201 عتر Lab اسبوع 1

تطور التربة تربة & صخور تربة= تعرية الجزء من الصخور الذى حدث لها تعرية Bedrock تربة= تعرية الجزء من الصخور الذى حدث لها تعرية الجزء المفكك الناتج من الصخور الآصلية bedrock

قطاع النربة يحتوى على طبفات A تربة soil E Development B نطور القطاع Bedrock C Bedrock

انتقال المواد/Development تطور التربة

Soil Profile قطاع تربة قطاع افاق تربة Soil Horizons

Soil Profile قطاع تربة Soil Horizons افاق التربة A Bw E BE Btb C

Master Horizons O horizon-Organic A horizon-Mineral & Organic E horizon-Eluviation (Loss) B horizon-Illuviation (Gain) C horizon- little Alteration from Parent Material R horizon- Bedrock

الأفق الرئيسى Master Horizons O horizons: Layers dominated by organic material. Some are saturated with water for long periods or were once saturated but are now artificially drained; others have never been saturated.

A horizons: Mineral horizons th Master Horizons الأفق الرئيسى A horizons: Mineral horizons th at formed at the surface or below an O horizon, that exhibit obliteration of all or much of the original rock structure -an accumulation of humified organic matter intimately mixed with the mineral fraction and not dominated by properties characteristic of E or B horizons -properties resulting from cultivation, pasturing, or similar kinds of disturbance.

Master Horizonsلأفق الرئيسى E horizons: Mineral horizons in which the main feature is loss (eluviation) of silicate clay, organic matter, iron, aluminum, or some combination of these, leaving a concentration of sand and silt particles.

Master Horizons B horizons: Horizons that formed below an A, E, or O horizon and are dominated by obliteration of all or much of the original rock structure (1) (illuvial) concentration of silicate clay, iron, aluminum, humus, carbonates, gypsum, or silica (2)coatings of sesquioxides that make the horizon lower in value, higher in chroma, or redder in hue than overlying and underlying horizons (3)alteration that forms granular, blocky, or prismatic structure

R horizons or layers: Hard Bedrock Master Horizons C horizons or layers: Horizons or layers, excluding hard bedrock, that are little affected by pedogenic processes and lack properties of O, A, E, or B horizons. Most are mineral layers. R horizons or layers: Hard Bedrock

12 Soil Orders I AM A SUAVE HOG or I GAVE US OMAHA Compliments of Prof. M.J. LaForce

I AM A SUAVE HOG Inceptisol- Soils with weakly developed subsurface horizons Alfisol- Soils with a subsurface zone of silicate clay accumulation and >35% base saturation Mollisol- Grassland soils with high base status Andisol- Soils formed in volcanic ash Spodosol-Acid soils with a subsurface accumulation of metal-humus complexes Ultisol- Subsurface zone of silicate clay accumulation and <35% base saturation

I AM A SUAVE HOG Aridosol- Soils in Arid environments with moderate to strong development Vertisol- Clayey soils with high shrink/swell capacity Entisol- Soils with little or no morphological development Histosol- Organic soils Oxisol- Intensely weathered soils of tropical and subtropical environments Gelisol- Soils with permafrost within 2 m of the surface

Twelve Soil Orders Entisol (recent) Inceptisol (L.-inceptum, begging) Mollisol (L.-mollis, soft) Alfisol (pedalfter) Ultisol (L.-ultimus, last) Oxisol (Fr.-oxide) Increasing Soil Depth Maturation (loss of Si)

Twelve Soil Orders Aridisol (L.-aridus, dry) Spodosol (Gr.-spodos, wood ashes Gelisol (Gr.-gelid, very cold) Vertisol (L.-verto, turn) Andisol (L.-aridus, dry) Histosol (Gr.-histos, tissue) Climate Specific Material Specific

Ideal Weathering Series Rock Ideal Weathering Series Entisol Inceptisol Aridisol (dry climate) Mollisol Vertisol (clay mineralogy) Alfisol Spodosol (cool and wet) Ultisol Oxisol

Entisol -(ent) Shallow to bedrock. Limited use and management. The most common uses are rangeland

Inceptisol- (ept) Steep slopes and cool climate slow soil development. Inceptisols are widely distributed and occur under a wide range of environmental settings.

Mollisol -(oll) Soil formation under native grassland vegetation

Alfisol (-alf) Alfisols are mostly found in temperate humid and subhumid regions of the world. Developmentally just past Mollisols

Histosol -(ist) Organic matter is highly decomposed and has few remaining plant fibers.

Vertisol -(ert) Abundant, ‘active’ clay particles are dominant

Aridosol -(id) Form in dry climates White crust at the soil surface is a mixture of various soluble salts (definitely not snow!).

Gelisol -(el) Permafrost persists below 38 cm year-around. The lack of significant microbial activity in these soils leads to an accumulation of organic matter.

Gelisols are in very cold climates and typically contain permafrost

Web Sites of Interest NRCS http://www.statlab.iastate.edu/soils/photogal/orders/soiord.htm Universities http://soils.ag.uidaho.edu/soilorders/index.htm http://soils1.cses.vt.edu/MJE/CSES3124/Laboratories.html Keys to Soil Taxonomy http://www.statlab.iastate.edu/soils/keytax/