A vocabulary of landscape — a landscape of words 1469 entries

geosmin

jee-OZ-min
Geosmin is the compound responsible for the smell of turned earth, of a beetroot, and of rain arriving on dry ground. It is made by soil bacteria, chiefly Streptomyces, as they sporulate, and by some blue-green algae in water. The human nose is extraordinarily good at it: People can detect geosmin at a few parts per trillion, which is a far lower threshold than a shark has for blood.
Etymology
The word is Greek for earth smell, coined in 1965 by the scientists who isolated the compound. What it names had been noticed and puzzled over for a very long time, and the term petrichor was coined earlier, in 1964, by two Australian researchers for the broader smell of rain on dry ground, which is geosmin together with plant oils that have accumulated on rock and soil during the dry spell.
Notes
Why we are so sensitive to it is an open question. Geosmin signals moist soil and therefore water, and camels are known to track it across desert to find an oasis; the bacteria that produce it are in turn dispersed by the springtails that come to the smell.
ecology Greek senses water
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