The Hidden Life in Soil
Submitted by ~ Ann McKean
As Master Gardeners, we know all about soil texture, pH, cations, nutrient and water holding capacity and how all these things affect soil’s ability to support the plant life above it. But there is a whole world of life in the soil which is mostly out of sight, and for most of us, out of mind. Apart from insects and other invertebrates which live in the soil, there is another form of life which plays a vital role in the health of the soil and the plants we love so much, and ultimately the health of every living thing including us. That life is fungi.
When we think of fungi we usually think of mushrooms, but these are only the fleeting fruiting bodies of mycelium, the vegetative body of fungus and the foundation of the food web, which forms a vast underground network and creates the rich soils we depend on for life. In fact, scientists believe that one of the largest (and oldest) single life forms on earth is a fungal network found on a mountain in Oregon. These fungal networks break down matter through decomposition and make nutrients available in soil. Without them, we would be buried in un-decayed matter.
The three general types of fungi are parasitic, saprobic (decomposers) and the mycorrhizal and endophytic (mutualists). Powdery mildew is a good example of a parasitic fungus which breaks down a living host. The cultivated mushrooms that we consume are saprobic fungi which live on dead organic matter; however, the most amazing type of fungus is mycorrhizal, which forms a symbiotic relationship with plants. As the mycelium of mycorrhizal fungi grows through the soil, it forms connections with the roots of plants and supplies available water and nutrients such as phosphorus to the plants. In exchange, the mycelium receives photosynthates such as sugars which it needs but cannot produce. It even stores these carbohydrates (a form of carbon sequestration) and releases them back to the plants in times of need. And mycelia not only help one particular plant, but they form a bridge between plants which transfers chemical information and nutrients back and forth between the plants, often allowing stronger plants to direct more nutrients to weaker plants. Scientists believe that over 90% of all plants have a natural mycorrhizal relationship and as a result these plants are more resilient to fluctuations in weather and even to the effects of climate change.
Just as we benefit from a healthy microbiome in our gut to digest our food, so does mycelium. Mycelium is a powerful digestive membrane with the ability to break down toxins in our environment, but to maintain healthy soils full of life, we must be thoughtful about the substances we use in our gardens. While chemical fertilizers and pesticides offer rapid gratification, they can often weaken and even kill the fragile microbiome in the soil. This, in turn, creates a cycle of dependence on these chemicals. The way to restore the healthiest possible soil (and plants) is to mimic nature and use gentle natural organic materials which protect the microbiome while feeding the complex mycorrhizal networks which have evolved to nurture our plants and the vast community of life in the soil. This promotes a healthy balance in our gardens and our environment.
By understanding and supporting the complex hidden community of life in the soil which depends on the miracle of mycelium, we can intentionally and actively contribute to the resilience and sustainability of our own communities and our planet.