This International Standard specifies a laboratory method for the simultaneous determination in soils of the unsaturated hydraulic conductivity and of the soil water-retention characteristic. It is applicable only to measurement of the drying or desorption curve. Application of the method is restricted to soil samples which are, as far as possible, homogeneous. The method is not applicable to soils which shrink in the range of matric head to . The range of the determination of the conductivity depends on the soil type. It lies between matric heads of approximately and . The range of the determination of the water-retention characteristic lies between matric heads of approximately and . NOTE 1 An infiltrometer method can be used to determine hydraulic conductivities near saturation. NOTE 2 ISO 11274 gives methods to determine the water-retention characteristic for matric heads between and−15 000 cm