In this topic, you will learn about how soil is formed and why it is necessary in your community.

Rocks and soil are natural resources. A natural resource is a material on Earth that is necessary or useful to people. Rocks are important building materials. Crushed limestone is used in making cement. Sand is used to make glass. Weathered rocks are part of the soil. Soil is the part of the ground that plants grow in. Without soil, there would be no plants on the land. People and animals need plants for food.

Soil is a mixture of tiny rock particles, minerals, and decayed plant and animal material. Growing plant roots, worms, and insects make spaces for air and water. There are usually two layers of soil. The top layer, called topsoil, is made up of very small particles that are dark in color. Topsoil has lots of minerals and decayed plant and animal material. Topsoil holds water well, which is also necessary for plant growth. A layer of soil called subsoil lies below the topsoil. Subsoil is made of bigger particles. It does not have decayed plant or animal material. Below the subsoil is solid rock.

There are many different kinds of soil. Different soils have different types of rock and minerals in them. Some soils have more water or plant and animal material than others. The type of soil in a particular place affects what kinds of plants can grow there.

Some natural resources are renewable resources. A renewable resource is a resource that can be replaced or be used over and over again. Soil is an example of a renewable resource. The erosion of soil happens quickly when soil is unprotected. Soil is unprotected when forests are cut down or farmland is left bare. Although soil is renewable, it takes many years for soil to form. It is important to conserve soil. To conserve something means to protect it and use it wisely. Good farming practices, like contour farming and planting cover crops, help conserve the soil.