scope:

This document specifies laboratory methods for determination of the soil water-retention characteristic. This document applies only to measurements of the drying or desorption curve. Four methods are described to cover the complete range of soil water pressures as follows: a) method using sand, kaolin or ceramic suction tables for determination of matric pressures from 0 kPa to -50 kPa; b) method using a porous plate and burette apparatus for determination of matric pressures from 0 kPa to -20 kPa; c) method using a pressurized gas and a pressure plate extractor for determination of matric pressures from -5 kPa to -1 500 kPa; d) method using a pressurized gas and pressure membrane cells for determination of matric pressures from -33 kPa to -1 500 kPa. Guidelines are given to select the most suitable method in a particular case.