Using a disposable transfer pipette, add your SLP acid mixture (step 1) dropwise to the stirring DI water. Add one or two drops at a time and wait for the pH reading to stabilize. If you are extracting soils from east of the Mississippi River, adjust the final pH to 4.2. For soils west of the Mississippi River, adjust to the final pH to 5.0. This should require 10-15 drops of the SLP acid mixture for about 1 L of extractant.