Chapter 10 - Field Capacity, Wilting Point, Available Water, and the Nonlimiting Water Range

Abstract

This chapter defines field capacity, permanent wilting point, and available water to plants, which is the difference between field capacity and the permanent wilting point. The permanent wilting point was described in 1912 by Briggs, a physicist, and Shantz, a botanist, who called it the wilting coefficient. The nonlimiting water range (NLWR), first defined by John Letey at the University of California in 1985, acknowledges that water may not be equally available to plants between field capacity and the permanent wilting point. The NLWR includes the effects of aeration and mechanical resistance on water availability. In follow-up Letey's work, researchers have defined the least limiting water range, which sets limits for water uptake based on the wetness and mechanical resistance of the soil. Biographies of Briggs and Shantz are given in the appendix along with documentation showing they were two of the most important scientists of their time.