PROBLEM TO BE SOLVED: To improve soil in a field where substratum soil is superior in quality to topsoil, and soil in a field where impoverishment of topsoil has reached an advanced state, using a working machine.SOLUTION: A plurality of sets of subtillage bottoms 5 and surface tillage bottoms 6 set in two tilling depth stages are equipped to improve efficiency in field soil improvement work, to reduce a work cost by shortening working hours, and to make the tilling depth shallow. Even a tractor with less traction force can thereby perform soil improvement work.COPYRIGHT: (C)2013,JPO&INPIT【課題】下層土壌の土質が表土より優れている圃場の場合や、表土の疲弊が進んでいる圃場の土壌を作業機を利用して土壌改良する。【解決手段】耕深を2段に設定した心土耕起用ボトム5と表土耕起用ボトム6を複数組装備することで圃場の土壌改良作業の効率化を向上し、作業時間の短縮で作業コストを軽減し、耕深を浅くして、より牽引力の少ないトラクタでも土壌改良作業を行うことを可能にする。【選択図】図1
