Topsoil is the upper layer of soil. It is composed of mineral particles and organic matter and usually extends to a depth of 5-10 inches (13–25 cm). Topsoil has the highest concentration of organic matter and microorganisms and is where most of the Earth’s biological soil activity occurs. It is the surface soil usually including the organic layer in which plants have most of their roots and which the farmer turns over in plowing. There are different types of topsoil, including sandy, clay, loam, and chalk.
