What is Soil Each soil occupies its respective landscape position because of the environmental action of climate organisms and relief acting upon the geologic materials through time What is soil Soil is a uniquely defined segment of the landscape designated by a name and delineated by map boundaries into soil map units usually drawn on aerial photographs Definitions of Soil What is soil Pedological Soil is a natural body on the earth s surface composed of mineral and organic matter formed by the interaction of Climate Organisms and Topography acting upon Parent Material over long periods of Time More than 21 000 individual soils have been identified defined mapped and interpreted in the United States Five factors of soil formation CORPT Physical Properties of Soils Texture Structure Density Porosity Color Consistence Moisture Temperature Aeration Organic Matter 1 Soil Texture Coarse Fragments 2mm Gravel cobbles stones boulders Sand 2 0 05mm Silt 50 2 m Clay 2 m Texture Class relative of soil separates Soil Color Dark organic matter Red iron Brown well drained Grey gley poorly drained Mottled redoximorphic concentrations depletions restricted aeration poor drainage 2 Munsell Soil Color Charts Hue Red in front of Book Brown in Middle Yellow in the Back Value Chroma 10YR 4 4 Dark Yellowish Brown SOIL STRUCTURE Soil structure refers to how the individual sand silt and clay particles are arranged into stable aggregates can be affected by management Structural units are know as aggregates or peds Soil structure results when soil particles are pushed together by freezing thawing important in temperate climates wetting drying important in humid climates tillage operations mixing organic material into soil SOIL STRUCTURE Stability of peds depends on cementing agents that bind the sand silt and clay particles together soil organic matter humus chemical bonds sticky polysaccharides secondary carbonate and iron oxides chemical bonds water films tension clay flocculation cationic bridges CLASSIFICATION OF SOIL STRUCTURE SOIL STRUCTURE 1 Structureless Massive or single grained C horizon or Sandy soils Clods vs Peds 2 Structured clods are produced by improper tillage Granular platy blocky prismatic and columnar A E Bt and Bn horizons Structure provides qualitative information about the physical condition of the soil Quantitative information can be obtained from bulk and particle densities wet soils heavy equipment peds are produced by soil forming processes more gentle and loving happier soils 3 Soil Structure and Permeability 4 Soil Consistence East Peoria Sediment Demonstration Site Response of soil to applied force at various moisture content Moist loose friable firm very firm brittle Wet plastic non plastic sticky Soil Horizons can be Terminology Zones of organic matter accumulation Pedon Smallest unit of a soil about 1 m hexagon 2 m deep Profile Vertical exposure of soil showing horizons Horizon Nearly horizontal layer in soil formed by pedogenic processes Zones of loss leaching eluviation of clay organic matter and various metal oxides Zones of gain illuviation of clay OM and metal oxides that has moved downward from surface horizons Zones that are altered in place Pedon 1m Soil Profile 2m Soil Morphology Soil Chemical Biological and Physical Properties A E BE Vary with Factors of Soil Formation Bt1 Horizons Diagnostic Horizons Bt2 BC 5 Soil Horizon Pedogenic layer in soil roughly parallel to surface Properties result from factors of soil formation Nomenclature Master O A E B C R Subordinate distinction p t x g h d f jj k a e i w Lithology 2 3 4 Master Horizons O A E B Master Horizons con t C R Parent material material which is unaltered can be altered to form A and B horizons Consolidated bedrock Subscripts to Master Horizons a b c d e f Subscripts to Master Horizons con t g h i k l strong gleying illuvial accumulation of organic matter slightly decomposed organic matter accumulation of organic matter strong cementation Organic horizon Mineral horizon formed at the surface with O M Leached or bleached horizon eluviated Horizon with accumulation of clay iron cations humus coatings alterations structure highly decomposed organic matter buried soil horizon concretions or nodules dense high bulk density horizon Intermediately decomposed organic matter Frozen soil Subscripts to Master Horizons con t n o accumulation of sodium residual accumulation of sequioxides p plowing or other disturbance q Accumulation of silica r weathered or soft rock s illuvial accumulation of sesquioxides Al 6 Subscripts to Master Horizons con t t v w x y z Learn accumulation of clay plinthite ironstone color or structural B fragipan characteristics brittle accumulation of gypsum accumulation of salts Soil Horizons O A organic surface mineral topsoil E eluvial leached Bt illuvial accumulation of weathering products clay BC transitional to C horizon C slightly altered parent material R bedrock Endoaquoll Landscape Note dark surface level topography and sump pump Transitional horizons between master horizons AB or EB AC BC CB Transitional horizon to B but more like an A or E than a B horizon Transition horizon to C but more like an A than a C Transition horizon to C but more like a B horizon More like C horizon than B Mollisol Typic Endoaquoll Horizon Parent Material Loess Location Western Illinois Native vegetation Prairie Age 10 000 years Ap Note mollic epipedon gleyed subsoil krotovina BA Bg1 Bg2 BCg Alfisol Typic Hapludalf A Parent Material Loess Location Western Illinois Native vegetation Forest Age 10 000 years E BE Note relatively dark surface light colored E horizon bright colored B horizon good structure Bt 2 Bt 1 BC 7 Alfisol Typic Fragiudalf Parent Material loess till Location Ap BE Bt Gleyed Prism Face in Typic Fragiudalf Evidence of Preferential Water Flow Bt E Southern Illinois Native vegetation Forest Age 150 000 years 2Btx1 2Btx2 Note abrupt lower Ap boundary 2Bt light color at top of Bx gray prism faces in Bx 2BC complex horizonation Aridisol Typic Salorthid Parent Material Alluvium Location Nevada Native vegetation halophytes Age 10 000 Horizon Anthropogenic Factor of Soil Formation Coal Mining Az Cz1 Cz2 2Cz3 3Cz4 Note limited horizonation salts on surface saline groundwater Entisol Entisol Fine loamy mixed active calcareous mesic Alfic Udarent Loamy skeletal mixed acid mesic Typic Udorthent Parent Material coal mine spoil Parent Material coal mine spoil Location Southern Illinois Age 40 years Note