What Is the Difference Between Topsoil & Subsoil & Bedrock?

Soil provides the first link in the food chain for land-based animals; growing plants nourish both herbivores and omnivores with nutrient-rich fruits, roots and foliage. Soil is not a lifeless mound of dirt holding plant roots, however. In fact, every square inch carries some form of existence, vitamin or mineral, for healthy plant growth. Soil layers, such as topsoil, subsoil and bedrock, offer different habitats to continually recycle this significant resource.


The initial layer, or horizon, is just several feet deep on the planet’s surface; that topsoil horizon provides the richest amount of organic matter for germinating seeds since plants and animals decay on the ground. As decomposition occurs at the topsoil, microorganisms, from bacteria to fungi, populate the soil to keep the decaying process active. As a result, topsoil is the best substrate for plant growth using its rich nutrients and protected moisture trapped in small, open underground pockets. You’re acquainted with this layer since you knowingly till it for just about any gardening activity, from sodding to cultivating roses.


Residing beneath the topsoil, the subsoil does not have high organic matter concentrations but provides rich minerals for searching root processes. Varying in colours like red and yellow, this hidden dirt layer is directly affected by water movement. Minerals from the topsoil find their way down into the subsoil through water runoff; clays also concentrate beneath the rich topsoil. As a result, mineral deficiencies in the topsoil force roots to plunge deeper for nutrients while letting them establish themselves deeper in the soil structure.


Forming the exterior layer of the Earth’s crust is the bedrock layer. This horizon lies beneath the topsoil and subsoil to form stone. Organic material and root nutrients don’t occur this deep in the ground, however, the bedrock provides the territory with future soil components. For example, earthquakes and regular tectonic plate motions expose this horizon to upheaval and eventual weathering in the ground surface. As a result, bedrock forms the basis for new soil creation, though at a really slow pace.

Erosion and Topsoil Neglect

Topsoil, subsoil and bedrock function in harmony to produce a fertile soil source for the planet’s flora and fauna. Topsoil removal or pollution, however, directly influences this complex relationship within the ground. In fact, it takes 1,000 years for its bedrock and subsoil to generate only 1 inch of rich topsoil. Curbing the use of herbicides, pesticides and poor planting strategies have to be enforced so that precious topsoil stays available and rich in nutrients and trace elements.

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