code: public static String calcMoisture33Kpa(String slsnd, String slcly, String omPct) {
  
          String ret;
          if ((slsnd = checkPctVal(slsnd)) == null
                  || (slcly = checkPctVal(slcly)) == null
                  || (omPct = checkPctVal(omPct)) == null) {
              LOG.error("Invalid input parameters for calculating 33 kPa moisture, normal density, %v");
              return null;
          }
          String mt33Fst = calcMoisture33KpaFst(slsnd, slcly, omPct);
          ret = sum(product(pow(mt33Fst, "2"), "0.01283"), product(mt33Fst, "0.626"), "-1.5");
          LOG.debug("Calculate result for 33 kPa moisture, normal density, %v is {}", ret);
  
          return ret;
      }
docs: Equation 2 for 33 kPa moisture, normal density, %v
  
  @param slsnd Sand weight percentage by layer ([0,100]%)
  @param slcly Clay weight percentage by layer ([0,100]%)
  @param omPct Organic matter weight percentage by layer ([0,100]%), (=
  SLOC * 1.72)