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Soils 2b03 Up to midterm.docx

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Earth Sciences
Sherry Smith

September 5, 2013 Soils and the Environment Earth Sci 2B03  James E Smith  TA David Camacho  lab assignments 25%  midterm 35% (thurs oct 31)  exam 40% Chapter 1 review  soil science is combination of geosphere, biosphere, hydrosphere and atmosphere  cryosoils- permafrost  systems are NOT in equilibrium. dynamic eq. because of climate change September 9, 2013  look up soil profiles online  0 horizon: biological diversity and plant growth  A- horizon: is the leaching profile, salts leach into soil except organic matter  18%organic matter  source of topsoil, nutrients for plants and crops  B- horizon: is net gain horizon, gains Fe, Mg, organic matter, clays, looks like parent material being weathered  c horizon: broken down rock, looks like unchanged permanent material; till left by glaciers and it does change.  soils are only 10,000 years old therefore very young soils in comparison to rainforests in brazil  A/B is the solemn, changes  A/B in urban environment are non-existent (when building the scrap till bedrock, then fill in with till  soil is in peds (study of soil = pedology)  when diagnosing soils, look at B-horizon for structure and material  soils in Northern Ontario are slightly acidic and causes acidic soils  soils in southern Ontario have carbonate buffers so ph is higher and has higher Fe, and high clay mobility and nutrients  in hydrology cycle: unsaturated soil hold water; drains out and stores water in comparison to the saturated zone underneath  spaces in soil: mineral:45%, air 20-30%, water 20-30%, organic 5%  when water enters soil it takes up air space  metabolic activity of plant roots, microbes and soil fauna later the composition if soil air  relative humidity approaches 100% unless soil is dry  carbon dioxide in soil air is often several hundred times more concentrated than the 0.03% in atmosphere  the amount and composition of air in soil is determined to a large degree by the water content of soil  organic matter: soil of organisms and organic compounds organic matter consists of living organisms (soil biomass) remains produced by current and past metabolic compounds  decomp. and nutrient cycling are important in biomass  OM influences physical, chemical and bio properties  water: water is major transport agent for fluxes within and between terrestrial ecosystems  it is a prerequisite for all active life, and participates in geochemical cycles by weathering geological substrates, by leaching materials to groundwater by moving ions and particles through soil profile  a dynamic equilibrium is maintained despite the fact that different types of substrates are exchanged and stored  halofites (halo=salt, fites=love) plants form at top of salty soils 2B03 Lecture 3: Chapter 2 Formation of Soils from Parent Materials Figure 2.10: moss can wear away at rocks, creating soil,  ice can carry almost anything, very vicious, hold up materials without breaking,  wind can't pick up a lot; can do wind and sometimes sand  different parent materials make different starting materials; beach sand is different than clay sands figure 2.23: Canada has a lot of peat lands (organic soils); fills a pond and organic matter dominates and fills the pond  Figure 2.30 topography is important with drumlins and moraines; top of hill = bt= luvasole, hill slope=bw= water driven, bottom of hill = a (weak formed hill), bt, btg glade horizons  overall same bedrock material, but topography changes  higher elevations have finer materials washed away, sand > clay  relationship between landscapes and soilscapes  A horizon: rich in nutrients, has a net lost; they are leached (not heavily) therefore more is coming out than being deposited  organic residues 100g; co2 = 60-80%, soil organisms 3-8%, non- humic compounds 3-8%, complex humic compounds 10-30%  organic carbon is the reason earth works  Ae is in palezoic soils are so leached and alluviated that only coarse sands are left  Figure 2.32 surface losses (rake leaves, translocation from A - B, transformations: chemical reactions within the soils, or can leach out bottom as a loss, or additions from the bottom of the soils eg salts (sodium), metals, and roots pulling water up, gas exchange,   ck-horizon sometimes gain extra carbonates; buffered system because it neutralizes acids  when plants start to grow on it; organic matter accumulates over c therefore it's a over c (b has not formed due to not translocation) REGOSOL  bm horizon forms (light orange) accumulated a bit of stuff, can be distinguished from ck BRUNISOL  bm becomes thick enough, forms a Ae and a Bt (MORE THAN 3 CM)(more definable b layer due to accumulation of clay) and ck LUVISOL Soil orders: one is organic soil order, the other one is chermozemic Ah (it is the type found in prairie grass lands) as you move North the chermozemic layer the natural as horizon changes because it gets wetter; deeper horizon, not as stressed, grasses more sucessful, gets wetter = more trees therefore it becomes a luvisol igneous rocks give acid waste; can have a negative ph  under acidic conditions Fe is mobile, causes mobility of metals moved into B from A (orange horizons are Bf horizons which have deceduous forests and is a PODZOL  Gleyed Horizion (water logged on an occasional basis; doesn't drain well) so will not be bright orange (greyish) because it is sooo waterlogged  with old root channels, orange halos form because o2 can react with iron creating blotches  as you move norther: less marine deposits, more soils moved by glaciers exposing Precambrian sheild, loosing horizons of palezoic rocks and the regolith (loose material)  as move north Ck is lost because less carbon is present  Summary of soil formation A horizon: a mineral horizon formed at or near the surface in the zone of removal of materials in the solution and suspension, or maximum in situ accumulation of organic carbon, or both B horizon: a mineral horizon characterized by one or more of the following: 1. An enrichment of silicate clay, iron, al or humus 2. a prismatic or columnar structure that exhibits pronounced coatings or staining associated with significant amounts of exchangeable sodium 3. An alteration by hydrolysis, reduction, or oxidation to give a change in colour or structure from the horizons above or below, or both C horizon: a mineral horizon comparatively unaffected by the Pedogenic processes operative in A and B, except Gleying and the accumulation of carbonates and more soluble salts  driving variables that control formation of soil or a soil or soil property in undisturbed ecosystems  climate: water source, temp  vegetation: grass horizons (chermozemic) compared to forests  parent material; is it silty or clay or sand to determine how water moves  topography of relief: when you have parent material is it helping its goal(ie sand cant drain at the bottom
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