Field scale tests of the modified moldboard plow

In 1989-90 four trials were conducted in southwestern Ontario to study the effect of moldboard modifications on the field scale residue management potential of the moldboard plough. It was found that when using a European type plough set at narrower bottoms (30.5 cm) and a ploughing depth of 15.2 - 19.0 cm there was no advantage to modifying the moldboard shape on the amount of residue remaining on the surface in a loam to silty clay soil texture. When using the same type of plough at wider bottom widths (40.6 cm) and a ploughing depth of 19.0 cm, the amount of residue left on the surface in a silt loam soil tended to increase as a greater portion of the moldboard was removed. Those sites which used the narrower bottoms left between 16 and 25 percent residue on the soil surface after spring run-off while only the 3rd cut treatments using the wider bottoms left residue amounts similar to these levels. In general, there were no consistent significant differences in subsequent soybean plant growth and seed yield among the treatments at the different sites in the growing season following fall treatment application.