What is Topsoil Made of?
Topsoil is the layer of soil that prevails on the surface of the earth, typically up to 8 inches or more depending on conditions. It is rife with microorganisms, organic matter and nutrients that feed plants. Most plants do not extend their roots lower than the layer of topsoil, for it is there that they derive their nutrition. Topsoil contains 13 essential nutrients to feed plants. They dissolve in water and are absorbed by plants’ roots.
These 13 nutrients certainly make up a part of the composition of topsoil, but there are many other elements to it. Good topsoil contains an abundance of broken down organic matter. As plants, vegetables and anything else organic dies, it slowly decays, and the nutrients are returned to the topsoil from where it came. Subsoil or the layer directly below topsoil, consists of hard-packed dirt and clay. It is largely unsuitable for anything organic except for large tree roots. Other elements of topsoil include sand, manure of various types and very small pieces of rock and stone. Its composition varies based on location, for topsoil is not the same everywhere.
Organic matter, microorganisms, nutrients, sand, manure, rock and clay can all be detected in topsoil as can water, one of its most difuse yet important elements.