2001-12-11_PERMIT FILE - C1980005 (4)

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State Reg. Sodium Adsorption Ratio (SAR) and Exchangeable Sodium Percentage (ESP). The SAR test reveals the relative dominance of sodium in The soil water solution whereas ESP reflects the exchangeable (reserve) sodium on the soil particle surface. The tests are complimentary and often interchangeable (U.S.D.A., 1964). ESP is determined when the SAR is greater then 10. Sodic soils, and .particularly those which are high in clay content, exhibit poor available water holding characteristics. Water infiltration and permeability rates are usually very low until the water content reaches the plastic limits. Root penetration and seedling emergence are often severely restricted. Low SAR and ESP levels reflect a dominance of the calcium and magnesium ions in soil water. Molybdenum and Selenium. Some native plants tend To accumulate high levels of molybdenum and selenium in the plant system. High levels of selenium are often associated with primary and secondary indicator plants (U.S.D.A., 1957). Elevated molybdenum levels often occur in legumes (especially white sweet clover) which require it for nitrogen fixation (Munshower, 1980). Although these elements are essential for animals, when overingested by the grazing animals, molybdenum or selenium toxicity may occur (Donahue, et al,. 1977). Boron, Copper, Iron, Manganese, and Zinc. These essential plant micronutrients serve as activators in numerous enzyme systems (Donahue, et al, 1977). If present in excess concentrations, plant toxicity symptoms may occur. Also as pH decreases, solubilities and the potential for toxicity increases. Cadmium, Lead, Mercury, and Nickel. These ore non-essential (to plant and animal life) heavy metals that could induce plant toxicity symptoms if present in excess quantities. Mercury, cadmium, and nickel ore appreciably more toxic than copper. Copper is approximately 10 and 13 times more toxic than zinc and manganese respectively (U.S.D.A., 1957). 6-13