A mechanism for protecting agricultural sources in order to increase and stabilizing of agricultural production and environmental protection is conservation agriculture. Intensive soil loosening and moldboard Plowing expose the soil to severe erosion. Leaving crop residues on the soil surface prevent it from the direct impact of raindro minimize surface runoff and condensation and increase the water permeability. Conservation tillage systems are usually implemented and developed in arid and semiarid regions. In primary tests, the performance of seven types of tip with different shape were studied by measuring draft, disturbed cross sectional area, specific draft and percentage of clod mean weight. The cone tip with head angle 45, width 45 mm and protruding distance 20 mm was chosen as the optimum tip. In this research, the field performance of a conservation sub-surface tillage tool named single bent blade sub-surface tillage tool was evaluated. For this purpose, four different single bent blade sub-surface tillage with different blades width (250 mm ¬ 350 mm) and with and without a tip of the wedge were designed and constructed. The sub-surface tillage tools were evaluated and compared with a winged chisel tine (control) in a clay loam soil at three water contents (0.5 PL, 0.7 PL and 0.9 PL; Plastic limit) using a randomized complete block design at Isfahan University of Technology Research Farm. Draft, specific draft, cross-sectional area of disturbed soil, soil up-heaving area, clod mean weight diameter (MWD), surface residue cover, and water infiltration rate were measured after tillage. The lowest mean draft of single bent blade sub-surface tillage tool was obtained at tip blade 250 mm and without tip. By increasing the width blade and adding the tip, the drafts sub-surface tillage tools were increased, but this increase was not significant. The draft of the control was significantly higher than all treatments. In single bent-blade sub-surface tillage tools, the soil failure was initiated from the side edges of the blades and therefore was perpendicular to the direction of the travel. This resulted in wider soil disturbance area as compared with the control. Depth and soil moisture had a significant influence on the soil disturbance area. The highest area of the disturbed soil was obtained with the single bent blade sub-surface tillage tool with 350 mm blades width and with tip .The specific draft was affected by the wedge tip and by adding the wedge tip the specific draft increased. The least specific draft, which means more soil loosening efficiency, was occurred in 350 mm blades width and with tip. The specific draft of the control tool was significantly higher than the sub-surface tillage tools. Adding the tip had significantly effects on MWD. The MWD in sub-surface tillage tools with tip was significantly less than the tipped ones. The highest MWD was at two blades width 250 and 350 mm and with tip. The MWD of all sub-surface tillage tools was significantly lower than the control. The surface residue cover with the control tool was significantly lower than the sub-surface tillage tools. The effect of adding the tip on soil up-heaving was significant and increased by adding tip. The infiltration rate in tillage tine with cone tip was clearly less than the tine without the tip. The lowest speed of infiltration rate was observed in the tine with cone tip and width 25 mm; the maximum was in the tine without the cone tip and width 35 mm. The infiltration rate in the control was significantly higher than all of the other treatment were. The sub-surface tillage tool with blades width 350 mm and tip having a significantly lower draft and MWD and higher surface residue cover could be suggested as the best alternative for the winged chisel tool in conservation tillage system.