ABSTRACT
Soil water desorption refers to the decrease in soil volumetric water content with decreasing
pore water matric head (drainage), while imbibition refers to the increase in volumetric water
content with increasing matric head (wetting). A discussion of the principles and parameters
associated with the determination of desorption and imbibition curves is given in Chapter 69.
This chapter briefly describes the psychrometer method (specifically the laboratory-based
dewpoint psychrometer) for measuring soil water desorption and imbibition curves. Alter-
native methods include the tension table, tension plate and pressure plate extractor (Chapter
72), long column (Chapter 73), soil core evaporation (Chapter 81), instantaneous profile
(Chapter 83), and estimation techniques (Chapter 84).
