Understanding the benefits of this fungi, greatly helps to improve the productivity and health of soil.
Among all the different soil organisms, bacteria and fungi are especially important to consider for soil health, and particularly, arbuscular mycorrhizal fungi (AMF), which interact with 80% of plant species. AMF developed a symbiotic relationship with plant roots 460 million years ago. It has many important roles in the life of soil.
- It aids in the decomposition of organic matter,
- facilitates nutrient cycles and the storage of carbon,
- helps to build soil structure and
- protects the plant.
The networks of mycorrhizal strands, also referred to as mycelium, extends the capacity of the plant’s roots and connect plants to one another. Understanding the multiple benefits of this fungi, greatly helps to improve the productivity and health of soil. For example in grasslands a greater number of fungi in the soil increases grass health and reduces weed growth. Many agricultural practices such as inversion ploughing, the growing of monocultural crops and the use of chemical fertilisers, fungicides, herbicides and pesticides cause damage to mycorrhizal fungi. As a result, much of our agricultural soil is impoverished, with low levels of fungi, and cannot benefit from the full range of services they offer to crops.
Access to nutrients: When a farmer wants to improve plant growth, they need to understand the nutrient content of their soil. The average soil test usually only identifies the soluble nutrients that are readily available to the plants in the short term. But beyond these soluble nutrients, there is a huge natural resource of other untapped nutrients in the soil. The trick is finding ways to make them available to the plants, and mycorrhizal fungi as well as other microorganisms can do this.
For example, mycorrhizal fungi:
- help plants to access soil reserves of phosphorous beyond the root zone.
- assist with accessing macro-nutrients such as calcium, magnesium, potassium and nitrogen,
- as well as micro-nutrients such as zinc, copper and iron.
If one or more nutrients are deficient in soil, farmers usually add chemical versions of these nutrients to boost plant growth. However this upsets the fragile soil ecosystem and inhibits the plant’s potential to make the most of the large store of nutrients already in the soil.
“Mycorrhizal fungi are incredible organisms, but they are also very sensitive, they don’t like excess moisture, they don’t like excess nutrients and of course they don’t like pesticides,” says Joel Williams.
Protection from disease: Plants grown as crops are susceptible to all manner of pests and diseases but when pesticides are used, the plants are effectively placed in a protective ‘bubble’ where they cannot develop their own natural immunity, “the rich suite of biological compounds that the plant would have naturally synthesised in order to protect itself will not be produced.” As a result, the plants themselves are weak and continually need more external chemical inputs to combat pests and diseases, causing damage to soil biology and ecosystems.Mycorrhizal fungi help plants to combat disease in several ways, such as by colonising the plant’s roots and penetrating the root cells with their branching structures, excluding and protecting the roots from pathogens. Mycorrhizal fungi also release several antibiotic substances into their mycorrhizospheres.
Drought resistance: Mycorrhizal fungi are also essential in helping plants to tolerate drought. The hyphae access moisture in soil micro-pores that roots are not able to access themselves. The symbiotic relationship between the plant and mycorrhizal fungi also improves plant hydration by activating specific cells in the plant that improve water uptake and transportation. At the same time, biochemical compounds are produced that allow plants to maintain high organ hydration and sustain overall physiological activity in the cell such as photosynthesis, in times of drought.
Ref: Hannah Steenbergen of Sustainable Food Trust reporting from RegenAg’s course, where Joel Williams details on how to farm in order to improve mycorrhizal fungi and build soil health.
