Inorganic ComponentsThe soil is made up of three main substances Silica, Clay and Chalk.(i) Silica is present in the soil, in the form of small crystalline grains. It is derived fromthe disintegration of rocks.(ii) Clay is a mixture of silicates and many other minerals such as irom, calcium,sodium, potassium and aluminium. It retains moisture.(iii) Chalk is also known as calcium carbonate. It provides the most essential elementfor plant growth, which is calcium.Organic ComponentsThese determine the fertility of the soil. They are derived from the decay of livingmatter. The ultimate form of organic matter is humus. It is not a mineral. It isorganic matter because it is formed by the decomposition of plant and animalremains. It helps the soil to retain moisture. It imparts a dark colour to the soil. It alsohelps the plant to draw the nutrients from the soil essential for its growth.Soil ProfileThe soil mainly consists of two layers i.e., Topsoil and Subsoil. Topsoil forms thelayer where the plant growth takes place; hence fertile topsoil yields good crops. It alsocontains bacteria, worms and insects which are important for the fertility of the soil.The formation of soil is a very slow and long process, but it can be washed away in avery short period. Therefore, conservation of the topsoil is very important as its losswould affect the economy of the country as well as the life of people.Subsoil is formed by the weathering of the parent rock. It also contains a part oforganic matter and moisture, but it is not very productive. For good crons it would​