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concentration in ground water. High salts cause an osmotic pressure barrier to the soil root <br />system interface and inhibit water and nutrient movement into the plant. The tolerance of <br />plants to high soil salt levels is species dependent and has been well documented (USDA, 1969 <br />and Donahue et al., 19771. Salinity levels are most critical during germination and most <br />detrimental in hot dry climates and on south facing slopes than in other landscape positions. <br />Saturation Percentage. Saturation percentage is a useful parameter for detecting low water- <br />holding capacity and clarifying the degree of sodic hazard as indicated by SAR (Merrill et al., <br />19871. The degree of saturation is highly influenced by the physical properties of the medium. <br />Soils tend to be droughty, coarse textured, and readily leached of nutrients when the water <br />holding capacity at saturation is 25 percent or less. A high saturation percentage (greater than <br />85 percent) indicates a fine textured medium with potentially poor air and water permeability <br />characteristics. <br />Particle Size (Texture). Texture refers to the relative proportion of sand, silt, and clay sized <br />particles and generally relates directly to saturation percentage. Texture influences water <br />infiltration and percolation, water and nutrient retention, surface crusting, shrinkage and <br />swelling, frost heaving, compaction, and erodibility. Textural problems are generally <br />encountered when either sand contents approach 85 percent or clay levels are greater than 50 <br />percent. Soils with high silt or very fine sand content are often more susceptible to wind and <br />water erasion. <br />Dominant Water Soluble Cations ICa, Mg, and Na), and SAR. The water soluble Ca, Mg, and <br />Na analyses reveal the type and concentration of salt that exists in solution. The ion <br />concentration is directly proportional to the soil conductivity (USDA, 19691. The ratio of <br />soluble Na to Ca plus Mg, referred to as SAR, is commonly used to predict both chemical and <br />physical properties of growth mediums. The ratio is an indicator of dispersion, flocculation, <br />porosity, infiltration, permeability, erodibility, surface crusting, and seedling emergence. SAR <br />reveals the relative dominance of sodium in the soil water solution. <br />Dominant Water Soluble Anions (Carbonate, Bicarbonate, and Sulfate). Sulfate is used in the <br />formation of many proteins and is therefore essential for both plants and animals. Sulfur is <br />needed by plants in about the same quantities as phosphorous. Spoils within the Northern <br />Great Plains Coal province are typically high in sulfate. (Barth et al., 19771. The sedimentary <br />rocks in association with coal seams will often yield substantial amounts of sulfate ions <br />through the oxidation of pyrite and/or marcasite. Sulfuric acid produced in the oxidation of <br />pyrite and marcasite is commonly dissociated and buffered by the bicarbonate and carbonate <br />ions dissolved from the associated carbonate rocks, thus liberating sulfate ions into solution. <br />The major portion of sulfate found in spoils may be derived from the dissolution of gypsum. <br />The bicarbonate and carbonate ion content or alkalinity is generally a measure of buffering <br />capacity. Common sources of these anions are the solution of carbonate rocks, diagenesis of <br />PR03 1 1 Revised 01 /02 <br />