Agree a disc drill wouldn't be my choice, sweep wing cultivators are shocking for lifting stone to the surface... looks like they want ploughing down, maybe a carrier type disc cultivator and tine drill, else most of the seed will be on the surfaceHow will a disc bury them? A tine or a suffolk coulter is only running at derilling depth, and pushes stones out of the way, dropping seed as it goes. A drilling disc mostly rides over the stones. A convex cultivating disc might go some way to burying them, but thats not the type found on a drill