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Table 2.05.4(2)(d)-1 Criteria for Evaluating Soil Suitability (Reproduced Table 2.04.9-2; <br />Revised with NRCS 2008) <br />PARAMETER - UNITS <br />THRESHOLD SUITABILITY LEVELS' <br /> Prime Farmland Prime Farmland Lift B <br /> Lift A and Single-Lift Soils <br />PH <6.1->8.4 <61->8.4 <br />Conductivity (mmhos/cm) 4.02 6.02 <br />Saturation percentage (%) >80% >80% <br /> <25% <25% <br />Sodium adsorption ratio3 >4 >4 <br />Exchangeable Sodium % >15 <br />Calcium carbonate percentage 15% >40% <br />Selenium (ppm) >.2 ppms >1 ppms <br />Particle size' All soil textures except: s, Is, sc, sic, c <br />Coarse fragments (%)5 >15% >35% one location; <br /> >10% 3" diam + (>25% average) <br />' The threshold levels are to be used as a guide in evaluating the suitability of a soil material for reclamation. An <br />evaluation should take into account the "total system". Interactive parameters may either nullify or verify the <br />significance of a potential problem. <br />' The actual maximum acceptable salt level will depend on the plant species proposed in the revegetation plan and <br />the potential for upward salt movement. As pointed out in the Baltzer report in Attachment 2.05.4(2)(d)-1, Dave <br />Dearstyne of the NRCS said that a level of 6.0 in the subsoil would not be detrimental to grasses or alfalfa. A study <br />done by Curtis Swift, PhD, of Colorado State University, titled Salt Tolerance of Various Temperate Zone <br />Ornamental Plants, shows that alfalfa handles a soil conductivity of 4-8 mmhos/cm. The specific species cited is <br />Medicago Sativa, which is exactly the same as that prescribed in the revegetation plan for irrigated cropland. Also, <br />this reference does not differentiate between topsoil and subsoil. Since WFC is maintaining a limit of 4.0 in the <br />topsoil (Lift A), the revised limit of 6.0 mmhos/cm in the subsoil (Lift B) should be conservative. <br />(Revised July 2008) 2.05.4(2)(d)-14 <br />12-14