Your type of soil is based upon the types of particles that make it up. For example, sandy soil is made up of mostly large particles that don't pack tightly together. This allows moisture and air to move through easily. Clay soil is made up of tiny particles that easily pack together. When soil is packed together to the point that moisture and air cannot move through the soil easily, you have compacted soil. Compacted soil provides a very poor medium for plant growth. Testing for it is really easy and can be completed in a few minutes.
Rent a soil compaction tester. These have a metal post that is 36 to 48 inches in length that you push into the soil, and they are available at your local rental center.
Push the compaction tester into the soil. Apply steady and even pressure. If you hit any areas of resistance, make a note on how deep this layer is. Resistance usually means the soil is compacted at that level.
Look for areas of standing water on your property. The best time to do this is after a rainfall. Areas that are compacted will retain pooled water at the surface for a longer period of time than non-compacted areas.
Dig down around trees and shrubs. Look for roots that are stunted or deformed. Roots will not grow into compacted soil easily. You may notice that the roots suddenly stop all at the same location. This is typically seen in compacted soils in which the root ball suddenly meets the compacted soil and the roots cannot grow down any farther.