There is a big difference between how natural topsoil is formed compared to how commercial topsoil is created.
The natural formation of topsoil is a much longer process than a lot of people may realise. Typically, it takes an average of 100 years per inch of soil to be produced. It is formed from rocks that have been weathered and, eventually, organic materials from decaying plants and animals, which enrich the soil and add essential plant-supporting nutrients. The breakdown of organic matter can take some 500 to 1000 years. Other than this, topsoil is made from four key ingredients: minerals (such as the rocks), organic matter (the decaying plants and animals), water and air – which fills the gaps between the mineral and organic matter parts. The plants that topsoil supports will absorb the nutrients from these materials through their root systems, and therefore it’s important that the soil is well aerated, as this means the soil has plenty of gaps between the material particles for the roots to grow in, water can move through easily, and bacteria and other micro-organisms can live in it.
Topsoil is the top most layer of soil – and usually the most the fertile. Natural topsoil is a product of its climate, and therefore changes based on factors such as climate, organisms and topography and acts on geologic material. Changes in temperature, rainfall, drought and wind, as well as biological factors such as microorganisms, animals and humans all have an effect on the overall production of the topsoil, thus resulting in the multiple different types and variants of soil available. The six main factors that directly affect the type and quality of the topsoil is the parent rock material (i.e., the type of rock the soil is initially developed from), climate, landscape, organisms, time and soil management.
Because of this long and complicated process, natural topsoil cannot be replaced with commercial topsoil, though commercial topsoil can be relatively easily made, and is still classed as a natural soil, though it goes through a man-made process. It is typically created for recreational, industrial and building purposes, to be purchased by individuals or companies, and there’s many different types available (see the list of the full range of topsoil’s we provide here).
The type of topsoil produced may depend on the person buying it and their intentions for use. For example, there can be topsoil’s intended for landscaping and gardening use, or for use in farming. Other differences include minerals the soil may be mixed with – which includes sand and clay. Macro and micro nutrients such as nitrogen, phosphorus, potassium, calcium, magnesium, and sulphur may also be combined with the soil.
The process of producing commercial topsoil is as follows; the soil is sourced from one or multiple soil sites and is cleared of any vegetation or other materials that may affect the production of the topsoil. It is then graded and pushed into manageable piles, and pre-mixed with other soils using the right quantities of sand, slit and clay, and pre-mixed with organic matter. It is then screened to filter out bigger materials such as stones, rocks, pieces of wood and plastic, metal or other types of manufactured waste, and tumbled to produce a better consistency. When this is completed, the topsoil can be bagged and delivered.