Compost feeds the soil for a season. Biochar improves it for decades. Together with a few other natural amendments, they solve the two big weaknesses of Mauritian volcanic soils: nutrients leach away in heavy rain, and coastal soils dry out fast.
Biochar in one paragraph
Biochar is organic material charred with little oxygen. The result is almost pure carbon, riddled with microscopic pores — one gram has the internal surface area of a small house. Those pores hold water, hold nutrients, and house soil microbes. Unlike compost, biochar does not decompose: added once, it works essentially forever.
The charging rule (do not skip this)
Fresh biochar is an empty sponge — put it in soil raw and it will absorb your soil's nutrients and set your plants back months. Charge it first: mix it 50/50 with compost or soak it in diluted manure tea or a JADAM microbial solution for two weeks. Then it enters the soil already full.
How much
- Garden beds: 5–10% of the top 15cm, once. Add more over the years if you like.
- Pots: up to 10% of the mix.
- Fruit-tree planting holes: one or two litres, mixed with the backfill.
Other amendments worth knowing
- Well-rotted manure — the classic. Cow, chicken or goat, always aged, never fresh on growing beds.
- Wood ash — potassium and calcium; a light dusting helps fruiting crops, but never on the same day as manure, and go easy: too much raises pH sharply.
- Rock dust (basalt) — we live on it; crushed basalt fines from local quarries slowly release minerals.
- Green manures — a quick crop of legumes dug or crimped into the bed feeds nitrogen for free.
The order of operations for a new bed
- 1Loosen soil without inverting it. 2. Work in compost plus charged biochar. 3. Plant. 4. Mulch heavily. That sequence, repeated season after season, turns tired ground into black, spongy, alive soil.