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This article in SSSAJ

  1. Vol. 60 No. 3, p. 703-709
    Received: Nov 7, 1994

    * Corresponding author(s): logsdon@nstl.gov
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Spatial Variability of Hydraulic Conductivity in a Cultivated Field at Different Times

  1. S. D. Logsdon  and
  2. D. B. Jaynes
  1. USDA-ARS National Soil Tilth Lab., 2150 Pammel Dr., Ames, IA 50011



Farming practices and climatic patterns may alter soil surface hydraulic conductivity (K) both spatially and at different times during a season. This study quantified spatial variability and spatial dependence of ponded and tension K measurements in a cultivated field at different times. Paired small-base infiltrometers (76-mm diameter) were used at four pressure heads (5, −30, −60, and −150 mm) to measure K across a transect four times during one and a half growing seasons (1–2 July 1991, 12–13 Aug. 1991, 29–30 Apr. 1992, and 28–29 May 1992). A natural log transformation best normalized ponded K data, but ln(K + 1) was better for the tension data. Periodicity was apparent for K at a head (h) of −150 mm, with a significant period of 46 m for July 1991, 147 m for April 1992, and 96 m for May 1992. The periods for the three dates may be three different harmonics. The July periodicity was consistent with expected wheel traffic patterns from the previous harvest; K measurements would have coincided with wheel tracks every 46 m for the July 1991 measurement date. Periodicity for other dates had no apparent cause. For ponded K, only within-pair data were spatially correlated (0.6–0.8 m). At a head of −150 mm, K values were spatially correlated over distances of 6.6, 16.8, and 0.6 m for the measurements of July 1991, April 1992, and May 1992, respectively. Correlation distances were intermediate for K-30 and K-60. Since spatial correlation and periodicity varied with measurement date, one set of transect measurements was not adequate to describe spatial variability of K.

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