3.4 the soil system.ppt

1. 3.4 The Soil System

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.

3. Vocabulary (Rutherford)
soil profile -
soil horizon -
leaf litter -
parent material -
weathering -
clay -
loam -
sand -
humus -
leaching -
aeration -
nitrification -
denitrification -
nitrogen fixation -
leguminous plants (legumes) -
erosion -
salinization -
irrigation -
overgrazing -
arthropod -
gully -
rill -

4. 3.4.1 Soil Integration
●Soil – more than just dirt
■ "The nation that destroys its
soil, destroys itself." -
Franklin Delano Roosevelt
●Mixes:
■ Atmosphere – gases
■ Hydrosphere – water
■ Lithosphere – solids
■ Biosphere – living things
●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

6. 3.4.1 Hydrologic (H2O) Cycle

7. 3.4.1 Nitrogen (N2 & NOx) Cycle

8. 3.4.1 The Fast Carbon
(COx) Cycle

9. 3.4.1 Rock Cycle

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. Decomposers
2. Mutualists - nitrogen-fixers
3. Pathogens
4. 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. Decomposers -
saprophytic
2. Mutualists -
mycorrhizal
3. Pathogens -
parasites

12. 3.4.1 Living Organisms
●Invertebrates -
a. Earthworms - dominant invertebrate biomass
■ Bury & shred plants
■ Stimulate microbes
■ Mix soil
● Improves water-holding capacity
● Improves infiltration
● Root growth channels
b. Arthropods
■ Shredders - millipedes, sowbugs
■ Predators - beetles, mites, spiders
■ Herbivores - cicadas, rootworms
■ Fungal feeders - springtail, mites

13. 3.4.2 Soil Formation
●North Carolina State University's animation

14. 3.4.2 Soil Profile
●What does it
look like?

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

19. 3.4.3 Soil Degradation
●Water erosion
○ surface, gully, rill, tunnel
○ precipitation(mm)
>infiltration(mm)
●Wind erosion
●Acidification - leach toxic
chemicals
●Salinization/Nutrient loss
○ coastal/marine; arid
regions (capillary action)
●Atmospheric deposition
○ heavy metals; POPs
●Desertification (irrigation)
●Climate change

20. 3.4.3 Soil Degradation

21. 3.4.3 Human Activity
●Deforestation
○ root-bound soil
○ slopes
●Cultivation
○ bare ground
○ irrigation
●Grazing - trampling
●Roads
●Mining
●Other impacts
increasing previous
slide

22. 3.4.3 Human Activity

23. 3.4.3 Soil Conservation
●Mechanical
○ contour ploughing -
○ bunding - raised levees
○ terracing - steppes
●Cropping & soil
husbandry
○ maintain crop cover
(multi-cropping year-round)
○ keep roots/stubble
○ plant grass crop
○ wind
■ shelterbelts
■ hedgegrows
○ steepest slopes should
remain forested

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