Without Fungi, How Could Our Agricultural Ecosystems Survive?
Foodthink Says
Distinct from plants and animals, these life forms exist as mysterious, powerful, and often overlooked presences, quietly guiding humanity’s quest to live in harmony with nature. How do fungi and plants flourish together? What crucial role do mycorrhizal fungi play in agricultural ecology, serving as the vital bridge between flora and soil? And under the relentless drive to maximise yields, how has this very foundation that sustains agricultural ecosystems been undermined?
We present an excerpt from the new book *The Mycelial Web*. By understanding the profound interactions between fungi and plants in the soil, we might consider a different possibility: the future of agriculture may not lie in more chemicals, but in recognising and safeguarding the subtle, complex symbiotic ties within soil ecosystems. 🍄🟫
“Human health and wellbeing inevitably depend on the functional efficiency of this mycorrhizal association.” This was written by Albert Howard, one of the pioneers of the modern organic agriculture movement and an ardent advocate for mycorrhizal fungi. In the 1940s, Howard posited that the widespread use of chemical fertilisers would sever mycorrhizal connections, emphasising that “it is precisely the mycorrhizal network… that binds fertile soil to the trees it nourishes.” The damage caused by chemical fertilisers can have far-reaching consequences. Severing these “living fungal threads” equates to compromising soil health. This would in turn impair crop health and yields, ultimately affecting the animals and humans that rely on them. “Can humanity moderate its own behaviour to safeguard its most fundamental asset—soil fertility?” Howard questioned. “The future of human civilisation rests on the answer to this question.”
Howard’s tone may have been somewhat hyperbolic, but over the following eighty years, the questions he raised have only grown more pressing. By some estimates, modern agriculture has proven highly efficient: crop yields doubled in the latter half of the twentieth century. Yet this narrow focus on yield has exacted a steep toll. Agricultural expansion has driven widespread environmental degradation and accounts for a quarter of global greenhouse gas emissions. Despite heavy pesticide use, 20% to 40% of crops are still lost to pests and disease each year. Even though fertiliser application increased 700-fold in the latter half of the twentieth century, the growth rate of global agricultural output has begun to plateau. Every minute, an area of topsoil the size of thirty football pitches is lost to erosion worldwide. Yet we waste a third of the food produced, and demand for crops is set to double by 2050. The urgency of this crisis cannot be overstated.
Could mycorrhizal fungi offer part of the solution? It may sound like a daft question. The mycorrhizal partnership is as ancient as plants themselves, having shaped the Earth’s trajectory for hundreds of millions of years. Whether we consider them or not, these fungal networks have always profoundly influenced crop yields. For millennia, traditional farming practices across much of the world have prioritised soil health, quietly preserving the symbiotic bond between plants and fungi. But throughout the twentieth century, our neglect of this dynamic has done considerable harm. In 1940, Howard’s greatest fear was that advances in modern agricultural technology would disregard “the life of the soil”. That fear has been realised. Conventional farming has treated soil as a largely lifeless medium, severely disrupting the subterranean communities that sustain edible plants. This parallels much of twentieth-century medical science, which frequently conflated “germs” with “microbes”. Admittedly, some soil organisms, like certain microbes within us, can cause disease; but the vast majority play a wholly beneficial role. Disrupt the delicate ecology of the gut microbiome and our health suffers; indeed, many contemporary human ailments are linked to the excessive eradication of so-called “germs”. Soil is the Earth’s gut; disrupt the complex ecology of soil microbes, and plant health will inevitably suffer.
In 2019, researchers at Switzerland’s Agroscope institute published a study measuring the scale of disruption by comparing the impact of organic and conventional “intensive” farming on fungal communities in crop roots. By sequencing fungal DNA, the researchers were able to compile networks illustrating how fungal species interconnect. They found “striking differences” between fields managed organically and those managed conventionally. In organically managed fields, mycorrhizal fungi were not only more abundant but also formed more complex communities: they identified 27 highly interconnected “keystone species”, whereas conventionally managed fields contained none. Numerous studies report similar findings. Through the combined effects of farming practices, chemical fertilisers, and fungicides, intensive agriculture has drastically depleted mycorrhizal fungi and altered their community structure. Regardless of organic status, more sustainable agricultural practices generally encourage the soil to sustain a greater diversity of mycorrhizal communities and a richer fungal mycelium.
Do these differences matter? A large part of agricultural history is a history of sacrificing ecology. Forests have been felled to clear land for crops, and shrubs removed to expand acreage. Why should soil microbial communities be exempt? We apply fertilisers to the fields, “feeding” our crops, which surely renders mycorrhizal fungi redundant. Since we have made them unnecessary, why should we care?
Mycorrhizal fungi do far more than simply nourish plants. While some researchers at Agroscope describe them as keystone species, others prefer the term “ecosystem engineers”. Mycorrhizal mycelium acts as a living, sticky needle and thread, weaving through the soil underground to bind earth and retain water; remove the fungi, and soil and water become prone to erosion. They increase the soil’s water retention capacity, and can reduce nutrient loss from rainwater runoff by as much as half. A substantial portion of the soil’s organic carbon—which stands at a staggering double the amount found in plants and the atmosphere combined—is locked within the tough organic compounds produced by mycorrhizal fungi. The organic carbon flowing into the soil through mycorrhizal channels sustains complex food webs. In a single teaspoon of healthy soil, alongside hundreds of metres or even kilometres of fungal hyphae, there exist more bacteria, protists, insects, and other arthropods than all humans who have ever lived.
There are now numerous projects seeking fungal solutions to agricultural challenges, and Katie Field is one of the researchers benefiting from such funding. “The relationship as a whole is far more variable and susceptible to environmental factors than we tend to assume,” she told me. “Often, the fungi do not help crops absorb nutrients. The effects of mycorrhizal associations are highly unpredictable, depending entirely on the species of fungus and plant involved, as well as the environment in which they grow.” Other studies have reported similar unpredictability. During the breeding of most modern crop varieties, the ability to form effective mycorrhizal associations was largely overlooked.We have bred wheat strains that grow rapidly in nutrient-rich soils, ending up with “spoilt” plants that have largely lost their capacity to cooperate with fungi.Field points out: “The fact that fungi still manage to colonise the roots of such crops is, in itself, something of a small miracle.”
The subtlety of mycorrhizal relationships lies in the fact that the most obvious intervention—supplementing plants with mycorrhizal fungi and other microbes—is a double-edged sword. Sometimes, as the hobbit Samwise Gamgee discovered in *The Lord of the Rings*, introducing soil microbial communities to plants can not only support crop and tree growth but also revitalize degraded soil. But whether this practice truly works depends on ecological fit. Poorly matched mycorrhizal fungi may do more harm than good; worse still, introducing opportunistic fungi into a new environment could allow them to displace native species, with unpredictable ecological consequences. The rapidly expanding commercial mycorrhizal fungi industry frequently overlooks this reality, marketing these products as a one-size-fits-all solution. Much like the booming human probiotic market, many strains are selected for commercial use not because they are particularly well-suited, but because they are easy to produce at scale. Even with sound guidance, applying fungal inoculants to the environment is no panacea. Like all living organisms, mycorrhizal fungi only thrive under specific conditions. Soil microbial communities are in a constant state of assembly; if continually disturbed, their connections will not endure. For microbial interventions to be effective, agricultural practices require deeper transformation—much like how restoring a damaged gut microbiome demands changes to diet or lifestyle.
Other researchers approach the problem from a different angle.If humans have inadvertently bred crops that form dysfunctional symbiotic relationships with fungi, it follows that we can reverse the process and cultivate varieties capable of recruiting highly effective symbiotic partners.Field is currently exploring this approach, aiming to breed crop varieties with stronger symbiotic capacities—“a new generation of supercrops capable of forming remarkable connections with fungi.” Kiel is equally intrigued by these possibilities, but views them from the fungus’s perspective. Rather than breeding plants that are more prone to forming symbioses, she is cultivating fungi that are more beneficial to crops: strains that hoard fewer nutrients for themselves and, where possible, prioritise the plant’s needs.
In 1940, Howard noted that we lacked a “complete scientific explanation” for mycorrhizal relationships.Today, our scientific understanding remains incomplete, yet as environmental crises intensify, there is growing hope that introducing mycorrhizal fungi can reshape agriculture and forestry, and restore degraded ecosystems.In the early days of terrestrial life, mycorrhizal associations continuously evolved to meet the survival challenges posed by barren landscapes and harsh climatic conditions. Plants and fungi co-evolved a form of agriculture—though we do not know whether plants learned to cultivate fungi, or fungi learned to cultivate plants.Regardless, we face a challenge: to alter our own practices so that plants and fungi may better cultivate one another.
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— Excerpt from the introduction to Entangled Life
Author: Merlin Sheldrake (UK)
Translator: Dinghao Luo | Proofreader: Songyan Zhou
ISBN: 978-7-5596-7775-4
Beijing United Publishing Co., Ltd. | First edition, October 2024