Soil fertility is the ability level of soil to grow and support plant life. Fertile soil contains the sufficient minerals and nutrients needed for plant growth, and it is often composed of large amounts of topsoil. An important characteristic of soil fertility is its sufficient amount of microorganisms such as bacteria, fungi, earthworms, protozoa and nematodes.
Fertile soil is rich in trace elements of minerals such as chlorine, copper, iron, zinc, boron, cobalt, manganese, sulfur and magnesium. Nutrients such as potassium, phosphorus and nitrogen must be abundant in the soil for it to be fertile as well. These minerals and nutrients effectively feed the plants that grow in fertile soil.
Soil that is deficient in its fertility will have a lack of any or all of these. Overpopulation and harmful agricultural practices leads to soil depletion, which results in poor plant life. Preservation of the topsoil is especially important to the fertility of soil; topsoil retains nutrients brewing from hundreds of years. While poor plant life damages the ecosystem as a whole, the poor crop yields that also result from inadequate soil fertility raise food costs and play a part in famine. Soil fertilization is used to supplement any deficiencies in soil. Nitrogen is often the most depleted nutrient in soil followed by potassium and phosphorus.