People living in San Francisco can find a soil tasting in a nearby art gallery; the rest of us can e-participate through a website (tasteofplace.info) run by performance artist and “agricultural activist” Laura Parker. Parker strives to answer the question “how does soil touch our lives and affect our food; and why does it matter?” To stimulate public dialogue, Parker fills wine goblets with various soils and adds a few teaspoons of water to release the aromas and flavors. The soils aren’t ingested, but participants place their noses deep into the wine bowls, inhaling the newly released molecules to the backs of their tongues, where taste receptors lie. The website even provides “Tasting Notes,” such as the soil of “Apple Farm-Indian Camp Ground, ‘Arrowhead Reserve,’” which has a “texture like ground espresso between your fingertips with a rich, chocolate color. The nose is both flinty and grassy with finesse and subtlety.” After the soil tasting, participants dine on food grown in the various soils and identify the qualities of the dirt in the food to strengthen the connection between what we eat and where it’s grown.

“It used to be,” writes William Bryant Logan in Dirt, “that a good farmer could tell a lot about his soil by rolling a lump of it around in his mouth.” Today, apparently, it is harder to find someone who literally eats dirt:

Not in Texas, nor Vermont, nor Kentucky, nor California, nor western New York. Everybody knew somebody who once did it, but nobody could quite remember the name of the fellow.

Finally, Logan came across Bill Wolf, an organic pioneer who started his environmental research under Buckminster Fuller and who used to eat soil, until his doctor forbade him.

Soil contains bad bugs as well as good ones, and the physician did not want to have to sort them out in Wolf’s guts. But back in the days when he chawed, Bill could tell acid from alkaline by the fizz of the soil in his mouth.

A very acid soil would crackle like those sour candies that kids eat, and it had the sharp taste of a citrus drink. A neutral soil didn’t fizz and it had the odour and flavour of the soil’s humus, caused by little creatures called “actinomycetes.” An alkaline soil tasted chalky and coated the tongue.

Having conducted this simple taste test, Logan explains, farmers could apply calcium carbonate to the Sprite-flavoured fizzy soil and gypsum to the Milk of Magnesia tongue-coating soil, which would then “react with the hydrogen of acid clays and the sodium of salt-clays, respectively,” in order to re-balance the soil’s pH and improve its structure.