Premium
Measurement of Water Potential and Osmotic Potential in Soil with a Combined Thermocouple Psychrometer and Salinity Sensor
Author(s) -
Ingvalson R. D.,
Oster J. D.,
Rawlins S. L.,
Hoffman G. J.
Publication year - 1970
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/sssaj1970.03615995003400040011x
Subject(s) - hygrometer , thermocouple , salinity , water potential , soil science , soil water , water content , environmental science , soil salinity , hydrology (agriculture) , chemistry , geotechnical engineering , materials science , geology , composite material , humidity , thermodynamics , oceanography , physics
A combined thermocouple psychrometer and salinity sensor, which is embedded in a single ceramic body, is described. This design makes possible the measurement of the water and osmotic potentials of soil water at the same location in the soil. Errors produced by spatial variations in soil solution concentration, shown to be large, were eliminated by the instrument's ability to make both measurements on a single sample of soil solution. The instrument was tested in a soil‐plant‐water system, and the data obtained are reported. Desaturation of the ceramic at matric potentials more negative than −2 bars was shown to have a significant effect on conductance of the salinity sensor. Correction for this effect is discussed. Measurements showed that cotton plants extracted more water from the less saline zones in the soil. This had the effect of lowering the water potential to approximately the same value at two depths in the soil profile at the end of a drying cycle.