2. Sub-subtopics
3.4.1
Outline how soil systems integrate aspect of living systems.
3.4.2
Compare the structure and properties of sand, clay, and loam soils,
including their relevance to primary productivity.
3.4.3
Outline the processes and consequences of soil degradation.
3.4.4
Outline soil conservation measures.
3.4.5
Evaluate soil management strategies in a named commercial farming
system and in a named subsistence farming system.
4. 3.4.1 Soil Integration
Soil – more than just dirt
●
■
"The nation that destroys its
soil, destroys itself." Franklin Delano Roosevelt
■
Atmosphere – gases
Hydrosphere – water
Lithosphere – solids
Biosphere – living things
Mixes:
●
■
■
■
Pedosphere -
●
(Gr. πέδον "soil" or "earth"
and σφαίρα "sphere")
■ the outermost layer of the
Earth that is composed of
soild and subject to soil
formation processes." Wikipedia
■
5. 3.4.1 Pedosphere = Soil
Atmospheric cycling
■
■
■
■
■
■
Hydrologic (H2O) cycle
Nitrogen (N2 & oxides NOX) cycle
Carbon (oxides COx) cycle
Sulfur (dioxide SO2) cycle
Oxygen (Ox) cycle
Phosphorous (TP & PO4) cycle
●
"There is a net loss of Total Phosphrous from many (but
not all) land ecosystems, and a net gain of TP by the
oceans (560 Gg P yr -1). More measurements of
atmospheric TP and phosphate PO4 will assist in reducing
uncertainties in our understanding of the role that
atmospheric phosphorus may play in global
biogeochemistry." 2009 Global Study
10. 3.4.1 Living Organisms
Bacteria "A teaspoon of productive
soil generally contains
between 100 million and 1
billion bacteria. That is as
much as two cows per acre."
- Elaine R. Ingham, NRCS
●
1.
2.
3.
4.
Decomposers
Mutualists - nitrogen-fixers
Pathogens
Chemoautotrophs (or lithotrophs)
11. 3.4.1 Living Organisms
Fungus "Fungal fruiting structures
●
(mushrooms) are made of hyphal
strands, spores, and some special
structures like gills on which
spores form. A single individual
fungus can include many fruiting
bodies scattered across an area
as large as a baseball diamond."
- Elaine R. Ingham,
NRCS
1.
2.
3.
Decomposers saprophytic
Mutualists mycorrhizal
Pathogens parasites
15. 3.4.2 Soil Separates
Name of soil separate
Diameter limits (mm)
Very coarse sand*
2.00 - 1.00
Coarse sand
1.00 - 0.50
Medium sand
0.50 - 0.25
Fine sand
0.25 - 0.10
Very fine sand
0.10 - 0.05
Silt
0.05 - 0.002
Clay
less than 0.002
* Note that the sand separate is split into five sizes (very coarse sand, coarse sand, etc.). The size
range for sands, considered broadly, comprises the entire range from very coarse sand to very fine
sand, i.e., 2.00-0.05 mm.
16. 3.4.2 Soil Texture
The USDA Textural
Triangle
●
○
12 soil
classifications
based on
particulate size
How would you find
out what type of soil
contains 25% clay,
15% sand, and 60%
silt?
17. 3.4.3 Soil Degradation
Primary productivity of soil depends on:
○ mineral content
○ drainage
○ water-holding capacity
○ air spaces
○ biota
○ potential to hold organic matter
- Davis & Nagle, pg127
●
18. 3.4.3 Soil Degradation
Universal soil loss equation (USLE):
●
A = RKLSCP
A = predicted soil loss
R = climatic erosivity
K = soil erodibility
L = slope length
S = slope gradient
C = cover & management
P = erosion controls
- Davis & Nagle, pg128
●
RUSLE for Michigan State, USA
24. 3.4.3 Soil Conservation
Salinized soils
●
flushing by drainage
(& leaching out of
salts)
○ chemicals
■ gypsum replaces
sodium ions
with calcium
ions
○ reduce evaporation
losses
○ strip cropping
○
25. 3.4.3 Soil Maps
World
●
Stresses
●
Human Induced Changes
●
Erosion
●
Water
●
"We abuse land because we regard it as a commodity
belonging to us. When we see land as a community to
which we belong, we may begin to use it with love and
respect." - Aldo Leopold, 1949. A Sand County Almanac.
●
26. 3.4.3 Soil Management
Case Study - using the previous maps, find and
report on how two countries or regions are
managing and conserving (or not) their soil
resources.
●
Report
●
○
○
○
○
250 words or slightly more
any format (paragraph, news article, narrative, etc.)
one commercial farming country/region
one subsistence farming country/region
