Macropore and surface seal interactions affecting water infiltration into soil
1992
Ela, S.D. | Gupta, S.C. | Rawls, W.J.
Macropores can increase water infiltration into soils whereas surface sealing decreases infiltration. Using Webster day bare (fine-loamy, mixed, mesic Typic Haplaquoll) and Port Byron silt loam (fine-silty, mixed, mesic Typic Hapluqoll) soils, this study examined the effect of simulated rainfall on water infiltration into soils with earthworm (Aporrectodea tuberculata) and artificial macropores. Treatments included bare and covered soil surfaces, soils with and without macropores formed by earthworms, and soils with artificially formed macropores of 2-, 3-, 4-, and 5-mm diameter. During simulated rain. fall, infiltration was measured by continuously monitoring the increase in container weight. Comparison or infiltration rates between bare and covered treatments showed that a surface seal developed on bare soils. The surface seal was effective in sealing visible macropores varying in diameter from 2 to 5 mm. Subsequent measurements with a disk permeameter at the surface and three subsurface depths showed that open macropores at the surface were ineffective in conducting water to deeper depths because they lacked continuity below the surface. Likewise, measurements of the water flux through individual earthworm macropores demonstrated that much of the increase in water flux due to macropores was due to the contribution of only a few of the visible macropores. The description of macropore size and number by themselves may be insufficient for developing models of water entry into soils containing earthworm macropores.
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