code: public static String calcMoisture1500Kpa(String slsnd, String slcly, String omPct) {
  
          if ((slsnd = checkPctVal(slsnd)) == null
                  || (slcly = checkPctVal(slcly)) == null
                  || (omPct = checkPctVal(omPct)) == null) {
              LOG.error("Invalid input parameters for calculating 1500 kPa moisture, %v");
              return null;
          }
          String ret = sum(product("-0.02736", slsnd), product("0.55518", slcly), product("0.684", omPct),
                  product("0.0057", slsnd, omPct), product("-0.01482", slcly, omPct), product("0.0007752", slsnd, slcly), "1.534");
          LOG.debug("Calculate result for 1500 kPa moisture, %v is {}", ret);
  
          return ret;
      }
docs: Equation 1 for calculating 1500 kPa moisture, %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)