Bell Ringer Test Thursday. Start studying! Type of Weathering How does it Weather? Climate Weathered by: Mechanical (Physical) Changes the __________ & ___________ of the rock _________ & _________ 1. 2. Chemical   Changes the ________________________ of the rock 3.

Soil

Soil Development Soil – the loose covering of weathered rock particles and decaying organic matter (humus) that covers Earth’s bedrock The result of both mechanical and chemical weathering

DID YOU KNOW? There are more organisms in a handful of soil than there are humans on Earth!

Soil Development Weathering breaks solid bedrock into smaller and smaller pieces Organisms like bacteria begin to live in these weathered materials Over time, the organisms die, decay, and add nutrients to the weathered materials to form soil

Soil Composition All soil forms on top of bedrock, a solid layer of rock Because all soil originates from bedrock, bedrock is called the parent material

Soil Composition The parent bedrock determines the type of minerals in the soil and how long it takes for the soil to form

Soil Composition Residual soil – soil located directly above its parent material Transported soil – soil that has been moved away from its parent bedrock Which soil is the result of erosion?

Soil Composition Soil profile – vertical sequence of soil layers Soil horizon – each layer in the soil profile horizon profile horizon horizon

Soil Composition Horizon O: organic layer Layer of leaves and organic debris at the top of a soil profile Doesn’t contain weathered rock, so not technically a soil layer

Soil Composition Horizon A: topsoil Dark and nutrient-rich Horizon B: subsoil Clay minerals, so red with slow water flow Horizon C: weathered bedrock Lies just above the bedrock First horizon to form

Soil Conservation In general, soil formation takes a long time. It can take hundreds of years for just one centimeter (cm) of soil to form! Soil Conservation – the protection of soil from erosion and/or infertility to ensure that it can be used responsibly

Methods of Soil Conservation Gravity increases erosion on sloped surfaces Terraces – “stair steps” cut into sloped fields to prevent soil from running downhill Contour farming – planting rows perpendicularly to the slope to reduce erosion

Methods of Soil Conservation Windbreaks – planting bushes/trees to reduce wind erosion

Methods of Soil Conservation Crop rotation – regularly changing which crops are planted in a particular field to keep the soil fertile Different plants remove and release different nutrients, so constantly changing the crops replenishes nutrients

Effects of Soil Erosion What happens if soil is not conserved? Tilling -- Plowing or leaving bare ground, which leaves the soil vulnerable to wind and water erosion

Effects of Soil Erosion In the 1930s, inexperienced farmers in the Midwestern US left exposed soil, creating the Great Dust Bowl The Great Dust Bowl led to widespread famine and economic loss (paired with the Great Depression)

Great Dust Bowl (1930s)

Effects of Soil Erosion In arid (dry) regions, topsoil erosion can lead to desertification Desertification – the process of good land becoming infertile (unable to grow plants) This can lead to loss of crops, and as well as famines for both livestock and humans

Soil Characteristics Four major types of soil: polar, temperate, desert, and tropical

Soil Characteristics Soil types vary, even in North Carolina!

Soil Characteristics Coastal Plain – sandy soil Piedmont – clay soil Blue Ridge – rocky, shallow soil

Soil Characteristics Fertility – ability to support plant growth Color – determined by the soil’s climate and composition Not a clear indicator of fertility (dark soil isn’t necessarily more fertile than light soil)

Soil Characteristics Texture – classified by particle size Smallest to largest particles: clay, silt, sand

Soil Characteristics Soil Texture Pyramid – use the %s of each particle size to classify the soil type

Practice: find the point where the %s intersect 20% clay, 40% silt, 40% sand Loam

Practice: find the point where the %s intersect  60% clay, 20% silt, 20% sand Clay

Practice: find the point where the %s intersect 10% clay, 30% silt, 60% sand Sandy loam

Today Soil Triangle WS. This is also INDIVIDUAL work. You may ask someone a QUICK question, but you are not working together today. Vocab. Please listen carefully!!!!

After Lab: Work AS A GROUP on the Soil Worksheet Take turns reading out loud or one person read When finished, answer the following questions ON THE BACK OF THE WORKSHEET about the soil pyramid: What type of soil is 30% sand, 60% clay, and 10% silt? What type of soil is 10% clay, 70% silt, and 20% sand? What type of soil is 50% clay, 20% silt, and 30% sand? What type of soil is 60% sand, 30% silt, and 10% clay? What type of soil is 40% silt, 20% clay, and 40% sand? Write TWO of your own. ________ type of soil is __% silt, _% clay, and ___% sand.