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Why does dirt have an odor?

by Belle Bergner Q. Why does dirt have an odor? A. Ok… you’ve got way too much time on your hands to come up with this one. Or… you’re a very scent-observant person! That brown stuff that most of us stay as far away from as possible consists of more than just minerals and nutrients. In fact, soil closest to the surface is largely a combination of fungal hyphae (the root-like structures of mushrooms), bacteria (mostly the good kind that plants need), and decaying leaves, roots, and other organic material (anything that is or was living at one point). When the ground first thaws in spring, that dirt “smell” is very apparent because there are a lot of fungi bursting out of their frozen hyphal mats, quite happy to wake up from winter and make a living on the leftover leaves and dead worms and insects from Fall. You’ll notice that soils with different smells also look and feel different too. That’s a direct result of the type and amount of organic material in the soil. Wisconsin dirt certainly smells differently than Texas dirt. Dare I wax poetic on the soil bouquet? Richly organic soil smells more “earthy” than more mineral- or clay-like soil, which to me, have a more subtle, clay-like smell. The next time you’re out walking, stick your nose to the ground and discover how many smells dirt can produce. Pretty soon, you’ll be a soil connoisseur! Readers: Send any environmental or ecological questions you’ve been dying to ask to
by Belle Bergner