Abstract
Reducing energy use in soil preparation has become increasingly important since it is a major cost in planting. Experiments were conducted with a combined tillage implement consisting of a subsoiler and a rotary harrow to reduce the cost due to step reduction in soil preparation. Three tillage operations, two forward speeds, and two rotational rotor speeds were determined as input factors in this study. Soil clod size, performance parameters, and the specific energy requirements of a combined tillage implement were investigated. The field experiments were using two different soil conditions. Increasing the rotor speed from 299 to 526 rpm decreased the mean soil clod diameter at a depth of 0-200 mm from 22.98 to 19.83 mm and from 31.77 to 26.57 mm for fields 1 and 2, respectively. The specific energy requirement was affected significantly by rotor speed and tillage operation. The specific energy requirements for the combined tillage implement with an on-frame pivot joint and an onpivotable-shank joint were less by 10.4 and 21.1% and by 18.4 and 24.7%, for fields 1 and 2, respectively, compared to the total power requirement for the separate use of a subsoiler and a rotary harrow.
