Why Everything You Know About “Bad” Microbes Might Be Wrong

Written By Martyn Richards

Soil Health, Market Gardening & the Power of Context in UK Horticulture

If you grow vegetables commercially in the UK — whether you’re running a no-dig market garden, an organic horticulture enterprise, or a regenerative growing system — you’ve probably been told the same story:

Some microbes are good.
Some microbes are bad.
Kill the bad ones.

But soil microbiology doesn’t work like that.

In regenerative horticulture, we’re learning something far more important:

Microbial behaviour is driven by context.

And when we change soil conditions, we change the biology.

Soil Health in UK Market Gardens: It’s About Balance, Not Sterility

In intensive vegetable production — salad crops, brassicas, roots, protected cropping — the pressure to “control” disease can be high.

Yet soil biology isn’t a battlefield. It’s an ecosystem.

Microbes often labelled as strictly pathogenic — such as certain Fusarium or Aspergillus species — exist in many UK soils as part of the broader microbial community.

Under stable conditions, with:

  • Active compost inputs

  • Strong fungal networks

  • Balanced pH

  • Good soil structure

  • Consistent carbon flow from roots

these organisms remain in ecological balance.

Problems arise when we create selection pressure.

The Hidden Cost of Chemical Shortcuts in Horticulture

High soluble nitrogen inputs, repeated disturbance, bare soil, and certain broad-spectrum agrochemicals alter microbial populations.

In UK horticultural systems this often leads to:

  • Reduced arbuscular mycorrhizal fungi (AMF)

  • Lower fungal-to-bacterial ratios

  • Weaker soil aggregation

  • Increased crop stress

  • Greater susceptibility to opportunistic pathogens

When we overfeed plants with soluble NPK, they reduce their natural microbial partnerships. In particular, AMF — critical for phosphorus cycling and drought resilience — decline.

We unintentionally disconnect the plant from its biological immune system.

DNA Is Not Destiny: Why Soil Microbes Adapt to Your Management

In soil science, especially within regenerative agriculture UK, there is growing awareness that:

Microbes adapt faster than we manage them.

Through horizontal gene transfer, microbial communities respond in real time to:

  • Oxygen levels

  • Redox potential

  • Chemical residues

  • Nutrient imbalances

  • Moisture stress

This is why two neighbouring market gardens, using different soil management strategies, can have completely different crop health outcomes.

It isn’t luck.

It’s context.

The Goldilocks Range: The Sweet Spot for UK Soil Biology

There’s a common narrative that soil must always be “fully aerobic”.

But resilient soils — particularly in compost-based, no-dig market garden systems — often operate in a facultative range.

This “Goldilocks” zone sits between:

  • Highly aerobic (oxidised)

  • Fully anaerobic (reduced)

When pH and redox potential (eH) sit within this balanced range:

  • Nitrogen cycling becomes more efficient

  • Phosphorus becomes biologically available

  • Fungal diversity increases

  • Natural microbial competition stabilises crop health

In UK horticulture, where rainfall patterns are unpredictable and soils vary dramatically (from sandy loams to heavy clays), maintaining this balance is critical.

Compost Is Not Just Organic Matter — It’s Biology

Not all compost is equal.

In market gardening, the difference between:

  • Mature, fungal-rich compost

  • Overheated, biologically inactive compost

  • Contaminated compost containing opportunistic spores

can define crop performance.

This is where soil microscopy becomes powerful.

Using brightfield and epifluorescence microscopy, growers can assess:

  • Fungal-to-bacterial ratios

  • Protozoa presence

  • Nematode diversity

  • Compost maturity

  • Root colonisation

For UK regenerative horticulture, this moves soil health from assumption to verification.

You’re no longer guessing whether your compost is biologically active.

You can see it.

From Pathogen Control to Context Management

The traditional approach in UK crop protection has been reactive:

See problem → apply treatment.

The regenerative approach in market gardening is preventative:

Build biological resilience → reduce problems.

When you:

  • Increase soil organic matter

  • Minimise disturbance

  • Maintain living roots

  • Support mycorrhizal networks

  • Apply biologically active compost

  • Monitor microbial life

you shift the system away from opportunistic dominance.

Microbes aren’t inherently “good” or “bad”.

They respond to the growing environment you create.

Why This Matters for UK Growers Right Now

With:

  • Rising fertiliser costs

  • Increasing pesticide regulation

  • Soil degradation across intensive systems

  • Climate volatility

  • Consumer demand for nutrient-dense produce

UK horticulture needs resilience more than ever.

Healthy soil structure improves:

  • Water infiltration

  • Drought tolerance

  • Nutrient efficiency

  • Crop consistency

  • Carbon retention

This is not theory. It’s measurable soil health.

The Bigger Question for Market Gardeners

Whether you run:

  • A small no-dig vegetable enterprise

  • A regenerative mixed horticulture farm

  • A commercial salad operation

  • A protected cropping system

the real question is:

Are you trying to control biology —
or are you creating the conditions where beneficial biology dominates?

Because when you change soil context,
you change microbial behaviour.

And when microbial behaviour changes,
so does crop resilience.

If you’re working in UK regenerative horticulture or market gardening and are exploring:

  • Soil microbiology

  • Compost quality

  • Mycorrhizal restoration

  • Biological inputs

  • Soil microscopy

  • Redox and pH balancing

I’d be interested to hear what you’re seeing in your own soil.

The future of UK soil health may not lie in more inputs —
but in better context.

🌱

Martyn Richards
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The Hidden Universe Beneath Your Feet