This report describes a tensiometer designed to be used for soil water sampling. Variations in the design include a solenoid transducer tensiometer for monitoring metric potentials at depths in excess of 10.3 m and instrumentation to automatically re-circulate fluid in the tensiometer. The designs were evaluated to determine whether their response to matric flow was "soil-limited" or "tensiometer-limited," as defined by Towner (1980). In a dry silt, the response time was soil-limited, but was tensiometer-limited in a wet silt and in a wet and dry sand. The effects of 11 mg/L of O2 dissolved in 236 ml of water and a 2-mm-diameter bubble upon the response time, compared with an ideal fluid, was calculated. Only a dry silt with dissolved oxygen in the tensiometer fluid was found to be soil-limited; a wet silt and a dry and wet sand were tensiometer-limited. The response time was affected more by gas in the tensiometer fluid than by the measurement device (Bourdon gauge or pressure transducer).
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