Good smells exude from crumpled earth.
The rough bark of humus erupts
knots of potatoes (a clean birth)
whose solid feel, whose wet inside
promises taste of ground and root.

Seamus Heaney, from "At a Potato Digging", Death of a Naturalist

Mid-winter thaw. The earth softens a bit under a soft rain. You wander outside, trying to shake off the heaviness of winter, to smell the awakening earth.

The mud disappoints your nose. Inert. Lifeless.

You wander back inside, dreaming of May.



Actinomycetes is a class of bacteria essential to making good dirt. They are what give compost the sweet, earthy smell that makes gardeners wild with desire.

Actinomycetes give us the smell of rain in the summer. Storms draw life from the mud. Poets and lovers already know this. Microbiologists now know why.

Actinomycetes, which look like strands of fungus, break down rotting piles of vegetation, producing geosmin, the source of the aroma of healthy soil.

The smell, considered pleasant by (most) humans, has been added to some perfumes to give them an earthiness.

So why does mud smell lifeless in February? Actinomycetes go dormant in colder climes. While it is possible to grow actinomycetes in a petri dish (and yes, it will smell like the rich, sweet soil that makes gardeners swoon), waiting for the Earth to awaken reminds me of the cycle of life.

I think I can wait.

Besides adding romance to summer showers, actinomycetes has antibacterial properties. Streptomycin and related antibiotics come directly from actinomycetes; Biaxin and Zithromax are semi-synthetic antibiotics made from this same class of bacteria.


Image from UK-JAPAN 2008 website,