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U:a. UtY~alatMl Ut AUa1l;ULlUAt rout i ur y NATURAL RESOURCES CONSERVATION SERVICE • . 11/11198 Endnote -- PRYSICAL PROPERTIES OF SOILS PIYSICAL PROPERTIES OF SOILS This report ehora eaticatee of seta characteriatica and feataree that effect soil behavior. These eatiutea are given tar the eajor layers of eec6 soil is the aarvey arse. The eatiutea are based on field obeervationa and oa test date for these end aieiler soils. CLAY ea a soil separate consists of eioeral soil particles that are leas than O.OOt eillieeter is diueter. la this report, the eatieated clay coolest of each eajor soil layer is given ea a percentage, by night, of the soil uterial that is leas than 1 eillieetere ie diueter, the uouet sad find of clq great b affect the fertility sad physical coaditios of the aoi L They deteniee the ability of the soil to adsorb catioae sad to retain eoisture. They influence ahrint-arell potential, pereeability, pleetieity, the cane of soil dispersion, sad other soil properties. The aeouet and tied of clay is a Boil also affect tillage sad eutheoving operatioaa. MOIST SDLI DENSITt is the night of soil (ovesdry~ per acit volace. Yoluee is eeaeared rhea the soil is at field eoiatore capacity, the eoisture coolant at I/J bar eoiatore teeaioo. (eight ie detereined after drying the soil at IOS degrees C. In this report, the eatisated eoiat bolt deeaity of each eajor soil horiaoe is erpreaaed in grass per cubic ceatieeter of soil uterial that is leas thou 2 eillieetera io disaster. Bolt density data ere used to teapots ahrint-arell potential, available rater capacity, total pore apace, aed other soil properties. She soiat bolt deeaity of a soil indicates the pore space available for rater aed roots. A balk deeaity of core than 1.6 can restrict rater storage aed root penetration. Noiat bolt deeaity is influenced 6y tenure, find of clay, contest of organic caller, sad soil atructare. PERMEABILITY raters to the ability of a soil to tranaeit refer or air. The eatiutea indicate the rate of dornnrd wveeent o[ refer Then the soil is eatarated. They ue based on soil characteriatica observed in the field, particularly structure, porosity, and tertore. Pereeability is considered in the design of soil drainage aystees, septic tank abeorptioe fields, sad coaetraction There the rate of rater eoreeent under saturated conditions affects behe-ior. AVAILABLE IATER CAPACITY ref era to the quantity of refer Chet the soil is capable of atorieg for ass by pleats. the capacity for rater storage is given in iachee of refer per inch of Boil for each eajor soil lever. The capacity varies, depeadiag oa soil properties that effect the retention of Teter and the depth of the root zone. The coat ieportant properties are the content of organic caller, soil tertore, bulk deeaity, cud soil structure. Available rater capacity is an ieportant factor ie the choice of pleats or crops to be grore and is the design and senegeseal of irrigation eyeless. Available refer capacity is sot ea estivate of the quantity of rater actually available to plants at any given lice. SHRINK-SiELL POtENtIAL is the potential for volute change is a soil rit6 a loan or gain of eoisture. Volute change occurs vainly because of the interaction of clay einerala rich refer and Tories rith the aroual aed type of clay einerala in the soil. The site of the load oa the soil end the ugnitude of the cheoge in soil eoisture content influence the eeount of arelling of soils in place. Laboratory eeasureeeota of arelling of uodiaturbed clods rare cede for cony soils. For others, welling ras eatiseted on the basis of the kind and eeount of clay einerala in the soil and on eeasureeents of aieiler soils. If the ahrint-arell potential is rated aoderate to very high, shrinking and arelling can cause dauge to buildings, reeds, end other structures. Special design is often needed. Shrink-well potential classes are based on the change in length at an uocoafiaed clod as eoisture content is increased free err-dry to field capacity. The cheoge is based on [he soil fraction less than 2 rilliseters in disaster. The classes ere 'Lor,' a cheoge of less than ] percent; 'Moderate," ) to 6 percent; end 'High,' core than 6 percent. 'Very high,' greater then 9 percent, is soeetisea used.