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This article in SSSAJ

  1. Vol. 60 No. 4, p. 1197-1201
     
    Received: Aug 14, 1995
    Published: July, 1996


    * Corresponding author(s): arshadc@em.agr.ca
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doi:10.2136/sssaj1996.03615995006000040034x

Pore Size Distribution and Hydraulic Conductivity Affected by Tillage in Northwestern Canada

  1. R. H. Azooz,
  2. M. A. Arshad  and
  3. A. J. Franzluebbers
  1. Agriculture and AgriFood Canada, Northern Agriculture Research Centre, Box 29, Beaverlodge, Alberta, Canada T0H 0C0
    USDA-ARS Southern Piedmont Conservation Research Center, 1420 Experiment Station Rd., Watkinsville, GA 30677

Abstract

Abstract

Tillage management can affect crop growth, in part by altering the pore structure and hydraulic properties of soil. We hypothesized that water retention, pore size distribution, and unsaturated hydraulic conductivity (k) differed under conventional tillage (CT) and no tillage (NT). We evaluated this hypothesis on a Donnelly silt loam (fine-loamy, mixed, frigid Typic Cryoboralf) and a Donnelly sandy loam (coarseloamy, mixed, frigid Typic Cryoboralf) in northwestern Canada. Soil cores were collected from the 0- to 300-mm depth in 75-mm increments. Water retention was measured at 10 pressure levels from -2 to −400 kPa to calculate pore size distribution and k. Both soils retained 0.04 to 0.09 m3 m−3 more water under NT than under CT. The volume fraction of total porosity with pores <7.5 µm in diameter (effective pores for retaining plant-available water) in the silt loam averaged 0.49 and 0.58 m3 m−3 under CT and NT, respectively, and in the sandy loam averaged 0.39 and 0.51 m3 m−3 under CT and NT, respectively. In contrast, the volume fraction of total porosity with pores >150 µm in diameter (pores draining freely with gravity) in the silt loam averaged 0.29 and 0.23 m3 m−3 under CT and NT, respectively, and in the sandy loam averaged 0.35 and 0.24 m3 m−3 under CT and NT, respectively. Conventional tillage appeared more likely to interrupt capillaries than NT, since large differences in k between tillage regimes were observed below a depth of 75 mm with increasing moisture deficit. Continuous NT management increased water storage of both silt loam and sandy loam soils in this cold, semiarid region.

Contribution no. BRS 9512.

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