Premium
Field Capacity in Laboratory Columns
Author(s) -
Miller Robert D.,
McMurdie John L.
Publication year - 1953
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1953.03615995001700030003x
Subject(s) - hydraulic conductivity , hysteresis , capillary action , wetting , soil water , conductivity , drainage , soil science , geotechnical engineering , materials science , geology , mechanics , chemistry , composite material , physics , condensed matter physics , ecology , biology
It is shown that the material decrease in downward movement observed as soils approach field capacity cannot be explained in terms of capillary conductivity alone. Instead, the combined effects of decreasing capillary conductivity in the drying zone, hysteresis and reduced hydraulic gradients at all levels are involved. The capillary conductivity of the drying zone is always greater (probably much greater) than that of the wetting zone. Hysteresis effects, if present, ought to result in larger reductions in hydraulic gradient for an increment of water transfer than would occur without hysteresis. The hydraulic gradients at all levels ought to decline during drainage. Experimental evidence is presented which is in general agreement with expectations. Hysteresis effects were large, and the hydranlic gradients greatly diminished after 48 hours of drainage.