Minimum tillage systems can possibly reduce soil erosion, conserve soil moisture, and also minimize labor and fuel consumption. To validate the effects of rice crop residues on drill performance, several field trials of four different slot openers were carried out to evaluate their drill performance on sandy loam soil with four different levels of residue density (0, 2, 4, 6t/ha) and three levels of soil moisture content (45%, 50%, 55% d.b.). The seeding of the drill operation was done with four models including a bubble coulter, a V-shaped slot opener, a VRA-slot opener and a VRB-slot opener. Field evaluations of these slot openers have been studied comparatively with regard to their slot formations, which are affected by the residue densities and the soil hardness in the influential zone that is near the bottom of each slot. Significant interactions between the residue density, the soil moisture content and the effects of residue densities have been discussed for each slot opener. In particular, soil penetration resistance tended to increase after the operations of a bubble coulter and a V-shaped slot opener under entire combinations of residue density. In terms of prediction, no significant effects of residue densities were found in the case of a VRA-slot opener and a VRB-slot opener. These two slot openers not only acted effectively to remove the residues prior to the seeding process but also confirmed the importance of a favorable slot profile preparation for stable plant growth.