3.4 the soil system.ppt

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3.4 the soil system.ppt

  1. 1. 3.4 The Soil System
  2. 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. 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. 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. 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. 6. 3.4.1 Hydrologic (H2O) Cycle
  7. 7. 3.4.1 Nitrogen (N2 & NOx) Cycle
  8. 8. 3.4.1 The Fast Carbon (COx) Cycle
  9. 9. 3.4.1 Rock Cycle
  10. 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. 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
  12. 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. 13. 3.4.2 Soil Formation North Carolina State University's animation ●
  14. 14. 3.4.2 Soil Profile What does it look like? ●
  15. 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. 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. 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. 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. 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. 20. 3.4.3 Soil Degradation
  21. 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. 22. 3.4.3 Human Activity
  23. 23. 3.4.3 Soil Conservation Mechanical ● ○ ○ ○ contour ploughing bunding - raised levees terracing - steppes Cropping & soil husbandry ● ○ ○ ○ ○ ○ maintain crop cover (multi-cropping yearround) keep roots/stubble plant grass crop wind ■ shelterbelts ■ hedgegrows steepest slopes should remain forested
  24. 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. 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. 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

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