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 describes the long column method for measuring soil water desorption and
imbibition curves. Alternative methods include the tension table, tension plate and pressure
extracter (Chapter 72), the dewpoint psychrometer (Chapter 74), soil core evaporation
(Chapter 81), instantaneous profile (Chapter 83), and estimation techniques (Chapter 84).
