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and Na analyses reveal the type and concentration of salt that exists in solution. The <br /> ion concentration is directly proportional to the soil conductivity (USDA, 1969). The <br /> ratio of soluble Na to Ca plus Mg, referred to as SAR, is commonly used to predict both <br /> chemical and physical properties of growth mediums. The ratio is an indicator of <br /> dispersion, flocculation, porosity, infiltration, permeability, erodibility, surface <br /> crusting, and seedling emergence. SAR reveals the relative dominance of sodium in the <br /> soil water solution whereas ESP reflects the exchangeable (reserve) sodium on the soil <br /> particle surface. These tests are complimentary and often interchangeable (USDA, 1969). <br /> ESP is often determined only when the SAR is greater than 11. <br /> Dominant Water Soluble Anions (Carbonate, Bicarbonate, and Sulfate). Sulfate is used in <br /> the formation of many proteins and is therefore essential for both plants and animals. <br /> Sulfur is needed by plants in about the same quantities as phosphorous. Spoils within the <br /> Northern Great Plains Coal province are typically high in sulfate. (Barth et al ., 1977). <br /> The sedimentary rocks in association with coal seams will often yield substantial amounts <br /> of sulfate ions through the oxidation of pyrite and/or marcasite. Sulfuric acid produced <br /> in the oxidation of pyrite and marcasite is commonly dissociated and buffered by the <br /> bicarbonate and carbonate ions dissolved from the associated carbonate rocks, thus <br /> liberating sulfate ions /into solution. The major portion of sulfate found in spoils may <br /> be derived from the dissolution of gypsum. <br /> The bicarbonate and carbonate ion content or alkalinity is generally a measure of <br /> buffering capacity. Common sources of these anions are the solution of carbonate rocks, <br /> diagenesis of CO2 from organic compounds, and CO2 from the atmosphere and soil . The <br /> presence of bicarbonate verses carbonate is usually determined by the pH. Above a pH of <br /> 8.2, bicarbonate ions dissociate to carbonate ions. Below a pH of 4.5, most of the <br /> bicarbonate ions are converted to carbonic acid (H2CO3). In between these two values, <br /> carbonate ions will normally add H+ ions to become bicarbonate ions (Dollhopf et al ., <br /> 1981). <br /> Carbonates and bicarbonates also increase the sodium buildup hazard in soils by <br /> precipitating calcium and magnesium as carbonates which have an extremely low solubility. <br /> Elevated levels of bicarbonate in soils (i.e., 10 meg/1) can also adversely affect <br /> sensitive crops (Traynor, 1980). <br /> Ammonium and Nitrate Nitrogen. Three major forms of soil nitrogen are typically found in <br /> 6-1-18 Revised 04/11/88 <br />