Whether you’re growing winter crops or raising livestock, healthy soil is the foundation of productivity. But what does ‘healthy soil’ really mean—and how can farmers achieve it?
By Glenneis Kriel | Featuring insights from Sheila Storey, Soil Health Support Centre
“Healthy soil isn’t just about what’s in it—but what it’s doing.”
— Sheila Storey, Soil Health Support Centre
Walk onto any successful farm, and beneath the surface lies a world teeming with microscopic life—an invisible ecosystem crucial to everything from yield performance to climate resilience. Over the past decade, soil health has moved to the forefront of sustainable agriculture discussions. But beyond buzzwords and bio-additives, what exactly makes soil “healthy”?
According to Sheila Storey, co-founder and consultant at the Soil Health Support Centre in Klapmuts, Western Cape, healthy soil is more than just fertile—it’s living.
“Healthy soil is the ongoing capacity to function as a vital living ecosystem that sustains plants, animals, and humans,” she explains.
This means evaluating soil not just by what it contains—like nutrients or organic matter—but by how its biological, chemical, and physical processes interact in balance.
THE TRIFECTA OF SOIL FUNCTION
Soil functioning hinges on three key elements:
🧪 Chemical – Nutrients, pH balance, organic content, and cation exchange capacity
🧱 Physical – Texture, structure, compaction, water infiltration, and drainage
🦠 Biological – Biodiversity, microbial life, organic carbon, and even nematodes
“Focusing on just one component in isolation is short-sighted,” Storey warns. For example, over-applying chemical fertilisers without addressing compaction or microbial health often leads to diminishing returns and environmental damage.
Assessing Soil Health: Back to Basics
You don’t need a lab coat to get started. Storey recommends simple, tactile assessments on the farm:
- Feel the texture. Is it crumbly or hard? Sandy or clay-like?
- Dig a root profile. Examine layers, root penetration, and compaction.
- Use a penetrometer. Measure resistance to gauge soil depth and density.
- Look for life. Earthworms are a great sign—but nematodes are even better indicators.
However, Storey cautions against “miracle courses” that promise soil expertise in just a few weeks.
“You can’t become a soil expert in 30 days by shaking a spoonful of soil in water,” she says. “It’s unscientific and misleading.”
LAB TESTS THAT MATTER
While simple on-farm observations are valuable, Storey encourages using scientific tests to get a deeper understanding:
1. Microbial Respiration Test
Measures CO₂ released by microbes—a direct sign of soil life.
2. Volumetric Aggregate Stability (VAS) Test
Assesses the structure-building activity of microbes.
3. Haney Test
Evaluates organic nitrogen and carbon availability using plant-like chemistry rather than harsh extractants.
4. Nematode Community Analysis
Identifies nematode species and their feeding roles—bacterial, fungal, plant-based, or predatory.
“A healthy nematode balance reveals a functional, living ecosystem,” says Storey.
Enzyme tests can also help farmers assess whether nutrient cycling processes are functioning correctly.
PRINCIPLES FOR BUILDING SOIL HEALTH
No matter your location, crop type, or farming system, Storey outlines five universal principles for nurturing soil:
📘 1. Keep it covered. Use mulch, compost, cover crops, or stubble to prevent erosion and drying.
🚜 2. Minimise disturbance. Limit tillage and stick to controlled traffic lanes.
🌱 3. Keep roots in the ground. Aim for living roots as much of the year as possible.
🌾 4. Maximise diversity. Rotate crops, integrate intercropping, and include legumes.
🐄 5. Add animals. Grazing can enhance nutrient cycling and biological activity.
Why Carbon Matters—but Context is Key
Carbon is a cornerstone of soil health, but Storey warns against becoming obsessed with carbon numbers alone.
“There are many forms of carbon, and not all tests measure the same kind. Choose a reliable test and stick with it annually.”
Improving soil carbon is a long-term game. In one example, it took a Western Cape orchard 20 years to increase soil carbon from 0.4% to 4%.
Also, know your region’s limits: “South Africa’s ancient, weathered soils are not going to mimic Amazon rainforest soils—nor should they,” Storey says.
A Process, Not a Prescription
Despite advances in research, Storey believes there’s no one-size-fits-all fix for soil health.
“Farmers ask me to identify specific organisms in their soil, but unless you’re testing for disease or specific functions like mycorrhiza colonisation, it’s not meaningful,” she says.
Adding microbial products may help in targeted ways (e.g. rhizobium for legumes), but they won’t solve systemic soil issues.
“Soil health is about processes, not quick fixes. And these processes must be nurtured over time.”
THE BOTTOM LINE
Healthy soil is not something you can buy or import—it’s something you cultivate, layer by layer, season by season. With careful observation, science-backed tools, and a commitment to holistic principles, South African farmers can build resilient soil that supports both their crops and their long-term sustainability.
“There’s no silver bullet—but there is a path forward. And it begins with understanding your soil.”
— Sheila Storey