The Ground Beneath Our Feet From Bedrock to Soil Chapter 10: Section 3

Section Vocabulary Soil: a loose mixture of rock fragments, organic material, water, and air that can support the growth of vegetation Parent Rock: a rock formation that is the source of soil Bedrock: the layer of rock beneath the soil Soil Texture: the soil quality that is based on the proportions of soil particles Soil Structure: the arrangement of soil particles

Section Vocabulary (cont) Humus: dark, organic material formed from the decayed remains of plants and animals Leeching: the removal of substances that can be dissolved from rock, ore, or layers of soil due to the passing of water

What Makes Up Healthy Soil? Mineral fragments, humus, air, water, and living things Plant roots, Insects, Worms Humus Organic (living) material formed from the decayed remains of plants and animals Can support the growth of vegetation Parent rock A rock formation that is the source of mineral fragments in the soil

Go to this link to watch and listen to the difference in residual and transported soils: http://my.hrw.com/sh2/sh07_10/student/flash/visual_concepts/80138.htm

Soil Formation Soil starts out as rock The surface rocks break down into smaller pieces and is mixed with organic matter. Over time this creates a thin layer of soil. Decaying matter makes the soil thick and rich

Soil Texture Soil Texture ~ the soil’s quality is based on the proportions of soil particles. Soil texture affects: Consistency: soil’s ability to be broken up. Infiltration: ability of water to move through soil.

Sizes of Weathered Rock That Make Up Soil

Different Types of Soil Every soil type is a mixture of sand, silt, clay. The right mixture is called loam. Loam = 40% sand 40 % silt 20 % clay

Soil Horizon Link to animation of soil horizon formation: http://courses.soil.ncsu.edu/resources/soil_classification_genesis/soil_formation/soil_transform.swf

Soil Horizon Each soil profile (horizon) is different from another. Soil often ends up in a series of layers called horizons: Humus rich soil at the top Sediment below hummus Bedrock on the bottom

Soil Horizon O Litter from dead plants and animals A Topsoil E Zone of intense leaching. B Collects dissolved substances from upper horizons C Weathered bedrock R Bedrock

Soil pH Soils can be acidic or basic pH scale is used to measure how acidic/basic Measuring pH levels: Range: 0 – 14; Soil @ 7 = neutral Soil below 7 = acidic Soil above 7 = basic

Soil pH Carbonic acid and Humic acid changed the pH of the soil to be more acidic. Carbonic acid come from Carbon Dioxide. Humic acid various organic acids produced from humus.

Soil and Climate Soil types vary from place to place Different climates have different types of soil, depending on the temperature and rainfall. This link describes how climates affects soil: http://my.hrw.com/sh2/sh07_10/student/flash/visual_concepts/80135.htm

Tropical Climate Climate = humid air, large amounts of rainfall, warm temperatures Rich humus because the warmer soils allows dead plants and animals to decay easily. However, soils are nutrient poor because very thin topsoil layer Heavy rains leach precious nutrients from topsoil. Plants demand a lot of nutrients from the soils.

Desert Climate Climate = less than 25 cm rain a year. This lack of rain causes low rates of weathering and ability to support plant and animal life Slow rate of weathering = Slow rate of soil formation. Due to no water, salt gathers in the ground. Salt is toxic to plants!

Temperate Climate Temperate areas get enough rain to cause a high level of chemical weathering Lots of weathering = lots of fertile soil Most productive soil in the world, nickname = “breadbasket” Most of Continental USA has a temperate climate.

Arctic Climate Very cold desert = Slow rate of soil formation because chemical weathering occurs slowly Low amount of humus due to cold soil temperatures. Cold temperatures slow down decomposition which limits available nutrients.

On a separate sheet of paper: Write your name, date, class color Number your paper 1 – 10 Answer the next ten following questions: Write the question and your answer. Turn in when completed

Review Questions 1. What is loam? A. Loam is the perfect combination of sand, silt, and clay. B. Loam is the combination of 30% sand, 40% mud, and 30% clay. C. Loam is located on in horizon B. D. Loam is the particle quality of any soil.

Review Questions 2. Because of the way soil forms, soil often ends up in a series of horizontal layers called ______________________

Review Questions 3. How does soil texture affect soil consistency? A. It has nothing to do with it. B. Allows water to pass through it easier. C. The soil’s ability to allow farmers to manipulate it. D. Allows for plants to grow easily.

Review Questions 4. What is the organic material formed in soil from the decayed remains of plants and animals called? - A. Bedrock - B. Parent rock - C. Residual soil - D. Hummus

Review Questions 5. Which particle is the biggest one that goes in soil? A. Clay B. Silt C. Quartz D. Sand

Review Questions 6. What acids can change the pH of the soil? A. Humic acid and Hydrochloric acid B. Carbonic acid and Humic acid C. Carbonic acid and water D. Water and citric acid

Review Questions 7. Which climate is called the “breadbasket of the world”? A. Tropical B. Desert C. Temperate D. Arctic

Review Questions 8. What is the difference between residual and transported soils?

Review Questions 9. Climate with enough rain to cause a high level of chemical weathering, but not so much that the nutrients are leached out of the soil is ________________________.

Review Questions 10. What do we call the removal of substances from soil due to water passing through it? - A. Wedging - B. Infiltration - C. Erosion - D. Leaching