Farming With Fungi

What’s orange, alive, heavier than a small car and something you could carve into with a chainsaw? A one-ton plus, giant pumpkin; the world’s heaviest tops the weight of a Ford Fiesta/ Hyundai Accent/Toyota Prius-C at a whopping 1,190.49 kg or 2,624.6 lb,. What’s even more impressive is that champion pumpkin record holders who grow these towering squashes mostly grow them organically and attribute part of that mind-boggling growth to the use of a simple fungus – mycorrhizal fungi.

Mycorrhiza (translating as fungus and root) refers to the symbiotic relationship that a plant’s root and fungus form together. Ninety five percent of the world’s plants enter into this partnership which evolved 450 million years ago. It’s so fundamental to life on earth, that we wouldn’t have any plant life living on its surface otherwise.

“There were no land plants before there was the mycorrhizal relationship,” says Dr. Michael Amaranthus, a former USDA Forest Service Soil Ecologist who has been working with mycorrhiza for over four decades. “It was that fortuitous marriage of a plant and fungus that allowed aquatic plants to colonize the surface.”

Back then, the land was a harsh environment, a lifeless mix of mineral rock and dirt. 

“It wasn’t soil because soil is organic, it’s carbon, hydrogen and oxygen bound to sand, silt and clay,” says Dr. Kris Nichols, a soil microbiologist and Founder of Kris Systems. “You didn’t have soil until you had aquatic algae that washed up on the land and started forming soil for the plants to evolve into that environment. Soil itself was formed by mycorrhizal fungi and plants.”

Visible fungi like mushrooms, and woody plants and trees form fungal connections based outside the plant’s root cells. What greatly benefits growers, that most crop plants associate with, is the subdivision of a type of mycorrhizal fungi, invisible to the eye called Arbuscular Mycorrhizal fungi (AMF) which grows into a plant’s root cells. AMF is what allows growers to grow mammoth pumpkins, marrows, carrots and more. If utilized to its fullest potential it can give us a completely different way to grow food.

So how exactly do they help?

The Mycorrhizal relationship 

Once the AMF encounters a living root, it colonizes it by extending minute pipeline like filaments called hyphae into the plant’s cell walls and the surrounding soil to set up an exchange system. Thinner than root hair, hyphae burrow into soil pores that plant roots can’t reach or are too big to get into, so much so, that within a healthy ecosystem, you’d have 300 miles of hyphae under one of your feet. 

Plants are in charge of this relationship, paying carbon (sunlight energy in usable form) produced through photosynthesis for nutrients and water which the mycorrhizal fungi mine and transport back to them on order. While the fungi get the carbon they require but can’t produce themselves to grow, the plant benefits by having its root’s reach extended several hundred to several thousand times, with everything it might need being delivered directly to its doorstep.

“They are basically the stomach of the plant,” says Amaranthus. “They digest the food and water in the soil to make it available to them.”

That’s not all they do.

Mycorrhizal fungi break down certain elements like Phosphorus that are chemically locked up in the soil into a form that plants can easily absorb, significantly increasing their nutrient uptake. Drought tolerance is higher thanks to the hyphae’s ability to hold and transport water. Plants experience greater immunity, as the fungi help out by ferrying more nutrients and water in the case of any damage, since the plant’s death results in their own dormancy and eventual demise as well. As the underground fungal network (mycelium) grows, connecting with the roots of more plants and different species, it enables better disease resistance, pest defense and pathogen protection, as plants are more able to quickly respond to chemical signals of any insect attack or trauma. 

“There are soils, growing conditions and even seasons where plants cannot survive without this symbiotic association.” says Scott Inman, Head of Technology/R& D at Mycorrhizal Applications, Oregon.

Moreover AMF are the only producers of a sticky carbon compound called glomalin that gives soil that smooth granular texture as it flows through your fingers. Not only does glomalin bind soil particles into aggregates giving it structure and stability, but it’s also 38 percent carbon and as the fungi grow and die they keep adding that carbon to the soil. A staggering one third of the world’s carbon reserves in soil is glomalin, which can persist in soil for 7 to 42 years.

“The carbon in the organic matter is like a savings bank, a slow release fertilizer that plant roots and hyphae have access to,” says Dr. Gladis Zinati, Director of the Vegetable Systems Trial, Rodale Institute, Pennsylvania. 

Unfortunately modern agricultural methods are a bane to AMF.

Modern Agriculture

“These fungi have sort of a hard time in modern agriculture, because several practices work against them,” says Matthias C. Rillig, a Professor of Plant Ecology, Institute of Biology, Berlin. “As a result, very often they cannot live up to their potential.”

Applying fungicides, pesticides and herbicides kills AMF and many beneficial soil organisms. Fallow/bare land means no AMF growth since there aren’t any plant roots to colonize. (Most weed plants are non-mycorrhizal). Adding huge quantities of chemical fertilizers don’t allow AMF to grow since plants get the major nutrients in abundance and don’t need to establish fungal trade connections. Heavy tilling machinery tears apart fragile AMF networks that inhabit the top 6 to 15 inches of soil and destroy the spores by which they propagate, so they don’t come back so readily.

“If people want to start a war, what’s the first two things they take out? Communications and logistics. That’s what we did on soil.” says Dr. David Johnson, Director of the Institute for Sustainable Agricultural Research, New Mexico State University, Las Cruces. 

To be clear, crops can still grow in soil that doesn’t have any AMF and microbial life but because they lack these critical biological tools to access their environment, they suffer.

“When the root system goes into the soil in a chemical agricultural field, there’s nothing there for it to grow on and the processes that it’s expecting to see, aren’t there,” says Dr. Elaine Ingham, a soil microbiologist and founder of Soil Foodweb Inc. “So of course, they don’t grow very well and are susceptible to diseases and pests.”

The more this delicate soil food web is destroyed, the more we need to intervene. 

“If there are no mycorrhizal fungi, then the grower has to figure out a way to take their place to provide the plants with water, nitrogen, phosphorous, copper, zinc and more or lose the crop,” says Jeff Lowenfels, an organic gardening expert.

Our interference isn’t pretty. Globally, 70% of freshwater is used for agriculture. Agricultural fields are losing soil between 13-40 /tons/hectare/year which is 13-40 times faster than soil can be renewed. Over 50 %of the nitrogen applied as fertilizer is wasted. The excess nitrogen and phosphorus fertilizer runoff pollutes water bodies leading to toxic algae blooms that deplete underwater oxygen levels and cause dead zones that can’t support marine life. And that’s just scratching the surface of the impact modern agricultural methods have had on our environment.

We routinely consume produce with pesticide residues and the farmers who grow them face a greater risk of contracting many types of cancers. The list of woes goes on. How did we get to this sad state of affairs?

Dovetailing Issues

A few generations ago, growing nutritious food was easy. Indigenous people didn’t disturb the soil as much and settlers profited from those natural practices because all they had to do get a great crop was plant and harvest. 

“We had the benefit of 53 million years of carbon accrual in the soil,” says Johnson. “Some of those carbon profiles were six feet or more deep.”

In the early 1900’s that soil carbon began to run out. There was little focus on adding it back.

“If you consider soil carbon to be like a bank account, we’ve pushed it past insolvent,” adds Johnson. “Now we’re borrowing everything and everything we are putting on these fields is fossil energy.”

Fossil energy in the form of initially inexpensive, Nitrogen, Phosphorus and Potassium (NPK) fertilizers; a plant version of junk food. It artificially boosted growth, but didn’t provide balanced plant nutrition and degraded soil life in the process.

“Farmers would see this yield response to adding fertilizers but they didn’t understand that part of that it was due to the activity of soil organisms that obtained not just the major nutrients like NPK but also the micronutrients plants were looking for,” says Nichols. “Back then we had more of a microbial community that was able to compensate for what the plant couldn’t obtain from the synthetic nutrients. We replaced the job of the mycorrhizal fungi and really reduced the soil organism population over time so much so that it’s hard to see a good response from them.”

Dropping yields brought in plant breeders who focused on selecting plants that grew faster, lived shorter lives, yielded larger produce and more of it per acre. The trade-off though was that these plants devoted less energy to activities like growing deeper roots, absorbing minerals and synthesizing vitamins. 

“We’ve selected for the stupidest and weakest,” says Nichols, “We’ve given them an environment rich in chemical inputs and while they are high yielding, they don’t know how to work as well with soil biology.” 

So there’s more food, as yields have gotten higher, but its nutritional worth is way less. A 50-year plus study pointed out that to get the same amount of iron from eating one apple in 1940, you’d need to eat three apples (in 1991).

Clearly, our methods aren’t sustainable. However global demand keeps rising. By 2050 we’re going to have produce 70% more food if we are going to feed 9.1 billion people. In a 2009 interview the former Chief Executive Officer of the CSIRO stated that “In the next 50 years we would have to produce as much food as has been consumed over our entire human history.”

That’s a very tall order. If we’re going to have any hope of meeting it and address all the problems we’ve caused, experts say, we need to start thinking biology instead of chemistry.

Put the Biology Back In Soil

Upgrading our agricultural mindset is key, beginning with not viewing plants as individual entities but seeing them instead as the tips of an unseen, living, food-producing iceberg.

“Understand that plants aren’t doing the work alone,” says Professor Heike Bucking, Head of Biology &Microbiology, South Dakota State University. “Whatever you see in terms of plant performance, of yields, performance under certain environmental conditions, or stress resistance is only the result of the microorganisms the plant associates with and they need these interactions to show you their whole potential.”

A relatively easy first step to restore soil biology is to re-establish the mycorrizhal fungi. AMF levels in the soil can only be gauged with a lab test but it’s safe to assume, say experts that any land that’s been intensively cultivated and allowed to lie fallow in between crops has little to no AMF.

Applying mycorrizhal inoculants that contain a few to several AMF species is one way to kickstart mycelial growth. Planting seeds rolled in inoculant ensures that the germinating roots can easily establish the fungal connection. For already existing crops, it helps to inject inoculants near the roots. Simply throwing the inoculant out into bare soil doesn’t change a thing if there are no plants for it to interact with.

“The trick is to not just add the mycorrizhal fungi and not just add plants, but to add them together at the same time,” says Amaranthus. “Whether you inoculate the plants at a nursery or whether you are planting them, if the mycorrizha is already on the roots and growing vigorously so the plants have the tools they need when you out plant them.”

Depending on how close the inoculant is to the root system, the mycorrhiza can develop quite fast. DR Mike states that they’ve seen mycorrhiza start to form within a week, with a colony developing in two months or less. Establishing a large biomass of mycorrhiza, he says, can take an entire growing season.

Ideally, a farmer would need to inoculate the land with AMF only once. Once established, they’d only need to maintain the mycelium long-term to be able to seed/plant crops into it and benefit from the power of plugging into a thriving fungal network. What’s exciting here is that the practices used to maintain the mycelium, also bring back good soil bacteria and all manner of beneficial soil microorganisms, restoring soil integrity over time. Doing all this is easy.

The Fungal Farmer

Once the soil life starts returning, the key principle is to disturb it as little as possible. Ideally one would stop tilling altogether, to avoid cycling between destroying the mycelium and then re-inoculating to recreate it for successive crops. Since the fungi stay alive in the soil for about one to six weeks post-harvest, it’s vital to get the next crop in as quickly as possible so that they can colonize the new plants, and carry the existing mycelial network forward.

Cover crops can serve as biological tillers and planting species known to promote AMF growth like sorghum, sun hemp etc. can greatly increase fungal populations. Growing perennial, short (a few inches) cover crops all through the year that you can plant your main crops into is even better. The goal is to have living plants in the soil to sustain the fungal network at all times.

“A true mycorrhizal plan must involve growing plants,” says Michael Phillips, an organic apple and herb farmer based in New Hampshire. “Our greatest sin as a species is putting so much ground into fallow after a relatively short cropping season.” 

Whenever you cut down a crop, it’s essential to leave some of that plant biomass behind to feed the soil life that feeds the plants. According to Johnson, 60% of the above ground crop biomass needs to go back into the soil.

“Our current way of doing things is like pirates going through a village who take everything and leaving nothing,” says Johnson. “What does that do to the community? 40% is what we are allowed to take as human beings or foraging cattle. Take any more than that and you start to degrade the system.”

Growing more plants as well as different types of them together also helps. Healthy ecosystems have between 20-50 species of mycorrhizal fungi.

“The single most important thing you can do is encourage biodiversity on your farm,” says Miranda Hart, a Biology Professor at the University of British Columbia, Canada. “With more plants, you get more different kinds of fungi, and these fungi bring with them different benefits.”

The biggest benefit being that with the biodiversity present, crop rotation becomes unnecessary.

“Say you’re growing corn and now you are trying to grow tomatoes in there – they need a little bit of a different species,” says Ingham. “If the biology in the soil is correct, then you don’t have to rotate your crops.”

To speed up the process of restoring soil biology, Ingham recommends putting your soil under a microscope, identifying the missing microbial life and then custom designing your compost to bring those specific microorganisms back into the soil. The astonishing result of applying this type of compost is that instead of taking years for the soil to be restored (a fact that’s widely acknowledged in the organic world when transitioning from chemical to organic agriculture), it takes months. 

“It’s not a three year process,” says Ingham. “We can do it fast. When you make sure that all of those organisms are in your compost, and when you put out that inoculum of compost, your plants, your soil gets back to that condition of health within one growing season.”

If the compost is done right, you need very little of it, according to Johnson who developed a special process to create a fungal-dominated compost. 

“700 lb (316 kg) will do 350 acres,” says Johnson. “We’re talking kilograms per hectare.” 

The Benefits

Adding AMF inoculants can straightaway increase both plant growth and yields. Amaranthus states he’s seen a 5-30% increase in productivity and large yield gains even when conditions were harsh, such as with saline soils or heavy clay soils. Farmers’ get more of a growing season as plants still have access to water, for example, when non-mycorrhizal plants have stopped growing.  Weeds don’t grow that well, since the fungal network competes with them and locks away a lot of the soil nutrients. Water requirements reduce so there’s less need for irrigation. Pest problems and diseases go down.

“It gets to be a very simple way of doing agriculture,” says Ingham. “As a farmer, you’re not out there applying stuff, or working in your field every day trying to keep ahead of the diseases or the pests. All of that just goes away.”

The biggest savings is in fertilizer costs. As more of the fertilizer ends up in the plant, fertilizer use efficiency improves and fertilizer leaching losses lessen. Since AMF makes use of fertilizer residues from previous applications, depending on their soil, farmers may not need to any more.

“We got a higher yield on potatoes with 30 to 50% less phosphorus fertilizer by adding mycorrizha,” says Amaranthus. “So that’s big savings for the farmer – a 30 to 50% reduction in the amount of fertilizer they needed to use.”

That’s just the start. When you bring back all the rest of the soil life in addition to the mychorrizhal fungi, the results take off. Ingham states that they were able to get between 50 to 1000% yield increases in fields worldwide after their compost applications because they had the biology on their side.

“When you’re applying the BEAM compost at 2 lbs (900 gm) per acre, you’re putting approximately 83 million bacteria and 10 million fungal spores per square foot,” says Johnson. “You are putting out a diverse and dynamic community.”

Johnson was able to witness the power of that microbial community when their Sesbania plants grew from being 4 feet tall in the first season to 12 feet tall in the third. They also harvested record crops – 20 tons of chilies/acre and six feet tall cotton plants that yielded over five cotton bales/acre (compared to 2.5 cotton bales/acre otherwise).

Will the full backing of microbial soil life, it’s entirely possible to get to a healthy, agricultural system that outperforms natural ecosystems.

“An old growth forest, one of the most productive systems on the planet produces 2200 gms/sq m of above ground dry biomass in a year,” says Johnson. “Agriculture normally averages 600 gms/sq m per year. We were able to do 2200 gms/sq m in ten weeks growth.”

Global Impact

It’s not an exaggeration to say that farming with fungi can literally change the world. As the fungi put carbon (in the form of glomalin) back into the soil, they can restore carbon soil reserves in our agricultural lands, given enough time.

“Some of the research indicates you can put 1000 lb (454 kg) of carbon into the soil per acre per year,” says Amaranthus. “That’s a tremendous amount if you multiply it over millions of acres that are in agricultural production. A 0.4% increase in the carbon content of the world’s soil would mitigate 75% of the world’s annual carbon output into the atmosphere.”

It’s possible to undo some of the damage we have done to the planet with the Green Revolution, that’s been responsible for adding more carbon dioxide and other greenhouse gases into the air we breathe.

 “If we could just get major parts of world to adopt the biological approach, we could take all the elevated Co2 in the atmosphere, and put it back into the soil as energy for our plants,” says Ingham. “And in less than six years, we could reduce the Co2 in the atmosphere to pre-industrial levels.”

Covid-19 has shown us how tragically broken all our food systems are. In a report that collated recommendations for resetting the food system, Danielle Nierenberg, President of Food Tank concluded that we couldn’t go back to normal and that “we need to reimagine how we grow and eat food.”

It can begin, says Nichols, with remembering what we have forgotten as a society, that ultimately what it is that we do as human beings, is work for food, whether we grow it ourselves or purchase it from others.

“We need to get connected back to that food again,” says Nichols. “Instead of paying for food on a mass scale, on the amount of food, we actually need to start paying for its quality, as well as the ecosystem services that food production provides us, to help farmers to put these practices into place and still be profitable.” 

That means going beyond chasing high yields at any cost and not letting all the damage we do slide as the price of progress.

“There are no chemicals or combinations of chemicals that can do what nature already does for us,” says Dr. Wendy Taheri, a microbiologist and AMF expert. “The closer we bring our cropping systems to resemble nature, the better it is for the earth, the atmosphere, the farmers and all that depends on them.”

By Lakshmi Sandhana
Dateline: 3/12/2020