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This article in SSSAJ

  1. Vol. 54 No. 6, p. 1739-1743
    Received: Nov 15, 1989

    * Corresponding author(s):
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Infiltration in Adjacent Cecil and Pacolet Soils

  1. D. E. Radcliffe ,
  2. L. T. West,
  3. G. O. Ware and
  4. R. R. Bruce
  1. Dep. of Agronomy
    Forestry School, Univ. of Georgia, Athens, GA 30602
    USDA-ARS Southern Piedmont Conservation Research Center, Watkinsville, GA 30677



Cecil (clayey kaolinitic, thermic Typic Kanhapludult) and associated soils cover two-thirds of the land area of the Southern Piedmont. Soybean [Glycine max (L.) Merr.] yields from severely eroded sites in these soils are about half of those from slightly eroded sites. Most of the severely eroded sites are on the Pacolet soil series (clayey kaolinitic, thermic, Typic Kanhapludult), which is shallower to the bottom of the Bt horizon. Differences in infiltration rates may cause these differences in yield. Our objectives were to quantify infiltration rate differences between Cecil and Pacolet soils and to determine the reason for the differences. Infiltration rate was measured using a cylinder infiltrometer at five sites with adjacent Cecil and Pacolet soils, and using a sprinkler infiltrometer at one site. Steady-state infiltration in the Pacolet was significantly lower than in the Cecil, 4.2 and 30.1 mm h−1, respectively. Cecil infiltration rates increased as depth to the Bt horizon increased. On Cecil, final sprinkler infiltration rate was 61.1 mm h−1 with a sod surface, but surface sealing reduced infiltration with a bare surface to 3.6 mm h−1 within 1 h. The final sprinkler-infiltration rates of the Pacolet soil were 4.5 mm h−1 for sod and 4.2 mm h−1 for bare surfaces. Pacolet infiltration rates were controlled by the Bt1 layer, which had a lower, saturated hydraulic conductivity (2.3 mm h−1) and fewer mesopores than adjacent horizons but was similar to the upper Bt of the Cecil soil. The Cecil soil's limiting Bt1 horizon occurred much deeper in the profile and had less effect on infiltration. Areas of Pacolet within the Cecil landscape, too small to map separately, can cause increased runoff and variability of yield potential of areas mapped as Cecil.

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