Origins of Soil: The Living Dead
By Jack Parlin, CGC Intern
Most folks are familiar with what plants need to survive: sun, water and nutrients. But the relationship between a plant and its environment is much more dynamic in reality. The soil that most plants grow in does indeed provide oxygen, water and nutrients, and in return receives all it needs to live. And yes, you read that right: soil is ALIVE! What scientists and gardeners call soil is actually a diverse and interdependent ecosystem that extends deep beyond the surface.
Soil begins its life when large masses of rocks and minerals are exposed to the atmosphere and hydrosphere (surface water, groundwater and precipitation). Water and wind erode this nonliving, or inorganic, material while decaying parts of plants and animals called organic matter steadily work their way into the mix. The first plants to take hold in this new soil continue to break apart the rock with probing roots that create channels for air and water. The heat from the sun speeds up this process, which can take up to 500 years! The duration of this natural development far exceeds the span of a human life, so we think of soil as a nonrenewable resource.
Mature soil is home not only to plants, but a plethora of organisms, from bacteria to fungi to microscopic worms and burrowing animals. Life in the soil resembles an orchestrated dance of give and take. Organic matter blankets the soil’s surface and provides nourishment for a special group of plants and fungi called Saprophytes. Just as the saprophytes rely on living things to eventually die, plants are dependent upon the decomposition process. The compounds from the organic matter are chemically altered during digestion, making them available for plants to use. The soil itself benefits from organic weathering and is in turn able to support a healthier ecosystem.
So the next time you’re out in nature or working in the garden, think about what’s going on beneath your feet. The diversity of life in the soil provides bountiful nutrients to support plant life; what we see growing above ground is only a fraction of the story!