Agricultural Research Service soil scientist Sara E. Wright discovered a unique fungal protein that holds soils together. This gooey protein is called glomalin”. It belongs to a group of common root-dwelling fungi that secrete the protein through hairlike filaments called hyphae. The fungal hyphae are found worldwide on the roots of many plants. Glomalin sloughs off of the hyphae and finds its way into soil.
“It coats soil particles and may be what holds them together in the stable structures…” says Wright. “Farmers and gardeners know them as the small grains of soil that sift through their hands and suggest to them that the soil has good structure.”
Glomalin permeates organic matter, binding it to silt, sand, and clay particles. Not only does glomalin contain 30 to 40 percent carbon, but it also forms clumps of soil granules called aggregates. These add structure to soil and keep other stored soil carbon from escaping.
“As a plant grows, the fungi move down the root and form new hyphae to colonize the growing roots. When hyphae higher up on the roots stop transporting nutrients, their protective glomalin sloughs off into the soil. There it attaches to particles of minerals (sand, silt, and clay) and organic matter, forming clumps. This type of soil structure is stable enough to resist wind and water erosion, but porous enough to let air, water, and roots move through it. It also harbors more beneficial microbes, holds more water, and helps the soil surface resist crusting.”
Image courtesy of USDA. A microscopic view of an arbuscular mycorrhizal fungus
growing on a corn root. The round bodies are spores, and the threadlike filaments are hyphae.
With the help of the green dye ot allows the glomalin which is coating the filaments to show.
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