ROCKS FOR JOCKS AND
SOIL FOR GUYRLS
ROCK CYCLE
IGNEOUS ROCK
• Formed when
– magma cools
underground
• EX: granite
– Or above ground
• EX: lava rock/pumice
SEDIMENTARY ROCK
• Repeated settling of
eroded soil.
• Compressed layer by
layer until it turns into
rock.
• Ex: shale, limestone
METAMORPHIC ROCK
• Sedimentary or
igneous rock that has
morphed into another
type of rock
• Due to intense
pressure or heat
• EX: schist, gneiss
SOIL
What is soil?
• The loose covering of
broken rock particles
and decaying organic
matter (humus)
covering bedrock.
Why is soil important?
•
•
•
•
Grow food
Wood for building
Plants provide oxygen
Filter pollutants
How is soil created?
• Rock is chemically and
physically weathered.
• Bacteria, fungi, lichens, &
insects live in weathered
rock.
• These organisms die and
add nutrients to weathered
rock.
• As soil builds, larger
organisms can move in
and colonize.
• Takes 100’s of years to
create a few cm of soil.
What is a soil profile?
• Vertical sequence of soil
layers (horizons).
• O Horizon- vegetation/ leaf
litter on top of soil
• A Horizon- dark-colored thin
layer; rich in organic matter;
humus
• B Horizon- thick layer of
subsoil; may be red or
brown; clay based soil
• C Horizon- contains
weathered parent rock; larger
particles of rock; no organic
matter
• R Horizon- unaltered parent
bedrock
O horizon
R horizon
TYPES OF SOIL
• Polar soil-Artic
Tundra/Alpine Tundra
– Form at high elevations
& high altitudes
– No distinct horizonssoil too thin
– Under top few inches
of soil, ground is
permanently frozenPERMAFROST.
• Temperate soils
– Vary depending on
rainfall & type of
vegetation
– Tropical Grasslandsvery thick, rich, humus
– Forests- thinner, less
fertile clay soil
– Prairies- less rain, so
soil not as thick, but
still fertile.
• Desert soils
– Very thin A horizon
– Very little organic
matter
– High in minerals
– Soil is usually light
colored and coarse
textured.
• Tropical soils-Tropical
Rainforest
– Intensely weathered
due to high
precipitation and temp.
– Very little humus &
very few nutrients
– High concentrations of
iron- when oxidizes
causes characteristic
red color.
SOIL TEXTURES
• Size of particles determines
– Water holding capacity
– How compacted soil is
– Ability to support plant
•
•
•
•
Sand- larger particles
Silt- smaller particles
Clay- smallest particles
Loam- equal mix of sand, silt,
and clay
SOIL FERTILITY
• Measure of how well soil
can support plant life.
• Factors that affect fertility
of soil:
– Level of minerals &
nutrients
– Level of bacteria
– Amount of precipitation
– Topography
– Acidity of soil
What nutrients are important in soil?
1. Nitrogen- (N)
– Need for making chlorophyll for leaves
– Rapid plant growth and healthy leaves.
– Important for leafy veggies- spinach, lettuce,
cabbage, soybeans, corn
– Deficiency results in yellow or reddish leaves.
What nutrients are important in soil?
2. Phosphorus- (P)
– Needed for root development & growth.
– Helps produce flowers & fruit
– Deficiency results in darkening of leaves then
reddish tinge around edges.
– Important for beets, potatoes, carrots, &
radishes.
What nutrients are important
in soil?
3. Potassium- (K)
– Also called potash
– Deficiency results in puckering & yellowbrown leaves.
– Needed for
• Rapid cell growth at root tips
• Resistance to disease
• Makes stems strong
Important for potatos, beets, carrots, radishes, bud crops
(asparagus, broccoli, cauliflower)
Why should we know about soil pH?
• pH of soil can affect how
plants absorb N, P, K
• Most plants like neutral to
slightly acidic soil (6.06.8)
• Some carnivorous plants
like more acidic (4.0-5.0)
• To adjust soil pH…
– Add lime to make more
basic
– Add alum to make more
acidic
Prefer
neutral
(6.0-6.8)
Prefer
slightly
acidic
(5.0-6.5)
Prefer
strongly
acidic
(4.0-5.0)
Grains
Holly
Sundew
Veggies
Orchids
Pitcher
plants
Evergreen
Venus fly
trap
Strawberrie Azalea
s
Potato
Rhododend
ron
Carrot
camellia
What do those numbers mean on a
bag of fertilizer?
• Indicates % of N, P, K in the
fertilizer
• Different plants have different
nutrient needs.
• Pros of commercial fertilizer:
– Greatly increases crop yield
– Greatly increase crop quality
• Cons of commercial fertilizer:
– Pollute & degrade soil
– Cause eutrophication
Alternatives to commercial
fertilizers
– Crop rotationalternating corn crop
with legume (peas,
beans, clover) to add
nutrients back to soil
Alternatives to commercial
fertilizers
– Limestone- reduces
acidity of soil
Alternatives to commercial
fertilizers
– Organic fertilizerscompost, manure, peat
moss
SOIL CONSERVATION
• Soil is easily eroded.
• Methods to prevent
erosion include:
Contour Farming- plowing along slope
instead of up and down it. Furrows
btwn rows of crops collect water.
•Terracing- series of platforms
are built into slopes. Effective
with steep slopes, slows water
flow.
•Shelter Belts- rows of trees
planted along outer edges of
s creating a windbreak to
prevent wind erosion.
Strip-Cropping- Farmers plow so that
plowed strips are separated by planted
strips. Roots of planted strips hold soil
in place.
Other methods of soil
conservation
• Reduce Grazing
Permits
• Put up fencing
– Animals cannot
compact and destroy
plants