From Cherry Waste to Carbon: How Coffee Farms Turn Pulp into Soil Fertility

Every coffee cherry processed produces waste — the pulp that surrounds the bean. On most farms, this pulp is discarded. In GAP77™, it’s the starting point of a closed-loop system that turns waste into carbon-rich soil amendments, rebuilding depleted soils while sequestering carbon for over 100 years.

The composting process

Coffee cherry waste is composted alongside banana leaves and grass in layered piles. Regular turning ensures proper aeration and accelerates decomposition. But GAP77™ adds a step that accelerates the process significantly.

Effective Microorganisms (EM) — specifically EM-2, created by mixing 1 litre of EM-1 with 1 litre of molasses and 18 litres of water, then fermenting for 10 days — are applied directly to the composting pulp. The EM-2 solution enhances microbial activity, speeds decomposition, and crucially, brings down the temperature of the compost pile.

This cooling step matters because the decomposed pulp needs to reach a temperature suitable for the next stage: worms.

Vermiculture

Once the coffee cherry pulp has been properly decomposed and cooled by the EM-2 solution, it’s fed into worm beds. Cali Redworms (Eisenia foetida) break the compost down into two products:

• Worm castings — nutrient-dense solid material packed with beneficial microbes
• Worm tea — a liquid by-product used as organic fertiliser

The worm beds are carefully managed — built with bamboo frames (1/2M high, 2m wide, 10m long) with a 1m dig canal around the boundary. Coffee parchment husk fills the trench to control ants and prevent pests from reaching the pulp. A plastic ground covering protects worms from bowing into the ground, and banana leaves cover the top to shield from rain that could bring worms to the surface where birds and insects eat them. Only Eisenia foetida — the “Cali Redworm”, referenced in Darwin’s research as “the macro biotics of the north American red worm” — is used.

Scouts check daily for birds, ants, and mites that could threaten the colony.

This isn’t just composting — it’s a managed biological process that produces consistently high-quality soil amendments.

Banana by-products in the loop

Intercropped banana trees contribute to this system too. The banana pendulum (flower stalk) is an ideal food source for the worms, creating another input in the cycle. Pruned banana leaves become mulch. Nothing is wasted.

Tera Preta 2.0

The final product is Tera Preta 2.0 — a soil amendment combining biochar, compost, and worm castings. Each component serves a purpose:

• Biochar — produced by burning organic material in a low-oxygen environment. It improves soil structure, retains nutrients, and locks carbon into a stable form with over 100 years of soil stability
• Compost — provides immediate organic matter and nutrients
• Worm castings — deliver beneficial microbes and slow-release nutrients

This mixture is added to every planting pit on the farm. It regulates soil acidity, improves water retention, boosts nutrient cycling, and increases carbon sequestration — addressing the depleted, acidic soils that years of poor management have created across coffee-growing regions.

The closed loop

The system is circular:

1. Coffee cherries are processed → pulp waste
2. Pulp is composted with EM-2 → decomposed organic matter
3. Worms process it → castings and worm tea
4. Biochar is produced from organic waste → stable carbon
5. All three combine into Tera Preta 2.0 → back into the soil

No chemical fertilisers. No waste leaving the farm. The farm’s own by-products become the inputs that rebuild its soil.

Processing quality control

The loop extends to processing. Cherry sugar content is tested with a Brix refractometer to assess ripeness. Cherries undergo 24-hour fermentation with yeast before pulp is collected for composting. This quality control at the washing station ensures both coffee quality and a consistent supply of organic material for the composting cycle.

This is what regenerative agriculture looks like in practice — not as a marketing term, but as an actual farming system.

---

Biochar production is one of the key carbon sequestration methods in GAP77™. See our FAQ on biochar and the full methodology for more detail. Related: banana intercropping feeds into this system, and soil testing measures its impact.