S4ag Composting

---
name: s4ag-composting
description: "Make good compost and use it well. Use when someone asks about composting methods, worm farms, bokashi, compost tea, how to apply compost, or says 'I want to build my soil biology cheaply'."
allowed-tools: [Read]
---

# Composting

Compost is the most direct tool you have for building soil biology — but only if you understand what you are actually making. A hot compost pile finished correctly is not a fertiliser; it is a biological inoculant that reintroduces organisms the food web needs to function. The method you choose determines the organisms you produce, and the organisms you produce determine what the compost does in the soil.

**How this skill works:** Each sub-tool pauses at a **Checkpoint** to confirm the assumptions it is about to build on before producing output. A recommendation built on a wrong assumption wastes time and money — confirm the checkpoint before acting. Each sub-tool ends with **Next steps** — the skills worth running once you have acted on this one.

---

## Expert Lineage

*The thinkers whose frameworks underpin this skill — and what they specifically discovered that changes how you farm.*

**Elaine Ingham — Compost as Biological Inoculant**
Ingham established that the goal of composting is not to produce nutrients but to produce organisms. The critical variables are: C:N ratio (high C:N, above 30:1, produces fungal-dominated compost suitable for perennials and trees; low C:N, below 20:1, produces bacterial-dominated compost suitable for annuals and vegetables); oxygen and moisture levels during thermophilic phase; and cooling time before application. Her most actionable finding: compost applied to soil at the wrong biological stage can suppress rather than stimulate the food web. Aerated compost tea made from good compost can achieve bacterial populations of 10^9/ml and fungal hyphal lengths of 10–40m/g — inoculant quality at almost zero cost.

**William Brinton — Compost Quality Research**
Brinton at Woods End Laboratories developed the most rigorous framework for assessing finished compost quality. His key finding: maturity and stability are separate variables. A compost can be mature (thermophilic phase complete) but unstable (still actively decomposing and consuming oxygen); applying unstable compost ties up soil nitrogen and damages seedlings. His Solvita test measures CO₂ and ammonia release as proxies for stability. The practical implication: rest compost for at least four weeks after the temperature drops before applying it to crops.

**Mary Appelhof — Vermicomposting Systems**
Appelhof's research established the feeding rate, bedding requirement, and harvest methodology that makes vermicomposting reliable at household and small farm scale. Her specific finding: worm castings have a consistently high bacterial population and measurable plant-growth-promoting hormones (auxins and cytokinins) that hot compost does not. Castings are not interchangeable with hot compost — they are most valuable as a seed germination medium and transplant amendment rather than a bulk soil amendment.

**Jeff Lowenfels — Rhizosphere Connection**
Lowenfels established the mechanism by which compost additions improve plant performance: the organisms introduced by compost re-establish the rhizosphere community, which then exchanges nutrients with the plant root directly. This is why compost applied to the soil surface above roots outperforms compost incorporated — it reintroduces biology at the point where root exudates are concentrated, rather than burying it in a zone of less biological activity.

**Cho Han-kyu — Bokashi as Fermentation, Not Decomposition**
Cho's Korean Natural Farming system developed bokashi not as compost but as a fermented pre-compost. The distinction matters: bokashi does not decompose material — it ferments and preserves it. The fermented material then breaks down rapidly when buried in soil, feeding bacterial populations. Cho's finding: bokashi is the correct tool for processing high-protein waste (meat, dairy, cooked food) that would putrefy in a conventional compost pile, not the correct tool for producing biology-rich soil amendment directly.

---

## Which tool fits

| You need to... | Tool |
|---|---|
| Build a hot compost pile that kills pathogens and weed seeds | hot-composting |
| Set up a worm system for castings and leachate | vermicomposting |
| Process kitchen scraps including meat and dairy | bokashi |
| Make a liquid biological inoculant to spray on soil or crops | compost-tea |
| Decide when, where, and how much compost to apply | application |

## Routing Decision

- **Have organic matter (manure, straw, crop residues) and want to process it well** → hot-composting
- **Small-scale, household, or indoor waste stream** → vermicomposting
- **Processing cooked food, meat, or dairy** → bokashi
- **Want to multiply the biological value of good compost for large-area application** → compost-tea
- **Have compost already, unsure how to get the most from it** → application
- **Unclear — haven't started composting yet** → hot-composting first; it handles the largest volume

---

## Hot Composting

*Builds a thermophilic compost pile that kills pathogens and weed seeds while producing fungal or bacterial compost depending on C:N ratio.*

Hot composting is the foundation of an on-farm composting system. Done correctly, it processes large volumes of farm waste — manure, straw, crop residues, wood chip — into finished compost in 6–12 weeks. The thermophilic phase (55–65°C) kills weed seeds and pathogens. The cooling and curing phase produces the biology you are after.

### C:N Ratio — Choose Your Compost Type

The C:N ratio of your pile determines the dominant biology in the finished product.

| Target | C:N Range | Bulking Ingredient | Result |
|---|---|---|---|
| Bacterial compost (annuals, vegetables) | 15–25:1 | Fresh manure, kitchen scraps, green material | Fast-cycling N-rich biology |
| Balanced compost (general use) | 25–35:1 | Straw + manure mix | General-purpose biological inoculant |
| Fungal compost (perennials, trees, shrubs) | 35–60:1 | Wood chip, straw, paper, dry leaves | Fungal networks; mulch-style application |

**Common materials and their approximate C:N ratios:**

| Material | C:N |
|---|---|
| Fresh grass clippings | 15:1 |
| Food scraps (mixed) | 15–20:1 |
| Fresh animal manure (cattle) | 20:1 |
| Straw (wheat, oat) | 80–100:1 |
| Wood chip (fresh hardwood) | 400–500:1 |
| Dry leaves | 60–80:1 |
| Sawdust | 300–500:1 |

### Building the Pile

**Minimum size:** 1m × 1m × 1m. Smaller piles lose heat too quickly to reach thermophilic temperatures.

**Layer method (works on any scale):**
1. Base layer: coarse woody material (15cm) — creates airflow
2. Brown layer: high-C material (straw, wood chip) — 15–20cm
3. Green layer: high-N material (manure, food scraps, green plant material) — 10–15cm
4. Water each layer until damp but not waterlogged (squeeze test: a handful should yield 1–2 drops)
5. Repeat layers until pile reaches 1–1.5m height
6. Cover with a final brown layer to reduce nitrogen loss and fly pressure

**Moisture target:** 50–60% moisture. Too wet → anaerobic, putrid smell. Too dry → no biological activity, pile stays cool.

### Managing the Thermophilic Phase

- Temperature should reach 55–65°C within 3–5 days.
- Below 50°C: pile is not heating — check moisture and C:N ratio.
- Above 70°C: turn immediately — temperatures above 70°C kill the biology you are trying to build.
- **Turn the pile when temperature drops below 50°C** — typically every 5–7 days in the active phase.
- Four to six turns over four to six weeks is standard for a well-managed pile.
- Each turn reintroduces oxygen and moves outer material (unprocessed) to the hot interior.

### Assessing Readiness

Finished compost:
- Smells earthy, not ammonia or putrid
- Temperature no longer rises after turning
- Original materials are no longer recognisable (except woody chunks)
- Dark brown, crumbly texture

**Stability test (Brinton):** Seal a small sample in a jar for 24 hours. No temperature rise and no strong odour = stable. If temperature rises or it smells of ammonia, rest it another 2–4 weeks before applying.

### Windrow Composting (Farm Scale)

For large volumes (livestock operations, market gardens):
- Build windrows 1.5–2m wide, 1–1.5m high, any length
- Turn with a tractor bucket or windrow turner
- Same temperature and moisture management applies
- Finished in 8–12 weeks with active management

**Checkpoint — confirm before finalising:**
- What materials are available on-farm (manure type, crop residues, wood chip)? The C:N ratio is set by what is accessible, not the ideal.
- What is the intended crop — annual vegetables, perennial fruits, trees, or pasture? This determines whether to aim for bacterial or fungal-dominated compost.
- Is pathogen kill required (e.g., processing sewage sludge, or using in certified organic production)? This requires a documented thermophilic cycle and may have regulatory requirements.

A recommendation that specifies a fungal compost recipe for a market gardener growing annual vegetables, or a bacterial recipe for an orchard, works against the biology the farmer is trying to build.

**Output:**
```
HOT COMPOST RECIPE
Target: [bacterial / balanced / fungal]
Crops this will serve: [crop type]

MATERIALS
Brown (high C): [material] — [volume or weight]
Green (high N): [material] — [volume or weight]
Water: [estimated litres to add]

PILE DIMENSIONS: [width × length × height]
Target C:N ratio: [ratio]

MANAGEMENT SCHEDULE
Day 1: Build pile — target temperature by Day [3–5]
Day [5–7]: Turn #1 — target temp [55–65°C]
Day [10–14]: Turn #2
Day [15–21]: Turn #3
Day [22–30]: Turn #4 (if needed)
Day [35–42]: Temperature stable — begin curing phase
Curing period: [2–4 weeks]

READINESS DATE: [estimated date]

FINISHED QUANTITY ESTIMATE: [approx. cubic metres or tonnes]
```

**Next steps:**
- Run **compost-tea** (within this skill) to multiply the biological value for large-area foliar or soil application.
- Run **application** (within this skill) to decide when, where, and how much to apply.
- `/s4ag-soil` — run test-interpretation to confirm which biology — fungal or bacterial — the soil needs most.

---

## Vermicomposting

*Sets up and manages a worm system to produce castings and leachate for high-value biological applications.*

Worm castings are not a substitute for hot compost — they are a different product for different uses. Castings are rich in plant-growth-promoting compounds (auxins, cytokinins), have a consistent bacterial population, and are most valuable applied in small quantities close to seeds and transplant roots. One litre of castings used as a seed germination medium or transplant amendment delivers more measurable plant benefit than ten litres applied as a bulk soil dressing.

### System Types

| System | Scale | Best For | Harvest Method |
|---|---|---|---|
| Stacked tray system (Worm Farm/Can-O-Worms) | Household to small market garden | Kitchen scraps, coffee grounds, vegetable trimmings | Trays processed from bottom up |
| Single bin | Household | Kitchen scraps only | Divide and harvest by hand |
| Windrow (outdoor) | Farm scale | Large volumes of pre-composted organic matter | Harvest from one end as worms migrate to fresh material |
| Continuous flow reactor | Commercial scale | Consistent large-volume waste stream | Harvest from bottom |

### Species Selection

**Eisenia fetida (red wigglers)** — the standard composting worm. Tolerates wide temperature range, processes material quickly, reproduces rapidly. Not a soil worm — it needs the organic-rich environment of a worm bed. Do not confuse with Lumbricus terrestris (earthworm), which lives in soil and cannot be farmed in a bin system.

### Setting Up

1. **Bedding:** Tear newspaper or cardboard into strips; dampen until damp but not dripping. Fill bin to two-thirds.
2. **Worm density:** 500g worms per square metre of surface area is a reasonable starting density.
3. **Feeding rate:** Start conservatively — 50% of the worm weight per day maximum. Overfeeding causes anaerobic rot and kills worms.
4. **Temperature:** Optimal 15–25°C. Below 10°C: worms slow dramatically. Above 35°C: worms die. Insulate outdoor systems in cold climates.
5. **Feeding materials:** Fruit and vegetable scraps, coffee grounds and filters, tea bags (no staples), crushed eggshell (buffers pH). Avoid citrus in large quantities, onion and garlic, salty food, oily food, meat, and dairy (these belong in bokashi).

### Harvesting Castings

**Tray system:** Simply move the top tray (fresh food) to the bottom and harvest the processed bottom tray when it is fully converted to dark, crumbly castings.

**Single bin:** Push all material to one side, add fresh bedding and food to the empty side. Worms migrate to the food over 4–6 weeks. Harvest the vacated side.

**Windrow:** Add fresh material to one end. Harvest from the opposite end after 8–12 weeks.

### Leachate (Worm Tea)

The liquid that drains from a worm system is often called "worm tea" but is technically leachate — it has variable and generally much lower biological value than aerated compost tea. Dilute 10:1 with water before applying to plants. If it smells unpleasant, it has gone anaerobic — do not use it on edible crops.

### High-Value Applications for Castings

- **Seed germination:** 20–30% castings in germination mix dramatically improves germination rates and seedling vigour.
- **Transplant amendment:** A handful of castings in each transplant hole for vegetables, fruit trees, and shrubs.
- **Potting mix:** Up to 20% castings in a potting mix; above this, castings can suppress germination.
- **Compost tea base:** Castings produce the highest-quality aerated compost tea — the bacterial and fungal populations are already concentrated.

**Checkpoint — confirm before finalising:**
- What is the primary waste stream going into the system (kitchen scraps, market garden trimmings, something else)? This determines the C:N ratio of the worm diet and the quality of the castings.
- What is the intended use — seed germination, transplant amendment, or bulk application? The quantity needed is very different for each.
- What is the ambient temperature range? Outdoor vermicomposting in a cold climate requires significant insulation or indoor siting.

Recommending a large outdoor windrow system to someone in a cold climate without noting the temperature constraint, or recommending vermicomposting as a bulk soil amendment solution, will both fail in practice.

**Output:**
```
VERMICOMPOSTING SYSTEM RECOMMENDATION
System type: [stacked tray / single bin / windrow / continuous flow]
Worm species: Eisenia fetida
Starting quantity: [kg worms]
Surface area: [m²]

BEDDING
Material: [newspaper / cardboard / coco coir]
Moisture: Damp (1–2 drops when squeezed)

FEEDING SCHEDULE
Daily maximum: [kg per day]
Materials: [approved materials list]
Avoid: [prohibited materials for this situation]

TEMPERATURE MANAGEMENT
[any insulation or siting notes for the climate]

HARVEST SCHEDULE
First harvest: [estimated weeks from setup]
Method: [harvest method for this system type]

PRIMARY USE FOR CASTINGS
[seed germination / transplant amendment / compost tea base]
Application rate: [rate and method]
```

**Next steps:**
- Run **compost-tea** (within this skill) — castings are the highest-quality base material for aerated compost tea.
- Run **application** (within this skill) — castings applied incorrectly deliver little benefit; placement and timing matter.
- `/s4ag-vegetables` — vermicomposting integrates well with market garden systems; connect to crop planning.

---

## Bokashi

*Ferments organic waste — including meat and dairy — as a pre-compost input for rapid soil breakdown.*

Bokashi is a fermentation process, not decomposition. The material that comes out of a bokashi bucket is not finished compost — it is fermented waste that will decompose rapidly once it contacts soil microorganisms. Its primary value is processing waste streams that conventional composting cannot handle: cooked food, meat, fish, dairy, and citrus. For farms and households producing this kind of waste, bokashi is the correct tool. For farms dealing primarily with manure, straw, and crop residues, hot composting is more appropriate and lower cost.

### How Bokashi Works

Bokashi bran — wheat bran, rice bran, or sawdust inoculated with effective microorganisms (primarily lactic acid bacteria, yeasts, and phototrophic bacteria) — is layered with food waste in an airtight container. The fermentation that results is anaerobic and acidic. The acidic environment preserves the material, prevents putrefaction, and kills most pathogens. When the fermented material is buried in soil, the acid is neutralised by soil buffering, and decomposition proceeds very rapidly — most material breaks down in 2–4 weeks in warm soil.

### Making Bokashi Bran

Commercially produced bokashi bran is widely available and reliable. For on-farm production:

1. Mix 1 kg of effective microorganism (EM) concentrate into 10 litres of water with 1 tablespoon of molasses
2. Add this to 5 kg of wheat bran or rice bran
3. Mix thoroughly until the bran is evenly moistened — not wet
4. Seal in an airtight bag or container and ferment for 5–7 days at room temperature
5. The finished bran should smell sweet-sour (like pickles) — not putrid
6. Dry if storing longer-term; use within 3 months of making

### The Bokashi Process

1. Add 2–3cm of food waste to an airtight bucket
2. Sprinkle 1–2 tablespoons of bokashi bran over the layer
3. Press down firmly to exclude air
4. Repeat until the bucket is full
5. Seal tightly and leave for 10–14 days at room temperature
6. Finished bokashi should smell tangy and sour. Any blue or black mould indicates air got in — the batch has failed and should be buried well away from crops.

### Using Finished Bokashi

**Burial method:** Dig a trench or hole 20–30cm deep, fill with bokashi material, and cover with at least 10cm of soil. Leave for 2–4 weeks before planting over it. Do not plant directly into fresh bokashi — the acidity will damage roots.

**Compost pile addition:** Add bokashi material to an active hot compost pile as a green, nitrogen-rich layer. The fermented organic acids accelerate decomposition.

**Soil factory method:** Mix bokashi with equal parts soil in a container, seal, and allow to mature for 4 weeks. The resulting mixture is a biologically rich soil amendment that can be added directly to planting beds.

**Leachate (bokashi juice):** The liquid that accumulates in the base of a bokashi bucket is a concentrated acidic liquid. Dilute 100:1 with water before applying to soil or plants. Undiluted, it will damage plants and soil biology.

**Checkpoint — confirm before finalising:**
- Is the primary waste stream cooked food, meat, or dairy — or is it raw fruit and vegetable waste? If the latter, vermicomposting or hot composting is simpler and produces a superior product.
- Is the intention to use bokashi as a final soil amendment, or as a pre-compost step into a hot pile? The method differs.
- What is the volume of waste being processed per week? Bokashi buckets are typically 15–20 litre containers — for large volumes, multiple buckets or a larger system is needed.

Recommending bokashi as the primary composting system for a farm processing large volumes of manure and crop residues misses the point of the tool — it is the right technology for the wrong waste stream.

**Output:**
```
BOKASHI SYSTEM SETUP
Waste stream: [types of waste to process]
Volume per week: [estimated kg/week]
Bucket size needed: [litres]
Number of buckets: [n — allows rotation while one ferments]

BOKASHI BRAN SOURCE
[Commercial product recommendation / on-farm production method]

FERMENTATION CYCLE
Fill time: [estimated days per bucket]
Fermentation time: 10–14 days sealed
Ready indicator: Tangy, sour smell — no blue/black mould

DISPOSAL METHOD
[burial / compost pile / soil factory]
Distance from planting: [2–4 weeks if burial]
Burial depth: [20–30cm]

LEACHATE USE
Dilution: 100:1 with water
Application: Soil drench or drain pour (not on edible crops undiluted)
```

**Next steps:**
- Run **hot-composting** (within this skill) — bokashi material is an excellent nitrogen-rich addition to a hot compost pile.
- `/s4ag-korean-natural-farming` — KNF and bokashi share the EM fermentation tradition; the two systems complement each other for farm fertility.
- Run **application** (within this skill) — if you are burying bokashi directly, timing and placement matter.

---

## Compost Tea

*Makes an aerated compost tea (ACT) — a liquid biological inoculant that multiplies the organisms in good compost for large-area application.*

Aerated compost tea is not the same as compost leachate or manure tea. It is a specifically managed aerobic fermentation that multiplies the bacterial, fungal, and protozoan populations present in quality compost into a liquid that can be applied by sprayer over large areas. A single 200-litre brew from 2kg of excellent compost, correctly made, contains more beneficial organisms than the compost itself — the food and oxygen provided during brewing cause the populations to multiply dramatically.

Compost tea only works if the source compost is good. Tea made from low-quality or immature compost multiplies pathogens as readily as beneficial organisms. Quality source compost is not optional.

### Equipment

**Basic setup:**
- Food-grade container (20–200 litres)
- Air pump (aquarium pump for small batches; regenerative blower for 200L+)
- Airstones or diffusers (adequate to bubble vigorously throughout the container — the goal is fully aerobic conditions throughout)
- Mesh bag for compost
- Non-chlorinated water (let tap water sit in the open for 30+ minutes to off-gas chlorine, or use rainwater)

**Output target for 200L brew:**
- Dissolved oxygen: maintain above 6 mg/L throughout
- Bacteria: 10^8–10^9 colony-forming units/ml
- Fungal hyphal length: 10–40m/g material

### Brewing Protocol (Ingham Method)

| Variable | Target |
|---|---|
| Water | Non-chlorinated; 18–25°C |
| Compost | 2–4kg per 200L (quality hot compost or castings) |
| Brew time | 24–36 hours (never more than 48) |
| Aeration | Continuous; vigorous bubble throughout |
| Food additions | See table below |

**Food sources for tea:**

| Addition | Rate per 200L | Purpose |
|---|---|---|
| Unsulphured blackstrap molasses | 30–60ml | Bacterial food — fast-multiplying species |
| Kelp powder | 30ml | Fungal food; micronutrient |
| Fish hydrolysate | 30ml | Bacterial and fungal food; amino acids |
| Humic acid | 30ml | Binds organisms to soil particles on application |

**For bacterial-dominant tea** (annuals, vegetables): Increase molasses, reduce or omit kelp.
**For fungal-dominant tea** (perennials, trees, orchards): Use fungal-dominant compost as your base; omit or reduce molasses; increase kelp.

### Readiness Indicators

- Strong earthy smell (like petrichor — the smell of rain on soil)
- No sour, ammonia, or rotten smell
- Foam on the surface (from organic acids and proteins)
- Bubbles actively throughout

**Do not use** tea that smells sour, eggy, or putrid — it has gone anaerobic. Tip it away from crops, dilute heavily, and apply to a non-food area.

### Application

- Apply within 4 hours of finishing the brew — the organisms die rapidly without food and oxygen
- Apply in early morning or late evening — UV light kills many beneficial organisms within hours
- Dilute 1:5 to 1:10 with non-chlorinated water for sprayer application
- Apply at 20–40 litres per 100m² as a soil drench, or undiluted as a foliar spray
- Follow with irrigation to move organisms into the soil profile

**Checkpoint — confirm before finalising:**
- Is the source compost genuinely finished and of good quality? If uncertain, run the stability test described in hot-composting before brewing from it.
- What target — soil drench or foliar? The dilution rate and application equipment differ.
- What biology is wanted — bacterial (annual crops) or fungal (perennials and trees)? This determines the food additions and the compost source.

Compost tea made from poor compost or applied incorrectly (in midday sun, without irrigation follow-up) delivers little value and wastes time and materials.

**Output:**
```
COMPOST TEA BREW PLAN
Volume: [litres]
Source compost: [type — hot compost / castings / combination]
Target biology: [bacterial-dominant / fungal-dominant / balanced]

EQUIPMENT
Container: [litres], food-grade
Air pump: [size — aquarium pump / regenerative blower]
Diffusers: [number]
Water: [non-chlorinated source]

INPUTS
Compost: [kg]
Molasses: [ml]
Kelp: [ml]
Fish hydrolysate: [ml]
Humic acid: [ml]

BREW SCHEDULE
Start: [time]
Check at: [12 hours]
Finish: [24–36 hours from start]
Apply by: [within 4 hours of finishing]

APPLICATION
Target: [soil / foliar / both]
Dilution: [ratio]
Rate: [litres per 100m²]
Timing: [early morning / late evening]
Follow with irrigation: [yes/no and quantity]

AREA COVERED: [approx. m² or hectares from this batch]
```

**Next steps:**
- Run **application** (within this skill) — compost tea is one component of a broader application strategy.
- `/s4ag-soil` — run test-interpretation before investing in a large tea programme; understand the food web baseline first.
- `/s4ag-pests` — compost tea applied as a foliar has documented suppressive effects on some fungal diseases; understand this dimension before using it as a spray.

---

## Application

*Decides when, where, and how much compost to apply — so it goes where it can do the most good.*

Having good compost is only half the work. Compost applied at the wrong rate, in the wrong place, or at the wrong time in the crop cycle delivers a fraction of its potential. This sub-tool translates a finished compost product into a practical application plan.

### Rates by Situation

| Situation | Recommended Rate | Notes |
|---|---|---|
| Annual vegetable beds, establishing | 5–10cm surface dressing (50–100t/ha) | Highest rate — high crop demand, building OM |
| Annual vegetable beds, maintenance | 2–5cm per season (20–50t/ha) | Reduce as OM builds |
| Fruit trees and perennial beds | 5–8cm surface mulch | Apply to dripline, not trunk |
| Pasture renovation | 5–10t/ha | Broadcast or harrow in |
| Seed starting mix | 20–30% compost by volume | Castings preferred; hot compost screened fine |
| Transplant amendment | Handful per hole | Castings or high-quality mature compost |
| Compost tea drench | 20–40 litres per 100m² | Not a substitute for solid compost |

### Placement Principles

**Annual vegetables — surface application:**
Apply as a mulch dressing after planting, 2–5cm deep, keeping compost away from direct stem contact. No-dig approach: apply fresh compost at the surface and allow soil biology to incorporate it from beneath. This is Lowenfels's principle — organisms applied at the surface move to the rhizosphere where root exudates attract them.

**Fruit trees and perennials:**
Apply under the canopy to the dripline — where feeder roots are concentrated. Pull back from the trunk to prevent collar rot. 5–8cm of fungal-dominant compost as a mulch layer is the most effective application for established trees.

**Pasture:**
Broadcast application followed by rain or irrigation. Compost improves pasture most dramatically in the second and third seasons after application as biology establishes and mineralises the applied organic matter.

**Cover crop incorporation:**
If incorporating a cover crop before planting, compost applied at the surface above the incorporated material allows soil organisms to migrate through the disturbed layer rapidly, re-establishing biology after tillage.

### Timing Relative to Crop Cycle

| Timing | Effect |
|---|---|
| 4–6 weeks before planting | Best — biology establishes before crop demand |
| At planting | Good — use only mature, stable compost |
| During growing season (top-dress) | Moderate — roots can access surface biology |
| After harvest (overwintering) | Good — long curing period before spring planting |

**The stability rule:** Only stable, finished compost should be applied close to or at planting. Immature compost (still actively decomposing) consumes nitrogen from the soil as it breaks down, competing with the crop. Use Brinton's jar test to confirm stability before planting-time applications.

### Integrating with Other Inputs

Compost and synthetic fertilisers are not straightforwardly compatible. Soluble nitrogen applied to biologically active compost-amended soil suppresses the organisms you have just introduced — bacteria and fungi that fix and cycle nutrients cannot compete with plants that are spoon-fed soluble inputs. If transitioning from synthetic fertility:

1. Do not remove synthetics immediately — the crop still depends on them
2. Introduce compost at the margin first (headlands, non-commercial beds)
3. Reduce synthetic rates by 10–20% per season as OM builds
4. Allow 2–3 seasons before expecting biology to replace purchased fertility

### Quantity Estimation

**Rule of thumb for available material:**
- 1 tonne of finished compost per 100m² at 10cm depth
- A standard 200L wheelie bin of compost weighs approximately 100–120kg

**Screen before applying to seeds or seedlings:** Pass compost through a 5–6mm screen to remove woody chunks that would interfere with germination. Unscreened compost is fine for mulching around established plants.

**Checkpoint — confirm before finalising:**
- Is the compost stable and mature (passed the Brinton jar test or equivalent)? Unstable compost near crops causes nitrogen drawdown.
- What is the crop situation — establishing, maintenance, or transplanting? The rate and placement differ significantly.
- Is the farm currently using synthetic fertility alongside compost? Transition pace matters — do not recommend eliminating synthetics in one step on a productive operation.

Applying unstable compost at planting, or recommending large compost volumes without asking what the farm's current fertility system looks like, produces poor results and undermines trust in the composting approach.

**Output:**
```
COMPOST APPLICATION PLAN
Crop / situation: [crop or enterprise]
Compost type: [bacterial / fungal / balanced]
Compost maturity: [confirmed stable / estimated]

APPLICATION
Rate: [t/ha or cm depth or litres per m²]
Placement: [surface mulch / incorporated / in-row / transplant hole]
Distance from stem/trunk: [cm]
Screening required: [yes — Xmm mesh / no]

TIMING
Apply: [date or crop stage]
Relationship to planting: [weeks before / at planting / top-dress]

QUANTITY NEEDED
Area: [m² or ha]
Total compost required: [tonnes or m³]

INTEGRATION WITH EXISTING FERTILITY
Current synthetic use: [products and rates]
Compost transition approach: [reduce synthetics by X% this season / parallel application / full replacement if system is ready]

NEXT APPLICATION DATE: [season or date]
```

**Next steps:**
- `/s4ag-soil` — run fertility-planning to slot compost applications into the full fertilisation programme and credit the compost nitrogen to the crop.
- `/s4ag-seasons` — schedule application timing across the year-round crop calendar so ground is never left with depleted biology.
- `/s4ag-regenerative` — if the compost programme is part of a wider transition, use regenerative to plan the multi-season journey and the pace of input reduction.