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v. ~. ucr nn ¢n, m nvna we un[ <br />pATU~AL jtESUURCES CONSERVATION SERVICE <br />PHYSICAL PROPERTIES UFsOILS <br />Endnote -- PHYSICAL PROPERTIES OF SOILS--Continued <br />roc <br />04l'[1~98 <br />ORGANIC MATTER is the plant end animal residue in the soil at various stapes of decomposition. In report J, <br />the estimated content of organic matter is expressed as a percentage, by veight, of the soil material that is <br />less then '[ millimeters in diameter. The content of organic matter in a soil can be maintained or increased by <br />returning crop residue to the soil. Organic matter affects the available eater capacity, infiltration rate, and <br />tilih. It is a source of nitrogen end other nutrients for crops. <br />EROSION FACTOR K indicates the susceptibility of the vhole soil (including rocks and rock fragments) to <br />sheet and rill erosion by eater, Factor K is one of six factors used in the Universal Soil Loss Equation (LISLE) <br />to predict the average annual rate of soil loss by sheet and rill erosion in tons per acre per Year. The <br />estimates are based primarily on vercentage of silt, sand, and organic matter (up to 6 percent) and on soil <br />structure and permeability. Values of K range from 0.05 to O.bg. The higher the value, the more susceptible <br />the soil is to sheet and rill erosion by eater. <br />EROSION FACTOR Kf is like EROSION FACTOR K but it is for the fine-earth fraction of the soil. Rocks and <br />rock fragments are not considered. <br />EROSION FACTOR T is an estimate of the mezimum average annual rate of soil erosion by vind or eater that can <br />occur vithout affecting crop vroductivity over a sustained period. The rate is in tons per acre per year. <br />WINO EROUIBILITY URUUPS are made uD of soils that have similar properties affecting their resistance co vind <br />erosion in cultivated areas. The groups indicate the susceptibility of soil to vind erosion. Soiis are grouped <br />according to the folloving distinctions: <br />i. Coarse sands, sands, fine sands, and very fine sands. <br />These soils are generally not suitable for crops. They ere <br />eztremelr erodible, and vegetation is difficult to <br />establish. <br />2. loamy coarse sands, loamy sands, loamy fine sands, loamy <br />very fine sends, and sapric soil material. These soils are <br />very highly erodible. Crops can be groan if intensive <br />measures to control vind erosion are used. <br />3, Coarse sandy looms, sandy looms, fine sandy looms, and <br />very fine sandy loans. These soils are highly erodible. <br />Crops can be grovn if intensive measures to control vind <br />erosion are used. <br />AL. Calcareous looms, silt looms, clay looms, and silty clan <br />looms. These soils are erodibie. Crops can be grovn it <br />intensive measures to control vind erosion are used. <br />4. Liars, silty clays, noncalcareous clay looms, and silty <br />ciay looms that are more than 35 Dercent clay. These soils <br />are moderateir erodible. Crops can be grovn if measures to <br />control vind erosion are used. <br />