Field method for separating the contribution of surface-connected preferential flow pathways from flow through the soil matrix

Authors

  • Emily C. Sanders,

    1. Department of Agricultural and Biological Engineering, Purdue University,West Lafayette, Indiana,USA
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  • Majdi R. Abou Najm,

    1. Department of Civil and Environmental Engineering, American University of Beirut,Beirut,Lebanon
    2. Biological and Ecological Engineering, Oregon State University, Corvallis, Oregon,USA
    3. Department of Civil and Environmental Engineering, Massachusetts Institute of Technology,Cambridge, Massachusetts,USA
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  • Rabi H. Mohtar,

    1. Department of Agricultural and Biological Engineering, Purdue University,West Lafayette, Indiana,USA
    2. Qatar Environment and Energy Research Institute, Qatar Foundation,Doha,Qatar
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  • Eileen Kladivko,

    1. Department of Agronomy, Purdue University,West Lafayette, Indiana,USA
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  • Darrell Schulze

    1. Department of Agronomy, Purdue University,West Lafayette, Indiana,USA
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Abstract

[1] Liquid latex was used as a method to seal visible surface-connected preferential flow pathways (PFPs) in the field in an effort to block large surface-connected preferential flow and force water to move through the soil matrix. The proposed approach allows for the quantification of the contribution of large surface-connected cracks and biological pores to infiltration at various soil moisture states. Experiments were conducted in a silty clay loam soil in a field under a no-till corn-soybean rotation planted to corn. Surface intake rates under ponding were measured using a simplified falling head technique under two scenarios: (1) natural soil conditions with unaltered PFPs and (2) similar soil conditions with latex-sealed large macropores at the surface. Results indicated that the contribution of flow from large surface-connected macropores to overall surface intake rates varied from approximately 34% to 99% depending on the initial moisture content and macroporosity present. However, evidence of preferential flow continued to appear in latex-sealed plots, suggesting significant contributions to preferential flow from smaller structural macropores, particularly in two out of four tests where no significant differences were observed between control and latex-sealed plots.

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