Topsoil is composed of soil containing a high amount of organic material that is rich in nutrients. Most topsoil contains various amounts of clay, sand and silt. Topsoil comes from the topmost layer of the Earth's surface.

The composition of topsoil varies according to where it is collected. Each type of topsoil has a unique mixture of earth, organic materials and soil nutrients. The texture of quality topsoil tends to be fine compared to general dirt, which can be lumpy. Topsoil consisting of mostly clay retains a high level of moisture, which is suitable for plants in dry heat areas where water is scarce.