When I was a kid, we would keep plywood or black plastic in our "natural" worm harvesting area to charm them more easily. An occasional sprinkle of corn meal for food and the moisture from the covering made a couple minutes of tapping bring up dozens of red wigglers and night crawlers.
We did something similar. Except in the center of our harvest area, My grandfather had driven a steel T-Post deep into the ground. It was at least 4 feet deep. We would peel the tarp or plastic back to "Feed" the worms. When we wanted to go fishing, we would peel back the plactic and tale turns tapping the post with a small hammer. Then we got smarter and would take a short piece of pipe and run it up and down the side of the post (rough side). Unless the ground was really dry for a extended time, this usually worked. If that didn't work we would break out 2 copper rods, drive them into the ground and hook them up to a old telephone crank, and start "Calling" them up.
