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Plants are vibrant living organisms that add beauty, color, food, medicine, oxygen and so much more to our lives. However, most depend on a thriving ecosystem below ground to help them live. That soil they’re anchored in is more than just dirt. Soil depends on many different species of living organisms, and may need human help to supply them.
The soil’s fertility determines how well it can support plant life. Many different organisms live in the soil, depending on a number of different factors. These organisms range from earthworms to microscopic bacteria, fungi, and even insects. Each has a role to play in the circle of life.
In its basic form, soil is composed of granules of weathered rock. It isn’t alive and can’t support life on its own. It’s the organisms that live in the soil pores and attach themselves to the plant roots or soil granules that support life. Earthworms, arguably the largest subterranean creature, are more than fish food. Their waste material, known as castings, are rich in nutrients plants need. In fact, worm castings have become so popular among gardeners that they launched an industry. There are businesses ranging in size from individuals to large corporations that grow worms in containers. They harvest, package and sell the castings to organic gardeners.
We’ve heard a great deal in recent years about mycorrhizae. Landscape and Plant Health Care professionals inject these microorganisms into the ground either mixed with liquid fertilizer or alone. Colonies of mycorrhizae affix themselves to plant roots to extend the roots’ reach as they search for water and nutrients. The mycorrhizae consume some of the water and nutrients they find to sustain themselves.
Mycorrhizae aren’t a single species. They’re a group of bacteria and fungi that form a symbiotic (cooperative) relationship to benefit themselves and the plants they attach themselves to. Mycorrhizae aren’t the only microorganisms, or microbes, that populate the soil. Soil literally teams with microbes.
We hear a lot about adding compost and other organic matter to soil. When we add organic matter, it’s the microbes that break it down so that its elements are available for plant roots to absorb.
Undeveloped land is self-sustaining. Plants shed leaves annually. Plants and animals die. Microbes immediately go to work breaking down those larger organisms. It’s called decomposition and its elements are returned to the soil as nature’s fertilizer, which we call organic matter. This rich soil remains near the top.
When land is developed, the rich layer is often scraped away. Occasionally, it’s stored and returned to its rightful place after construction is complete. More often, however, topsoil is trucked away and either sold or used for another of the builder’s developments. Sometimes, the bulldozers just move the soil around to form the site’s final contour. When finished, the topsoil may be several layers down from the top or just mixed in with the subsoil. Humans messed up the soil profile so humans have to fix it to sustain plant life. That when property owners call in landscape professionals.
If your plants are looking stressed and appear to be declining, conventional wisdom may indicate that they have a disease, insect infestation, animal damage or other above ground environmental issue. The actual cause may be below ground and require professional help.
