Ingredients in Topsoil

Topsoil serves as a protective layer of soil that covers an area. When referring to garden areas, healthy plots have 2 to 8 inches of topsoil to produce a good planting area. Topsoil consists of a variety of plant and rock material. It forms very slowly from the decomposition of plant material and breakdown of rock material. This process takes as long as 100 years to create a mere inch of topsoil. Topsoil serves as the primary location for biological activity at the soil surface.


Soil particles form from the breakdown of rock materials. Over time, rocks split apart to become smaller and smaller particles. These tiny particles take the form of clay, silt or sand. Each one serves as an integral part in topsoil composition. Soil mineral composition varies depending on the location and often features imbalances of particle types that requirement amendment with ingredients such as compost, peat and humus to improve the soil.

Organic Matter

It might be difficult to consider soil as a living thing, but it really is alive. Soil contains millions of decomposing pieces of plant and animal matter than breaks down through exposure to the elements. Plant debris, worm casings, dead flowers and waste products get released into the soil to increase organic content. These nutrients break down slowly over years and mix with underlying soil to create a rich organic mixture of particles and decomposed organic matter.


Air works to move mineral particles around, constantly depositing and removing minute pieces over time. Air also circulates through the layers of decomposing plant matter. The process of weathering reduces rocks from larger size to small particles with water, wind and movement of rocks.


Daily rain helps remove plant petals and foliage from existing growth, dropping these items onto the soil surfaces. Water also drains through decomposing material and rock particles to transport these items to different locations. Moisture serves as an integral ingredient aiding in the decomposition of organic material.


It might seem odd to consider that life makes new topsoil. This process serves as a major component to soil formation. Living plants must be present in upper soil levels to create organic matter than falls to the soil surface. Living things help create organic matter that eventually forms topsoil.

Keywords: topsoil ingredients, topsoil composition, What is topsoil?

About this Author

S.F. Heron is an avid gardener with three years of experience in online writing and a working background in aviation and earth and ocean sciences. She is published on various sites, including Helium, eHow and Xomba. She holds a Bachelor of Science degree in journalism from the University of Maryland.