In a functioning Living Soil system, it's not just the soil itself that plays a role. The soil surface is also an important part of the entire ecosystem.
In nature, soil is almost never bare. Plant residues, leaves, wood pieces, or dead plant material form a natural protective layer over the earth.
This layer is called mulch.
In Living Soil, a mulch layer performs several important tasks simultaneously:
It protects the soil, stabilizes the microclimate, and continuously supplies the soil microbiome with organic material.
What is a mulch layer?
A mulch layer is a layer of organic material that lies on the surface of the soil.
Typical mulch materials in Living Soil include:
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cut cover crops
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leaves
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plant residues
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straw
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compost
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worm castings
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wood fibers
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dried plants
These materials are not incorporated into the soil but remain on the surface.
There, they are gradually broken down by microorganisms and integrated into the natural nutrient cycle.
Why mulch is so important in Living Soil
Protection of the soil surface
Without mulch, the soil lies directly exposed.
This leads to:
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rapid drying out
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greater temperature fluctuations
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less microbial activity
A mulch layer acts like a natural protective cover for the soil.
It reduces evaporation and ensures that moisture stays in the soil longer.
Food for the soil microbiome
The soil life in Living Soil consists of:
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bacteria
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fungi
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protozoa
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nematodes
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microarthropods
These organisms continuously need organic material as food.
Mulch provides exactly this food.
As microorganisms break down the organic matter, they create:
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humus compounds
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plant-available nutrients
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stable soil structures
Thus, the mulch layer becomes a central component of the biological nutrient cycle.
More stable soil climate
A mulch layer creates a more balanced microclimate in the soil.
It protects against:
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strong solar radiation
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drying out
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temperature fluctuations
Especially in indoor growing, mulch ensures that soil moisture remains more stable.
This is crucial for:
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microorganisms
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mycorrhiza
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root activity
Mulch and the soil microbiome
The most important effect of mulch occurs beneath the surface.
When plant residues lie on the ground, microorganisms immediately begin decomposition.
This creates complex interactions between:
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bacteria
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fungi
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soil fauna
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plant roots
Fungi play a particularly important role in this, as they efficiently decompose organic material and can also transport nutrients.
The result is a more active and stable soil ecosystem.
Which materials are suitable as mulch in Living Soil?
In a Living Soil system, primarily organic materials should be used.
Very suitable are:
Cover crops
One of the most popular methods is the so-called Cut & Drop method.
Cover crops are cut back and left directly on the soil surface.
These plant residues form a natural mulch layer.
Plant residues
Cut leaves or smaller plant residues can also be used as mulch.
They are gradually decomposed and contribute to humus formation.
Straw or dried plants
Straw is a classic mulching material and is particularly helpful in retaining moisture in the soil.
Compost
A thin layer of compost can also serve as mulch and additionally provides microorganisms.
How thick should a mulch layer be?
A mulch layer does not have to be very thick to be effective.
In pots, usually 1–3 cm of mulch material is sufficient.
It is important that the soil is not completely sealed off from the air.
The mulch layer should be loose so that:
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air exchange remains possible
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microorganisms can work actively
Mulch and Cover Crops – a perfect combination
Cover crops and mulch complement each other perfectly.
Cover crops:
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protect the soil alive
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supply microorganisms via root exudates
Mulch:
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provides organic material
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stabilizes the soil surface
Regular cutting of cover crops automatically creates a new mulch layer.
This principle is often called Cut & Drop.
Typical mistakes when mulching
There are also some common mistakes when it comes to mulch.
Mulch layers that are too thick
Too much material can lead to the soil getting less oxygen.
Fresh, heavily decomposing material
Very fresh material can temporarily bind nitrogen.
Therefore, a mixture of various organic materials is ideal.
Completely bare soil
Many growers leave the soil completely uncovered.
This deprives the soil of an important protective and nutrient layer.
Conclusion: Mulch as the foundation of a functioning Living Soil system
Mulch is more than just a soil cover.
It is a central component of a functioning Living Soil system.
A mulch layer:
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protects the soil
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stabilizes moisture and temperature
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nourishes the soil microbiome
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supports the natural nutrient cycle
In combination with cover crops, a living soil ecosystem is created that works more stably and productively in the long term.
