It is standard practice in Western Australia for the pH of acidic soil, with pH below 6, to be measured in a weak calcium chloride solution (1 part soil to 5 parts 0.01 molar calcium chloride). In alkaline soil with a pH above 8, the standard practice is to measure pH in the extract of 1 part soil to 5 parts water. Soil pH measured in calcium chloride is designated pHCa and gives a lower value than pH measured in water (pHW).
