You cannot see it, smell it, or taste it, but glomalin is the glue that holds soil together and the path by which nutrients move from beneficial fungi to plants.
When most of us think of fungi, we usually think of mushrooms or disease. Mycorrhizal fungi are an entirely different critter. These beneficial fungi live in soil, and in and around plant roots. They are responsible for helping over 70% of the Earth’s plants get the nutrients they need from the soil. They do this with glomalin. Glomalin is found on the tiny hairs, or hyphae, of mycorrhizal fungi. This coating helps the fungi to retain water and nutrients as they interact with local plant root systems.
Soil is made up of 45% minerals, 1-5% organic matter, 25% water, and 25% air, on average. Soil structure tells us the size of the mineral particles, which can be sand, loam, or clay. Air and water are found in tiny spaces, called macropores and micropores. The chunks of organic matter and minerals are called soil aggregates. Those aggregates are held together with glomalin. Soil aggregates improve water infiltration, drainage, nutrient cycling, root penetration, and water retention near roots. They also help counteract soil compaction.
What is glomalin?
Glomalin is a tough, resilient glycoprotein that contains significant levels of iron. It does not dissolve in water and it is resistant to decay. Also known as glomalin-related soil proteins (GRSP), glomalin stores carbon and nitrogen, and binds mineral particles together, coating them with the same protective barrier used to protect the fungi. It is now believed that up to 30% of the carbon sequestered in undisturbed soil is held specifically by the glomalin. This is one of the reasons behind no-dig gardening, in that it reduces the negative impact on the fungi responsible for creating glomalin and helping soil hold onto that carbon.
How does glomalin improve soil quality?
Glomalin was discovered in 1996 by Sara F. Wright, a USDA Agricultural Research Service scientist. She discovered that soils depleted of mycorrhizae and their glomalin, whether through exploitation, solarization, or fungicide use, had significantly reduced crop sizes.
Glomalin helps hold organic matter in place, improving soil aggregate stability. Soil aggregate stability is a measure of the combined physical, chemical, and biological properties of a soil sample, as well as its ability to resist degradation and erosion. Without glomalin, every drop of rain and every gust of wind would grind and disperse soil in a global Dust Bowl.
Glomalin is also what gives soil its brown color. Removing glomalin from soil leaves it a gray, rocky color.
So, what’s glomalin to you?
Recognizing the importance of mycorrhizal fungi and glomalin to soil health, you can improve plant and soil health with these tips:
By keeping your soil healthy, the natural processes needed by your plants to acquire nutrients and fight disease can continue.
You can grow a surprising amount of food in your own yard. Ask me how!
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