SOIL NOTES Soil Formation Soil is a mixture
- Slides: 8
SOIL - NOTES
Soil Formation • Soil is a mixture of: – Weathered rock and mineral fragments. – Decayed organic matter, HUMUS. – Water and air spaces. • Organic matter (dead plants & animals) decomposes and changes into HUMUS. • Soil composition : how well a soil holds water, important for plant growth
Factors Affecting Soil Formation • CLIMATE: affects weathering. – (Hot humid tropics vs. cold regions) • SLOPE of the Land: gravity moves soil downhill soil is thinner at the top of hills, and thicker in low spots and valleys • TYPES OF ROCK: minerals in the original rock weather differently • PLANTS: hold soil and decay into HUMUS • TIME: how long rock has been weathering
SOIL PROFILES • SOILS have different characteristics. • Soil layers are called HORIZONS. • Soil Horizons contain different mixtures of material.
LEACHING • How minerals (and chemicals) get carried by water from Horizon A down to Horizon B. Like a Drip Coffee-maker!
Most SOILS have 3 HORIZONS (Some soils have HORIZON O organic matter on the surface) Horizon A: topsoil more HUMUS, less rock particles, usually darker & more fertile Horizon B: subsoil less organic matter (HUMUS), more rock, minerals leached down from Horizon A Horizon C: substrate partly weathered rock, little humus (Horizon R: Solid ROCK not weathered)
Sciencesaurus • Go to page 191. – Draw a picture of each layer on the front flap of your foldable. – On the inside of the flap: • Define each layer – In Horizon A, define HUMUS as well. • What is included in each layer. • Answer the questions on the back.
Homogeneous mixture and heterogeneous mixture class 9
Soil is a mixture of what
Mixture of weathered rock and organic matter
Soil layers
Is rock is a mixture
Is soil a pure substance or mixture
Formation initiale vs formation continue
Mechanical and chemical weathering venn diagram
Soil formation begins with the weathering of
