It depends on the soil as mentioned. You can figure 20-35 hp per bottom for a plow, and about the same for a ripper shank - one tends to go deeper with a ripper & might hit a good hard plowpan, which takes power.
Both take traction, ag tires work, the industrial type like to spin. So there are several factors, tires, ground type, size of the implement.
But, with 50 hp you should find something to match your conditions.
I'm in Minnesota, so I understand the other person's comment on the tough soils needing more power/traction here than many other places!
--->Paul