Operational characteristics of the watermark model 200 soil water potential sensor for irrigation management

McCann, I.R. and Kincaid, D.C. and Wang, D. (1992) Operational characteristics of the watermark model 200 soil water potential sensor for irrigation management. Applied Engineering in Agriculture. 8(5):603-609. ASAE, 2950 Niles Rd., St. Joseph, MI.

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Abstract

The static and dynamic response characteristics of the
Watermark model 200 soil water potential sensor were
evaluated using the pressure plate method and greenhouse
experiments. The sensor had a nearly linear resistance
versus water potential relationship within the 0 to –200
kPa (0 to –29 psi) range. At saturation, sensor resistance
was approximately 1 kΩ, and at –103 kPa (-15 psi)
resistance was approximately 23 kΩ, with a coefficient of
variation of 11% (49 sensors). Using three to six sensors at
each location and depth should yield estimates of soil water
potential within 10% of the actual value with a 90%
confidence level. The dynamic response was good during
typical soil water drying cycles following complete
rewetting, but the sensors did not respond fully to rapid
drying or partial rewetting of the soil. Response was
improved, without affecting the basic calibration, when a
finer textured material with greater unsaturated hydraulic
conductivity was used in the transmission portion of the
sensor.

Item Type:	Article
NWISRL Publication Number:	0783
Subjects:	Soil > Soil water (soil moisture) Research methodology Mass Import - autoclassified (may be erroneous)
Depositing User:	Dan Stieneke
Date Deposited:	20 Nov 2010 21:53
Last Modified:	01 Dec 2016 22:34
Item ID:	586
URI:	https://eprints.nwisrl.ars.usda.gov/id/eprint/586