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Custom Soil Resource Report <br />Physical Soil Properties (Yuma County - Moser Pit) <br />This table shows estimates of some physical characteristics and features that affect <br />soil behavior. These estimates are given for the layers of each soil in the survey area. <br />The estimates are based on field observations and on test data for these and similar <br />soils. <br />Depth to the upper and lower boundaries of each layer is indicated. <br />Particle size is the effective diameter of a soil particle as measured by sedimentation, <br />sieving, or micrometric methods. Particle sizes are expressed as classes with specific <br />effective diameter class limits. The broad classes are sand, silt, and clay, ranging from <br />the larger to the smaller. <br />Sand as a soil separate consists of mineral soil particles that are 0.05 millimeter to 2 <br />millimeters in diameter. In this table, the estimated sand content of each soil layer is <br />given as a percentage, by weight, of the soil material that is less than 2 millimeters in <br />diameter. <br />Silt as a soil separate consists of mineral soil particles that are 0.002 to 0.05 millimeter <br />in diameter. In this table, the estimated silt content of each soil layer is given as a <br />percentage, by weight, of the soil material that is less than 2 millimeters in diameter. <br />Clay as a soil separate consists of mineral soil particles that are less than 0.002 <br />millimeter in diameter. In this table, the estimated clay content of each soil layer is <br />given as a percentage, by weight, of the soil material that is less than 2 millimeters in <br />diameter. <br />The content of sand, silt, and clay affects the physical behavior of a soil. Particle size <br />is important for engineering and agronomic interpretations, for determination of soil <br />hydrologic qualities, and for soil classification. <br />The amount and kind of clay affect the fertility and physical condition of the soil and <br />the ability of the soil to adsorb cations and to retain moisture. They influence shrink- <br />swell potential, saturated hydraulic conductivity (Ksat), plasticity, the ease of soil <br />dispersion, and other soil properties. The amount and kind of clay in a soil also affect <br />tillage and earthmoving operations. <br />Moist bulk density is the weight of soil (ovendry) per unit volume. Volume is measured <br />when the soil is at field moisture capacity, that is, the moisture content at 1/3- or 1/10- <br />bar (33kPa or 10kPa) moisture tension. Weight is determined after the soil is dried at <br />105 degrees C. In the table, the estimated moist bulk density of each soil horizon is <br />expressed in grams per cubic centimeter of soil material that is less than 2 millimeters <br />in diameter. Bulk density data are used to compute linear extensibility, shrink-swell <br />potential, available water capacity, total pore space, and other soil properties. The <br />moist bulk density of a soil indicates the pore space available for water and roots. <br />Depending on soil texture, a bulk density of more than 1.4 can restrict water storage <br />and root penetration. Moist bulk density is influenced by texture, kind of clay, content <br />of organic matter, and soil structure. <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 field, <br />particularly structure, porosity, and texture. Saturated hydraulic conductivity (Ksat) is <br />considered in the design of soil drainage systems and septic tank absorption fields. <br />23