Biochar
A stable, porous carbon material produced by heating organic matter without oxygen that improves soil structure, water retention, and microbial habitat for decades.
What it is
Biochar is produced by pyrolysis, the controlled heating of biomass (wood chips, straw, or other organic material) in the absence of oxygen. It is a form of charcoal used specifically as a soil amendment rather than fuel. Once incorporated into soil, biochar is stable for hundreds to thousands of years and is approved for use in certified organic production.
What it does
Biochar's highly porous structure creates vast surface area within the soil, providing habitat for beneficial soil microorganisms and retaining moisture and nutrients that would otherwise leach away. It raises soil pH slightly and improves drainage in clay soils while increasing water-holding capacity in sandy soils. Over time, biochar-amended soils develop richer and more diverse microbial communities.
When to use
Incorporate biochar when establishing new beds or at the start of a growing season before planting. It is most effective when charged (pre-soaked in compost tea, liquid fertiliser, or worm-casting extract) before application, which pre-loads its pores with beneficial microbes and nutrients rather than drawing them away from plant roots initially.
When not to use
Avoid applying large amounts of uncharged biochar to actively growing crops as it can temporarily immobilise nitrogen by absorbing it into its pores. Do not use biochar produced from treated wood, construction waste, or plastic-contaminated feedstocks, which may contain harmful residues.
How to apply
- 1
Charge the biochar before use: soak it in compost tea, diluted worm-casting liquid, or a dilute liquid fertiliser for at least 24 hours until it is thoroughly wetted.
- 2
Allow excess liquid to drain until the biochar is moist but not dripping.
- 3
Incorporate the charged biochar into the top 6 - 8 inches of soil at a rate of 5 - 10% by volume (roughly a 1/2 - 1 inch layer turned in across the bed).
- 4
Mix thoroughly with existing soil and apply a generous layer of compost on top to further support the microbial community.
- 5
Water in well and plant as normal. Biochar effects are cumulative - the full benefit builds over multiple growing seasons.
Garden, by Willowbottom recommends only organic, wildlife-friendly solutions. No synthetic pesticides, no harmful chemicals - ever.