Question
The soil of my land is of old volcanic origin, in some places rather reddish brown, in others just brown, is poor, acid and well draining, sometimes it can get quiet dry, but with plenty of organic matter, mulch on top. I also applied the from the agricultural laboratory, based on a soil analysis recommended quantity of calcified seaweed to adjust the ph to a neutral level and added the reqired amount of potassium and phosphorus. However I rarely see any worms, which are supposed to live from organic material and to be essential in the fertility and health of the soil. They do not mix the mineral soil with the organic parts and do not transform much of the latter into for the plants absorbable matter, like I have seen it in other soils. Could it be that I do not have the right species of worms or is there another soil amendment required.
Alternatively I would also appreciate it very much, if you could send me a contact, where I can get the needed information.

Answer
Hi Vital, The only thing that stands out to me in your comments is the statement "it can get quite dry".  Moisture is critical for worms and they die or "move" to a more suitable environment if it's not right.
I'd continue to add more organic matter to improve the texture and moisture retention and bi-monthly I'd feed the worms with a dusting of corn meal over the area.
Don't let the area get too dry.
As far as the species, try to collect some locally.  Many of the worms sold in bait shops where I live do not survive in our soils.  Jim