Transcript SOIL
SOIL SOL 3.1 & 3.7 Soil provides support and nutrients for plant growth EROSION is the movement of sediment and rock to new places. Soil Erosion • Soil may have deep gullies. • Earths materials move in a general downward direction due to erosion. • Soil is most likely to erode when plant cover is gone. Examples of erosion • Water flowing downhill moving dirt with it. • Wind carrying small sediment particles as in a desert sandstorm. • Streams and rivers carrying sediment loads as seen in the muddy Mississippi River. • Glaciers plucking and carrying rocks. • Landslides • Floods, which transport great amounts of rock and soil. How can we stop erosion on a hill? • Plant grass and shrubs! Weathering breaks down rocks to create soil. It can be caused by weather, water, or living things There are five components of soil: • • • • • 1. 2. 3. 4. 5. Rock Sand Silt Clay Humus • After rocks have been weathered for many years sand is formed. • Can you match each type of soil to its picture? Rock Rock is solid and made of minerals Sand Sand is tiny grains of worn down rock. It doesn’t hold water or have many nutrients. Silt Silt is very small, broken pieces of rock. It is larger than clay, but smaller than sand. It is powdery when dry. Sand ------------Silt---------------Clay (smaller particles) (larger particles) CLAY Clay holds water well. It is sticky and can be shaped when it is wet. But, it is very hard when dry. Clay has many nutrients. Clay is used for adobe or brick houses. Humus Humus is made of leaves, twigs, small animals, or other decayed substances. Humus adds many nutrients to the soil. Humus is in the topsoil. 3 Layers of Soil 1. Topsoil (The layer on TOP) Mostly made up of organic matter. That is why it is darker in color. 2. Subsoil (The prefix SUB means under) Mostly made up of clay and sand. 3. Bedrock (It’s hard as rock down there!) Natural Resources • Made by NATURE • Cannot be replaced • Must be conserved (saved)! Ways to Conserve Soil • • • • Plant trees Plant grass Healthy farming Plant gardens to grow crops • What else can you do to conserve soil? What can we add to soil if plants are not growing well? • Nutrients