Why soils are losing their diversity

I wanted to know if the term "Raubbau" (exploitation) is scientifically sound. Or if it is merely an emotionally charged term in the sustainability discourse. So I looked at the data. And the data is clear. Soils worldwide are losing:

• organic matter
• microbial diversity
• structural stability
• water retention capacity
• functional resilience

This is not ideology. This is soil science. And if we want to understand why soils are losing their diversity, we need to look at two central processes:

1. Functional simplification through monocultures
2. Loss of organic matter through intensive cultivation

 

1. Soil is a highly complex ecosystem

Before speaking of "loss," it must be clear what is being lost. Healthy soil consists of:

• 45% mineral substance
• 25% water
• 25% air
• 5% organic matter

These 5% organic matter are the key. Because they are habitat and energy source for:

• bacteria
• fungi
• actinomycetes
• protozoa
• nematodes
• arthropods
• earthworms

A teaspoon of fertile soil contains billions of microorganisms. These organisms are not just inhabitants.

They are functional agents.

They:

• mineralize nitrogen
• mobilize phosphorus
• stabilize soil aggregates
• produce polysaccharides
• form mycorrhizal networks
• store carbon

Soil is not a substrate.
Soil is a functional network. And precisely this network is increasingly being simplified.

2. Monocultures – when biological diversity is systematically reduced

2.1 Plant diversity controls microbial diversity

A key study by Lange et al. (2015, Nature Communications, DOI: 10.1038/ncomms7704) examined 60 European grassland areas. Result: The higher the plant diversity, the higher the:

• microbial biomass
• mycorrhizal density
• functional activity

Plants release so-called exudates through their roots:

• sugars
• amino acids
• organic acids
• secondary metabolites

These substances act selectively on microorganisms. Above-ground diversity creates below-ground diversity. This is a measurable correlation

Long-term studies show: Venter et al. (2016, Soil Biology & Biochemistry, DOI: 10.1016/j.soilbio.2016.04.017):

• Reduced bacterial diversity in monocultures
• Lower enzymatic activity
• Dominance of fewer functional groups

This means: The soil ecosystem is functionally simplified. And reduced functional diversity means:

• lower resilience
• higher susceptibility to disease
• greater dependence on external inputs

Monoculture is not just an agro-economic model.
It is a systemic reduction of biological complexity. And complex systems lose their stability through simplification.

3. Humus degradation – the central driver of functional loss

If I had to name only one indicator that describes the state of a soil, it would be: organic matter content.

3.1 Global development of soil carbon

Rattan Lal (2004, Science, DOI: 10.1126/science.1097396) describes:

• Intensive agriculture has released significant amounts of organic soil carbon worldwide.
• Soils have transitioned from carbon sinks to carbon sources.

Organic matter is:

• carbon storage
• water reservoir
• nutrient buffer
• structural stabilizer

When it is lost, the soil loses several functions simultaneously.

Six et al. (2002, Soil & Tillage Research, DOI: 10.1016/S0167-1987(02)00059-8):

Intensive tillage:

• increases oxygen input
• accelerates microbial decomposition
• destabilizes soil aggregates

The result:

• CO₂ release
• structural degradation
• increased susceptibility to erosion

Humus degradation is not a passive process.
It is actively accelerated by cultivation.

Rawls et al. (2003, Geoderma, DOI: 10.1016/S0016-7061(03)00094-6):

An increase in organic matter by 1% significantly increases:

• field capacity
• plant-available water

In times of increasing drought, this is not a minor matter. Humus is a water reservoir. If we lose it, we lose resilience to climate stress.

4. Why this is not a neutral development

I want to be clear here: The loss of soil biodiversity is not a natural cycle.
It is man-made. It results from:

• intensification
• simplification
• decoupling of cycles
• focus on short-term yields

And it is measurable. Soil stores more carbon than the atmosphere and vegetation combined. When humus is lost:

• CO₂ increases
• water retention capacity decreases
• erosion increases
• biodiversity decreases

Soil is a climate actor.
A water regulator.
A foundation of life. This is not a romantic perspective.
This is system analysis.

5. Soil compaction – the underestimated physical factor

In addition to biological impoverishment and humus loss, there is a third central factor: structural collapse due to compaction. Soil does not just consist of material –
it consists of pore spaces.

• Macropores → air circulation
• Mesopores → water conduction
• Micropores → water storage

When soil is compacted:

• the air content decreases
• roots grow less effectively
• microorganisms lose habitat
• water infiltrates less effectively

Studies show that compaction significantly reduces microbial activity because oxygen limitation restricts biological processes. A compacted soil is biologically and physically disturbed.

And what particularly concerns me: compaction is often irreversible or regenerates only very slowly.

6. Nutrient buffering – why structure and minerals are crucial

In discussions about humus, it is often overlooked that the mineral matrix also plays a central role. A crucial term here is: Cation Exchange Capacity (CEC). It describes the soil's ability to bind positively charged nutrients:

• Potassium (K⁺)
• Magnesium (Mg²⁺)
• Calcium (Ca²⁺)
• Ammonium (NH₄⁺)

Soils with high CEC:

• store nutrients
• prevent leaching
• supply plants more consistently

Humus contributes to CEC.
But also certain clay minerals and structurally stable silicate minerals. This is where an often overlooked level of soil regeneration begins: Not just thinking organically.
But organically + minerally. A stable system needs both.

7. Silicon – a functional but underestimated building block

Silicon is the second most abundant element in the Earth's crust after oxygen. However, plant-available silicon is not self-evidently present. Scientific studies show:

• Silicon can stabilize plant cell walls
• It increases mechanical strength
• It can improve stress resistance to drought
• It supports tolerance to biotic stress

Especially in intensively managed soils, the plant-available silicon fraction decreases. Silicon is not a classic "fertilizer".
It is a structural and stability factor. And this is where the circle closes for me: structure determines stability – in the soil as well as in the plant.

8. The logical consequence: Regenerative gardening practices

Once I understand the mechanisms, the practice emerges not from ideology – but from system logic.

8.1 Promote diversity

Mixed cropping
Crop rotation
Flower strips
Green manure

Diversity increases functional stability.

8.2 Build humus

Compost
Mulch
Retain plant residues in the cycle
Incorporate cover crops

Humus increases:

• water storage

• nutrient buffering

• microbial activity

8.3 Disturb the soil as little as possible

• no unnecessary digging

• no permanent exposure

• protection against erosion

Disturbance reduces stability.

8.4 Supplement mineral structure specifically

A stable soil needs:

• organic matter

• microbial activity

• mineral structural components

Structurally stable silicate minerals can:

• buffer nutrients
• store water
• stabilize the soil matrix
  

Regeneration means integrating all levels.

9. So: Now, an attitude about it

I now consider the term "Raubbau" (exploitation) to be scientifically justified. Not because I want to be alarmist. But because the data shows: In many places, we are extracting faster than systems can regenerate. But I also maintain: Soil regeneration is possible. And it does not begin with global politics. It begins in the square meter. My garden is not an isolated space. It is part of a larger system.

If I:

• build humus
• promote diversity
• stabilize structure
• support mineral balance

then I am not just working on yield. I am working on system stability.

Why Understanding Changes Action

I wanted to know if soil loss is real. It is.

I wanted to know if it is scientifically explainable. It is.

And I wanted to know if I could do something. I can.

Regeneration is not a utopia.
It is applied soil science.

And it begins exactly where I take responsibility.

In the soil beneath my feet.

→  Those who want to use zeolite in their own garden will find further information on application and products on the page Zeolite for Garden and Soil Improvement.

Classification from our practice at Steinkraft

At Steinkraft, we have been studying for many years how natural minerals work in the soil and what role they can play in stable soil processes. Zeolite, in particular, is a fascinating example of how geological structures – formed from volcanic activity and long natural processes – possess properties that can fulfill a special function in the soil.

In our work, we combine scientific knowledge with practical experience from horticulture and agriculture. It consistently shows that a deeper understanding of soil processes is the key to sustainable soil care.

Our aim is to convey this knowledge in an understandable way. Because those who understand how water, nutrients, microorganisms, and mineral structures interact in the soil can act more consciously and contribute to living soils and long-term fertile garden cycles.