This International Standard specifies laboratory methods for determination of the soil water-retention characteristic.

This International Standard 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:

• method using sand, kaolin or ceramic suction tables for determination of matric pressures from 0 kPa to - 50 kPa;
• method using a porous plate and burette apparatus for determination of matric pressures from 0 kPa to - 20 kPa;
• method using a pressurized gas and a pressure plate extractor for determination of matric pressures from - 5 kPa to - 1500 kPa;
• method using a pressurized gas and pressure membrane cells for determination of matric pressures from - 33 kPa to - 1500 kPa.

Guidelines are given to select the most suitable method in a particular case.