Tim R wrote:
http://ecosystems.serc.si.edu/earthworm-invaders/

That's an interesting link. I'm not in an old-forest area, so environmental disruption isn't an issue.

But, as others point out, there are a few worms around. If there aren't more, it's not because something
is wrong with the worms. The environment is wrong, most likely moisture. Drip irrigation will help a little,
but it's impractical to raise the soil moisture significantly.

Looks like the best course is to wait and watch, and dry to devise a tool to efficiently bury dripline.

Thanks to all for your thoughts,

bob prohaska