Transcript From Bedrock to Soil

FROM BEDROCK TO SOIL
Section 10-3 pg. 288-293
WHAT IS SOIL?
ANSWER

Soil
is a loose mixture of
small mineral fragments
 organic material
 water
 Air
 that can support the growth of vegetation

VOCAB:

Parent Rock


Rock formation that is the source of mineral
fragments
Bedrock
Layer of rock beneath the soil
 So bedrock is the parent rock
 The soil above it is call residual soil


Transported soil
Soil that is blown or washed away from its parent rock
 Can be done by wind, water, glaciers moving, weather

SOIL TEXTURE

Is the soil quality that is based on the
proportions of soil particles

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Can be small to big (2mm)
This affects the soil’s consistency

This is the soil’s ability to be worked/farmed
Large proportions-clay is difficult to farm in
 Soil texture influences the infiltration

(ability of water to move through soil)
 Water needs to get to plants
 But don’t want soil to be saturated in water

SOIL STRUCTURE
Water and air movement through soil is
influenced by soil structure
 This is the arrangement of soil particles


How spread out they are
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Clumpy-won’t let air or H2O through
SOIL FERTILITY
Is the soil’s ability to hold nutrients and to
supply nutrients to a plant
 Nutrients can come from parent rock
 Nutrients can come from Humus

Organic material formed in soil from the decayed
remains of plants and animals
 Broken down by decomposers

SOIL HORIZONS
Soil ends up in a series of layers = Horizons
 Top layer- is humus—rich layer

Called top soil
 Good top soil is necessary for farming

Sediment middle
 Parent rock—bed rock bottom
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SOIL PH
Soil can be acidic or basic
 Scale 0-14, 7 neutral
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below 7 = acidic
above 7 = basic
This influences how nutrients dissolve in the soil
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Basic
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Acidic
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nutrients don’t dissolve-hurts plants
plants can’t take in other certain nutrients
Right pH decides what plant can grow there
TROPICAL RAIN FOREST
Air is humid, large amounts of rain, warm temp.
 Crops grown yr round
 Decay is at a high rate- so nutrients in soil
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Soil
Nutrients low- heavy rain takes it to deeper part
 Top soil is thin
 Plants grow—take a huge toll on nutrients
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DESERT
Not a lot of rain,
 Very low rates of chemical weathering
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soil is created slower
Less able to support plants
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Groundwater- comes from surround areas-comes to
surface-then evaporates
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can’t get all nutrients in time
High is salts
toxic to plant
TEMPERATE FOREST/GRASSLANDS
Much of USA is this
 Lots of weathering
 Get enough rain—

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chemical weathering to happen
Change in temp

-get frost action
Get thick fertile soil
 Most productive soil
 Midwestern = Breadbasket
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ARCTIC
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Little rain—
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Soil forms slowly

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chemical weathering is low and slow
Thin and don’t support life
Low temp.—
low decomposition rate
 Low number of nutrients
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THE END