Dobson also says you should have an implement of discipline after the toddler years.
I spank. I'm reluctant to use a belt if need be when he is older. I never used anything but my hand on my girls...rarely, they simply didn't need it. Ping pong paddles used to be in frequent use when I was a boy, of course back then we didn't have all this touchy feely stuff about spanking. Everyone was spanked or worse...except maybe really meek little girls or very sissy little boys.
When my girl was little, the shoe stores gave out balloons on plasticised rope-sticks. Those were great as a rod. Very flexible, not too thick, and they didn't get brittle with age. My second choice was an appropriately sized branch from a tree. Do file off the rough places, though.
I would never use my hands to hit a child. Never.
And I would never use a belt, or anything other than what God tells us to use. A rod.
A rod will never leave any lasting injuries, no matter how hard you hit with it (as long as you only hit on the fleshy part of the buttocks.)
Get a copy of Fugate's book, What the Bible Says about Child Training. He makes a great deal of sense and lays out the entire plan for child training, not just the part about the rod.