Get to know your soil

Today was a nice day in the garden--sunny and a bit warm for February. The kids in the Oakland school garden transplanted pansies and fertilized the fruit trees and blueberries. I'm planning to transplant some blueberries to my yard tomorrow, and all of this gets me thinking about soil.

You want to know the secret to sustaining life on the planet? It's in the soil. Soil is a whole world unto itself, and can make all the difference in the quality of the food you grow--it will even determine what you can grow, or at least what you will start with. If you want to grow food, or really anything, it all starts with the soil.

In permaculture, the basis of all gardening is prolonged and thoughtful observation. First thing to do is go out and look at your soil. If it's covered with weeds, clear a little patch (a foot square to start) and look at the color. If it's dark, that may mean it has the potential to be nutrient rich. If it's red, it may contain lots of iron. If it's pale, it may lack nutrients. The next thing to do is dig up a handful and wet it a little. If you pick out (or sift out) all the little gravel and roots, it's easier to feel the texture. Rub it in your hands. See if you can make it into a ribbon that holds together. Soil has three components when it comes to the rock particle matter--from largest to smallest pieces, there's sand, silt, and clay. Most soil contains all three, but in different amounts. The "ideal" soil for vegetables is a mixture of all three particle types in equal amounts. That's called loam. If your soil feels gritty, that's the sand you feel. If your soil clings together very well, and you can make a pot out of it, that's the clay. Soil scientists classify soils into different textures and types, and for the home garden it isn't necessary to know all that. But a general sense of soil texture is useful to know because that can determine whether nutrients in the soil are available to plants. Your soil may be nutrient rich, but if the plants can't access them, it's as if they aren't there.

Here in zone 9b (I should say, in the East Bay area of zone 9b) we tend to have clay soil. Without even touching it you can tell if you have clay if it clumps together in big chunks when you dig it. If it's impossible to get a spade into it during the dry season, that's a good indication you have clay. Finally, if you walk through a wet muddy field or down a muddy path and if at the end the bottom of your shoes are covered with six inches of hard packed mud, and your feet weigh at least ten pounds more than usual, you'll know that you just walked through clay soil.

O.k., maybe you don't have clay soil where you live. Well, clay isn't all that bad, anyway. I'll tell you more about that another day. The best way to know what nutrients your soil has, before you start loading it with bone meal and other things, is to get your soil tested. I'll talk about how to do that in my next post.