Above a pH 8.5, the soil is too alkaline for most plants, while if the soil pH is below 3.5 it will be too acid. If you really want to know about your soil, the best way to start is to obtain a cross-section of the various layers. This can be done fairly easily if you use a soil core tool. A soil core tool is little more than a hollow tube 2 to 4 feet in length with a handle and cross piece like a shovel to help push it in. Once the tool has been inserted into the soil, it should be turned to loosen the soil and then pulled out.
Many soils have three major layers or horizons, top soil, subsoil and parent material.
The top soil is typically darker colored and usually has more organic matter, higher biotic activity, abundant roots, and commonly lower in nutrients than underlying layers. The first inch of top soil may be lighter in color because many of the nutrients may have been leached out by water, and organic material may have been partially oxidized by sunlight and heat. The soil immediately below the first inch is usually somewhat darker, has many roots, moderate organic matter, and provides most of the nutrients for the plants. The next major layer is the subsoil. This layer is typically 1 to 2 feet below the surface and is characterized by a lighter color with much fewer, larger roots.