Texture Flashcards
Surface area per unit volume: sand silt Clay.
1 g sand equals .1 m², 1 g silt equals 1 m², 1 g clay equals 10 to 1000 m².
> 2 inch ribbon
1 to 2 inch ribbon
Clay, Sandy Clay, silty clay.
Sandy Clay loam, clay loam, silty clay loam.
Sandy loam, loam, silt loam.
Not included silt, loamy sand, sand.
Structure.
Binding agents our route exit dates, organic matter, clays. Organic compounds include polysaccharides, proteins, bacterial clues. Mineral sources include oxides, carbonates, silicates (clays).
Characterization of structure
Type: granular, platy, blocky, prismatic.
Size: fine, medium, coarse.
Grade: strong, moderate, weak.
Hi organic matter makes granular structure, high clay content make stronger structure, bigger blocks.
Soil class structures, shape of structure.
There is fine, fine, medium, course, very coarse, extremely coarse.
Consistence, or rupture resistance.
Friability by hand. Response to pressure and adhesion. Stickiness, plasticity, rupture resistance. Non-sticky to very sticky, nonplastic to Gary plastic. Loose two very rigid.
Root and pore size and quantity.
Very fine to very coarse. Root or pore quantity classes: few, common, many.
Mineral versus organic soil materials.
Either organic or mineral. Diagnostic for horizons. Middle soil materials are saturated less than 30 cumulative days with water, less than 20% SOC. Organic soils material has greater than 20% SOC.
Mineral soil materials
Albic – Clay, iron, SOC removed. Andic-short range order minerals. Densic-route restricting on altered by pedogenesis. Durinodes – nodules cemented by silicon oxide. Gelic – churning by freezing and thawing. Secondary carbonates. Paralithic– partially weathered bed rocks, roots enter. Permafrost – below 0°C for more than two years. Spodic at BH S-illuvial om. Sulfidic-oxidizable Z.
Organic soil materials
Fibers-plant tissue 40%. Hemic-partially decomposed organic soil material less than 40% fibers. Humilluvic– accumulation of colloidal organic material. Limnic material – materials deposited underwater by algae or diatoms. Sapric – decomposed soilmaterial less then 1/6 fiber
Soil texture affects:
Water and nutrient retention, infiltration, drainage, aeration, SOC, PH buffering, porosity. Course textured soils have larger pores, find textured soils have greater total poor space.
Two broad groups of mineralogical composition
1- Sand and silt size (usually 1 mineral) particles from parent rock
2-Clay size silicate minerals, oxides and amorphous fine grained compounds from parent rock or formed
Clay types
Aluminosilicate clays, kaolinites, smectites, micas and vermiculites; also Fe and Al oxides in size fraction. Best determined by thermal analysis, xrd, specific surface area measurement, sem
Clay mineral quantification
Very difficult to quantify. Properties are more important than species.
