Presentation on theme: "How important is soil? What is soil? Soil is a mixture of minerals, weathered rock, and humus. Humus is bits of decayed plant and animal material that."— Presentation transcript:
How important is soil? What is soil? Soil is a mixture of minerals, weathered rock, and humus. Humus is bits of decayed plant and animal material that makes up part of the soil. Humus adds nutrients to the soil.
Soil formation Soil forms when weathering occurs. Rocks are broken down into smaller and smaller pieces which eventually becomes layers of compressed decayed plant and animal material. The top layer is the topsoil, which is usually darker than the subsoil and bedrock. The subsoil is lighter because it has less humus. It is estimated that it takes approximately 1000 years for the formation of 1 centimeter of soil.
The importance of soil Soil is a natural resources that is necessary or useful to people. How is it useful to people? 1.It provides nutrients for plants. 2.These plants then provide food for people. 3.People also use plants for clothing, shelters, and air.
Not all soils are equal Soils contain different amounts of humus and different kinds of rocks. Some hold water and others do not. Why is this important? If soil does not hold water can it provide the nutrients to plants ? We will experiment with different types of soils to test which type of soil holds water best by using variables. What are variables? They are the things in an experiment that can be changed. Today, we will use the type of soil as our variable.
Question: Which type of soil will hold more water?
Which soil holds more water? Variable My Observation Volume that Drained