Since 1994 we have used this tool for our primary tillage. It is a Sundance Disk and works by peeling open the bed, shallow cultivation and then hilling  the soil back onto the bed. This keeps the nutrient rich top soil where it belongs near the surface. It also allows us to reduce the number of times the tractor passes through the field to prepare for the following crop. The beds remain in the same place each year so we do not need to 'rip' the field to remove the tractor paths from the previous crop. It works better for us every year. This is due to the increased organic matter of our soil and our tractors and drivers are getting better at keeping the disk on the bed.