Download presentation
Presentation is loading. Please wait.
Published byMelvin Nelson Modified over 9 years ago
1
Soil Formation and Weathering CH 10 uvm.edu
2
It’s not just dirt? Medium for plant growth (food, feed, fiber) Mechanical support for living organisms Regulates water flow (runoff, infiltration, storage, recharge) Provides nutrients & cycles nutrients Acts as filter (physical, chemical & biological)
3
How is soil formed? Parent rock material breaks down into smaller and smaller pieces. Pieces are changed chemically by weathering. Weathering changes rock at deeper and deeper levels. Eventually different layers or zones (horizons) are noticeable
4
Soil Loose material at Earth’s surface capable of supporting plants with root systems Mixture of: – Small mineral fragments – Decaying organic material – Water – Air – Organisms physicalgeography.net
5
Soil http://www.organicgardeninfo.com/soil.html
6
Soil food web From Miller’s Living in the Environment
7
Soil horizons O horizon – Leaf litter A horizon – topsoil B horizon – subsoil C horizon – parent material eoearth.org
8
Soil texture Clay <.002 mm Silt <.06 mm Sand.06 mm – 2 mm http://140.254.84.203/wiki/index.php/Fines
9
Soil texture chart
10
How is soil formed? Mechanical weathering – Breakdown of rocks into smaller pieces by physical means Chemical weathering – Breakdown of rocks into smaller pieces by chemical reactions
11
Mechanical weathering Ice Abrasion Wind Water Gravity Plants Animals
12
Chemical weathering Water Acid in rainwater Acid in groundwater Air
13
Soil types in different biomes From Miller’s Living in the Environment
14
Soil types in different biomes From Miller’s Living in the Environment
15
Tropical Rain Forest Thin, nutrient poor soils Heavy rains leach nutrients from soil Plants use nutrients very rapidly, so few nutrients are in soil
16
Desert Slow rate of chemical weathering, so soil created slowly Salts build up because there is little water to dissolve them & wash away
17
Temperate forest & grassland Much weathering occurs due to much rain Freeze/thaw breaks apart rocks Rain causes chemical weathering Most nutrient rich soils in the world
18
Arctic Chemical weathering occurs slowly due to little precip. Soils occur slowly Thin soil = few plants Decomposition happens slowly due to cold
19
Soil Erosion http://www.maine.gov/dep/blwq/doceducation/dirt.htm http://www.otsego.org/conservationdistrict/erosion.htm
20
Erosion in Africa is widespread http://www.shef.ac.uk/research/stories/engineering/27.html
21
Soil erosion Overused soils > fewer nutrients > fewer plants > exposed soils > wind & water carry away soil > people go hungry Desertification = land degradation = areas that are now unable to support crops
22
Stream side erosion http://www.newechotarivers.org/about-the- oostanaula/ecological-threats http://www.newechotarivers.org/about-the- oostanaula/ecological-threats http://www.newechotarivers.org/about-the-oostanaula/ecological-threats
23
Soil Conservation Contour plowing http://teachers.sduhsd.k12.ca.us/hherms/herms/GEOLOGY/conservatio n/desertification.htm
24
Soil Conservation Buffers along streams http://www.treehugger.com/files/2010/10/the-global-battle-to- conserve-and-rebuild-soil.php
25
Soil Conservation Terracing http://factoidz.com/terracing-an-environmentfriendly-agricultural-approach /
26
Satellite image of circular crop fields characteristic of center pivot irrigation in Kansas (June 2001). Healthy, growing crops are green. Corn would be growing into leafy stalks by late June. Sorghum, which resembles corn, grows more slowly and would be much smaller and therefore, possibly paler. Wheat is a brilliant gold as harvest occurs in June. Fields of brown have been recently harvested and plowed under or lie fallow for the year.
27
Vermicomposting turning kitchen scraps to soil http://kids.niehs.nih.gov/worms.htm
28
Homework Read pages 278 - 297
29
Output Soil horizons activity
Similar presentations
© 2024 SlidePlayer.com Inc.
All rights reserved.