* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Ch4weatheringppt_001..
Survey
Document related concepts
Human impact on the nitrogen cycle wikipedia , lookup
Agroecology wikipedia , lookup
Plant nutrition wikipedia , lookup
Soil erosion wikipedia , lookup
Soil respiration wikipedia , lookup
Surface runoff wikipedia , lookup
Soil salinity control wikipedia , lookup
Terra preta wikipedia , lookup
Soil compaction (agriculture) wikipedia , lookup
Crop rotation wikipedia , lookup
Soil food web wikipedia , lookup
Soil horizon wikipedia , lookup
No-till farming wikipedia , lookup
Canadian system of soil classification wikipedia , lookup
Soil microbiology wikipedia , lookup
Transcript
Chapter 4 Weathering and Soil Formation Weathering breaks down rocks into smaller pieces 1. Mechanical weathering 2. Chemical weathering Mechanical weathering produces physical changes in rocks: • Ice wedging • Pressure release-causes rock to expand, cracking and leading to exfoliation Exfoliation-process in which layers of exfoliation rock gradually break off. • Plant root growth • Abrasion-wearing down by friction, the rubbing of one object or surface against another (example: running river) Chemical weathering • Breakdown of rocks by chemical reactions that change the rocks composition (what it is made of) • Water (dissolving) • Rusting Weathering occurs at different rates • Surface area-the more exposed area, the faster the break down of rock (chemical) • Rock composition ex: Granite compared to limestone • Climate: • chemical weathering occurs in wet, hot areas faster than cold, dry regions • Mechanical weathering caused by freezing and thawing Weathering and organic processes form soil • Soil- a mixture of weathered rock particles and other materials • Humus-decayed organic (living things) in the soil Soil formation is affected by: • • • • • Rock in an area Climate: tropical, desert, temperate, artic Landforms: mountains and valleys Plant cover: provide organic matter Living organisms: microorganisms and animals • Time Soil composition • Soil horizon-a layer of soil with properties that are different than the layers above and below it • Soil profile- soil horizons in a specific area Soil Properties • Texture-determined by size of weathered rock particles it contains • Color-most comes from iron and humus • Pore space-the spaces between the particles • Chemistry-minerals and organic nutrients (Does it react with water such as bubbling?) Human activities • Soil is a valuable resource for humans 1. Farming-soil loss and overgrazing results in desertification- expansion of desert in areas where natural plant cover has been destroyed 2. Construction and development 3. Mining • Strip mining • Open pit Soil conservation • • • • • Crop rotation Conservation tillage Terraces Contour plowing Windbreaks Info for Soil lab • Climate in Missouri- Temperate soils form in region with moderate rainfall and temperatures. Some temperate soils are dark-colored, rich in organic matter and minerals, and good for growing crops. Soil Horizons • The A horizon- is the upper layer of soil and is commonly called topsoil. • It contains the most organic matter out of all the horizons due to the humus that it contains gives it the dark color • (Moderate pore space). The B Horizon • This layer lies just below the A horizon. It has a little organic matter and is usually brownish or reddish color and contains clay (very little pore space for water) and minerals. The C horizon • This is the deepest layer of soil. This layer contains the largest and least-weathered rock particles. It is usually light yellowish brown (sand which has high amount of pore space).