By some estimates, 95% of plant species host some form of mycorrhizal fungi on their roots, and at least 60% of all known plant species are entirely dependent on this symbiotic relationship. Mycorrhizal fungi facilitate more efficient uptake of water and nutrients into plant cells, and in exchange obtain carbohydrates produced through photosynthesis. Many agricultural scientists think harnessing the power of these beneficial fungi could prove revolutionary for smallholder farmers and food security. Yet, the revolution hasn’t arrived.
Scientists know that this class of fungi could be used to improve soil health. “Soil fertility is among the primary challenges faced by smallholder farmers,” wrote Kenyatta University researchers Marjorie Oruru and Ezekiel Njeru in a 2016 look at arbuscular mycorrhizal fungi (AMF) and agriculture. “AMF can be incorporated in smallholder farming systems to help better exploit chemical fertilizers, inputs which are often unaffordable to many smallholder farmers.”
Incorporating fungi can mean promoting their growth as well as adding them. Oruru and Njeru argue that intercropping different crop species with one another not only leads to a more diverse plant community and reduces soil erosion, but also encourages greater microbial diversity within the soil itself, thereby “promoting the colonization of symbiotic microbes such as indigenous AMF in soil” and enhancing soil fertility in the process (http://dx.doi.org/10.1155/2016/4376240).
Mycorrhizal fungi could also make crops more resistant to drought. As Oruru and Njeru explain elsewhere in their paper, mycorrhizal fungi increase root surface area, which helps crops absorb water as well as nutrients.
The 2016 Kenyatta University study concludes that although the potential for enhancing smallholder agriculture through fungus seems apparent, too little is known about how to develop practical applications of symbiotic interactions between mycorrhizal fungi and crops, or how to turn such knowledge into usable technology. “Although beneficial fungi such as AMF play a fundamental role in producing important ecosystem services such as soil fertility, they have received little attention,” the two Kenya-based scientists noted.
Flash forward to today, and the situation hasn’t improved much.
A special issue embedded within the September 2021 edition of the journal Plants, People, Planet is devoted entirely to the topic of mycorrhizal fungi, under the title “Mycorrhizas for a changing world” (https://nph.onlinelibrary.wiley.com/toc/25722611/2021/3/5). Four agricultural scientists from the United Kingdom underscored this special issue’s broad findings in their opening editorial (https://doi.org/10.1002/ppp3.10223). They note that research on the relationship between crops and mycorrhizal fungi is sparse compared to that on wild plants.
The new special issue highlights multiple potential applications of mycorrhizal fungi, in carbon sequestration, forest health, and crop resistance to soil contamination and insect pests. But it’s mostly theoretical, especially for smallholder farmers on marginal lands where the benefits might be largest.
We know that mycorrhizal fungi are critical to plant growth. The potential to revolutionize smallholder agriculture is there. A handful of farmers are already tapping into the potential, such as those in India using Bioensure® inoculant. But we don’t know exactly how to fully realize the potential of mycorrhizal fungi because they just haven’t been studied enough in agriculture. Future projects supported by Grow Further may help to change that.
— Grow Further