After preparation and installation, soil variations in areas such as Carnarvon account for most of the problems associated with using tensiometers to schedule irrigation. Wetting-up' the soil to the desired depth before trying to use the tensiometer to schedule irrigation can be difficult. Slow infiltration rates, impeded drainage and poorly designed irrigation systems, often cause excessive ponding and irrigation water run-off. A hard pan layer in the soil at 20 to 60 cm can cause the reading to be higher than expected. Try to determine how much of the cropped area the hard pan affects and avoid such areas as tensiometer sites.
Water lying in isolated areas also gives the illusion of over-watering.
Often an isolated area of heavy soil with a shallow, non-wetting, hard pan beneath it will cause water to pond. If most of the cropped area is responding as desired, these wet areas are best ignored. Deep ripping and gypsum applications will often improve drainage. Trouble shooting Problem Solution Air in tensiometer, reading high Soil is dry. The tensiometer may be installed in a 'dry' spot, or further irrigation may be needed to wet the soil to the desired depth.