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Tarchitzky, J., The Seagram Centre for Soil and Water Sciences, The Hebrew University of Jerusalem, P.O.B. 12, Rehovot, 76100, Israel
Banin, A., The Seagram Centre for Soil and Water Sciences, The Hebrew University of Jerusalem, P.O.B. 12, Rehovot, 76100, Israel
Morin, J., The Seagram Centre for Soil and Water Sciences, The Hebrew University of Jerusalem, P.O.B. 12, Rehovot, 76100, Israel
Chen, Y., The Seagram Centre for Soil and Water Sciences, The Hebrew University of Jerusalem, P.O.B. 12, Rehovot, 76100, Israel
Research was conducted to investigate: (1) the structure, formation and nature of soil crusts which develop as a result of raindrop impact under controlled conditions of simulated rain, and (2) the crust effect on infiltration rates. Scanning electron microscope (SEM) observations performed on sandy, sandy-loam and clayey soil samples show the crust to be composed of two layers: (1) a "skin", 0.1 mm thick, and (2) a layer, 2-3 mm thick, with a higher bulk density in which aggregates have been destroyed. A "washing-in" zone described by earlier investigators could not be detected. The soil beneath the crust maintains its original structure and particle orientation. The chemical composition of the rain water was found to have a significant but not very large effect on the infiltration rate vs. cumulative rain curve of the clayey soil material only; final infiltration rate was about 20% lower when distilled water was applied compared to tap water (electrical conductivity ≈ 0.6 mmho cm-1). An increase of the bulk density from 1.35-1.48 g cm-3 in undisturbed soil to 1.74-1.88 g cm-3 in crusts was found. The amount of eroded material increased gradually with increase of runoff and decrease of infiltration. At steady state the erosion rates were 0.45, 1.25, and 0.76 g m-2 min-1 in the sandy, sandy-loam and clayey soil specimens, respectively. Percentages of clay and silt in the eroded material were higher than in the bulk samples. Three stages to describe the changes in nature and effects of crusts during their formation are suggested: (1) the rate of infiltration decreases to a point at which runoff beings, (2) the initiation of runoff until infiltration and runoff rates become stabilized, and (3) infiltration and runoff maintain steady rates. © 1984.
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Nature, formation and effects of soil crusts formed by water drop impact
33
Tarchitzky, J., The Seagram Centre for Soil and Water Sciences, The Hebrew University of Jerusalem, P.O.B. 12, Rehovot, 76100, Israel
Banin, A., The Seagram Centre for Soil and Water Sciences, The Hebrew University of Jerusalem, P.O.B. 12, Rehovot, 76100, Israel
Morin, J., The Seagram Centre for Soil and Water Sciences, The Hebrew University of Jerusalem, P.O.B. 12, Rehovot, 76100, Israel
Chen, Y., The Seagram Centre for Soil and Water Sciences, The Hebrew University of Jerusalem, P.O.B. 12, Rehovot, 76100, Israel
Nature, formation and effects of soil crusts formed by water drop impact
Research was conducted to investigate: (1) the structure, formation and nature of soil crusts which develop as a result of raindrop impact under controlled conditions of simulated rain, and (2) the crust effect on infiltration rates. Scanning electron microscope (SEM) observations performed on sandy, sandy-loam and clayey soil samples show the crust to be composed of two layers: (1) a "skin", 0.1 mm thick, and (2) a layer, 2-3 mm thick, with a higher bulk density in which aggregates have been destroyed. A "washing-in" zone described by earlier investigators could not be detected. The soil beneath the crust maintains its original structure and particle orientation. The chemical composition of the rain water was found to have a significant but not very large effect on the infiltration rate vs. cumulative rain curve of the clayey soil material only; final infiltration rate was about 20% lower when distilled water was applied compared to tap water (electrical conductivity ≈ 0.6 mmho cm-1). An increase of the bulk density from 1.35-1.48 g cm-3 in undisturbed soil to 1.74-1.88 g cm-3 in crusts was found. The amount of eroded material increased gradually with increase of runoff and decrease of infiltration. At steady state the erosion rates were 0.45, 1.25, and 0.76 g m-2 min-1 in the sandy, sandy-loam and clayey soil specimens, respectively. Percentages of clay and silt in the eroded material were higher than in the bulk samples. Three stages to describe the changes in nature and effects of crusts during their formation are suggested: (1) the rate of infiltration decreases to a point at which runoff beings, (2) the initiation of runoff until infiltration and runoff rates become stabilized, and (3) infiltration and runoff maintain steady rates. © 1984.
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