_PERMIT FILE - M2000052

• Permit No: M2000052
• IBM Index Class Name: Permit File
• Doc Name: MAPS & EXHIBITS
• Media Type: D
• Archive: No

U.S. DEPARTMENT OF AGRICULTURE PAGE 3 OF 5
NATURAL RESOURCES CONSERVATION SERVICE 01/28/00
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PHYSICAL PROPERTIES OF SOILS
Endnote -- PHYSICAL PROPERTIES OF SOILS
This report shows estimates of some characteristics and features that affect soil behavior. These estimates
are given for the major layers of each soil in the survey area. The estimates are based on field observations
and on test data for these and similar soils.
CLAY as a soil separate consists of mineral soil particles that are less than 0.002 millimeter in diameter.
In this report, the estimated clay content of each major soil layer is given as a percentage, by weight, of the
soil material that is less than 2 millimeters in diameter. The amount and kind of clay greatly affect the
fertility and physical condition of the soil. They determine the ability of the soil to adsorb cations and
to retain moisture. They influence shrink-swell potential, permeability, plasticity, the ease of soil
dispersion, and other soil properties. The amount and kind of.clay in a soil also affect tillage and
earthmoving operations.
MOIST BULK DENSITY is the weight of soil (ovendry) per unit volume. Volume is measured when the soil is
at field moisture capacity, the moisture content at 1/3 bar moisture tension. Weight is determined after
drying the soil at 105 degrees C. In this report, the estimated moist bulk density of each major soil
horizon is expressed in grams per cubic centimeter of soil material that is less than 2 millimeters in
diameter. Bulk density data are used to compute shrink-swell potential. available water capacity, total
pore space, and other soil properties. The moist bulk density of a soil indicates the pore space available for
r and roots. A bulk density of more than 1.6 can restrict water storage and root penetration. Moist
density is influenced by texture, kind of clay, content of organic matter, and soil structure.
PERMEABILITY refers to the ability of a soil to transmit water or air. The estimates indicate the
race of downward movement of water when the soil is saturated. They are based on soil characteristics
observed in the field, particularly structure, porosity, and texture. Permeability is considered in
the design of soil drainage systems, septic tank absorption fields, and construction where the rate of
water movement under saturated conditions affects behavior.
AVAILABLE WATER CAPACITY refers to the quantity of water that the soil is capable of staring for use by
plants. The capacity for water storage is given in inches of water per inch of soil for each major soil layer.
The capacity varies, depending on soil properties that affect the retention of water and the depth of the root
zone. The most important properties are the content of organic matter, soil texture, bulk density, and soil
structure. Available water capacity is an important factor in the choice of plants or crops to be grown and in
the design and management of irrigation systems. Available water capacity is not an estimate of the quantity of
water actually available to plants at any given time.
SHRINK-SWELL POTENTIAL is the potential for volume change in a soil with a lass or gain of moisture. Volume
change occurs mainly because of the interaction of clay minerals with water and varies with the amount and type
of clay minerals in the soil. The size of the load on the soil and the magnitude of the change in soil moisture
content influence the amount of swelling of soils in place. Laboratory measurements of swelling of undisturbed
clods were made-for many soils. For others, swelling was estimated on the basis of the kind and amount of
clay minerals in the soil and on measurements of similar soils. If the shrink-swell potential is rated moderate
to very high, shrinking and swelling can cause damage to buildings, roads, and other structures. Special design
is often needed. Shrink-swell potential classes are based on the change in length of an unconfined clod as
moisture content is increased from air-dry to field capacity. The change is based on the soil fraction less
2 millimeters in diameter. The classes are "Low," a change of less than 3 percent; "Moderate," 3 to 6
11 cent; and "High," more than 6 percent. "Very high," greater than 9 percent, is sometimes used.