I'm a little slow joining this discussion - I never till anything. When building a new garden, we just build it right on top of the sod! We put thick layers of old black and white newspaper down, then soil, leaves, straw, grass clippings, compost, manure, etc. on for a year or so in the outline that we plan to garden. By the time the newspaper has decomposed, the sod underneath has decomposed as well and turned into it's own compost! We then plant, and continue year after year to add mulch of the above items, and have gorgeous lush gardens.
I began this way, because about ten years ago, the disks in my back began degenerating so badly that I could not do alot of digging. The things we discover when we have to rethink the way we do things!
VAL (Grandpa's Rose)