogen)
- Brown: dried leaves, straw, cardboard, wood chips
- Green: kitchen scraps, fresh grass, manure, coffee grounds
2. Moisten each layer (damp sponge consistency)
3. Pile must be at least 1m × 1m × 1m to reach temperature
4. Internal temperature should reach 55-65°C (130-150°F) within 3-5 days
5. Turn pile when temperature drops below 45°C (every 5-7 days)
6. After 3-4 turns, cure for 2-4 weeks without turning
7. Finished compost: dark, crumbly, smells like forest floor, no recognizable inputs
Never Compost:
- Meat, dairy, oils (attract pests)
- Diseased plant material (unless hot compost reaches 60°C+ for 3 days)
- Treated wood, glossy paper
- Pet waste (pathogen risk)
Expected: Composting system established and first batch in progress.
On failure: If hot compost won't heat up: check moisture (too dry or too wet), check C:N ratio (add more green for nitrogen), check pile size (below 1m³ won't heat reliably).
Step 4: Apply No-Till and Cover Cropping
Protect and build soil structure without inversion.
No-Till Sheet Mulching (New Bed from Lawn or Weeds):
1. Mow or scythe existing vegetation as low as possible
2. Layer cardboard (overlapping edges) directly on ground — no gaps
3. Wet cardboard thoroughly
4. Add 5cm compost on top of cardboard
5. Add 10-15cm organic mulch (straw, wood chips, leaves)
6. Wait 3-6 months (autumn application → spring planting)
7. Plant through mulch by pulling it aside — do not till
Cover Crop Quick Reference:
┌─────────────────┬────────────────┬───────────────────────────────┐
│ Crop │ Season │ Benefit │
├─────────────────┼────────────────┼───────────────────────────────┤
│ Crimson clover │ Autumn sow │ Nitrogen fixation, bee forage │
│ Winter rye │ Autumn sow │ Biomass, weed suppression │
│ Buckwheat │ Summer sow │ Fast cover, phosphorus mining │
│ Phacelia │ Spring/autumn │ Pollinator magnet, breaks up │
│ │ │ compaction │
│ Daikon radish │ Autumn sow │ Deep root breaks hardpan, │
│ │ │ decomposes in place over │
│ │ │ winter (bio-drill) │
└─────────────────┴────────────────┴───────────────────────────────┘
Terminate cover crops by:
- Crimp and roll (best — leaves roots in place)
- Scythe and lay as mulch
- Never rototill — this destroys the soil structure you're building
Expected: Soil protected year-round, biology undisturbed, organic matter increasing.
On failure: If cover crop fails to establish, check sowing depth (most need surface or shallow sowing) and moisture. Resow or apply thick mulch as substitute ground cover.
Step 5: Biodynamic Preparations (Optional — Advanced)
For practitioners following Demeter or biodynamic principles.
Biodynamic Preparations Overview:
┌──────┬───────────────┬──────────────────────┬─────────────────────────┐
│ Prep │ Material │ Application │ Purpose │
├──────┼───────────────┼──────────────────────┼─────────────────────────┤
│ 500 │ Horn manure │ Spray on soil, │ Stimulate soil biology, │
│ │ │ autumn & spring │ root growth, humus │
├──────┼───────────────┼──────────────────────┼─────────────────────────┤
│ 501 │ Horn silica │ Spray on foliage, │ Light metabolism, fruit │
│ │ │ morning, summer │ quality, ripening │
├──────┼───────────────┼──────────────────────┼─────────────────────────┤
│ 502 │ Yarrow │ Added to compost │ Sulphur and potassium │
│ 503 │ Chamomile │ Added to compost │ Calcium, stabilizes N │
│ 504 │ Stinging nettle│ Added to compost │ Iron, stimulates soil │
│ 505 │ Oak bark │ Added to compost │ Calcium, disease resist │
│ 506 │ Dandelion │ Added to compost │ Silica, light forces │
│ 507 │ Valerian │ Sprayed on compost │ Warmth, phosphorus │
├──────┼───────────────┼──────────────────────┼─────────────────────────┤
│ 508 │ Horsetail tea │ Spray on foliage │ Fungal disease prevent │
└──────┴───────────────┴──────────────────────┴─────────────────────────┘
Preparation 500 Application:
1. Stir 100g horn manure in 35 litres warm water
2. Stir dynamically for 1 hour — create vortex, reverse, create vortex
(alternating direction every minute)
3. Apply within 1 hour of stirring
4. Spray in large droplets on soil surface — late afternoon, descending moon
5. Apply autumn (before winter) and early spring (before sowing)
Note: Biodynamic preparations are available from certified suppliers
or local biodynamic farming groups. Making your own requires the
previous season's preparations and specific animal horn sheaths.
Expected: Preparations applied at correct time and moon phase. Soil biology activation visible over 1-2 seasons.
On failure: If preparations are unavailable, good compost and cover cropping achieve 80% of the biological benefit. Preparations enhance but are not a substitute for sound soil management.
Step 6: Heal Checkpoint — Post-Amendment Assessment
Six weeks after amendment, reassess the soil.
Post-Amendment Soil Health Check:
1. Repeat the spade test:
- Has structure improved? (Crumbles more easily)
- Are roots penetrating deeper?
- Any remaining hardpan layers?
2. Repeat the earthworm count:
- Has the count increased? (Even 2-3 more is progress)
- Are worms distributed through the depth or just at surface?
3. Drainage test:
- Dig a 30cm hole, fill with water, let drain, refill
- Second fill should drain within 1-4 hours
- <1 hour: very free draining (may need more organic matter)
- >4 hours: still compacted or clay-heavy (continue treatment)
4. Surface observation:
- Fungal threads visible in mulch layer? (Good — decomposition active)
- Green algae on surface? (Too wet or too compacted)
- Mulch layer breaking down? (Biology is working)
Triage:
- All improving → Continue current approach, reassess next season
- Structure improved but worms low → Add more diverse organic matter
- Worms present but drainage poor → Broadfork again, add coarse material
- No improvement → Soil may have contamination — consider lab test for heavy metals
Expected: Measurable improvement in at least 2 of 3 indicators (structure, biology, drainage).
On failure: If no improvement after 6 weeks, the issue may be deeper than topsoil amendment can address. Consider raised beds with imported soil mix as a parallel strategy while continuing to improve the in-ground soil over multiple seasons.
Validation Checklist
Common Pitfalls
- Adding without testing: Random amendments waste money and can worsen imbalances. Always test first
- Rototilling: Feels productive but destroys soil structure, kills earthworms, and brings weed seeds to surface. Use a broadfork if you must loosen
- Bare soil: Exposed soil loses moisture, structure, and biology. Always mulch or plant cover crops
- Fresh manure on beds: Burns roots and introduces pathogens. Compost all manure for at least 6 months before soil contact
- Lime without testing pH: Overliming makes nutrients unavailable. Only adjust pH based on actual test results
- Expecting instant results: Soil building is measured in seasons and years, not weeks
Related Skills
cultivate-bonsai — Bonsai soil mix (akadama/pumice/lava) is a specialized soil preparationplan-garden-calendar — Soil amendment timing aligns with seasonal calendar (autumn for lime, spring for compost)read-garden — Soil observation is part of the garden reading protocolheal — Post-amendment assessment follows the heal triage patternforage-plants — Understanding soil-plant relationships aids wild plant habitat readingmake-fire — Wood ash from fire is a traditional soil amendment (potassium + lime)
