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Physical Soil Properties—El Paso County Area,Colorado <br /> Saturated hydraulic conductivity(Ksat) refers to the ease with which pores in a <br /> saturated soil transmit water. The estimates in the table are expressed in terms of <br /> micrometers per second. They are based on soil characteristics observed in the <br /> field, particularly structure, porosity, and texture. Saturated hydraulic conductivity <br /> (Ksat) is considered in the design of soil drainage systems and septic tank <br /> absorption fields. <br /> Available water capacity refers to the quantity of water that the soil is capable of <br /> storing for use by plants. The capacity for water storage is given in inches of water <br /> per inch of soil for each soil layer. The capacity varies, depending on soil properties <br /> that affect retention of water. The most important properties are the content of <br /> organic matter,soil texture, bulk density,and soil structure.Available water capacity <br /> is an important factor in the choice of plants or crops to be grown and in the design <br /> and management of irrigation systems. Available water capacity is not an estimate <br /> of the quantity of water actually available to plants at any given time. <br /> Linear extensibility refers to the change in length of an unconfined clod as moisture <br /> content is decreased from a moist to a dry state. It is an expression of the volume <br /> change between the water content of the clod at 1/3-or 1/10-bar tension (33kPa or <br /> 10kPa tension) and oven dryness. The volume change is reported in the table as <br /> percent change for the whole soil. The amount and type of clay minerals in the soil <br /> influence volume change. <br /> Linear extensibility is used to determine the shrink-swell potential of soils. The <br /> shrink-swell potential is low if the soil has a linear extensibility of less than 3 percent; <br /> moderate if 3 to 6 percent; high if 6 to 9 percent;and very high if more than 9 percent. <br /> If the linear extensibility is more than 3, shrinking and swelling can cause damage <br /> to buildings, roads, and other structures and to plant roots. Special design <br /> commonly is needed. <br /> Organic matter is the plant and animal residue in the soil at various stages of <br /> decomposition. In this table, the estimated content of organic matter is expressed <br /> as a percentage, by weight, of the soil material that is less than 2 millimeters in <br /> diameter. The content of organic matter in a soil can be maintained by returning <br /> crop residue to the soil. <br /> Organic matter has a positive effect on available water capacity, water infiltration, <br /> soil organism activity,and tilth. It is a source of nitrogen and other nutrients for crops <br /> and soil organisms. <br /> Erosion factors are shown in the table as the K factor(Kw and Kf)and the T factor. <br /> Erosion factor K indicates the susceptibility of a soil to sheet and rill erosion by <br /> water. Factor K is one of six factors used in the Universal Soil Loss Equation(USLE) <br /> and the Revised Universal Soil Loss Equation (RUSLE) to predict the average <br /> annual rate of soil loss by sheet and rill erosion in tons per acre per year. The <br /> estimates are based primarily on percentage of silt, sand, and organic matter and <br /> on soil structure and Ksat.Values of K range from 0.02 to 0.69. Other factors being <br /> equal, the higher the value, the more susceptible the soil is to sheet and rill erosion <br /> by water. <br /> Erosion factor Kw indicates the erodibility of the whole soil. The estimates are <br /> modified by the presence of rock fragments. <br /> Erosion factor Kf indicates the erodibility of the fine-earth fraction, or the material <br /> less than 2 millimeters in size. <br /> USDA Natural Resources Web Soil Survey 6/10/2016 <br /> am Conservation Service National Cooperative Soil Survey Page 2 of 5 <br />