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Wollenhaupt, N.C. and J.L. Richardson. 1982. The role of <br />topography in revegetation of disturbed lands. In Mining <br />and Reclamation of Coal Mined Lands in the Northern <br />Great Plains, Proceedings, Montana Agric. Exp. Sta. <br />Res. Rpt. 194. <br />GLOSSARY <br />AGGREGATE: Many fine soil particles held together in a <br />single cluster, such as a clod or crumb. Many properties <br />of an aggregate differ from those of an equal mass of <br />unaggregated soil. <br />BULK DENSITY: The weight of oven -dry soil per unit bulk <br />volume, Including air space. Usually expressed as <br />grams /cubic centimeter. <br />ELECTRICAL CONDUCTIVITY (EC): A physical quantity <br />which measures the readiness with which a medium <br />conducts electricity. EC can be related to the soluble <br />salt content of saturated soil extracts, and is expressed <br />as mmhos /cm at 25 °C. (See Salinity). <br />EXCHANGEABLE SODIUM PERCENTAGE (ESP): The de- <br />gree of saturation of the soil cation exchange complex <br />with sodium. It may be calculated by the formula: <br />ESP = Exchangeable Sodium x 100 <br />Cation Exchange Capacity <br />Units are usually expressed as milliequivalents per 100 <br />g. soil. For characterization of soil materials for <br />reclamation suitability in North Dakota, current regula- <br />tions assume that ESP 5 is equivalent to SAR 4, and ESP <br />12 equivalent to SAR 10 (See Sodium Absorption Ratio, <br />Sodicity). <br />FIRST LIFT: The uppermost layer of undisturbed soil <br />materials removed and segregated during surface min- <br />ing to be respread as topsoil. (See Topsoil). <br />HYDRAULIC CONDUCTIVITY: The rate of flow of water <br />through a unit cross section of soil per unit of hydraulic <br />gradient under specified temperature and hydraulic con- <br />ditions. Usually expressed as centimeter /hour, but time <br />may be expressed in minutes or days. <br />MOLARITY: A measure of the chemical concentration of a <br />solution, expressed as gram molecular weight per liter <br />of solution. <br />NONPRIME SOILS: Any soils not classified as prime soils. <br />(See Prime Soils). <br />OVERBURDEN: Undisturbed consolidated or unconsoli- <br />dated materials overlying a coal seam to be mined. <br />PERMEABILITY: The ease with which water can pass <br />through a bulk mass of soil or a layer of soil. This can be <br />either a qualitative term, or a quantitative term if the rate <br />of movement is specified (See Hydraulic Conductivity). <br />23 <br />PRIME SOILS: Productive soils that meet technical criteria <br />established by the U.S. Department of Agriculture, <br />among which are rooting depth, water - holding capacity, <br />temperature, pH, susceptibility to erosion, and soluble <br />salt and sodium levels. Prime soils in North Dakota oc- <br />cur in well- drained depressional areas and in lower posi- <br />tions of concave slopes which receive runon water. <br />Federal and North Dakota reclamation laws require <br />segregation and separate handling of prime soil <br />materials. <br />ROOT ZONE: That part of the soil which is invaded by plant <br />roots. <br />SALINITY: A measure of the concentration of soluble salts <br />in soil; salinity in this bulletin is measured by electrical <br />conductivity (EC) of the saturation extract expressed as <br />mmhos /cm, as given below: <br />Category <br />Nonsaline or very slightly saline <br />Slightly saline <br />Moderately saline <br />Strongly saline <br />Very strongly saline <br />Category <br />Non or very slightly sodic <br />Somewhat sodic <br />Moderately sodic <br />Sodic <br />(See Sodium Absorption Ratio) <br />EC <br />< 2 <br />2 -4 <br />4 -8 <br />8 -16 <br />>16 <br />SATURATION EXTRACT: The solution extracted from a <br />saturated soil paste prepared using distilled water. <br />SECOND LIFT: The second layer of undisturbed soil <br />material which underlies the first lift, and which is <br />removed and segregated during surface mining to be <br />replaced as subsoil. (See Subsoil). <br />SODICITY: A measure of the relative level of exchangeable <br />sodium in a soil. A sodic soil typically contains a suffi- <br />cient level of exchangeable sodium to interfere with the <br />growth of most plants. Sodicity in this report will be <br />measured by the sodium absorption ratio (SAR) as given <br />below: <br />SAR <br /><4 <br />4 -10 <br />10 -20 <br />>20 <br />SODIUM ABSORPTION RATIO: A ratio used to express the <br />relative activity of sodium in a saturation extract, as given <br />in the following equation: <br />Na <br />SAR =V Ca -4- Mg <br />2 <br />in which ionic concentrations are expressed in millie- <br />quivalents per liter. (See Sodicity, Saturation Extract). <br />SPOIL: Overburden that has been disturbed and haphazard- <br />ly mixed during surface mining. <br />SUBSOIL: The soil below the topsoil in which plant roots <br />grow, used synonymously with second lift in this <br />bulletin. The root zone of reclaimed soils can be com- <br />posed partially of reshaped spoil materials as well as <br />subsoil materials removed as second lift. Current North <br />Dakota stripmine regulations base the suitability of sub- <br />soil materials upon EC below 4 and SAR below 10 (ESP <br />below 12). (See Second Lift, Topsoil). <br />