the soil system

ESS dirt primer

1. The Soil SystemThe Soil System
1.Read over this presentation
2.Read over the questions that come at the end
3.Read the assigned pages from the book
4.Check out the links provided
5.Answer the questions that come at the end.

2. Who Cares About Dirt?Who Cares About Dirt?
•Soil is the source of nutrients for plants and Soil is the source of nutrients for plants and
the basis for root systemsthe basis for root systems
•Soil is the habitat for millions of species of Soil is the habitat for millions of species of
plants, microorganisms, and plants, microorganisms, and
macroorganismsmacroorganisms
•Soil also acts as a filter, as a recycling Soil also acts as a filter, as a recycling
system, and as a pollution control system, and as a pollution control
mechanism mechanism

3. What is Dirt?What is Dirt?
•The Soil System integrates biotic and abiotic components The Soil System integrates biotic and abiotic components
•The Soil System also integrates other systems!! i.e. lithosphere, The Soil System also integrates other systems!! i.e. lithosphere,
atmosphere, and hydrosphereatmosphere, and hydrosphere
•Soil is a complex mixture of Soil is a complex mixture of
-eroded rockeroded rock
-mineral nutrientsmineral nutrients
-decaying organic matterdecaying organic matter
-WaterWater
-air air
-and billions of living organisms (microscopic decomposers).and billions of living organisms (microscopic decomposers).
•HUMUS -HUMUS - partially decomposed organic matter; the organic partially decomposed organic matter; the organic
component of soil component of soil

4. Soil formation is a slow process:Soil formation is a slow process:
1.1.Weathering of rock (mechanical).Weathering of rock (mechanical).
2.2.Deposition of sediments by erosion Deposition of sediments by erosion
(mechanical).(mechanical).
3.3.Decomposition of organic matter in dead Decomposition of organic matter in dead
organisms (chemical).organisms (chemical).

5. SOIL HORIZONS:SOIL HORIZONS:

6. Mature soils are arranged in a series of zones Mature soils are arranged in a series of zones
called SOIL HORIZONS:called SOIL HORIZONS:
““O” HORIZONO” HORIZON = freshly fallen and partially = freshly fallen and partially
decomposed leaves, twigs, animal waste. decomposed leaves, twigs, animal waste.
You can find fungi and other organic You can find fungi and other organic
materials.materials.
““A” HORIZONA” HORIZON = porous mixture of partially = porous mixture of partially
decomposed organic matter (decomposed organic matter (humushumus) and ) and
some inorganic mineral particles. Also some inorganic mineral particles. Also
called TOPSOIL.called TOPSOIL.

7. MORE SOIL HORIZONS:MORE SOIL HORIZONS:
““B” HORIZONB” HORIZON = has less oxygen due to its = has less oxygen due to its
depth below the surface. SUBSOILdepth below the surface. SUBSOIL
““C” HORIZONC” HORIZON = consists of sand, clay, or = consists of sand, clay, or
pebbles and rocks. Very little living or dead pebbles and rocks. Very little living or dead
organic matter. Often yellow or orange. organic matter. Often yellow or orange.
PARENT MATERIALPARENT MATERIAL

8. These top two layers are most fertile, have the highest These top two layers are most fertile, have the highest
concentration of organic matter, and contain large amounts of concentration of organic matter, and contain large amounts of
living organisms.living organisms.
Flatworm
Rove beetle
Ant
Centipede
Mite
Pseudoscorpion
Ground
beetle
Adult
fly
Millipede
Fly
larvae
Sowbug
Mite
Earthworm
Slug
Snail
Roundworms
Protozoa
Bacteria
Organic debris
Beetle
Mite
Fungi
Springtail
Actinomycetes

9. Soil ParticlesSoil Particles
•ClayClay (very fine particles) (very fine particles)
•Silt Silt (fine particles)(fine particles)
•Sand Sand (medium-size particles)(medium-size particles)
•Gravel Gravel (coarse to very coarse particles)(coarse to very coarse particles)

SOIL TEXTURESOIL TEXTURE is determined by the relative is determined by the relative
amounts of the different types and sizes of amounts of the different types and sizes of
mineral particles.mineral particles.

10. 100%clay
Increasing
percentage silt
Increasing
percentage clay
0
20
40
60
80
80
60
40
20
0
100%sand 80 60 40 20 100%silt
Increasing percentage sand
sandy
clay
clay
silty
clay
silty clay
loam
clay
loam
loam silty
loam
silt
sandy clay
loam
sandy
loam
loamy
sandsand
Soil Texture Triangle

11. SOIL POROSITYSOIL POROSITY
•Soil texture helps determine Soil texture helps determine SOIL POROSITYSOIL POROSITY
-the measure of the volume of pores or spaces per volume of soil and the measure of the volume of pores or spaces per volume of soil and
the average space between those spaces.the average space between those spaces.
•INFILTRATIONINFILTRATION is the downward movement of is the downward movement of
water through soils.water through soils.
•As the water seeps down, it dissolves various soil As the water seeps down, it dissolves various soil
components in upper layers and carries them components in upper layers and carries them
down to lower layers in a process called down to lower layers in a process called
LEACHINGLEACHING..

12. SOIL PERMEABILITYSOIL PERMEABILITY is the rate at which is the rate at which
water and air move from upper to lower soil water and air move from upper to lower soil
layers.layers.
Water Water
High permeability Low
permeability

13. Properties of Soils with Different Textures
Texture Nutrient
Capacity
InfiltrationWater-
Holding
Capacity
AerationWorkability
Clay Good Poor Good Poor Poor
Silt Medium Medium Medium Medium Medium
Sand Poor Good Poor Good Good
Loam Medium Medium Medium Medium medium

14. Take a brief pause......

15. Quick ReviewQuick Review
•Where does SOIL come from??Where does SOIL come from??
• From rocksFrom rocks
•Decayed plantsDecayed plants
•Decayed animalsDecayed animals
•AirAir
•WaterWater
•LIFE!!LIFE!!

16. SOIL DEVELOPMENTSOIL DEVELOPMENT
•Soil is not made overnight!!!!Soil is not made overnight!!!!
•Results from many years of Results from many years of weatheringweathering
•ALL the loose weathered material on the surface of the ALL the loose weathered material on the surface of the
Earth is called the Earth is called the REGOLITHREGOLITH --- soil is the top layer that --- soil is the top layer that
supports plant growthsupports plant growth
•Soil layer is 1m to 3m deepSoil layer is 1m to 3m deep
•Soil varies from place to place depending on its Soil varies from place to place depending on its
COMPOSITIONCOMPOSITION and and PARENT ROCKPARENT ROCK

17. WEATHERINGWEATHERING
•The process where big rocks are broken The process where big rocks are broken
down into smaller rocks is referred to as down into smaller rocks is referred to as
WEATHERINGWEATHERING
•There are 2 main types:There are 2 main types:
1.1.MechanicalMechanical
2.2.ChemicalChemical

18. Mechanical WeatheringMechanical Weathering
•Predominates in severe environmentsPredominates in severe environments
•No chemical changesNo chemical changes
•Cracks or abrades rocks (e.g., glaciers)Cracks or abrades rocks (e.g., glaciers)
•Produces coarse textured soilsProduces coarse textured soils
•Creates new surfaces for chemical weatheringCreates new surfaces for chemical weathering

19. Mechanical WeatheringMechanical Weathering
1.1.Ice wedgingIce wedging
2.2.Plant weatheringPlant weathering
3.3.Animal weatheringAnimal weathering
4.4.Temperature changeTemperature change
5.5.Water abrasionWater abrasion
6.6.Wind abrasionWind abrasion

20. Chemical weatheringChemical weathering
•Involves chemical changeInvolves chemical change
–Conversion from primary to secondary mineralConversion from primary to secondary mineral
•Promoted by water and heatPromoted by water and heat
•Depends on parent materialDepends on parent material
•Stimulated by acidityStimulated by acidity
–What are main acids in soils?What are main acids in soils?

21. Chemical weatheringChemical weathering
•Reactions Reactions
–Acid-baseAcid-base
–OxidationOxidation
–ChelationChelation
•Environment for weatheringEnvironment for weathering
•Susceptibility to weatheringSusceptibility to weathering

22. Chemical WeatheringChemical Weathering
1.1.OxidationOxidation
2.2.WaterWater
3.3.CarbonationCarbonation
4.4.Sulfuric acidSulfuric acid
5.5.Plant and fungal acidsPlant and fungal acids
6.6.LeachingLeaching – where water carries minerals deeper into – where water carries minerals deeper into
the ground. the ground.

23. Soil PropertiesSoil Properties
1.1.Particle ShapeParticle Shape – – roundround, , flatflat, or , or angularangular. The shape . The shape
affects the affects the porosityporosity of the soil of the soil
2.2.Particle SizeParticle Size – – clayclay——siltsilt——sandsand
3.3.FertilityFertility – depends on the amount of dissolved – depends on the amount of dissolved
nutrients in the soil. Some come from bacteria, and nutrients in the soil. Some come from bacteria, and
others from bedrockothers from bedrock
4.4.Acid LevelAcid Level – depends on – depends on
5.5.organic matter and organic matter and
6.6.minerals in bedrock. minerals in bedrock.
Affects plant growthAffects plant growth

24. Generic soil profileGeneric soil profile

26. Relationships among soil orders

27. Nitrogen fixing
by lightning
Commercial
inorganic
fertilizer
10-6-4
N-P-K
Organic fertilizers,
animal manure,
green manure, compost
Crop
plant
Dead
organic matter
Application
to land
Nitrogen fixing
by bacteria
Nitrogen fixing
Weathering
of rock
Nutrient removal
with harvest
Decomposition
Supply of
available plant
nutrients in soil
Nutrient loss
by bacterial
processes
such as
conversion
of nitrates to
nitrogen gas
Nutrient loss
from soil erosion
Absorption of nutrients
by roots
Pathway of
plant
nutrients in
soil.

28. Soil ErosionSoil Erosion
Soil erosionSoil erosion is the movement of soil components, is the movement of soil components,
especially surface litter and especially surface litter and topsoil.topsoil.
•The two main agents of erosion are The two main agents of erosion are windwind and and
flowing waterflowing water. .
•Loss of plant coverLoss of plant cover by farming, logging, by farming, logging,
construction, overgrazing by livestock, off-road construction, overgrazing by livestock, off-road
vehicles, deliberate burning of vegetation and vehicles, deliberate burning of vegetation and
other activities leave soil vulnerable to erosion.other activities leave soil vulnerable to erosion.

29. Two major harmful effects of soil erosion:Two major harmful effects of soil erosion:
1.1.Loss of soil fertility and its ability to hold Loss of soil fertility and its ability to hold
waterwater
2.2.Runoff of sediment that pollutes water, kills Runoff of sediment that pollutes water, kills
fish and shellfish, and clog irrigation ditches, fish and shellfish, and clog irrigation ditches,
boat channels, reservoirs, and lakes.boat channels, reservoirs, and lakes.
serious concern
some concern
Stable areas

30. Desertification Desertification is the enlargement of is the enlargement of
deserts through human activities.deserts through human activities.
ConsequencesCauses
Worsening drought
Famine
Economic losses
Lower living
standards
Environmental
refugees
Overgrazing
Deforestation
Surface mining
Erosion
Salinization
Soil compaction

31. SALINATION
1.Irrigation water
contains small
amounts of dissolved
salts.
2.Evaporation and
transpiration leave
salts behind.
3.Salt builds up in soil.
WATERLOGGING
•Precipitation and
irrigation water
percolate
downward.
•Water table
rises.
Both result in stunted
plant growth, lower
crop yields, dead plants
and ruined land.

32. Evaporation
Evaporation
Transpiration
Evaporation
Waterlogging
Less permeable
clay layer

33. Soil ConservationSoil Conservation involves reducing involves reducing
soil erosion and restoring soil fertility.soil erosion and restoring soil fertility.

34. Advantages Disadvantages
Reduces erosion
Saves fuel
Cuts costs
Holds more soil water
Reduces soil compaction
Allows several crops
per season
Does not reduce crop
yields
Can increase herbicide
use for some crops
Leaves stalks that can
harbor crop pests and
fungal diseases and
increase pesticide use
Requires investment
in expensive equipment
Advantages and disadvantages of using
Conservation Tillage.
http://www.ncsu.edu/sustainable/tillage/tillage.html

35. Contour plantingContour planting and and strip cropping:strip cropping: each each
row acts as a small dam to help hold soil row acts as a small dam to help hold soil
and slow water runoff.and slow water runoff.
http://www.peisland.com/agrtour/xslope.html

36. Alley cropping or agroforestry:Alley cropping or agroforestry: several crops are several crops are
planted together in strips or alleys between trees planted together in strips or alleys between trees
and shrubs that can provide fruit or fuel-wood, and shrubs that can provide fruit or fuel-wood,
shade, help retain and slowly release soil moisture, shade, help retain and slowly release soil moisture,
and fodder for livestock.and fodder for livestock.

37. Windbreaks or shelterbeltsWindbreaks or shelterbelts of trees reduce wind of trees reduce wind
erosion, help retain soil, supply wood for fuel, and erosion, help retain soil, supply wood for fuel, and
provide habitats for birds, pest-eating and pollinating provide habitats for birds, pest-eating and pollinating
insects, and other animals.insects, and other animals.

38. TerracingTerracing retains retains
water for crops at water for crops at
each level and each level and
reduces soil reduces soil
erosionerosion
by controlling by controlling
runoff.runoff.

39. Soil RestorationSoil Restoration
Organic fertilizerOrganic fertilizer
Animal manureAnimal manure
Green manureGreen manure
CompostCompost
Crop rotationCrop rotation
Commercial inorganic fertilizerCommercial inorganic fertilizer

40. Dirty Questions
1. Use a systems approach to draw diagrams that show links between
the soil, lithosphere, atmosphere and living organisms.
2. The soil as a living system should be considered with reference to a
generalized soil profile.
3. Transfers of material (including deposition) result in reorganization
of the soil. There are inputs of organic and parent material,
precipitation, infiltration and energy. Outputs include leaching,
uptake by plants and mass movement. Transformations include
decomposition, weathering and nutrient cycling. Make a flow
diagram that represents this. LABEL ALL FLOWS AND
STORAGES.

41. More Dirty Questions
4. Compare and contrast the structure and properties of sand, clay and
loam soils, including their effect on primary productivity. Consider
mineral content, drainage, water-holding capacity, air spaces, biota
and potential to hold organic matter, and link these to primary
productivity. How do all these factors influence NPP? You may
want to organize this into a table.
5. Human activities such as overgrazing, deforestation, unsustainable
agriculture and irrigation cause processes of degradation. These
include soil erosion, toxification and salinization. Desertification
(enlargement of deserts through human activities) can be
associated with this degradation. Make a table of soil degradation
causes, consequences, and possible solutions/clean up that can be
performed.

42. More Dirty Questions
6. Evaluate the following soil conservation measures:
•soil conditioners (for example, use of lime and organic materials)
•wind reduction techniques (wind breaks, shelter belts, strip
cultivation)
•cultivation techniques (terracing, contour plowing)
•efforts to stop plowing of marginal lands.
7. a) What’s the story behind the green revolution?
b) What are some limitations to expanding it?

43. Check This Site Out!!!
•http://www.globalchange.umich.edu/globalchange2/current/lectures/land_deg/land_deg.html