chapter 12 soil resources. chapter overview questions what is soil? how is soil formed? what are...
TRANSCRIPT
Chapter 12Chapter 12
Soil ResourcesSoil Resources
Chapter Overview QuestionsChapter Overview Questions
What is soil? What is soil? How is soil formed?How is soil formed? What are the major components of soil?What are the major components of soil?
BiosphereBiosphere
AtmosphereAtmosphere Membrane of air around the planet.Membrane of air around the planet.
StratosphereStratosphere Lower portion contains ozone to filter out most of Lower portion contains ozone to filter out most of
the sun’s harmful UV radiation.the sun’s harmful UV radiation. HydrosphereHydrosphere
All the earth’s water: liquid, ice, water vaporAll the earth’s water: liquid, ice, water vapor LithosphereLithosphere
The earth’s crust and upper mantle.The earth’s crust and upper mantle.
SOIL: A VALUABLE RESOURCESOIL: A VALUABLE RESOURCE
Soil is a Soil is a SLOWLYSLOWLY renewed resource that provides renewed resource that provides most of the nutrients needed for plant growth and most of the nutrients needed for plant growth and also helps purify water. IB considers soil to be also helps purify water. IB considers soil to be nonrenewable resource because it takes hundreds nonrenewable resource because it takes hundreds to thousands of years to replace a few inches.to thousands of years to replace a few inches. Soil formation begins when bedrock is broken down by Soil formation begins when bedrock is broken down by
physical, chemical and biological processes called physical, chemical and biological processes called weatheringweathering..
Mature soilsMature soils, or soils that have developed over a , or soils that have developed over a long time are arranged in a series of horizontal long time are arranged in a series of horizontal layers called layers called soil horizonssoil horizons..
SOIL: A VALUABLE RESOURCESOIL: A VALUABLE RESOURCE
Figure 3-23Figure 3-23
Fig. 3-23, p. 68
Fern
Mature soil
Honey fungus
Root system
Oak tree
Bacteria
Lords and ladies
Fungus
Actinomycetes
Nematode
Pseudoscorpion
Mite
RegolithYoung soil
Immature soil
Bedrock
Rockfragments
Moss and lichen
Organic debrisbuilds upGrasses and
small shrubs
Mole
Dog violet
Woodsorrel
EarthwormMillipede
O horizonLeaf litter
A horizon
Topsoil
B horizonSubsoil
C horizon
Parent material
Springtail
Red Earth Mite
Layers in Mature SoilsLayers in Mature Soils
Infiltration: the downward movement of water Infiltration: the downward movement of water through soil.through soil.
Leaching: dissolving of minerals and organic Leaching: dissolving of minerals and organic matter in upper layers carrying them to lower matter in upper layers carrying them to lower layers.layers.
The soil type determines the degree of The soil type determines the degree of infiltration and leaching.infiltration and leaching.
Soil Profiles of the Soil Profiles of the Principal Terrestrial Principal Terrestrial
Soil Types Soil Types
Figure 3-24Figure 3-24
Fig. 3-24a, p. 69
Mosaic of closely packed pebbles, boulders
Weak humus-mineral mixture
Dry, brown to reddish-brown with variable accumulations of clay, calcium and carbonate, and soluble salts
Alkaline, dark, and rich in humus
Clay, calcium compounds
Desert Soil(hot, dry climate)
Grassland Soilsemiarid climate)
Fig. 3-24b, p. 69
Tropical Rain Forest Soil(humid, tropical climate)
Acidic light-colored humus
Iron and aluminum compounds mixed with clay
Fig. 3-24b, p. 69
Deciduous Forest Soil(humid, mild climate)
Forest litter leaf moldHumus-mineral mixtureLight, grayish-brown, silt loamDark brown firm clay
Fig. 3-24b, p. 69
Coniferous Forest Soil(humid, cold climate)
Light-colored and acidic
Acid litter and humus
Humus and iron and aluminum compounds
Some Soil PropertiesSome Soil Properties
Soils vary in the size Soils vary in the size of the particles they of the particles they contain, the amount contain, the amount of space between of space between these particles, and these particles, and how rapidly water how rapidly water flows through them.flows through them.
Figure 3-25Figure 3-25
Fig. 3-25, p. 70
0.05–2 mmdiameter
High permeability Low permeability
WaterWater
Clayless than 0.002 mm
diameter
Silt0.002–0.05 mm
diameter
Sand
Soil is a non-renewable resourceSoil is a non-renewable resource
Soil formation takes a very long time.Soil formation takes a very long time. Under the best conditions (wet, temperate Under the best conditions (wet, temperate
climate) only a few millimeters of soil are climate) only a few millimeters of soil are formed each year.formed each year. This is only after initial chemical and physical This is only after initial chemical and physical
weathering has occurred.weathering has occurred. Soil use often exceeds soil formation.Soil use often exceeds soil formation. Soil should be considered a non-renewable Soil should be considered a non-renewable
resource.resource.