Soil is everywhere. It’s under our cities, our farms, and our forests. It supports the plants we eat, the animals we rely on, and the ecosystems we depend on. It holds water, cycles nutrients, and stores more carbon than all the world’s vegetation combined.

But studying soil is a complex business. Soil varies dramatically from place to place. It changes over time. It’s influenced by geology, climate, land use, vegetation, and other factors. And because it’s underground, it’s hard to observe directly. That complexity has made it difficult to classify, difficult to measure, and difficult to manage at scale.

The term ‘soil health’ has helped to draw attention to these challenges, but its definition has also been open to interpretation. What does healthy soil actually mean? Is it productive? Stable? Full of life? And how can we tell when it’s under threat?

To answer these questions, Prof Alex McBratney and his team of researchers in Australia are working with a broader and more structured idea: soil security.

At its heart is the Soil Security Assessment Framework, which breaks soil down into five key dimensions: capacity, condition, capital, connectivity, and codification. Together, they form a clearer and more holistic picture of how soil functions, how we interact with it, and how we can protect it.

The team is using this framework to reshape how Australia understands and manages its soil. In a series of recent studies, they’ve developed new ways of mapping, measuring and managing soil by integrating the idea of soil health into a broader, more useful model. Their work is helping to bridge science, policy and practice, and in doing so, it’s offering a powerful example of how we might secure the soil beneath our feet.

Soil security is about more than just nutrients and yields. It’s about understanding soil as a system, a living, changing, human-influenced part of the environment.

The Soil Security Assessment Framework uses five distinct but interconnected dimensions to assess soil. The first is capacity, which refers to what the soil can actually do: grow food, filter water, support biodiversity, and cycle nutrients. Then there’s condition, meaning the physical, chemical and biological state of the soil at a given time, referring to whether the soil can still perform its role. Capital focuses on the soil’s value to people and economies, particularly through agriculture and ecosystem services. Connectivity explores how people understand and relate to soil: their knowledge, their attitudes, and their willingness to act. And finally, codification looks at the governance of soil, meaning the policies, regulations, laws and institutional structures that shape how it’s managed and protected.

These dimensions don’t exist in isolation. They interact. And together, they give us a way to understand soil as something that’s not just natural, but deeply social too. The ultimate goal of the framework is to develop a shared language that helps farmers, scientists, policymakers and communities make better decisions about how we manage our soil.

Conventional soil maps typically focus on classifying soils based on texture, mineral composition, or chemical properties. While these characteristics are useful, they don’t always capture how soils function within their broader environmental context. This functional understanding is essential for informing soil management, particularly under changing climatic and land use conditions.

Prof. McBratney and his team developed a more functional way to classify soil, one that captures how they initially formed. To achieve this, they used the concept of pedogenons, which are units that combine traditional soil data with environmental information like climate, vegetation, geology, and landscape.

Using national datasets and statistical clustering, they identified 1370 pedogenons which were further grouped into 236 distinct soil districts across Australia. Each one reflects a different combination of environmental and soil conditions, offering a better picture of soil function and utility.

That means more useful maps for farmers. Better data for planners. And a stronger foundation for managing soil in a changing climate. This approach is linked to the framework’s capacity and codification dimensions, helping translate complex science into practical policy tools.

Water is vital to all life, and soil plays a critical role in water cycling. As such, one of the most important indicators of soil function is how much water it can retain and make available to plants, particularly in regions prone to variability in rainfall and droughts like Australia.

In another of their studies, the researchers looked at available water capacity. That’s the amount of water a soil can store and release for use by crops and vegetation. Available water capacity is crucial for food production and its relationship with farmland prices was investigated in Australia. The researchers processed high-resolution maps showing how available water capacity varies across the country and its contribution to farmland prices.

These maps allow farmers and land managers to see where water-holding capacity is low and helps them identify how they might overcome this. For example, by adding organic matter, planting different crops, or adopting land practices that improve soil structure and water retention.

By mapping available water capacity, and its effect of farmland prices, the team has provided a powerful tool for managing soil, and understanding to what extent they are improving or decreasing their productivity. They found that a 1 mm increase in available water capacity results in an increment of 293.6 $/ha in farmland prices in Australia. It also ties directly into the framework’s capital dimension by showing the economic value of better soil data. And because the study is based on open-source data, its methods can support decisions at every level, from individual farms to national planning.

Soil is more than just a physical and biological system, it is also a resource shaped by human activity. As such, the ways in which people understand, value, and manage soil are crucial to its long-term sustainability and function. The team also explored the human side of soil, tying into the connectivity dimension of the framework.

They developed a self-assessment tool to explore how landowners and land managers, including agronomists, consultants and advisors across Australia, relate to the soil they manage. The survey asked participants to evaluate their understanding of soil processes, their feelings about soil and its value, and the specific actions they take to care for it. In other words, it measured their knowledge, their attitudes, and their actions.

Participants were also asked to reflect on how they respond to different soil functions and threats, including nutrient cycling, erosion, acidification, and salinisation.

The results were revealing. Most land managers had a strong level of knowledge, and many were actively engaged in practices that protect and care for the soil. However, their emotional connection to soil, and their responses to specific threats, varied widely.

One notable finding was that salinisation consistently scored lowest across knowledge, attitude, and action. This suggests that despite its impact, it may not be fully recognised or understood by many land users.

By quantifying these relationships, the study provides valuable insights into where targeted education or policy support could help bridge important gaps.

The concept of soil health has gained significant traction in recent years, particularly in agricultural and environmental discussions. However, despite its widespread use, the term remains ambiguous, with varying definitions and interpretations across disciplines and stakeholder groups.

In the research that provides the final piece of the puzzle, Prof. McBratney and his team examined how the concept of soil health aligns with the Soil Security Assessment Framework. They found that while soil health encompasses many important attributes, it most closely corresponds to the condition dimension of the framework, incorporating the physical, chemical, and biological state of the soil.

By placing soil health within the broader framework, the team aims to bring greater clarity and consistency to how the term is used in science, policy, and practice. Rather than replacing the concept, they propose refining it, supporting more rigorous definitions, more effective monitoring, and stronger alignment with measurable outcomes.

This integration strengthens the concept of soil health and enhances communication between researchers, land managers, and decision-makers. It also reinforces the idea that caring for soil is not just about maintaining its current state, but understanding its role within broader systems of production, regulation, and resilience.

Soil is more than just the ground we walk on. It’s a vital, complex system that underpins food security, ecosystem function, water regulation, and climate stability. The work of Prof. Alex McBratney and his colleagues marks a shift in how we think about soil. Through the Soil Security Assessment Framework, they’ve created new ways to map, measure, and manage this essential resource, combining scientific rigour with real-world relevance.

Their research shows that soil security isn’t just a theoretical concept. It’s a practical approach to understanding soil’s functions, its threats, and its place in both natural and human systems. It offers tools to guide better policy, better land management, and ultimately, better outcomes for people and the planet.

If we want resilient landscapes, sustainable agriculture, and stronger responses to climate change, we need to take soil seriously. This work shows us how, and why, that future starts from the ground up.