It is helpful to the gardener if he knows his soil class, but it is not generally necessary to go to the trouble and expense of finding more exact information. The farmer who is economically dependent on his soil may vary crops or even change locations to have the best soil type for the crop he wants to grow. But we gardeners must learn to work with what we have.
The soil of any area is made of many components. The mineral composition may be classified as clay, sandy, clay-loam, etc. This material will vary from the surface to the subsoil and from place to place on the property.
The vertical composition is divided into the furrow-slice or topsoil and subsoil. The biggest problem for us comes when the furrow-slice or topsoil has been removed, leaving the subsoil as the growing area for plants. Our effort now becomes the making of topsoil out of subsoil. In other words, we must accomplish in a very short time what nature has taken thousands, perhaps millions, of years to do.
Besides the mineral structure of the soil and subsoil, the major ingredient is organic matter. This is referred to as the humus content of the soil. Humus gives life to the soil, binds together the soil particles, and, in the proper amount, keeps the clay soil from feeling slick and sticky when wet.
Humus also gives the soil greater moisture-holding capacity and allows excess moisture to drain through the soil. The constant replenishment of the soil with organic matter is an absolute need in gardening. Otherwise, our gardens are no better than the one-crop farms which died and eroded away.
Think of your land as being like the earth was millions of years ago. Unless you keep adding humus, your garden will become like starved farmland which can support little growth. Then you or the next gardener on your land must start all over again. Humus alone, however, cannot make the land as fertile as you wish. You must also add nutrients or plant growth minerals.
Fertilizers are not food for your plants, despite what the bag might say. Fertilizer adds chemical nutrients to the soil to support the growth of the plant. Through the process of photosynthesis, the plant makes its own food. We can only add the major and minor nutrients which are necessary for the plant to grow properly; we never “feed” plants because they do that for themselves.
Organic material is an absolute necessity for a good garden. Inorganic materials are also absolutely necessary. They are the quickest, easiest, and most sensible way to add the needed nutrients, both major and minor, to our soils.