Design of a model 'spot plough' for inversion of the soil slice within thefurrow

A model spot plough to invert the soil slice within its own furrow was desi gned and tested in a soil bin, with a view to overcoming the disadvantages of conventional tillage systems with mouldboard ploughs. The model was espe cially designed to avoid soil clogging, whilst the basic structure was not altered from that surveyed from previous research. Followed by the share an d main mouldboard at the beginning of the inversion, a tilted disc coulter (TDC) was located on the other side of the main mouldboard to assist the sp ot inversion and to reduce relative motion to the soil. Towards the end, th e tilted disc coulter was replaced by a sub-mouldboard. Optimum width-to-de pth ratio and width of the mouldboards were also considered. The mouldboard s were expressed as helicoidal surfaces, and were fabricated from a plate o f polyvinyl chloride. A series of experiments showed that the model spot pl ough performed well in wet-plastic soil, acceptably in dry-powdery soil at higher speed, and somewhat less steadily in dry-solid soil conditions. In a ny soil condition, the function of the rotating tilted disc coulter was fou nd to be essential for stable operation. (C) 2001 Silsoe Research Institute .