Resistance to water flow in soil and plant. II. A review of experimental evidence on the rhizosphere resistance.
Experimental evidence claiming to show appreciable rhizosphere resistances in soils much wetter than permanent wilting point (sometimes even at soil matric potentials above -1 bar) is reviewed. It is concluded that the results of some of the experiments under review do not fit conclusions previously drawn from them; other experimental results can be explained without an appreciable rhizosphere resistance. Therefore there is no conflict with the theoretical evidence that for many species the rhizosphere resistance will not become appreciable until the soil is near or beyond the permanent wilting point.