Compost is Like Yogurt for the Soil - Probiotics in the Garden

compost yogurt soil photo

Image credit: Lindsay Dee Bunny, used under Creative Commons license.

I've been reading a lot about compost recently and one thing keeps bothering me. Almost every article refers to this magical substance as a "natural fertilizer", and on one level it is true. Yet it is so much more than just a drop in replacement for chemical feeds. I've already noted that composting is really a form of animal husbandry, but the implications go way beyond what lives in our heap, and how we treat it. As one friend said to me not so long ago, compost is really like yogurt for the soil. But what difference does that make to how we use it? On one level, the answer is "very little." Just like my ramblings on compost as animal husbandry, much of this has to to do with semantics and perception. After all, what does it matter to the earthworms whether you call compost a soil amendment, fertilizer, or a magic elixir.

Yet we know that words and descriptions matter. And just as it is important to recognize that healthy soil is a living, breathing treasure trove of biodiversity, and that understanding should help us to nurture and protect it. So too, understanding how compost can bring soil to life, and 'seed' even relatively arid dirt with the life it needs to become soil (sorry, I am betraying my linguistic biases in the soil versus dirt debate again) will impact how we use, and how we value, this magical stuff.

Many of us already eat live yogurt and other probiotics to keep the microfauna in our bellies healthy (remember we are 90% bacteria!). So it's not a great leap in our understanding to reflect that the next time we spread compost on our garden beds, or give our ailing plants a little compost tea pick-me-up, we are doing so much more than just applying "nutrients", or even adding organic matter and carbon to the soil. We are, in fact, feeding life.

The other lesson to take away from this perspective is that not all compost is created equal. I have heard of gardeners baking their compost to kill weed seeds, and hot compost heaps are in many ways intended to do the same. Yet these high-heat methods may just also kill many of the beneficial microorganisms present in compost, creating something more akin to the traditional description of "fertilizer" or "soil amendment" that started this whole round of compost related pontification. (Most likely that hot heap will, over time, cool down and develop an entirely different set of microorganisms before it is applied - so I'm not saying it ain't worth using.)

So next time you are wondering whether to go with worm composting, a hot compost, a slow, gradual process, or buying those bags of sterile-looking cow poop from the store, consider the life inside them. Take a good sniff of some lively compost—you'll know what I am talking about.

More on Composting, Soil Life and Organic Gardening
How Worm Compost Suppresses Plant Disease
Composting as Animal Husbandry
40 Tons of Life in One Acre of Soil (Video)

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