ALLOSUN Environmental Concepts Probe Soil PH Meter Garden Farming Tool The PH Meter is designed for measurement in soils/plants/gardens vegetables/trees. Prepare the earth sample for test.Take away all the stones, clod, glass etc. Tenderly clean the probe shafts with an abrasive soft paper and dry cloth or a toilet paper. Lightly wipe off the earth and then plant the probe. If the earth is too dry, wet it. Read the PH degree after 60 seconds. Quantities required will vary depending on the type of soil, consult a gardening book or professional.