PROBLEM TO BE SOLVED: To improve draining, water management, well draining on a paddy field surface, activation of microbes breeding, and growth of a deep part of a root of paddy rice, which can be attained in a manner that, because water on a field surface reaches a culvert from an opening of a penetration mark groove and a vertical port passage via a digging groove, and thereby a distance from the field surface to the culvert is reduced.SOLUTION: The culvert forming device includes: a machine frame 4 arranged on an attachment frame 3 with a pivotal attachment mechanism 5 so as to be freely rotated horizontally a penetration beam 6 vertically arranged on the machine frame so as to be oscillatingly operated in a travel direction a bullet body 18 arranged on a lower part of the penetration beam and capable of forming a culvert H an expansion member 19 arranged on the machine frame, capable of forming a vertical port passage T by expanding a side face of a penetration mark groove S formed by the penetration beam and extended in a vertical direction in a field soil W and opened on a ground surface M an expansion mechanism 20 for forcibly expansion-operating the expansion member and a plow member 28 arranged on the machine frame, for scooping the field soil to be discharged to a lateral side, and thereby forming a digging groove U at a vertical port passage formation position D.SELECTED DRAWING: Figure 16COPYRIGHT: (C)2016,JPO&INPIT【課題】圃場表面の水は掘取溝を介して穿入跡溝及び縦口路の開口から暗渠に至ることになり、圃場の地表面から暗渠までの距離も短くなり、水はけの良化、水管理、田面の乾田化、微生物繁殖の活性化、水稲等の根の深部への生育を良化することができる。【解決手段】取付枠3に機枠4を枢着機構5により水平旋回自在に設け、機枠に穿入ビーム6を進行方向に揺振動作自在に縦設し、穿入ビームの下部に暗渠Hを形成可能な弾丸体18を配設し、機枠に穿入ビームにより圃場土中Wの上下方向に延びて形成される穿入跡溝Sの側面を拡張して地表面Mに開口する縦口路Tを形成可能な拡張部材19を配設し、拡張部材を強制拡張動作させる拡張機構20を設けてなり、上記機枠に圃場の土を掬い取って側方に排出して縦口路形成位置Dに掘取溝Uを形成可能なすき部材28を設けてなる。【選択図】図16
