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6. Soil Texture 6. SOIL TEXTURE 6.0 Definition of soil texture Texture indicates the relative content of particles of various sizes, such as sand, silt and clay in the soil. (...) If the soil retains the shape of your hand , there is probably enough clay in it to build a fish pond;   If the soil does not retain the shape of your hand , there is too much sand in it. 6.2 How to find the approximate proportions of sand, silt and clay This is a simple test which will give you a general idea of the proportions of sand, silt and clay present in the soil. (...) The shaking test: how to differentiate clay from silt Both silt and clay soils have a very smooth texture.
Language:English
Score: 2112911.1 - https://www.fao.org/fishery/do...ng/General/x6706e/x6706e06.htm
Data Source: un
6. Soil Texture 6. SOIL TEXTURE 6.0 Definition of soil texture Texture indicates the relative content of particles of various sizes, such as sand, silt and clay in the soil. (...) If the soil retains the shape of your hand , there is probably enough clay in it to build a fish pond;   If the soil does not retain the shape of your hand , there is too much sand in it. 6.2 How to find the approximate proportions of sand, silt and clay This is a simple test which will give you a general idea of the proportions of sand, silt and clay present in the soil. (...) The shaking test: how to differentiate clay from silt Both silt and clay soils have a very smooth texture.
Language:English
Score: 2112911.1 - https://www.fao.org/fishery/st...ng/General/x6706e/x6706e06.htm
Data Source: un
They are: Cobbles : particles with a diameter larger than 75 mm; Gravel : particle sizes from 4.75 to 75 mm; Sand : particle sizes from 0.075 to 4.75 mm; Fines : particles smaller than 0.075 mm (silt and clay). The particle sizes used in the Unified Soil Classification are somewhat different from the other classification systems shown earlier in Table 2 . (...) TABLE 20A The Unified Soil Classification (definition of major coarse-grained soil groups) TABLE 20B The Unified Soil Classification (definition of major fine-grained soil groups) TABLE 21 Typical names and group symbols of the Unified Soil Classification System USC group symbol Typical names for soils Coarse-grained soils GW Well-graded gravel, gravel and sand mixtures, little or no fines GP Poorly graded gravel, gravel and sand mixtures, little or no fines GM Silty gravel; gravel; sand and silt mixtures GC Clayey gravel; gravel; sand and silt mixtures SW Well-graded sands, gravelly sands, little or no fines SP Poorly graded sands, gravelly sands, little or no fines SM Silty sands, sand and silt mixtures SC Clayey sands, sand and clay mixtures Fine-grained soils ML Inorganic silts and very fine sands, rock flour, silty or clayey fine sands, or clayey silts with slight plasticity CL Inorganic clays of low to medium plasticity, gravelly clays, sandy clays, silty clays, lean clays OL Organic silts and organic silty clays of low plasticity. MH Inorganic silts, micaceous or diatomaceous fine sandy or silty soils, elastic silts CH Inorganic clays of high plasticity, fat clays OH Organic clays of medium to high plasticity, organic silts Highly organic soils Pt Peat and other highly organic soils TABLE 22 An example of the field classification of the USC fine-grained soils USC soil group Plasticity (wet soil) Dry consistency Shaking test reaction Plastic limit, toughness of thread Odour ML 0 0 - 1 Rapid to slow None Uncharacterized, often nil CL 2 2 - 4 None to very slow Medium Slight earth smell OL 1 1 - 3 Slow Slight Decomposed organic matter MH 1 1 - 3 Slow to none Slight to medium Uncharacterized, often nil CH 3 3 - 5 None High Strong earth smell OH 2-3 2 - 4 None to very slow Slight to medium Decomposed organic matter TABLE 23 An example of the field classification of the USC coarse-grained soils Soil group Total sample, except cobbles over 12-cm Part of the sample: particles less than 3-mm diameter only GW Relatively few fines Clean material; not enough clay to agglomerate the sand particles GP One or several sizes of coarse particles dominant Clean material; not enough clay to agglomerate the sand particles GM Dirty material; good range of sizes for coarse particles only; many fines Plasticity nil or very small GC Dirty material; good range of sizes for coarse particles only; many fines Plasticity moderate to high SW All sizes of coarse particles well represented; relatively few fines Clean material; not enough clay to agglomerate the sand particles; plasticity nil SP One or several sizes of coarse particles dominant Clean material; not enough clay to agglomerate the sand particles; plasticity nil SM Dirty material; good range of sizes for coarse particles only; many fines Plasticity nil or very small SC Dirty material; good range of sizes for coarse particles only; many fines Plasticity moderate to high TABLE 24 Soil properties for engineering use corresponding to USDA textural classes and the USC system 1 USDA textural class USC group Soil properties 2 Fine sand (0.25-0.1 mm) SP Fines less than 10 percent SP-SM Fines 5-10 percent SM Fines more than 10 percent Very fine sand (0.1-0.05 mm) SM Low plasticity ML Little or no plasticity Coarse sand (1-0.5 mm) SP or GW Fines less than 5 percent SP-SM Fines 5-12 percent SM Fines more than 12 percent Loamy sand SM Non- to slightly plastic Sandy loam SM Slightly plastic SC Plastic Loam, silty loam ML Slightly plastic CL Plastic Silt ML Slightly plastic Clay loam, silty clay loam CL Liquid limit less than 50; plastic ML-CL Liquid limit less than 50; slightly plastic CH Liquid limit more than 50; high shrink-swell clays MH Liquid limit more than 50; mica, iron oxide, kaolinite clays Sandy clay loam SC Plastic; fines less than 50 percent CL Plastic; fines more than 50 percent Clay, silty clay CH LL > 50; high shrink-swell clays (for example, montmorillonite clays) MH LL > 50; mica, iron oxide, low shrink-swell clays (for example, kaolinite clays) CL Liquid limit less than 50; generally less than 45 percent clay 1 USDA textural classes as defined in Table 4. 2 Fines: silt + clay particles smaller than 0.075 mm; degree of plasticity as in Chapter 8 .
Language:English
Score: 2111515.6 - https://www.fao.org/fishery/do...ng/General/x6706e/x6706e11.htm
Data Source: un
They are: Cobbles : particles with a diameter larger than 75 mm; Gravel : particle sizes from 4.75 to 75 mm; Sand : particle sizes from 0.075 to 4.75 mm; Fines : particles smaller than 0.075 mm (silt and clay). The particle sizes used in the Unified Soil Classification are somewhat different from the other classification systems shown earlier in Table 2 . (...) TABLE 20A The Unified Soil Classification (definition of major coarse-grained soil groups) TABLE 20B The Unified Soil Classification (definition of major fine-grained soil groups) TABLE 21 Typical names and group symbols of the Unified Soil Classification System USC group symbol Typical names for soils Coarse-grained soils GW Well-graded gravel, gravel and sand mixtures, little or no fines GP Poorly graded gravel, gravel and sand mixtures, little or no fines GM Silty gravel; gravel; sand and silt mixtures GC Clayey gravel; gravel; sand and silt mixtures SW Well-graded sands, gravelly sands, little or no fines SP Poorly graded sands, gravelly sands, little or no fines SM Silty sands, sand and silt mixtures SC Clayey sands, sand and clay mixtures Fine-grained soils ML Inorganic silts and very fine sands, rock flour, silty or clayey fine sands, or clayey silts with slight plasticity CL Inorganic clays of low to medium plasticity, gravelly clays, sandy clays, silty clays, lean clays OL Organic silts and organic silty clays of low plasticity. MH Inorganic silts, micaceous or diatomaceous fine sandy or silty soils, elastic silts CH Inorganic clays of high plasticity, fat clays OH Organic clays of medium to high plasticity, organic silts Highly organic soils Pt Peat and other highly organic soils TABLE 22 An example of the field classification of the USC fine-grained soils USC soil group Plasticity (wet soil) Dry consistency Shaking test reaction Plastic limit, toughness of thread Odour ML 0 0 - 1 Rapid to slow None Uncharacterized, often nil CL 2 2 - 4 None to very slow Medium Slight earth smell OL 1 1 - 3 Slow Slight Decomposed organic matter MH 1 1 - 3 Slow to none Slight to medium Uncharacterized, often nil CH 3 3 - 5 None High Strong earth smell OH 2-3 2 - 4 None to very slow Slight to medium Decomposed organic matter TABLE 23 An example of the field classification of the USC coarse-grained soils Soil group Total sample, except cobbles over 12-cm Part of the sample: particles less than 3-mm diameter only GW Relatively few fines Clean material; not enough clay to agglomerate the sand particles GP One or several sizes of coarse particles dominant Clean material; not enough clay to agglomerate the sand particles GM Dirty material; good range of sizes for coarse particles only; many fines Plasticity nil or very small GC Dirty material; good range of sizes for coarse particles only; many fines Plasticity moderate to high SW All sizes of coarse particles well represented; relatively few fines Clean material; not enough clay to agglomerate the sand particles; plasticity nil SP One or several sizes of coarse particles dominant Clean material; not enough clay to agglomerate the sand particles; plasticity nil SM Dirty material; good range of sizes for coarse particles only; many fines Plasticity nil or very small SC Dirty material; good range of sizes for coarse particles only; many fines Plasticity moderate to high TABLE 24 Soil properties for engineering use corresponding to USDA textural classes and the USC system 1 USDA textural class USC group Soil properties 2 Fine sand (0.25-0.1 mm) SP Fines less than 10 percent SP-SM Fines 5-10 percent SM Fines more than 10 percent Very fine sand (0.1-0.05 mm) SM Low plasticity ML Little or no plasticity Coarse sand (1-0.5 mm) SP or GW Fines less than 5 percent SP-SM Fines 5-12 percent SM Fines more than 12 percent Loamy sand SM Non- to slightly plastic Sandy loam SM Slightly plastic SC Plastic Loam, silty loam ML Slightly plastic CL Plastic Silt ML Slightly plastic Clay loam, silty clay loam CL Liquid limit less than 50; plastic ML-CL Liquid limit less than 50; slightly plastic CH Liquid limit more than 50; high shrink-swell clays MH Liquid limit more than 50; mica, iron oxide, kaolinite clays Sandy clay loam SC Plastic; fines less than 50 percent CL Plastic; fines more than 50 percent Clay, silty clay CH LL > 50; high shrink-swell clays (for example, montmorillonite clays) MH LL > 50; mica, iron oxide, low shrink-swell clays (for example, kaolinite clays) CL Liquid limit less than 50; generally less than 45 percent clay 1 USDA textural classes as defined in Table 4. 2 Fines: silt + clay particles smaller than 0.075 mm; degree of plasticity as in Chapter 8 .
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Score: 2111515.6 - https://www.fao.org/fishery/st...ng/General/x6706e/x6706e11.htm
Data Source: un
Optimum moisture content for various types of soils are as follows: Soil Optimum moisture content for compaction (range in %) Clayey sands, sand-clay mix 11 - 10 Sand-silt-clay mix with plastic, silt + clay fraction 15 - 11 Inorganic silt, clayey silt 24 - 12 Inorganic clay 24 - 12 Organic silt 33 - 21 Inorganic clay, highly plastic 36 - 19 Organic clay 45 - 21 Note : the optimum moisture content is usually 2-3 percent less than the plastic limit of the soil. 10.3 Compressibility Compressibility is the degree to which a soil mass decreases in volume when supporting a load. (...) The volume change of the soil mass is influenced by the amount of moisture change as well as by the amount and kind of clay present in the soil. (...) The highest resistance to sliding occurs in soils that are composed of clean gravel with less than 5 percent silt + clay.
Language:English
Score: 2098460.4 - https://www.fao.org/fishery/do...ng/General/x6706e/x6706e10.htm
Data Source: un
Optimum moisture content for various types of soils are as follows: Soil Optimum moisture content for compaction (range in %) Clayey sands, sand-clay mix 11 - 10 Sand-silt-clay mix with plastic, silt + clay fraction 15 - 11 Inorganic silt, clayey silt 24 - 12 Inorganic clay 24 - 12 Organic silt 33 - 21 Inorganic clay, highly plastic 36 - 19 Organic clay 45 - 21 Note : the optimum moisture content is usually 2-3 percent less than the plastic limit of the soil. 10.3 Compressibility Compressibility is the degree to which a soil mass decreases in volume when supporting a load. (...) The volume change of the soil mass is influenced by the amount of moisture change as well as by the amount and kind of clay present in the soil. (...) The highest resistance to sliding occurs in soils that are composed of clean gravel with less than 5 percent silt + clay.
Language:English
Score: 2098460.4 - https://www.fao.org/fishery/st...ng/General/x6706e/x6706e10.htm
Data Source: un
Both the liquid and plastic limits depend upon the amount and type of clay present in the soil: A soil with a high clay content usually has high LL and PL; Colloidal clays have higher LL and PL than non-colloidal clays; Sand, gravel and peat have no plasticity, their PL= 0; Silts have plasticity only occasionally, their PL being equal to or slightly greater than 0. (...) Examples Plasticity of various silt/clay soils Category Soil PI (percentage) Degree of plasticity I Sand or silt traces of clay little clay 0-1 Non-plastic 1-5 Slight plasticity 5-10 Low plasticity II Clay loam 10-20 Medium plasticity III Silty clay Clay 20-35 High plasticity >35 Very high plasticity Some critical values of the plasticity index for aquaculture To construct a pond dike without a clay core*, the plasticity index of the soil material should have a value between 8 and 20 percent. (...) Comments: Predominantly silt with a good clay percentage; Textural class from silty clay loam to silt and silty clay; The Atterberg Limits show that the soil is fairly plastic and suitable for embankment construction (good stability and low seepage losses).
Language:English
Score: 2095876.2 - https://www.fao.org/fishery/do...ng/General/x6706e/x6706e08.htm
Data Source: un
Both the liquid and plastic limits depend upon the amount and type of clay present in the soil: A soil with a high clay content usually has high LL and PL; Colloidal clays have higher LL and PL than non-colloidal clays; Sand, gravel and peat have no plasticity, their PL= 0; Silts have plasticity only occasionally, their PL being equal to or slightly greater than 0. (...) Examples Plasticity of various silt/clay soils Category Soil PI (percentage) Degree of plasticity I Sand or silt traces of clay little clay 0-1 Non-plastic 1-5 Slight plasticity 5-10 Low plasticity II Clay loam 10-20 Medium plasticity III Silty clay Clay 20-35 High plasticity >35 Very high plasticity Some critical values of the plasticity index for aquaculture To construct a pond dike without a clay core*, the plasticity index of the soil material should have a value between 8 and 20 percent. (...) Comments: Predominantly silt with a good clay percentage; Textural class from silty clay loam to silt and silty clay; The Atterberg Limits show that the soil is fairly plastic and suitable for embankment construction (good stability and low seepage losses).
Language:English
Score: 2095876.2 - https://www.fao.org/fishery/st...ng/General/x6706e/x6706e08.htm
Data Source: un
The finest soil particles, called colloid clay * , are invisible. (...) Inorganic clay Clay is the finest part of the soil and some clay particles are not even visible under the microscope. (...) Composite soils Composite soil Predominant Less prominent Clayey silt Silt Clay Silty sand Sand Silt Sandy clay Clay Sand 1.8 Some examples of particular names for soils Hardpan A soil offering an exceptionally strong resistance to penetration by boring tools.
Language:English
Score: 2093601.2 - https://www.fao.org/fishery/do...ng/General/x6706e/x6706e01.htm
Data Source: un
The finest soil particles, called colloid clay * , are invisible. (...) Inorganic clay Clay is the finest part of the soil and some clay particles are not even visible under the microscope. (...) Composite soils Composite soil Predominant Less prominent Clayey silt Silt Clay Silty sand Sand Silt Sandy clay Clay Sand 1.8 Some examples of particular names for soils Hardpan A soil offering an exceptionally strong resistance to penetration by boring tools.
Language:English
Score: 2093601.2 - https://www.fao.org/fishery/st...ng/General/x6706e/x6706e01.htm
Data Source: un