1992 Fiscal Year Final Research Report Summary
Internal Soil Erosion and Soil Properties
| Project/Area Number |
02454087
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
農業土木
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| Research Institution | MIYAZAKI UNIVERSITY |
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Principal Investigator |
HOSOYAMADA Kenzou MIYAZAKI, Univ. Agriculture, Professor, 農学部, 教授 (10040833)
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| Co-Investigator(Kenkyū-buntansha) |
KUSAKA T YAMAGUTI Univ. Agriculture, Professor, 農学部, 教授 (50038238)
TOYOMITU Y MIYAZAKI Univ. Agriculture, Assis.Prof., 農学部, 助手 (70197979)
MUTO I MIYAZAKI Univ. Agriculture, Asso.Prof., 農学部, 助教授 (70040863)
AKIYOSI Y MIYAZAKI Univ. Agriculture, Asso.Prof., 農学部, 助教授 (30041031)
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| Project Period (FY) |
1990 – 1992
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| Keywords | Soil Erosion / Intensity of Rainfall / Topography / Surface Water Flow / Physical Properties of Soil |
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| Research Abstract |
Several kinds of experiment on soil erosion carried out using the soil erosion test fields. For Masa soil having high gravel content, it was confirmed that only a fine surface soil in about 1cm layer flew down as falling energy of rain and surface runoff leaving behind coarse gravels on top of the surface, therefore resulting little soil loss. From the result of the laboratory experiment, it was recognized that at about 1cm below surface layer of Masa soil, fine soil particles layer was accumulated known as the soil crust.
For the soil erosion tests on ridging using Kuroboku soil, it was resulted that the ratio for the amount of soil erosion loss were 1.4 in longitudinal ridging, 0.06 in horizontal ridging, 1.6 (indeterminable value) in diagonal ridging.
From the erosion tests of Shirasu soil, it cleared that the erodibility of Shirasu is high and erosion through ditches occurred easily, and the netting (4mm-2mm mesh) on soil surface brings the reduction of soil loss of 1/2 - 1/10. Scattering gravels on soil surface reduces the soil loss of 1/30.
The mechanism of soil erosion for Masa soil originating in soil compaction and surface flow was investigated and following results were obtained.
The increasing of the tractive force is accompanied with the progressing of surface flow and brings soil erosion more. But, on the contrary, when the erosion ditches(micro rill) are formed and water flow converges and the tractive force acts only on erosion ditches, soil erosion loss decreases. When surface flow is relatively high, then erosion on the ditches occurs in every dry density, but when surface flow is low, 1)in case of low dry density, there are no formation of erosion ditches being able to recognize, and 2)in case of high dry density it was found that the tractive force was evenly high and many micro rills formed looks like net.
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