When most people look at soil, they just see dirt. When I look at soil, I see billions of microorganisms crawling atop one another, consuming the dead in a feasting frenzy that stops for nothing save a deep freeze. I see microbes and their enzymes, the digestive juices that break down, transform and release all the energy tied up in our planet’s terrestrial ecosystems.
Through their remarkable ability to decompose nearly anything that comes their way, soil microbes collectively represent a planetary recycling factory, one that takes carbon from dead organic matter back to the atmosphere as CO2. Soils “exhale” CO2 for the same reason you and I do. We’ve eaten something, broken down the carbon bonds that hold it together, and extracted all the energy that we could. CO2 is the generic waste product of cellular metabolism, the last bit of carbon that our own metabolic inefficiency precludes us from using. Ecologists have coined the term soil respiration to describe the collective exhaling of microbial carbon decomposition.
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