3.4 the soil system.ppt
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3.4 The Soil System
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Transcript of 3.4 the soil system.ppt
3.4 The Soil System
Sub-subtopics3.4.1 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.
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 -
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
3.4.1 Pedosphere = SoilAtmospheric 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
3.4.1 Nitrogen (N2 & NOx) Cycle
3.4.1 Rock Cycle
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, NRCS1. Decomposers2. Mutualists - nitrogen-fixers3. Pathogens4. Chemoautotrophs (or lithotrophs)
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
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
3.4.2 Soil Formation
●North Carolina State University's animation
3.4.2 Soil Profile●What does it look like?
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.
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?
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
3.4.3 Soil Degradation●Universal soil loss equation (USLE):
A = RKLSCP
A = predicted soil lossR = climatic erosivityK = soil erodibilityL = slope lengthS = slope gradientC = cover & managementP = erosion controls
- Davis & Nagle, pg128
● RUSLE for Michigan State, USA
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
3.4.3 Soil Degradation
3.4.3 Human Activity●Deforestation
○ root-bound soil○ slopes
●Cultivation○ bare ground○ irrigation
●Grazing - trampling●Roads●Mining●Other impacts increasing previous slide
3.4.3 Human Activity
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
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
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.
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
