The equations used to compute these values are modified equations 
     obtained from the "Soil texture triangle hydraulic properties
     calculator" available online at:
         http://hydrolab.arsusda.gov/soilwater/Index.htm
             Source:
               Dr. K. E. Saxton
               USDA/ARS
               Pullman, WA 99164-6120
               Phone: (509) 335-2724
               FAX: (509) 335-7786
               E-mail: ksaxton@wsu.edu
               Homepage:http://www.bsyse.wsu.edu/saxton
             Reference:
               K.E. Saxton et al., 1986
               Estimating generalized soil-water characteristics from
               texture.  Soil Sci. Soc. Amer. J. 50(4):1031-1036

      Convert from decimal fraction to percent
        pctsand = sand * 100
        pctclay = clay * 100

      acoef = (float)(exp(-4.396 - 0.0715 * pctclay - 4.88e-4 *
              pow(pctsand, 2) - 4.285e-5 * pow(pctsand, 2) * pctclay))
      bcoef = (float)(-3.14 - 0.00222 * pow(pctclay, 2) - 3.484e-5 *
              pow(pctsand, 2) * pctclay)
      sat = (float)(0.332 - 7.251e-4 * pctsand + 0.1276 * log10(pctclay))

      wp_raw = (float)(pow((15.0 / acoef), (1.0 / bcoef)))
      fc_raw = (float)(pow((0.333 / acoef), (1.0 / bcoef)))
      ksat_raw = (float)(exp((12.012 - 0.0755 * pctsand) + (-3.895 + 0.03671 *
                 pctsand - 0.1103 * pctclay + 8.7546e-4 * pow(pctclay, 2)) / sat))
      bd_raw = (1 - sat) * 2.65

      Corrections from Steve Del Grosso 

      wiltpt = wp_raw + (-0.15 * wp_raw)
      fieldc = fc_raw + (0.07 * fc_raw)
      ksat = ksat_raw / 1500
      bulkd = bd_raw + (-0.08 * bd_raw)