Soil moisture effects on energy requirements and soil disruption of subsoiling a coastal plains soil

ABSTRACT. An experiment was conducted to determine the optimum moisture content to subsoil based on tillage forces and soil disruption. Two different shanks, a straight shank and a “minimum−tillage ” shank, were tested in a Coastal Plain soil in the soil bins of the National Soil Dynamics Laboratory in Auburn, Alabama. A three−dimensional dynamometer measured tillage forces, and a laser profilometer measured soil disruption. Tillage forces and soil disruption measured in the driest soil condition were greatest. The “minimum−tillage ” shank required more energy and disrupted less surface soil than the straight shank. An index, the trench specific resistance (TSR), was developed to aid in determining the minimum amount of draft force necessary for maximally disrupting a deeper soil profile. Reduced values of TSR were found for the straight shank compared to the “minimum−tillage ” shank, as minimum draft produced maximum soil disturbance. Reduced values of TSR were also found for subsoiling operations conducted at all soil conditions other than the driest. Based on this research, subsoiling should not be conducted at the extreme driest soil condition due to increased draft forces and increased aboveground soil disruption