Quite a few years ago we used a chisel plow spike that was made out of angle iron. That shape naturally kept its point as it wore down and the fields were very smooth to drive across. But even with the four inch model, it would not bury much trash. Back then we were wanting a lot less trash on top so we did not purchase them again.
Now with the equipment I farm with today I think I would like to try them again. It seems to me they were made in a machine shop in the upper Midwest somewhere. They even had come out with an angle iron sweep. The paint they used on them was a sort of turquoise blue.
If anyone knows the number or name of the place, I would like to see if they still have a few around or still would manufacture on a small batch basis.