Name ______________________
Period ________
Soil Notes
Why is soil considered an ecosystem?
Soil Formation
____________________ the base material of soil (solid rock)
What causes parent material to turn to soil? ___________________
1
Weathering = the physical, chemical, or
biological processes that break down rocks to
form soil
Example
wind and rain, no chemical changes
in the parent material
substances chemically interact
with parent material
organisms break down parent
material
organisms break down parent
material
Draw Parent Material
Draw product of weathering
Biological Process that form soil
Biological Process that forms organic
material
The organic material formed
2
Soil Profiles
____________= each layer of soil
____________= the cross-section of soil
as a whole
• Up to six major horizons may occur
in a soil profile
- _________ = inorganic and
organic material most
nutritive for plants
-
_________= dissolved
particles move down through
horizons
Horizon O
Horizon A
Horizon E
Horizon B
Horizon C
Horizon R
3
Classification of Soil
•
Soils are classified based
1.
2.
3.
4.
1. Soil Color
How is soil color determined?
What does color indicate?
Black or dark brown =
Pale gray or white
2. Soil Texture
How is soil texture
determined?
What does particle size
determine?
Particle sizes from small to
large
What does loam mean?
Water holding capacity
•
•
•
Should retain water for plant growth
During heavy rains, if water is not absorbed water can pool and take a long time to
drain or run off resulting in flooding
Most important factor: Spaces of air between the soil particles
4
Infiltration rate
•
•
Gravitational flow through soil
Soils with high infiltration rate are easily leached (removing nutrients)
Capillary action
•
•
•
Strong attraction between water molecules and soil causes water to be drawn
upward from the water table.
Capillary action increases when soil is packed close enough to provide a continuous
film of surface
Soils with high rate of capillary action lose water more quickly through evaporation
than soil where capillary action is slower.
5
Water Holding Capacity depends on ___________________ and
___________________
What do ions do for plants?
gives plants green color
helps seed production
gives fruit color, helps with fruit production
6
Classifying soils based on textures
% sand
% silt
% Clay
70
10
42
10
83
15
7
37
Texture Name
3. pH of soil
pH Scale
Soil pH = influences a soil’s ability to support plant growth (plants grow best at pH of 7)
-
Soils that are too acidic or basic can kill plants
When pH of soil gets too low, ______________________
7
Soil with nutrients
If pH of soil is too low
4. Soil Structure
What is soil structure a
measurement of?
How do large clumps of soil
affect plants?
We are losing more soil every year!!
•
•
•
•
Feeding the world’s rising human population requires changing our diet or increasing
agricultural production
Land suitable for farming is running out
We must find ways to improve the efficiency of food production
Mismanaged agriculture turns grasslands into deserts; removes forests; diminishes
biodiversity; and pollutes soil, air, and water
- Fertile soil is blown and washed away
Soil degradation results from ____________, and ___________________________
What can reduce soil erosion? ________________
Types of soil erosion
water impacts surface loosening and breaking up soil particles
rainfall intensity of a storm exceeds the infiltration capacity of the
soil
is caused by water concentrating into closely closely-spaced areas
forming small channels
steep-sided trenches formed by rill erosion
8
Rank the types of erosions based on which one causes the most loss of soil to the least
loss of soil
Most loss
least loss
Where does all the soil end up after it erodes from the land?
___________________________
• ________________
the arrival of eroded material at its new location
What is the relationship between the rate soil is eroded to the rate soil is formed?
Erosion increase through these three processes:
1. Overgrazing
•
•
Overgrazing = too many animals eat too much of the plant cover
- Impedes plant regrowth
A leading cause of soil degradation
How much of the world’s range land is classified as degraded? _________
9
Effect of overgrazing
2. Clearing forests
•
__________________ = the removal of all trees from an area at once
- Leads to soil erosion, especially on steep slopes
3. Tilling the land
Tilling the land = ________________
Excessive Watering can lead to Salinization of Soil
Artificially providing water to support agriculture
over-irrigated soils (Water suffocates roots)
the buildup of salts in surface soil layers
Salinization inhibits production of 20% of all irrigated cropland, costing more than $11
billion/year
Salinization Prevention
10
Desertification
•
•
____________________= a process by which fertile land turns into barren land
Causes
Most prone areas = arid and semiarid lands
Transformation of fertile soil to barren or desert land
11
Using Fertilizers to add nutrients back to the soil
substances that contain essential nutrients
mined or synthetically manufactured mineral supplements
remains or wastes of organisms
-
manure, crop residues, fresh vegetation
produced when decomposers break down organic matter to produce
humus
How has the use of fertilizers changed over the past 50 years?
Effects of over-fertilizing
What occurs
Effect on environment
Effect on Humans/plant/animal
life
Excess fertilizer runoff into
fresh water
Chemicals in the fertilizers
evaporate into atmosphere
Chemicals in the fertilizers
are leached into
groundwater
12
Protecting the Soil
Term
Definition
How does it help
alternating the crops grown field
from one season or year to the
next
protect soil when main crops aren’t
planted
plowing furrows sideways across a
hillside, perpendicular to its slope,
to prevent rills and gullies
level platforms are cut into steep
hillsides, sometimes with raised
edges
planting different types of crops in
alternating bands or other spatially
mixed arrangements
rows of trees or other tall,
perennial plants that are planted
along the edges of fields to slow
the wind
13