Life in the soil

Yes! There is life down there! It is so complex, even soil scientists have yet to plumb the depth and breadth of all the species and interactions that make the soil work like one living organism.

For gardeners, it’s important to know that a lively soil feeds your plants. Feeding the life in the soil makes everything better for your plants.

Here is one very important type of soil microorganism to consider: fungi. Specialized fungi called mycorrhizae mine nutrients from the soil and bring them to plants they associate with – literally extending the reach of plant roots. Other fungi help create what is known as soil structure: fungal strands (hyphae) bind soil particles together into aggregates. Many other organisms join soil aggregates together into complex, stable units (peds) like the one in the photo below.

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Soil aggregate. Photograph by Colette Kessler, USDA Natural Resources Conservation Service, South Dakota

Why is this important?

Peds are soil structures that act like bricks or stones in a wall. They resist erosion, clump together, and act like sponges because of their cohesiveness and air spaces. The name for this is soil structure. A soil with good structure slows runoff from storms and holds vast quantities of water, which allows organisms and physical particles to filter runoff or rain and discharge clean water to lakes, streams and springs. Like magic, but not magic at all – it’s biology!

Another critically important function of good soil is to store carbon. A healthy soil stores and reduces the amount of carbon dioxide in the air for months to decades or even centuries.

Below is a photo I took while moving a pile of wood chips for mulch. The pile has been sitting around for awhile and fungal hyphae have colonized the chips. The fungus is digesting the carbon and nutrients in the chips.

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Fungal hyphae are visible as a white mycelial mat linking the chips together as they form soil. This mycelium will eventually form a mushroom fruiting body above ground to disperse spores. Here is one mushroom that popped up after these chips were spread on the soil.

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As fungus digests the wood, it liberates nutrients and chemicals the tree stored there when it was alive. Fungal hyphae exude sticky substances that glue particles together and provide food for other organisms. All these soil organisms literally stitch the soil together (stunning demos at this link). Organic matter – compost, grass clippings, leaves, a cover crop – is the raw material soil organisms use to make soil softer, spongier, more resilient, nutritious, and oxygenated. All things your plants need.

Be sure to check out all the links to more info and videos to learn about how cool soil organisms are and how to recognize and take care of them!!

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