Often, the buffer solutions get in contact with a soil sample, and pH reduction is observed, and this relates to the potential acidity content of the soil. I prefer stronger buffer like SMP as they are better at distinguishing between close acidity soils.

Besides SMP buffer, Adams-Evan buffer starting at pH 8.0 is another method that is often used for acid soils of the Southeast, USA. In any case, calibration curves must be obtained to convert the decrease in the buffer pH value to potential acidity of the soil.