Plants and Soil Soil Degradation Addressing Soil Degradation.
Soil
-
Upload
penelope-mcdowell -
Category
Documents
-
view
20 -
download
0
description
Transcript of Soil
Soilhttp://www.youtube.com/watch?v=qajjl3esi5E(intro sent out via kmail)
Topsoil Soil is the topmost portion of the
earth's crust; it supports life.
Soil is composed of minerals and organic material.
Composition is based on "parent" material (in the lower crust).
How Soil Forms Residual Soil: parent material is
bedrock beneath the soil EX: Transported Soils: soil is made from
deposits left by wind, rivers and glaciers EX:
SOIL FORMATION It can take 1,000 yrs to form topsoil. A soil forms as parent material is
weathered away. Organic material (dead plants and
animals) are mixed with weathered rock)
Soil composition Every soil is a mixture
of clay, silt, and sand Clay: Very fine/small
particle, tiny space between particles, dense
Silt: Too light, blown away (found in floodplains)
Sand: course, big spaces between particles
Soil composition Cont’d Perfect soil for plants is Loam LOAM: mixture of sand (40%), silt
(40%), and little clay (20%)
Stalinization of soils
Build up of salts in soil—toxic for plants (can’t take up water)
Associated with excessive irrigation of water
Problem associated with poorly drained soils (CA, Colorado River Basin)
Treatment: flush soils with lots of water
Extreme cases: salt crust too thick to be flushed
Check In 1. Which zone
contains weathered parent rock?
2. Which zone contains inorganic materials that have been washed from A horizon?
3. Which zone contains microorganisms that breakdown material into nutrients?
Soil Composition Parent material Plants and animals Topography---flow of water Climate
Heavy rains wash away nutrients Rainfall/high temp result in high clay
Soil loss Erosion: soil lost by water or wind Chemical contamination Salinization Compacting by cattle hooves/machinery
40% of cropland is degraded
Stalinization of soils
Build up of salts in soil—toxic for plants (can’t take up water)
Associated with excessive water application/irriga6tion of water
Problem associated with poorly drained soils (CA, Colorado River Basin)
Treatment: flush soils with lots of water
Extreme cases: salt crust too thick to be flushed
Soil Horizons A Horizon: (topsoil)humus,
inorganic particles, microorganisms decompose organic compounds into nutrients
B Horizon: (subsoil) inorganics (iron, clay, calcium) that have been washed down into the B-horizon
C Horizon: slightly weathered parent material—rock fragments
Bedrock
Extension: Soil Scientists Some things to think about:
What do scientists do? What type of schooling do they have? Do we need soil scientists?
http://www.youtube.com/watch?v=53pNGEO08ck&feature=related
Soil as a Resource Countless living organisms and
numerous species live in soil Chemical processes by these organisms
enable food to grow. Soil provides the fertility for food to
grow. Soil is a very important part of an
ecosystem