2007-12-19_REVISION - M1988112 (11)

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TECHNICAL MEMORANDUM To: Bill Lyle Date: October 19, 2007 Page 3 <0.1% to 2.9% and increased with increasing depth at both locations. The EC and major ion composition indicate that the soils contain low salinity and have exchange sites dominated by calcium and magnesium; as a result, calculated SAR values are low (<2.0). The soil pH values range from 6.5 to 8.0 and increase with depth in association with carbonates. 2.3 Baseline Water Soluble Soil Anions The hot water extraction method for boron was used to determine the easily-soluble concentrations of arsenic, boron, fluoride, and selenium in soils (Sparks, 1996). The concentrations of water-soluble anions often correlate to those dissolved chemical forms that are plant-available. The soluble levels of arsenic, boron, and selenium were low and generally consistent with depth (Tables 2-2 and 2-3). Soluble fluoride concentrations are generally slightly higher at the surface when compared to the subsurface soils (Tables 2-2- and 2-3) and well-within the normal concentration range for fluoride in soils (Kabata- Pendias and Pendias, 1984; Reddy and Gloss, 1993). 2.4 Baseline Extractable Soil Micronutrients Baseline soil micronutrient concentrations were assessed using the DTPA soil test, originally developed to assess plant availability of soil micronutrients in alkaline soils of Colorado (Soltanpour, 1991). Therefore, the DTPA soil test provides better sensitivity when assessing differences in plant-available metal levels in soils. The DTPA-extractable metals concentrations for all soils are given in Table 2-4. Certain metals, such as cadmium, copper, iron, manganese, nickel, and lead, tend to be concentrated at the surface (0-1 foot interval) due to their strong association with organic matter in agricultural soils (Alloway, 1990). P:V'rojecisllll-Nmmom(SanLuis)LY=LuisTam-Shalom Rm MSWIAYak=r_Cha leriwfionJiraLdoc