Science - Lesson 15
Kinds of Soils
What Makes Up soil?
Soil is made of many different materials/ They include small rocks, sand, minerals, and clay.
Other materials in soil come from living things and form humus. Humus is a material that was once living or was formed by a living thing. Humus adds nutients to the soil.
Soil has spaces for air and water. These spaces anre often made by plant roots and insects.
There are usually two layers of soil. The top layer is called topsoil. It is made of very small, dark particles.
Top soil has a lot of humus and minerals. It also can hold a lot of water.
Below the topsoil is a layer called subsoil. Subsoil is made of bigger, lighter colored particles.
Subsoil lacks humus. Subsoil does hold water and some minerals. Below subsoil is bedrock.
Bedrock is solid rock.
There are many kinds of soils. Each kind is made of different types of rocks and minerals.
Some soils hold more water than other soils. Some soils have more humus, too.
Different soils are found in different parts of the world. In some places the soil ahs al ot of clay.
In places have loam. Loam is a kind of soil with clay and sand. Plants grow well in loam.
Soil layers can be thick or thin. Plants grow better in thick soil than in thin soil.
Windy, dry weather can make soil thinner. Mountains have thin soil because gravity pulls soil downhill.
Soil takes a long time to form. Farmers take good care of their soil. They want to use it year after year.
Good soil helps many different types of plants to grow.