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U. DEPARTMENT OP AGRICULTURE pAGE 3 OF 4 <br />NA RESCVRCES CONSERVATION SERVICE . . OB/17/9B <br />PHYSICAL PROPERTIES OP SOILS <br />E>'ote -- PHYSICAL PROPERTIES OF SOILS--Continued <br />O IC MATTER ie the plant and animal residue in the soil at Various et ag es of dec ompoaition. In report S, <br />tetimated content of organic matter ie expressed ae a percentage, by weight, of the soil material that is <br />1 Chan 2 millimeters in diameter. The content of organic mortar Sn a eo it can be maintained or inc reseed by <br />returning crop residue to the soil. Organic matter affects the available water capacity, infiltration rate, and <br />t ~h. IC ie a source of nitrogen and other nutrients for crops. <br />EROSION FACTOR K indlcat ee the susceptibility of the whole soil (including rocks and rack fragments) [o <br />sheet and rill erosion by water. Factor K is one of six fat tore used in the Universal Soil Loea Equation (US LE) <br />c redic[ the average annual race of soil lose by sheet and rill erosion in Cons per acre per year. The <br />e mates are based primarily on percentage of silt, sand, and organic matter (up to 4 percent) and on soil <br />at ructuze and permeability. Values of K range from 0.05 [0 0.69. The higher the value, [he more suecep[ib le <br />c ~eoil ie to sheet and rill erosion by water. <br />E ION FACTOR Kt ie like PROSION FACTOR K but i[ 18 for the Eine-earth fraction of Che soil. Roc ke and <br />rock fragments are not considered. <br />ETON PACTOR T Se an estimate of the maximum average annual rate of soil erne ion by wind or water that can <br />occur without affecting crop productivity over a sustained period. The rate is in Cons per acre per year. <br />N ERODIBI LITY GROUPS are made up of soils that have similar propert iee affecting their re eietance to wind <br />e Son in cultivated areas. The groups indicate [he eueceptibility of soil to wind erosion. Soils are grouped <br />according to the following diet inc crone: <br />' 1. Coarse eande, eande, fine sands, and very fine eande. <br />The ee soils are generally no[ suitable for crops. They are <br />extremely erodible, and vegetation ie difficult to <br />' set abl ieh. <br />2. Loamy coarse eande, loamy eande, loamy fine eande, loamy <br />very tine eande, and esprit Boil material. These soils are <br />' very highly erodible. Crops can be grown if intensive <br />measures to control wind eroe ion are used. <br />' 3. Coaiee Bandy looms, sandy looms, Elne sandy looms, and <br />very fine Bandy looms. These soils aze highly erodible. <br />Crops can be grown if intensive measures to control wind <br />erosion aze used. <br />' 4L. Calca reoue looms, silt looms, clay looms, and silty clay <br />looms. These soils are erodible. Crops can be grown Sf <br />Snteneive meaeuree to control wind erosion are used. <br />' 9. Clays, silty clays, noncalcareoue clay lcame, and silty <br />clay loamy that are more than IS percent clay. The ee soils <br />are moderately erodible. Crops can be grown if meaeuree to <br />control wind eroe ion are used. <br />1 <br /> <br /> <br />