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 at a whopping 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."
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.
"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."
Mycorrhizal fungi break down certain elements like phosphorus that are chemically locked up in the soil into a form that plants can easily absorb. 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.
Modern Agriculture vs. the Fungi
Unfortunately, modern agricultural methods are a bane to AMF.
"These fungi have sort of a hard time in modern agriculture, because several practices work against them," says Matthias C. Rillig, Professor of Plant Ecology at the 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. Adding huge quantities of chemical fertilizers doesn'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 and destroys the spores by which they propagate.
"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.
Globally, 70% of freshwater is used for agriculture. Agricultural fields are losing soil between 13-40 tons per hectare per year -- 13-40 times faster than soil can be renewed. Over 50% of the nitrogen applied as fertilizer is wasted.
Put the Biology Back in Soil
A relatively easy first step to restore soil biology is to re-establish mycorrhizal fungi. Applying mycorrhizal 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.
"The trick is to not just add the mycorrhizal 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 mycorrhiza is already on the roots and growing vigorously so the plants have the tools they need when you outplant them."
The Benefits
Adding AMF inoculants can 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 when non-mycorrhizal plants have stopped growing. Weeds don't grow that well, since the fungal network competes with them. Water requirements reduce. Pest problems and diseases go down.
"We got a higher yield on potatoes with 30 to 50% less phosphorus fertilizer by adding mycorrhiza," says Amaranthus. "So that's big savings for the farmer."
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 1,000 lb 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."
"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. Datelined 3/12/2020.