Force requirements and soil disruption of straight and bent leg subsoilers for conservation tillage systems

In conservation tillage systems, belowground soil disruption should be maximized while aboveground disruption should be minimized. To assist in choosing the best shank for strip-tillage systems, comparisons among several shanks commonly used to provide in-row subsoiling prior to planting in conservation systems were made. A three-dimensional dynamometer measured draft, vertical, and side forces for the experiments, which were conducted in the USDA-ARS National Soil Dynamics Laboratory soil bins in Auburn, Alabama. A portable tillage profiler measured both above- and belowground soil disruption. Two parameters, spoil resistance index and trench specific resistance, were developed from the data to assess draft force, aboveground soil disruption and belowground soil disruption. Based on these selection criteria, the two best shanks for conservation tillage systems were the Bigham Brothers Paratill shank and the Worksaver Terramax shank, both of which were bentleg shanks.