Degraded urban soils can be difficult to restore. They may be compacted, stripped of organic matter, contaminated, poorly drained or affected by repeated disturbance. Fungi cannot solve every soil problem, but they may support practical assessment, restoration and ongoing management when used as part of a broader site plan.
For councils and municipal remediation teams, the most useful approach is to treat fungi as one possible tool rather than a stand-alone treatment. The right choice depends on the soil’s physical condition, the contaminants present, the intended future use of the site, available maintenance resources and the results of monitoring.
How fungi may contribute to urban soil work
Fungi are natural components of healthy soils. Their thread-like structures, called hyphae, can grow through soil and organic material. Fungi help break down plant residues and other organic matter, contributing to nutrient cycling. Some fungi also form partnerships with plant roots. These partnerships, known as mycorrhizae, may help plants access water and nutrients, although the benefits depend on the fungal species, plant species and site conditions.
These functions suggest several possible uses in urban soil projects:
- Supporting soil restoration: Fungal activity may be encouraged through the careful addition of suitable organic matter, mulches or plantings. This can form part of a wider effort to rebuild biological activity in soils that have been disturbed or depleted.
- Helping vegetation establish: In appropriate situations, beneficial root-associated fungi may be considered alongside plant selection, soil improvement and irrigation planning. They should not be treated as a substitute for suitable soil, healthy plants or adequate watering.
- Contributing to organic matter breakdown: Fungi can help decompose plant residues and other biodegradable material. This may be relevant to managed composting or soil-amendment programs, provided materials are suitable and contaminants are controlled.
- Supporting investigation of biological processes: Changes in fungal activity or soil biology may provide useful information about soil condition. Biological indicators are most meaningful when interpreted with chemical and physical test results, rather than used alone.
- Exploring pollutant treatment: Some fungi have been studied for their ability to transform or immobilise certain contaminants. These approaches are often site-specific and may remain experimental or require controlled testing. A council should not assume that a laboratory result will translate directly to a field site.
Start with site assessment
Before considering a fungal approach, establish what is wrong with the soil and what the site must support in future. A soil that is compacted requires a different response from one affected by hydrocarbons, excessive salinity, poor drainage or an unsuitable imported fill.
A preliminary assessment should consider:
- the proposed land use, such as open space, streetscape planting, habitat, construction or public access;
- the history of the site, including demolition, industry, waste disposal, flooding, earthworks and previous landscaping;
- soil depth, texture, compaction, drainage, pH, organic matter and salinity;
- possible contaminants and the pathways by which people, plants, animals or water could be exposed;
- existing vegetation, invasive species and the availability of water for establishment;
- any relevant legal, planning, waste, occupational health and environmental requirements.
Sampling should be planned by a suitably qualified person and should reflect the size and variability of the site. Contaminated soil should be handled under an appropriate health and safety plan. If the site presents a potential exposure risk, biological amendments or fungal inoculants should not be introduced simply because they are described as natural. Natural materials can still contain contaminants, affect exposure pathways or behave unpredictably.
Where fungal approaches may fit
Fungal methods are more likely to be useful where the main objective is to improve soil function, support vegetation or manage organic material, and where risks can be controlled. They may be considered in planting beds, revegetation areas, community gardens, green infrastructure or other sites where soil conditions are understood and ongoing management is possible.
They may also be investigated as part of a carefully designed treatment trial for particular organic contaminants. Such work requires a clear performance objective, baseline testing, controls where appropriate and a plan for dealing with unsuccessful results. It should be undertaken with the involvement of environmental specialists and relevant regulators where required.
Fungi are less likely to be the right first response where contamination is severe, rapidly mobile or presents an immediate human health risk. Excavation and disposal, containment, soil replacement, capping, chemical treatment, engineered drainage or other established methods may be more appropriate. In some cases, the safest decision is to restrict access or change the proposed land use rather than attempt biological restoration.
Use fungi alongside established practices
A fungal approach should normally be integrated with conventional soil and landscape work. This might include removing unsuitable material, reducing compaction, improving drainage, adding verified soil amendments, selecting plants suited to the site and protecting newly restored areas from repeated disturbance.
For example, encouraging beneficial soil biology will be difficult if heavy vehicles continue to compact the soil, if imported fill is poor quality or if plants are allowed to dry out during establishment. Fungal products cannot compensate for a basic mismatch between the soil and the intended vegetation.
When selecting a product or material, ask for clear information about its contents, intended use, handling requirements, storage conditions and quality controls. Avoid materials with vague claims about detoxification, guaranteed plant growth or universal suitability. Any amendment should be checked for contaminants, weed seeds, pathogens and other risks relevant to the site.
Questions to ask before adoption
A council or project team should be able to answer the following questions before committing funds or changing a remediation plan:
- What specific soil problem is the fungal approach intended to address?
- Is the proposed method established for this type of soil and land use, or is it experimental?
- What evidence is available for comparable conditions?
- What baseline chemical, physical and biological measurements will be collected?
- What result would count as success, and over what timeframe?
- Could the treatment increase exposure risks, spread unwanted organisms or interfere with another remediation method?
- Who will install, inspect and maintain the treatment?
- What is the fallback plan if the expected improvement does not occur?
- Are approvals, permits, waste controls or public communications required?
Plan for monitoring and maintenance
Monitoring should match the project objective. A revegetation project may track plant survival, canopy development, soil moisture, erosion and signs of compaction. A contamination project may require repeat laboratory testing, risk assessment and verification that contaminants have been removed, contained or changed into less harmful forms. A change in fungal activity alone does not prove that a contaminant has been made safe.
Record the materials applied, application rates, dates, weather conditions, irrigation and maintenance activities. Inspect for unexpected plant decline, odours, surface growth, runoff, pest issues or movement of amended soil. Results should be reviewed at agreed decision points, with the option to adjust, stop or replace the approach.
Maintenance may include watering, mulching, protecting soil from traffic, controlling competing vegetation and replacing failed plants. Fungal activity is influenced by moisture, temperature, oxygen, organic matter and disturbance, so benefits may decline if the restored area is not managed appropriately.
A measured role for fungi
Fungi can be valuable partners in urban soil restoration, particularly when the goal is to rebuild soil function and establish suitable vegetation. Their use is most responsible when it is based on site evidence, integrated with proven remediation and landscape practices, and followed by practical monitoring.
For municipal teams, the key question is not whether fungi are natural or innovative. It is whether a clearly defined fungal intervention is suitable for the site, safer and more useful than available alternatives, and capable of being evaluated over time. In many projects, the best outcome will come from combining biological processes with careful engineering, good soil management and realistic long-term maintenance.