So, what do we mean by soil health? The International Union of Soil Sciences (IUSS, 2006) defines soil as:
“the biologically active, porous medium that has developed in the uppermost layer of Earth's crust. It is created through weathering processes and organic decomposition and plays a crucial role in sustaining plant growth and supporting ecosystems.”
The key phrase here is “biologically active.” Healthy soil is teeming with life—from microscopic fungi and bacteria to earthworms and insects. Yet, much of our soil today has lost this biological richness, leaving us with what many now call “dirt”—lifeless, compacted, and lacking in organic matter.
Healthy soil isn’t inert; it’s a dynamic ecosystem that cycles nutrients, supports diverse life forms, and underpins every aspect of our environment. It influences water retention, carbon storage, and even plant disease resistance. When soil is alive, it acts as a robust buffer against climate change and sustains ecosystem productivity.
Modern land management practices have disrupted the delicate balance of our living soils. Intensive grazing, overuse of chemical fertilisers, herbicides, and pesticides have decimated the natural microbial communities—especially the mycorrhizal fungi that form vital underground nutrient-exchange networks with plants. When synthetic inputs replace natural processes, we lose the very life that sustains soil structure and fertility.
The scale of soil loss is staggering. Global estimates suggest that due to unsustainable practices and land-use changes, up to 36 billion tons of soil are eroded each year (Borrelli et al., 2017). To put it into perspective, the UN Food and Agriculture Organization (FAO) warns that if current practices continue, 90% of Earth’s topsoil could be at risk by 2050—and we lose the equivalent of one soccer pitch of soil every five seconds (FAO, 2022). These figures underscore the urgency of shifting toward restorative soil management, prioritizing methods that rebuild soil integrity rather than deplete it.
The Impact of Fungal Loss on Soil Health
One of the most fundamental—but often overlooked—drivers of soil stability is its fungal communities. Beneficial fungi play a crucial role in maintaining soil health, nutrient cycling, and ecosystem resilience. Their decline has profound consequences for soil health, affecting everything from nutrient availability to biodiversity. For instance, mycorrhizal fungi play a crucial role in facilitating the uptake of essential nutrients like phosphorus and nitrogen (Smith & Read, 2008). Without their presence, plants struggle to access these nutrients effectively, leading to weakened growth and reduced overall productivity (van der Heijden et al., 2015). Their decline results in pastures dominated by fewer, hardier species, reducing ecological resilience and limiting ecosystem complexity (van der Heijden et al., 1998; Hartnett & Wilson, 1999).
Beyond nutrient absorption, fungi significantly influence soil structure. Their hyphal networks bind soil particles, improving aeration and reducing compaction (Rillig & Mummey, 2006). When these fungal communities diminish, soils become more vulnerable to erosion, losing their stability and resilience (Lehmann et al., 2017). In addition, fungal networks help retain moisture, preventing excessive drying and improving drought resistance (Augé, 2001). Their absence accelerates soil dehydration, increasing susceptibility to prolonged droughts and reducing water availability for plant roots (Querejeta et al., 2003).
Fungi also contribute to plant defence mechanisms, shielding roots from harmful pathogens (Cameron et al., 2013). As fungal populations decline, vegetation becomes more susceptible to disease, further weakening ecosystems (Jung et al., 2012). Similarly, their role in carbon cycling cannot be overstated—fungi convert organic material into stable soil carbon, supporting long-term carbon sequestration (Treseder & Allen, 2000). The disruption of this process leads to decreased organic matter, heightened CO₂ emissions, and diminished climate resilience (Clemmensen et al., 2013).
While fungi are indispensable to soil function, they do not act alone. Bacteria, nematodes, earthworms, and other microorganisms also contribute to the intricate web of soil life, ensuring that ecosystems remain balanced. Their collective efforts break down organic material, releasing nutrients in forms accessible to plants while also improving soil aeration and decomposition. Soil microbes are key regulators of nutrient cycling, supporting plant growth and maintaining soil fertility.
Restoring the full spectrum of soil biology—not just fungi—enhances soil resilience, benefiting agricultural productivity and natural ecosystems alike. A healthy soil community supports more vigorous plant growth, it stabilises landscapes against erosion, and strengthens microbial defences against pathogens.
The Link Between Soil Health and Horse Well-Being
The condition of the soil directly influences the health of horses, particularly through its effect on forage quality. Nutrient-dense forage thrives in biologically active soils rich in essential microbes, ensuring that grazing animals receive the minerals they need to maintain optimal health. Conversely, depleted soils produce lower-quality forage, which can lead to hidden malnutrition even when horses appear well-fed (Harris et al., 2017).
Another crucial factor is how soil biology affects plant sugar composition. Imbalances in microbial communities can alter sugar levels in forage, increasing the risk of conditions such as laminitis and Equine Grass Sickness (EGS) (McCarthy et al., 2004; Wright et al., 2005). Poor soil structure further exacerbates disease risks, as compacted or degraded soils become breeding grounds for harmful pathogens. Environments that encourage Clostridium species, for example, heighten the risk of tetanus and pneumonia in horses (Giguère et al., 2011; Green et al., 1994).
Beyond biological concerns, excessive use of herbicides and pesticides in degraded soils can introduce chemical residues that negatively impact equine health. Long-term exposure to these toxins may disrupt gut function, compromise liver health, and interfere with endocrine regulation (Galli et al., 2024; Smith, 2012).
Building Climate Resilience Through Healthier Soil
Investing in soil health is one of our most effective strategies for climate resilience. Healthy soils store more carbon, better regulate water, and support diverse ecosystems that can withstand environmental stresses. For horses, this means access to more nutritious forage and a lower risk of health issues linked to poor pasture quality.
Restoring soil biology requires a holistic approach—reducing chemical inputs, adopting regenerative agricultural practices, and frequently monitoring soil health. Whether you manage a small paddock or undertaking landscape scale projects, preserving and enhancing soil health is essential for sustainable agriculture, climate resilience, and ensuring our horses genuinely thrive.
References
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