傾斜農地の侵食に関する研究(II) : 傾斜農地におけるウネの土壌侵食について

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In general, the direction of ridge in sloped farmland has been making a parallel (contour ridge) or right angle(up-down ridge) with the contour line. The contour ridge is tillage method for privention of soil erosion by rain-water in sloped farmland. But, the contour ridge occure greater soil erosion than the up-down ridge in case of heavy rainfall. This reports are discussed mechanism of soil erosion of the contour ridge. The main points of result obtained are as follows :
(1) The contour ridge does not get soil erosion when it be able to store rainwater between ridges. (2) Soil erosion of the contour ridge is occured by break of ridge because store of rain-water between ridges overflows its ridge. (3) A location of break shows a pattern of zigzag for direction of slope. These results will be of use the planning for land reclamation or soil and water comservation.