code: private static String calcLamda(String slsnd, String slcly, String omPct) {
  
          String mt33 = divide(calcMoisture33Kpa(slsnd, slcly, omPct), "100");
          String mt1500 = divide(calcMoisture1500Kpa(slsnd, slcly, omPct), "100");
          String ret = divide(substract(log(mt33), log(mt1500)), CONST_LN1500_LN33);
          LOG.debug("Calculate result for Slope of logarithmic tension-moisture curve is {}", ret);
          return ret;
      }
docs: Equation 15 for calculating Slope of logarithmic tension-moisture curve
  
  @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)