PROBLEM TO BE SOLVED: To suppress entering of mud on cultivated field from opening of longitudinal path and closing of the longitudinal path due to narrow mud port on inner surface of the longitudinal path by the presence of chaff since a chaff charging mechanism capable of charging chaff into the longitudinal path is arranged so that the chaff may be charged to the longitudinal path by the chaff charging mechanism and the chaff is stuffed in the longitudinal path.SOLUTION: A machine frame 3 is jointed to a traveling machine 1 by a joint mechanism 2. A puncture beam 4 is longitudinally arranged on the machine frame in a swingable manner in moving direction by a swing mechanism 5. An extension member 14 is arranged at rear position in moving direction of the puncture beam, which may extend side surface of puncture trace groove S formed by the puncture beam in cultivated field W in an extended manner in vertical direction to form longitudinal path T opening to ground surface M. An extension mechanism 15 extending the extension member is arranged. A chaff charging mechanism 25 capable of charging chaff C into the longitudinal path is arranged.SELECTED DRAWING: Figure 2
