To provide a water circulation system which is capable of promoting root growth of rice fields and Hasuda. A Place the header tube 2 and the steam-water mixer 6 to a position above the water surface of the field 1, connecting the pump 3 and the steam-water mixer 6 of water fields through the connecting pipe 4 It is to be connected to the header pipe ends of the gas-water mixer via a T-joint 10. Then, it supplies the water containing dissolved oxygen into fields of a plurality of supply pipes 5 of the header pipe. Gas-water mixer, a throttle portion which in cross-section on the downstream side is narrowed gradually and on the enlarged part cross-section downstream of the throttle portion is enlarged gradually is provided, the position where the flow passage cross section of the narrowed portion is minimized, feed One end of pores 9 communicates, feed holes are open to the atmosphere.BACKGROUND 1【課題】稲田や蓮田の根の成長を促進させることができる水循環装置を提供する。【解決手段】田1の水面より上方位置にヘッダ管2と気水混合器6を配置し、田の水中のポンプ3と気水混合器6とを接続配管4を介して連結し、気水混合器の端部をT字継手10を介してヘッダ管に連結する。そして、ヘッダ管の複数の供給管5から溶存酸素を含む水を田に供給する。気水混合器は、下流側に断面が次第に絞られる絞り部と、絞り部の下流側に断面が次第に拡大する拡大部とが設けられ、絞り部の流路断面が最小となる位置に、給気孔9の一端が連通すると共に、給気孔が大気に開口されている。【選択図】図1
