PROBLEM TO BE SOLVED: To provide a sowing groove widening device in which large size seed such as soybean can be sown in a position close to the bottom of a sowing groove by using a grooving ring for direct sowing of small size seed such as rice or wheat.SOLUTION: A direct sowing machine includes a grooving device having many grooving rings, and a sowing device for respectively supplying seed S in the bottom of each sowing groove V having a sharp V-shaped cross section immediately after being formed by each grooving ring on a field surface through a seeding hose. The direct sowing machine is configured such that a rod-like sowing groove widening tool for forming a sowing groove widened portion Va with a widened portion close to the bottom of the sowing groove V is disposed between the grooving ring of the grooving device and the seeding hose of the sowing device in order to sow large size seed S being sown while being caught in the middle of a sowing groove V in a position close to the bottom of sowing groove V.SELECTED DRAWING: Figure 13【課題】米、麦等の小サイズの種子の直播き用の作溝輪を用いて、大豆等の大サイズの種子を播種溝の底部に近い位置に播種させることができる播種溝拡幅装置を提供する。【解決手段】多数の作溝輪を有する作溝装置と、前記各作溝輪により圃場面に形成された直後の鋭いＶ字状の横断面を有する各播種溝Ｖの底部に播種ホースを介してそれぞれ種子Ｓを供給する播種装置とを備えた直播機において、前記播種溝Ｖの途中に引っ掛かった状態で播種される大サイズの種子Ｓを、当該播種溝Ｖの底部に近い位置に播種可能にすべく、当該播種溝Ｖの底部に近い部分が拡幅された播種溝拡幅部Ｖａを形成する棒状の播種溝拡幅具が、前記作溝装置の作溝輪と前記播種装置の播種ホースとの間に配置された構成とする。【選択図】図１３
