Friend not foe: fungus improves soil quality

This microscopic view of a U.S. Agricultural Research Service soil project shows fungal filaments catching soil particles

June 2, 2000
Web posted at: 12:10 p.m. EDT (1610 GMT)

By Environmental News Network staff

There's a fungus among us, and, according to a researcher from the U.S. Agricultural Research Service, farmers and home horticulturists should be happy about it.

Mention the word "fungus" in the company of a farmer and images of a black, brown or white scourge rush to mind. Fungus blankets plants and ruins entire harvests.

But TheCan Caesar-TonThat, a microbiologist at the ARS Northern Plains Agricultural Research Laboratory in Sidney, Montana, has discovered that members of the fungus family basidiomycetes may be essential to the health of soil in crop fields, vegetable gardens and other places where soil quality is key.

The basidiomycetes group of fungi includes edible mushrooms such as chanterelles and boletes. These mushrooms are most often found in cool, moist and shaded forest areas, where they help decompose fallen trees and other organic matter.

Caesar-TonThat has learned, however, that these fungi are also present in open areas such as crop fields. In these environments, the fungi do not usually assume the familiar cap-and-stem form, yet microscopic underground fungi structures — filament and hyphae — are present in the soil.

"Basidiomycetes form fruiting bodies only when the conditions are perfect for them to do so," said Caesar-TonThat. "If not, they simply propagate in the soil, making a large network of filament and hyphae."

These unseen webs of tiny subsoil fungi parts produce a sugary film that binds soil particles together. This binding of particles, called aggregation, prevents soil compaction and allows roots, water and oxygen to move through the earth, a process that is fundamental to soil health.

The fungi also work to make the soil richer in nutrients. They feed on dead plant matter left from the previous year's harvest, and in the process break down carbons, making them available for absorption by new crops.

TheCan Caesar-TonThat is a microbiologist at the Northern Plains Agricultural Research Laboratory

"The fungi are implicated in nutrient cycling," said Caesar-TonThat. "They live off plant residue and litter, and recycle them in the soil like in a compost pile."

But fungus filament and hyphae take a long time to form a network, said Caesar-TonThat, and must remain undisturbed to do their good work. As a result, standard tilling practices are an enemy to these underground webs.

Farmers usually plow to prevent weeds and incorporate last year's harvest residue into the soil, Caesar-TonThat said.

According to her studies, fields that are not tilled every year before planting have much larger populations of beneficial basidiomycetes fungi than land that has been plowed.

"This is why 'no-till' practices are so popular with the scientific community," said Caesar-TonThat. Agricultural scientists also prefer the no-till method because it reduces erosion.

As Caesar-TonThat continues her research, she will try to determine the best agricultural management practices to enhance the fungi population. She'll also try to pin down which crops the basidiomycetes like to eat most.

Copyright 1999, Environmental News Network, All Rights Reserved

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U.S. Agricultural Research Service
TheCan Caesar-TonThat
Northern Plains Agricultural Research Laboratory
basidiomycetes
The basidiomycetes family of fungi

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