Good soil is the secret to successful gardening

THE FIRST principle of organic gardening is to feed the soil, not the plant. This wisdom was lost during the years people piled chemical fertilizers onto their gardens. Remember that all gardening used to be organic. That's just how people went about growing flowers and food, and in many parts of the world they still do.

Soil building makes sense, but where to start? Plants crave rich, free-draining loam, but how can you actually achieve such mythic soil in your own garden?

Experts recommend a soil test as the first step, because you don't know how to improve what you have until you understand what it lacks. And it's not like you can tell much about soil by looking at it or feeling it, except for how wet or dry it is at the moment. Even though it might seem extreme to mail hunks of dirt across the country, the soil test lab of choice is the University of Massachusetts in Amherst. Its standard test is inexpensive and identifies soil's pH, texture, available nutrients and heavy metals, if they are present. The Web site (www.umass.edu/plsoils/soiltest/) supplies all the information you need.

Bottom line? Any kind of soil can be made more hospitable to plants by adding organic matter. As Jeff Gillman says in his useful book, "The Truth About Organic Gardening" (Timber Press, $12.95), "Compost is the most common form of organic matter, but dead hamsters buried in the backyard will add organic material, too, as will anything that was once living." The point of adding organic matter is that it boosts nutrition and improves soil structure.

If your garden's soil is sandy, organic matter enriches it and holds water more efficiently. If your soil tends toward heaviness, organic matter loosens it up and improves drainage. In well-amended soil, plants grow deep roots, are hardier and more resistant to disease.

But here's the new thinking: Never dig mulch or compost into the soil. Remember all that double digging? Turns out it destroys soil's tilth, or composition. It's best to simply layer compost and/or mulch on top of the soil and let it slowly decompose and filter down into the earth. How often is the easiest way the best way? Revel in it.

It's been said that dirt is what you have under your fingernails and soil is what's under your feet. It's actually the living skin of the earth, rich in a writhing conglomeration of living organisms.

In his book, "Home Ground: Language for an American Landscape," nature writer Barry Lopez said this about dirt: "A soil that is chemically or organically exhausted, that's been pulverized or become deeply parched, that has been invaded by decomposing rock, or that's been fouled by sewage or industrial pollution to the point where it no longer can support plant life, is called dirt."

That's what we don't want.

Valerie Easton is a Seattle freelance writer and author of "The New Low-Maintenance Garden.." Check out her blog at www.valeaston.com. Susan Jouflas is a Seattle Times assistant art director.