The topsoil or soil layer, is considered to be the most significant layer. If you’ve visited the banks of a river, you’ll see the more dark layer that is underneath the other layers. It’s also fairly dense. For soil classification the top layer is referred to as the A horizon.
This soil is basically it’s the top 2-7 inches of soil. It contains the highest amount of organic matter and microorganisms. The top layer of soil comprises mainly carbon and nitrogen, along with the living organisms that are found within the soil. If the soil is fertile and has nutrients, it will also be rich in that can help plants grow in it.
The primary function that topsoil serves is to supply nutrients to plants that are living within it. Microorganisms from a variety of species which live in the topsoil also plays a part in nurturing the growth of plants, which creates an ecosystem that’s favorable to the expansion of life within the soil.
In essence, there’s quite a bit more to topsoil then simply having a nice layer of soil on top to look at. 15um5bffjr.