Organic farming is not simply farming without chemicals. It is a system that works with nature to build living soils, healthy crops, resilient ecosystems, and sustainable food production. At the centre of this system is soil organic matter.

Understanding Soil Organic Matter (SOM)

Soil Organic Matter

Soil organic matter is all the organic material found in the soil. It includes:

• Dead plant residues
• Decomposing roots
• Animal manure
• Compost
• Microbial bodies
• Earthworm waste
• Fungi and bacteria remain
• Organic carbon compounds

Soil organic matter is made of many different components. Some organic matter:

• Breaks down very fast
• Feeds microbes quickly
• Releases nutrients rapidly

Other organic matter:

• Is highly stable
• Remains in the soil for many years
• Stores carbon safely
• Improves long-term soil structure

This difference is extremely important in organic farming because not all organic matter behaves the same way

Organic Matter and Organic Carbon

Soil organic matter is organic carbon.

Carbon is the backbone of life in soil.

Plants capture carbon dioxide from the atmosphere through photosynthesis and convert it into:

• Sugars
• Starches
• Fibres
• Plant tissues

When plants die or release root exudates, this carbon enters the soil.

This carbon:

• Feeds microorganisms
• Builds soil structure
• Improves fertility
• Helps water retention
• Stores atmospheric carbon underground

This process is called carbon sequestration.

Organic Matter is Important in Organic Farming

Healthy organic matter transforms soil from “dead dirt” into a living ecosystem.

1. Improves Soil Structure

Good organic matter:

• Binds soil particles together
• Creates stable aggregates
• Prevents compaction
• Improves aeration
• Makes soil easier for roots to penetrate

Healthy soil structure allows:

• Better root development
• Better water infiltration
• Better microbial activity

2. Increases Water Holding Capacity

Organic matter acts like a sponge.

It absorbs and stores water, then slowly releases it to plants.

This helps:

• During droughts
• In dry seasons
• In sandy soils
• In areas with irregular rainfall

In organic farming systems, soils with high organic matter are usually more drought-resistant.

3. Reduces Nutrient Leaching

Without organic matter:

• Nutrients wash away easily
• Fertilisers are lost
• Water pollution increases

Organic matter holds nutrients like:

• Nitrogen
• Phosphorus
• Potassium
• Calcium
• Magnesium

This keeps nutrients available to crops for longer periods.

4. Supports Soil Life

Organic matter is food for:

• Bacteria
• Fungi
• Earthworms
• Protozoa
• Nematodes
• Arthropods

A living soil food web develops.

These organisms:

• Decompose residues
• Release nutrients
• Build soil aggregates
• Protect plants from diseases

Organic farming depends heavily on these natural biological processes.

5. Carbon Sequestration and Climate Change

The article strongly emphasises carbon sequestration.

When carbon is stabilised in the soil:

• Atmospheric CO₂ reduces
• Soil fertility improves
• Climate resilience increases

This is why some carbon programs pay farmers for improving soil carbon.

But Joel Williams stresses:

“There’s no sequestration without stabilisation.”

This means carbon must be protected and stabilised in soil, otherwise it quickly escapes back into the atmosphere.

The Two Main Types of Organic Matter

The article introduces two major forms:

1. Particulate Organic Matter (POM)

2. Mineral-Associated Organic Matter (MAOM)

These are very important concepts in soil science.

1. Particulate Organic Matter (POM)

POM?

POM consists mainly of:

• Decaying plant residues
• Straw
• Leaves
• Roots
• Woody materials
• Brown organic materials

These materials usually have a high carbon-to-nitrogen ratio.

Examples:

• Dry grass
• Maize stalks
• Sawdust
• Straw mulch
• Dry leaves

How POM Forms

Microorganisms can not absorb large plant materials directly.

So they release enzymes that act like scissors.

These enzymes:

• Cut complex plant materials into smaller compounds
• Break cellulose and lignin
• Begin decomposition

Earthworms and insects also help physically break down the material.

This entire process creates particulate organic matter.

Importance of POM

Provides Long-Term Food

POM acts as a slow food source for microbes.

Improves Soil Structure

It increases:

• Porosity
• Aeration
• Root penetration

Enhances Water Infiltration

Water enters soils rich in particulate matter more easily.

Builds Surface Mulch

POM protects soil from:

• Erosion
• Heat
• Evaporation

But POM is Less Stable

This is one key lesson from the article.

POM is vulnerable because:

• It is not chemically attached to soil minerals
• Disturbance exposes it to oxygen
• Tillage speeds decomposition

Once disturbed:

• Carbon escapes quickly
• Organic matter declines rapidly

The article uses peat bogs as an example.

Peat bogs accumulate huge amounts of organic matter over centuries. But once disturbed or drained, they lose carbon rapidly.

2. Mineral-Associated Organic Matter (MAOM)

What is MAOM?

This is the highly stable form of organic matter.

It forms when:

• Microbes digest simple carbon compounds
• Microbial bodies die
• Their remains attach to clay and silt particles

Soil organic matter comes from dead microbial bodies.

This is a fascinating discovery in modern soil science.

How MAOM Forms

Plants release:

• Sugars
• Amino acids
• Organic acids
• Root exudates

These are easy for microbes to consume.

Microbes rapidly convert them into microbial biomass.

When microbes die:

• Their remains stick tightly to soil minerals
• Especially clay and silt

This creates very stable carbon storage.

Why MAOM is Important

Extremely Stable

It can remain in soil for decades or centuries.

Better Carbon Sequestration

This is the true long-term carbon storage mechanism.

Improves Fertility

MAOM improves nutrient-holding capacity.

Increases Soil Resilience

Soils become:

• More drought-tolerant
• More stable
• More biologically active

Role of Soil Type

The soil texture strongly influences organic matter storage.

Clay Soils

Clay soils:

• Have many mineral surfaces
• Hold more stable carbon
• Form more MAOM

These soils are better at long-term carbon storage.

Sandy Soils

Sandy soils:

• Have fewer binding surfaces
• Lose carbon faster
• Store less stable organic matter

Organic farming on sandy soils, therefore, requires:

• Continuous organic inputs
• Mulching
• Cover crops
• Reduced disturbance

Role of Calcium

Calcium helps carbon bind to clay particles.

It acts like a bridge between:

• Organic matter
• Soil minerals

This improves:

• Soil aggregation
• Carbon stabilisation
• Soil structure

Soil Aggregates and Carbon Protection

Soil Aggregates

These are clumps of soil particles held together by:

• Fungal hyphae
• Root exudates
• Microbial glues

Inside these aggregates:

• Carbon becomes physically protected
• Oxygen penetration reduces
• Decomposition slows

This stabilises organic matter.

Minimising Soil Disturbance Matters

Tillage:

• Breaks soil aggregates
• Exposes protected carbon
• Increases oxygen exposure
• Accelerates decomposition

This causes:

• Carbon loss
• Reduced microbial activity
• Declining soil health

This is why organic farming increasingly promotes:

• Minimum tillage
• Reduced cultivation
• Conservation agriculture

Living Roots: The Engine of Soil Health

Living roots build soil organic matter.

Roots continuously release exudates:

• Sugars
• Carbon compounds
• Amino acids

These feed soil microbes directly.

Why Roots Matter More Than Shoots:

Root material is about five times more likely to form stable soil organic matter than shoot material.

This is because roots:

• Feed microbes underground
• Produce exudates
• Build aggregates
• Deliver carbon deeper into the soil

Deep Roots and Carbon Storage

Deep-rooted plants:

• Move carbon deeper underground
• Protect carbon from rapid oxidation
• Improve subsoil structure
• Increase water infiltration

Examples include:

• Lucerne/alfalfa
• Sunflower
• Radish
• Pigeon pea
• Napier grass
• Trees

Cover Crops in Organic Farming

The article highlights cover crops as critical tools.

Cover crops:

• Keep living roots in the soil
• Prevent erosion
• Feed microbes year-round
• Capture nutrients
• Build carbon

Research mentioned in the article found:

• About 15% increase in soil organic carbon in clay soils

Diverse cover crop mixtures increase:

• Root biomass
• Microbial diversity
• Soil carbon

Why Intensive Agriculture Reduced Soil Carbon

Even though crop yields increased over 50 years:

• Soil carbon often declined.

Why?

1. Shift from Perennials to Annuals

Perennials:

• Invest heavily in roots
• Store energy underground
• Build more soil carbon

Annuals:

• Focus on seed production
• Invest more above ground
• Build less root biomass

This reduced carbon inputs below ground.

2. Crop Breeding for Yield

Modern breeding selected crops that:

• Produce more grain
• Produce more shoots
• Allocate less energy to roots

Result:

• Less root carbon
• Lower soil organic matter

3. Excess Nitrogen Fertiliser

Nitrogen increases shoot growth.

But excessive nitrogen:

• Suppresses root development
• Reduces microbial balance
• Limits carbon stabilisation

Hence,  too much nitrogen eventually decreases root biomass.

This is a major lesson in organic farming:

• More fertiliser does not always mean healthier soil.

Compost and Organic Amendments

Making compost is one of the most effective tools.

Why?

Because compost has already undergone:

• Microbial transformation
• Stabilisation
• Decomposition

Compost adds:

• Stable carbon
• Beneficial microbes
• Nutrients
• Humus

Organic amendments include:

• Compost
• Animal manure
• Vermicompost
• Biochar
• Green manure
• Plant residues

Role of Livestock in Organic Farming

It is evident and practically known that livestock improve soil health.

Animals:

• Digest plant material
• Convert residues into manure
• Stimulate microbial activity
• Increase nutrient cycling

Even trampling has benefits.

Moderate trampling:

• Presses plant residues into the soil
• Improves microbial access
• Enhances decomposition

Integrated crop-livestock systems are therefore powerful in regenerative and organic farming.

Key Principles of Building Soil Organic Matter

The several core principles are:

1. Minimise Soil Disturbance

Avoid excessive:

• Ploughing
• Harrowing
• Cultivation

Protect soil aggregates and microbial life.

2. Keep Living Roots Year-Round

Use:

• Cover crops
• Intercropping
• Agroforestry
• Relay cropping

3. Increase Plant Diversity

Different plants:

• Feed different microbes
• Build diverse root systems
• Improve resilience

4. Use Organic Amendments

Apply:

• Compost
• Manure
• Mulch
• Crop residues

5. Integrate Livestock

Managed grazing improves:

• Carbon cycling
• Soil biology
• Nutrient recycling

6. Avoid Excessive Nitrogen Fertiliser

Too much nitrogen:

• Weakens root growth
• Reduces carbon storage
• Disturbs microbial balance

Organic Farming as a Living System

Organic farming is about relationships between:

• Plants
• Roots
• Microbes
• Fungi
• Earthworms
• Organic matter
• Minerals
• Water
• Carbon

Healthy soil is alive.

The goal is not merely to feed crops.

The goal is:

• Feeding the soil ecosystem
• Building stable carbon
• Improving resilience
• Creating sustainable productivity

When organic matter is managed correctly:

• Soil becomes softer
• Water retention improves
• Fertility increases naturally
• Erosion reduces
• Biodiversity expands
• Crops become more resilient

That is the true foundation of successful organic farming.