1. Remove about 2 inches (5cm) of the top layer soil and collect different locations’ soil samples at approximately 6 inches (15cm) deep.
  2. Thoroughly mix all collected soil. Ideally, dry the soil in the air or bake in an oven at 104˚F / 40˚C.
  3. Weigh out 20g of the mixed soil sample into a glass jar and add 100g of distilled or deionized water in it.
  4. Shake well for 5 minutes or use a magnetic stirrer to automatically stir for 15 minutes. Leave overnight. 
  5. Shake or stir again next morning, then allow it to settle for 15-30 minutes. 
  6. Then take the pH measurement of the soil slurry. Remember to thoroughly clean off the probe after test.