Download Soil

Notes on Soil
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Where food is grown (no farms, no food)
Wood for shelter
Clothing (cotton)
Clay for dishes
Wood for paper
Habitat for many animals and plants
Oxygen
Medicine
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Rocks are broken down by weathering
Erosion, freezing and thawing, lightning,
rain dissolving rocks and minerals, plant
roots, animals burrowing, chemical
decomposition, etc..
Dead organisms are decomposed into their
simpler components
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Chemical – a chemical reaction causes the
rock to break down into smaller components
Mechanical – rock is broken down by
mechanical forces such as wind, water,
temperature changes, gravity, tree roots ,etc
Made of five things
1.
2.
3.
4.
5.
Rocks and minerals 45%
Water 25%
Air pockets 25%
Decomposed organic matter (Humus)5%
Living things
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pH – The amount of acid or base in the soil determines
which vegetation grows best and which nutrients are
available
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Macronutrients – The nutrients that plants need the
most of to be healthy:
i.
ii.
iii.
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Nitrogen (N)
Phosphorus (P)
Potassium (K)
Fertility: Healthy soils have the right amount of all
three macronutrients. The plants can grow and
reproduce best in fertile soil.
Soil Texture
 Sand – largest particle
size, feels grainy or gritty
 Silt - medium sized, feels
smooth and silky
 Clay – smallest sized,
feels sticky
Loam is a mixture of all
three textures with humus
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Is made of decomposed organisms
(plants, animals, bacteria, etc…) in the
top soil
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Best soil is dark brown. Also known as
detritus
 Decomposers like worms, insects,
animals, bacteria, fungi take dead
organisms and change the
chemicals N, P, and K to substances
that can be reused by plants
What is the best soil for growing plants?
The best soil has equal amounts of all 3
types of particles.
 This is called loam
 The soil is fertile with the right amounts
of nutrients available
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What is the difference between them?
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This is how fast the water moves or
percolates through the sample
Soil size determines permeability
Clay tends to hold soil/water better; sand
increases permeability
Porosity – how much water the soil can hold
Increasing the humus/detritus increases the
porosity
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Different parent rock
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Different climate
Warm & moist climates increase chemical and
biological weathering
ii. Moist & large temperature ranges increase
physical weathering
i.
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Different organisms