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This article in SSSAJ

  1. Vol. 52 No. 3, p. 893-896
     
    Received: Oct 22, 1987


    * Corresponding author(s):
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doi:10.2136/sssaj1988.03615995005200030054x

Design for an Automated Tension Infiltrometer

  1. M. D. Ankeny ,
  2. T. C. Kaspar and
  3. R. Horton
  1. Dep. of Agronomy, 3206 Agronomy Building, Iowa State Univ., Ames, IA 50011

Abstract

Abstract

An automated tension infiltrometer useful for a range of water tensions from 0.02 to 0.50 m and for infiltration rates of 1 × 10−8 to 5 × 10−4 m s 1 is described. Infiltration rates are calculated from the change in water height in a Mariotte column. Water height is automatically measured by using the difference in tension between two pressure transducers, one installed at the top, and the other at the bottom, of the Mariotte column. Precision of water height measurement using two transducers (SD = 2.2 mm) is increased as compared with height measurements made with only one transducer (SD = 6.2 mm). With only one transducer, much of the measurement error is due to tension fluctuations or “noise” caused by bubbling in the Mariotte column. The new design also incorporates several features used or suggested by other workers. A bubble tower is used for tension regulation, and interchangeable Mariotte columns of different diameters are used to match column volume with expected cumulative infiltration. Advantages of the new device include (i) quick and accurate tension control at low tensions, (ii) improved measurement precision at low flow rates, and (iii) automatic measurement and data collection, which increases measurement speed and eliminates bubbling-induced variability.

Joint contribution from USDA-ARS and Iowa State Univ. Paper no. J-12814 Iowa Agric. and Home Econ. Exp. Stn. Project no. 2659.

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