Soil Mr. Gilmore
Monday, October 15 th Grab a textbook! Objective: We will explain the formation of different soils and classify soils according to particle size. Review: 1. The four limestone samples illustrated below have the same composition, mass, and volume Under the same climatic conditions, which sample will weather SLOWEST? a. Sample A b. Sample B c. Sample C d. Sample D
Review 2. As particles of sediment in a stream break into several smaller pieces, the rate of weathering of the sediment will a. decrease due to a decrease in surface area. b. increase due to a decrease in surface area. c. decrease due to an increase in surface area. d. increase due to an increase in surface area.
Review 3. Which event is an example of chemical weathering? a. rocks falling off the face of a steep cliff b. feldspar in granite being crushed into clay sized particles c. water freezing in cracks in a roadside outcrop d. acid rain reacting with limestone bedrock
Review 4. What type of weathering caused the following rock feature?
Review 5. What type of chemical weathering is shown below? 2Fe + 3O2 Fe2O3
You are a Farmer You want to plant tomatoes You need to figure out what type of soil to use What characteristics do you look for in making your soil choice?
What is soil and where does it come from? Broken down rocks Four components: Minerals Air Water Organic
What is soil and where does it come from?
Summary What is soil and where does it come from?
Why are soils so different?
Why are soils so different? Why are you all so different? Factors of formation Parent Material (Bedrock Type) Climate Organisms Slope (Topography) Time Group activity
14a (left below Monday s review) Warm-up: 1. What are the factors affecting soil formation? 2. Which one has the greatest affect? See me if you did not take the test or finish the test yesterday.
Why are soils so different? Parent Material (Bedrock Type) Rocks/minerals/elements we are starting with Climate Weathering of starting materials Organisms Plants, animals, and microorganisms affect chemical content Slope (Topography) Slopes causes soils to slide or form differently Time Newer soils will look different from older soils
Summary Why are soils so different?
How does particle size affect soil characteristics? Three soil sizes/textures Clay Silt Sand Other important Soil particle: Humus
Humus Decayed organic material
Particle Size
Particle Size Soil separate particle diameter (mm) Sand......... 2.0-0.05 Silt.......... 0.05-0.002 Clay.......... <0.002 SAND SILT CLAY
How does particle size affect soil characteristics?
How does particle size affect soil characteristics? Sand Silt Clay Most Permeability (How fast does water flow through) Least Most Penetrability (How easily can roots push through) Least Least Nutrients Held Most
Page 14a (if room) Warm-up: 1. List the different sized particles found in soil from largest to smallest. 2. What is humus? 3. How does particle size affect water retention?
How does particle size affect soil characteristics?
How does particle size affect soil characteristics?
What soil is 30% clay, 30% Silt, and 40% Sand?
What soil is 30% clay, 30% Silt, and 40% Sand?
Summary How does particle size affect soil characteristics?
Think-Pair-Share Why is there such a danger of flash floods in the Las Vegas Valley?
How does soil change as you keep Soil Profile: A few of a cross section of soil. Soil Horizon: Zones or layers in a soil profile. digging down?
How does soil change as you keep digging down? 4 Main Horizons A Horizon B Horizon C Horizon Bedrock
How does soil change as you keep A Horizon Top Soil Humus (decaying Organic material) Organisms (including plant roots) digging down?
How does soil change as you keep B Horizon Beneath Top Soil: Subsoil Contains fine clay particles Lowest layer for organisms Holds more water digging down?
How does soil change as you keep C Horizon Above Bedrock Partially weathered Bedrock Pieces of Parent Rock can be found in the C Horizon digging down?
Summary How does soil change as you keep digging down?
Quick Questions 1. The cross section below shows a soil profile. This soil was formed primarily by a. Erosion by running water over a relatively long period of time. b. Weathering and biological activity over a relatively long period of time. c. Erosion by running water over a relatively short period of time. d. Weathering and biological activity over a relatively short period of time
Quick Questions 2. Which soil layer is least likely to contain humus?
Quick Questions 3. In the four following situations which two soils would be most similar? Soil A forms from Mafic rock in a humid climate. Soil B forms from Mafic rock in a dry climate. Soil C forms from Felsic rock in a humid climate. Soil D forms from Intermediate rock in a polar climate.
Quick Questions 4. Use the Soil-Texture triangle to answer the following question. What soil type is 30% clay, 50% sand, and 20% silt?
Quick Questions 5. A certain type of cactus needs to grow in soil that drains easily. Additionally, the roots of this cactus cannot penetrate dense soils, but does not need nutrient rich soil to grow. Of the following soils, which would be best for this cactus to grow in? a. Silty Clay b. Clay Loam c. Sandy Loam d. Silt