proudly sponsored by
|
archiving of SOWACS proudly sponsored by |
|
There might be another alternative - soil water potential calibration: Water moves in and out of the probe matrix along soil water potential gradients, reaching equilibrium with the surronding soil water potential. Calibrating the inner water potential with sensor readouts (creating sensor matrix water release curve) enables reading surrounding equilibrium soil water potentials. This is not soil water content, but will eliminate problems of soil disturbance, compaction, sensor contact etc..., which are inherent in all dielectric sensors and most of the small volume soil water content sensor. Soil water potentials tend to equilibrate across non homogeneous soil sections (given proper time, distance and conductivity scales), decreasing SWP spatial variability in the surrounding soil volume. Inversely, soil water content variability will increase with time in the same volume. For automated irrigation control purposes soil water potentials will be adequate actuating indicators in most cases. If the Cambrone probe matrix and design allows 15 minutes equilibration with the surrounding soils on WETTING and on DRYING, as specified, the calibration procedure might be rather simple. Under adequate manufacturing uniformity, even a single and universal factory calibration can do the job. M. Meron ========================================================================= MIGAL Galilee Technology Center Crop Ecology Laboratory Kiryat Shmona PO Box 90 000 Rosh Pina 12 100 ISRAEL Phone +972-6-953559 Fax: +972-6-944980 Email: MERON@migal.co.il =========================================================================