What is Topsoil?
The roots of most plants and all of the soil organisms need oxygen to survive. Life in the soil is dependent on both air and water. Topsoil differs from subsoil primarily because topsoil has a more open structure that contains sufficient oxygen to support both root growth and soil organisms. Topsoil is usually a darker color because of it’s higher organic content. The thickness of the topsoil layer tends to be thin in arid or semi-arid regions. The thickness can be increased by mixing subsoil with the topsoil and adding additional organic material. The mix becomes topsoil once the blend establishes it’s new ecosystem and begins to support new communities of soil micro and macro-organisms.
