Healthy Soil, the Future of Composting, and Why the Biochar Humus Composite Matters
For years, we’ve talked about healthy soil in abstract terms: “better structure,” “more nutrients,” “good biology.” But as we move into an era of high fertiliser prices, increased nutrient run-off, soil degradation, and mandatory carbon accounting, the meaning of healthy soil is shifting from a gardening ideal to an economic necessity.
This blog acts as a staging point for several connected ideas we’ll expand on across the site:
- What healthy soil actually is,
- Why do different land-management systems need different solutions,
- Why our composting process must evolve,
- Convergence to the next major innovation: Biochar Humus Composite™ (BHC).
1. What Do We Really Mean by “Healthy Soil”?
Healthy soil isn’t one thing. It is a system where biology, chemistry, physics, and water regulation operate in balance. The priorities look different depending on the land-management approach:
Organic, regenerative, or biologically-driven systems
In an organic, regenerative, or biologically-driven system, the goal is to build long-term fertility through:
- stable soil carbon
- aeration and structure
- microbial diversity
- natural nutrient cycling
- moisture regulation
These systems rely heavily on organic amendments. The challenge is achieving enough stable carbon, rather than short-term composted material that disappears within months.
Conventional/chemically-driven systems
In conventional/chemically-driven systems, soil is often treated as a substrate for targeted nutrient delivery. Fertilisers provide the chemistry, but:
- biological life is often suppressed,
- structure declines,
- humus levels fall,
- and soils become increasingly fragile.
Both systems eventually face the same scientific truth:
Without humus and stable carbon frameworks, soils cannot maintain structure, retain water, or cycle nutrients efficiently.
This is where the conversation shifts.
2. Humus: The Missing Link We Don’t Talk About Enough
Most people assume compost creates humus. It doesn’t—at least not reliably and not at scale.
Humus is not “compost.”
Humus is a colloidal, chemically stable, long-lived carbon complex that gives soil its dark colour, sponge-like structure, nutrient-binding capacity, and water-holding ability.
The UK’s composting regime, PAS100, has been dominated by woody feedstocks screened to 15–40 mm. The problem is simple:
- woodchip is slow to break down,
- adds almost no plant-available nutrients,
- and contributes very little true humus formation.
To truly tackle soil degradation, we need more humus, and humus cannot be generated at national scale unless composting systems evolve.
3. Why Biochar is Only Half the Solution
Biochar is an enabling technology. It increases:
- water retention,
- nutrient buffering,
- microbial habitat,
- and long-term carbon storage.
But biochar on its own does not solve humus scarcity. For biochar to deliver its full value, it must be combined with humus-rich organic matter—and the UK does not currently produce enough humus for this pairing.
To get both at scale, we need to rethink composting itself.
4. The Future of PAS100: From Woodchip to the Biochar Humus Composite
If the industry wants to produce humus at scale, the production system must change.
A future PAS100 must include three shifts:
(1) Remove woodchip as the default bulking agent
Chip slows decomposition and adds little functional value. We should repurpose woodchip upstream into biochar.
(2) Use biochar as the structural aeration medium
Biochar replaces woodchip inside the windrow, increasing:
- airflow,
- surface area for microbial colonisation,
- and humification pathways.
(3) Optimise windrows for humus formation, not just “compost throughput”
Higher biological activity, higher oxygen, better moisture regulation, and biochar-supported micro-habitats increase the formation of true humus, not just partially decomposed organic matter.
This creates the foundation for the next generation of soil amendments.
5. Why the Biochar Humus Composite (BHC) is the Logical End Point
When biochar and humus are co-created and stabilised in situ (rather than using a mix of biochar and compost), the result is the Biochar Humus Composite (BHC): a stable, high-functioning soil carbon “matrix” that behaves differently from either component alone.
The BHC gives soils:
This convergence—biology, carbon stability, water, nutrients—is why the BHC sits at the centre of our work at AC Innovations.
- long-term stable carbon
- improved infiltration and water retention
- reduced erosion and surface sealing
- increased nutrient efficiency
- stronger microbial networks
- slow-release fertility
- and measurable carbon-credit potential
6. The Economics: Why Scale Matters
None of this works unless farmers can afford it.
To be adopted at scale, BHC must:
- be cost-effective per hectare,
- deliver measurable improvements in yield or input reduction,
- be simple to handle,
- address long-term soil health and risk of erosion,
- take on the role of carbon sequestration to offset climate change
That means:
- large-scale biochar production (as explored via A Healthier Earth, Crappers/Sustain Wiltshire, Pyreg systems),
- plus large-scale humus production via evolved PAS100 systems.
This is not a niche product. This is a future industry standard—if economics, supply chains, and evidence align.
Whether BHCs reach farmers as:
- “advanced fertilisers,”
or - “soil-carbon solutions” that deliver agronomic benefit plus carbon-credit revenue,
…is still an open strategic question. But both routes require the same foundation: biochar + humus at scale in defined formulations that meet real agricultural needs.
7. Where We Go Next
Across the AC Innovations ecosystem, we’ll be exploring:
- The science of humus formation
- Biochar supply chains and economics
- The redesign of PAS100 composting
- BHC formulations for different crops and soils
- Routes to market and farm-scale trials
- Carbon-credit models and risk mitigation
- Implications for gardeners, growers, and commercial horticulture
This blog marks the start. Healthy soil is not a single product—it’s a system. Building that system requires new thinking, new standards, and new materials built for the realities of modern agriculture.
When biochar meets humus at scale, soil finally gets what it has been missing.