Soil as Urban Infrastructure: The Hidden System Shaping City Resilience
Urban soil is a living infrastructure system that regulates water, temperature, carbon, biodiversity and even human health, yet it is routinely sealed, polluted or built over. When soils lose their ability to absorb rainfall, retain moisture, support vegetation and filter pollutants, cities experience hotter streets, higher flood risk, declining ecological function and weakened local food systems. As urban expansion consumes some of the world’s most fertile peri-urban soils, and climate pressures intensify, the state of the ground beneath our feet becomes a determining factor in whether cities remain safe, resilient and liveable. Recognising soil as core infrastructure, not a landscaping afterthought, is essential for designing urban environments that can withstand heat, manage water, sustain biodiversity and support public wellbeing.
Healthy soils are not merely environmental assets; they are functional systems that determine the long-term performance and cost-efficiency of entire districts. When cities design with soil, not against it, they unlock measurable climate benefits, lower maintenance burdens and stronger public health outcomes.
When talking about sustainable cities, soil isn’t the first thing we think about. We talk about buildings, infrastructure, transport networks, energy systems; everything that is built on top of the soil. But soil is a form of hidden urban infrastructure. It absorbs water, stores carbon, cools neighbourhoods, feeds pollinators, filters pollutants, and supports the vegetation that keeps cities liveable. When we block it, we disable all of those services at once.
Soil sealing is the term for the process of permanently covering soil with materials that can’t easily be removed. It’s one of the most overlooked drivers of heat, flood risk and ecological decline in cities. As cities continue to expand, this matters. For World Soil Day, we explore how soils will shape how liveable, safe and resilient those cities become.
Sealed soils create hotter, riskier cities
Impervious surfaces trap heat, prevent water infiltration and increase energy demand for cooling. Anyone who has walked across a sun-baked car park in a hot climate knows how these surfaces radiate heat. Healthy soils, by contrast, act like natural sponges and heat buffers. They hold moisture and support diverse vegetation.
Urban soils are home to far more biodiversity than most people realise. Nearly 59% of Earth’s species spend part of their lifecycle in soil. When soils are sealed, polluted or fragmented, we lose ecological richness and the consequent soil productivity and nutrient cycling that underpin healthy green spaces.
On the flip side, healthy soils retain water during heavy rainfall, reducing runoff, lowering flood risk and filtering pollutants. They anchor slopes, lowering landslide risks, and support the root systems of trees that shade streets and soften heat islands.
In practice, this means soil quality directly shapes neighbourhood microclimates, operational costs and disaster risk profiles—core metrics that determine whether urban districts function effectively over decades.
Urban expansion is consuming the world’s most fertile soils
City expansion is closely linked to our food systems. As more people move into urban areas, less land is actively farmed, and cities require more space to accommodate growing populations. By 2030, expanding cities could convert up to 2.4% of global cropland, much of it fertile peri-urban land. These areas are, on average, 1.77 times more productive than typical croplands and losing them would threaten 3–4% of global food production.
Integrated land-use planning, compact growth strategies and urban–agrifood system integration can slow this trend. Protecting peri-urban soils protects future harvests, reduces supply chain vulnerabilities and secures the farmland that feeds expanding cities.
Healthy soils support safe, local food production
Urban and peri-urban agriculture already produces up to 10% of the world’s vegetables, legumes and tubers. However, pollution from traffic, industry, untreated wastewater and poor waste management can contaminate soils with heavy metals and toxins. Identifying, managing and restoring these soils is essential for safe food production, community gardens, allotments and green spaces that support public health.
As Dr Michał Słota, Director of Scientific Affairs at the Institute of Microbiological Technologies in Poland, notes, healthy food production begins with the physical structure of soil. His research shows that roots can only grow, branch and take up nutrients when the soil around them has enough air space and appropriate softness. When soils become compacted or lose structure, roots cannot spread, access nutrients or form the microbial relationships they rely on. This directly reduces plant growth and weakens the stability of local food systems.
Healthy soils and the microbiomes within them influence human immune development. Children, especially, benefit from exposure to living soils and biodiverse green spaces. This is a reminder that soil health is inseparable from human health.
This connection between soil microbiomes and human physiology is central to the One Health approach: environmental quality, ecological stability and public health are interdependent, not separate policy domains.
Turning urban waste into soil wealth
Cities generate about 70% of global municipal waste. It comes from food scraps, agricultural residues and other organic materials. This waste can be transformed into soil-building assets. Compost, biochar and biowaste converted through black soldier fly systems can return nutrients to urban soils, restore degraded land and support productive green spaces.
When architects and developers integrate circular organic waste strategies into new projects, they create healthier landscapes and reduce pressure on landfill. Municipalities can scale composting infrastructure, they turn a major waste challenge into a climate solution. The City of Adelaide in Australia has been implementing widespread composting initiatives that involve the city council, a commercial mall, a music festival, and initiatives led by local residents.
Circular soil systems close the loop between consumption and regeneration—an essential shift if cities are to become net contributors to environmental stability rather than drivers of degradation.
Incorporating soil into urban planning
Urban soils rarely appear on drawings or in development briefs. However, they influence stormwater performance, planting success, microclimates, maintenance costs and long-term resilience. Treating soil as infrastructure opens the door to better streetscapes, more reliable green roofs, thriving public spaces and more climate-resilient neighbourhoods.
Investing in soil health is cost-effective: it reduces flood damage, lowers energy demand for cooling, and boosts the performance and longevity of landscape assets. Studies also show that human connection to soil can improve public health.
The hidden shield beneath our feet
Healthy soils absorb and retain rainfall, slowing runoff and reducing erosion, while protecting infrastructure and lowering disaster risk. For cities facing more intense storms, this natural capacity acts as a shield.
The ground beneath our cities is alive, and that its health shapes ours. As we design, build and plan for the future, recognising soil as living infrastructure isn’t a nice-to-have. It’s essential to creating cooler, greener and healthier cities that can thrive under the pressures ahead.
Ultimately, soil is one of the most powerful climate, water and health infrastructures available to cities—and one of the least utilised. Embedding soil science into urban development is a structural shift, not an aesthetic upgrade, and it is fundamental to building truly resilient, nature-positive cities.
