Soil Study Guide
Directions: Fill in the blank with the word that best completes the sentence. Use
the word bank provided.
erosion
parent material
inorganic matter
1.
topsoil
bedrock
composition
organic matter
scientific observation
weathering
subsoil
fertilizer
The richest layer of soil is the loose layer which often includes biological
activity and organic matter known as loam. This is called topsoil.
2. The next 3 layers of soil are from top to bottom:



subsoil
parent material
bedrock
3. Erosion is when wind or water washes away soil. This often occurs where
there is little existing vegetation to hold the soil in place.
4. Weathering is when wind, water, or chemicals break rocks into smaller
particles.
5. Leaves, twigs, decomposing animals, and waste are examples of organic
matter found in soil.
6. Sand, silt, and clay are examples of inorganic matter found in soil.
7. The specific ingredients of soil (sand, silt or clay) are referred to as its
composition.
8. A complete and accurate description in science is called a scientific
observation.
9. When providing missing nutrients to the soil, the best fertilizer is one in
which provides MORE of the missing nutrients.
10. Characteristics (description) of Soil: Write the words that are used to
describe these characteristics of soil.
Texture
Color
Consistence
Grainy – large sized pieces, feels gritty like sand
Silky – medium sized pieces, feels powdery like silt
Sticky – small pieces, feels gummy like wet clay
Brown, gray, reddish, and combinations of all three of
those colors
Loose – breaks apart when held
Friable – breaks with small amount of pressure from one
finger
Firm – breaks with a lot of pressure between two
fingers
11. Composition of Soil: Write facts about the following words. (ex. Particle
size, where it is found, etc.)
Sand
Silt
Largest pieces of rock in soil - .05-2.0mm – largest are
less than 1/5 of a centimeter –called “grains” – easily
visible but not as big as pebbles
Smaller than sand, bigger than clay (medium sized
pieces - .002mm-.05mm
Clay
Smallest pieces of rock in soil – so small they can’t be
seen w/o a microscope
Organic
Matter
Comes from decomposing organic matter like plants
and animals – “organic” refers to material from living
organisms
organic matter breaks until it becomes basic chemicals
– they are important for plant growth – plant roots
absorb nutrients
Nutrients
12. Needed by all plants: Write the four things needed by all plants.
soil
air
water
sunlight
Understand the definition for the following words:
13.
14.
Permeability: The soils ability to transmit air or water.
Porosity: The volume of all open spaces (pores) between the solid grains
of soil.
15. Horizon O: The uppermost soil layer made up mostly of organic matter.
Fresh litter and humus is found here.
16. Evidence: Unbiased data or information that is gathered by direct
observation and is reproducible.
17. Opinion: A view someone takes about a certain issue based on his/her own
judgment, often w/o the support of factual evidence.
Understand the order and characteristics of the soil layers known as horizons.
O Horizon - The top, organic layer of soil, made up mostly of leaf litter and
humus (decomposed organic matter).
A Horizon - The layer called topsoil; it is found below the O horizon and above
the E horizon. Seeds germinate and plant roots grow in this dark-colored layer.
It is made up of humus (decomposed organic matter) mixed with mineral
particles.
E Horizon - This eluviation (leaching) layer is light in color; this layer is beneath
the A Horizon and above the B Horizon. It is made up mostly of sand and silt,
having lost most of its minerals and clay as water drips through the soil (in the
process of eluviation).
B Horizon - Also called the subsoil - this layer is beneath the E Horizon and
above the C Horizon. It contains clay and mineral deposits (like iron, aluminum
oxides, and calcium carbonate) that it receives from layers above it when
mineralized water drips from the soil above.
C Horizon - Also called parent material or regolith: the layer beneath the B
Horizon and above the R Horizon. It consists of slightly broken-up bedrock.
Plant roots do not penetrate into this layer; very little organic material is found
in this layer.
R Horizon - The unweathered rock (bedrock) layer that is beneath all the other
layers.
Dust Bowl:
18. Identify several causes and effects regarding the Dust Bowl.
Cause
Effect
Farmers removed native
plants and planted crops
Crop plants were not adapted
to live in that area – their
roots couldn’t hold soil down
Several years of drought
Soil dried out, crops died, soil
was left bare
Farming techniques didn’t
work – their extra watering
failed
Crops dried out and died
Farmed soil had very little
organic matter in it (no
nutrients)
Natural nutrient cycle was
broken and the land was
ruined – farmers left the land
Large areas of abandoned land
existed where no plants could
grow
The dry, nutrient-poor soil could
be easily picked up by the wind –
became dust storms
19. Describe the following soil regions:
Desert
Forest
-
-
Grassland
-
-
Tropical grassland
-
-
form in places with little rainfall
high temperatures all year round
dry and sandy
limited # of plants
easily moved by wind and water
light in color
firm consistence
gritty texture
form in places with hot and cold
seasons and have enough rain year
round to support a lot of tree growth
good for farming
grayish brown to reddish brown in
color
loose consistence
silky texture
form in places with both wet and dry
seasons but less overall rain than
forest regions
top layer has a lot of nutrients due
to lots of decomposing plant matter
good for farming
reddish brown in color
loose consistence
silky texture
form in places that are very warm all
year long with both wet and dry
seasons unlike tropical areas that are
always wet
grayish brown in color
texture is sticky
loose consistence