Do added soil microbes improve sports turf quality?

Soil microbes play a vital role in soil health, influencing everything from nutrient cycling to organic matter breakdown.

Turf professionals are increasingly exploring microbial inoculants—such as compost teas or commercial microbial products—as a tool for enhancing turf quality.

Understanding how they interact with existing soil microbiology is key to making informed decisions on their use.

Understanding soil microbes in turf management

Soils naturally contain vast microbial populations, including bacteria, fungi, and other microorganisms that contribute to organic matter decomposition and nutrient transformations. The idea behind microbial products is that increasing microbial numbers will enhance these processes, leading to better turf health.

However, research suggests that in well-maintained sports turf, microbial populations are already diverse and abundant. This raises an important question: In soils already rich in microbial life, will adding more make a meaningful difference?

What does the research Say?

Recent studies have examined how microbial amendments influence soil biology and turf quality, with key findings including:

• In well-managed sports turf, microbial populations are naturally diverse and abundant.
• Applying microbial products does not always lead to significant improvements in turf health.
• Standard maintenance practices—such as aeration, nutrient management, and moisture control—have a greater influence on soil microbial balance than the addition of inoculants.

For example, a study investigating commercial mycorrhizal inoculants found that their colonisation rates were often below 10%, meaning they had minimal impact on overall soil microbiology.

Similarly, trials on compost teas and microbial amendments have shown little measurable improvement in turf performance when applied to soils already rich in microbes.

While certain situations—such as newly constructed or degraded soils—may present a greater potential for benefits, research has yet to establish consistent improvements from these products.

Why do some turf professionals see results?

As with many aspects of turf management, the effectiveness of microbial inoculants depends on a variety of factors. Several reasons may explain why some professionals report positive results:

• Soil conditions vary – In some situations, such as newly constructed pitches or soils lacking organic matter, microbial inputs may help improve soil function.
• Multiple factors at play – Microbial products are often applied alongside fertilisers, wetting agents, and other treatments. If turf quality improves, it can be difficult to isolate the specific impact of the microbial inoculant.
• The power of observation – When a product is expected to work, there is a natural tendency to attribute success to its application, even if other factors are playing a greater role.

Rather than viewing microbial products as a universal solution, it’s important to consider their role in the wider context of soil health and turf management.

How to support healthy soil microbial activity

Instead of focusing solely on adding more microbes, an effective approach is to create the right conditions for beneficial microbial activity. This includes:

• Optimising soil conditions – Microbes thrive when soils are well-aerated, have adequate moisture, and contain sufficient organic matter.
• Managing inputs carefully – While fungicides are sometimes blamed for harming microbial life, research suggests their impact on overall microbial diversity is minimal.
• Focusing on sustainable turf management – Good agronomic practices, such as balanced fertilisation, organic matter management, and regular aeration, naturally support healthy soil microbial communities.

ICL’s approach to microbial products

Soil microbes are undoubtedly important, but the idea that simply adding them will always lead to better turf quality depends on the specific conditions of the site. Rather than thinking of microbes as an external input, it’s more useful to consider how turf management practices influence the microbial populations already present in the soil.

ICL is actively exploring this area and working internally and with external partners to shed further light on the role of microbial products in sports turf.

However, we will only supply products in this category if their benefits are proven by robust trial work.

We remain committed to our technical values—offering products that perform, making claims based on research, and providing progressive and responsible advice to the industry.