You might be surprised at exactly what topsoil is composed of, the importance of it, and ways it is being destroyed and renewed. Topsoil is a critical topic in today's world, along with global economics and global warming, and there is much to be said about this fertile, delicate layer of our Earth.
Topsoil is the uppermost layer of earth on the planet; it is on average about 8 inches in depth, though it can reach up to 10 feet deep. In some areas the topsoil is thin and sandy, and in others it is rich and fertile. Topsoil is the earth that is most agreeable to plant life, mixing earth with decomposing matter, vitamins and minerals into a natural fertilizer. Plants hold topsoil together and to the earth, allowing it to maintain itself and replenish from year to year.
Directly or indirectly, topsoil feeds all living things on earth. Direct feeding occurs when the soil nourishes plant life and growth. Indirectly, topsoil produces healthy living plants of all kinds that feed other organisms, beginning a whole food chain. Healthy and fertile topsoil is extremely important to the world's food supply, as many agricultural farms and companies grow the food that the world eats using this fertile topsoil.
There are a couple of techniques farmers and agriculturalists use to maintain the vitamins, minerals and fertility of the topsoil they use in their farms. One of these, called crop rotation, involves growing a different crop each planting/growing season to use up different nutrients in the topsoil than were used by the previous year's crop. Another technique, letting the crop lie fallow, means that the leftovers of a crop after harvesting are allowed to lie on the ground and decompose; it is tilled into the ground the next planting season to allow the nutrients to be redistributed into it.
The depletion of the minerals in topsoil is a growing concern in modern-day farming. Farmers who do not rotate crops or let the ground lie fallow are killing the topsoil, resulting eventually in infertile land, limited plant life and, as a consequence, limited animal life.
Farming also causes topsoil to erode faster, a concern among geologists. Clearing land and tilling the topsoil breaks it up; with no plant life to hold it together and against the earth, rain, snow and flooding loosen the topsoil so that it slides away. Erosion removes as much as 1 percent of the earth's topsoil every year. This may soon become a problem by making fertile land hard to come by in terms of growing food for the countries of the world.