Soil

Along with sufficient water, sunlight, air, heat, and nutrients, a well built-up and maintained soil is key to a healthy garden, so let's take a look at soil. (See also More... below.)

Getting to Know Our Soils

Soil is a mixture of variable proportions of sand, silt, and clay... Soil benefits plants by providing an environment for roots that is appropriate for the plant by offering appropriate amounts of water and other nutrients... Roots need to have a sufficient supply of water available to supply the metabolic needs of the plant, but must not have so much that they drown the plant resulting in root rot. In addition to water, the soil must store and provide the plants with nitrogen (N) for green growth, phosphorus (P) to help the plant establish roots, and potassium (K) for general health. These are the basic elements that make up fertilizer. The soil must provide certain secondary nutrients such as calcium (Ca), magnesium (Mg), and sulfur (S) as well as micronutrients (present in very small but important amounts) such as iron (Fe), manganese (Mn), zinc (Zn), copper (Cu), and chlorine (Cl).

The structure of the soil is very important in determining the quality of the environment for the plant and of the three basic elements, clay is the most influential. Clay particles are small, flat, and carry a negative electrical charge, all of which causes clay to attract and hold water. Without enough clay, the soil tends to retain neither water nor nutrients. With too much clay, the soil tends to lock in the water and nutrients so tightly that the plants can't get any. A good soil is a balanced mixture of sand, silt, and clay appropriate for the particular plants living in the soil.

Different areas of a yard can have different types of soils so it's important early in the process of landscaping to analyze the soil to determine two things: 1.) what the soil needs to grow the desired plants, and 2.) what plants will grow best in the soil that we have. Sometimes it makes more sense to accept what life throws at us than to spend our lives fighting it. Because soil makeup can vary greatly even within a given yard, analyzing samples from several areas can be helpful.

Soils around Tucson generally have the same nutrients and actually have plenty of nutrients because they're locked in by large amounts of clay. That's good news that their are lots of nutrients but bad news that they're locked into the soil. So what do we do about it?

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