This is a personal opinion and goes against everything I have read on the net about worm castings.
Please note that I am only addressing worm castings, not worms in the soil.
I don't think worm castings add any benefit to the soil. It is the worms and the organic materials added to the soil to feed the worms that provide the benefit of vermicomposting.
When I started my garden in 2004, my soil was totally dead. It consisted of tightly compressed small rocks with clay and silt between them. I could not dig in the stuff. I used a no-till gardening approach to develop the garden. Since the house pad garden was cut out of a rocky slope and was located about four feet down from what would have been the natural surface of the soil, I was actually gardening in rocky subsoil with no plant organic materials in it. There were no worms and I could not see the strands of white fungi one finds in healthier soils.
However, I did have, and still do have, perfect drainage.
I have come to believe that gardening often consists of compensating for what Nature did not put in the artificial environments we are creating when we develop our gardens.
Over the years of constantly adding new mulch, at least twice a year, which decomposed quite rapidly in the high temps of my summer, the humic acid, which is a by-product of organic material decomposing, has broken down the rocks that were the primary component of my soil. A few years ago, I went to plant some bulbs and found that I could dig in the beds I had been mulching with a trowel. No rocks. I found lots and lots of worms and the missing strands of fungi.
I've compensated for the lack of nitrogen by using chemical fertilizers. I found I could use lower number fertilizers as time went on and the soil became healthier.
At no time did I add worms or worm castings.
When I searched for published research on worm castings, every study I found talked about the addition of worms and materials to feed the worms ... vermicomposting ... as adding great benefit to the soil. None of them addressed only worm castings.
It's possible that worm castings may improve the structure of the soil, but I doubt if they provide any other benefit. This is just from observation in my own garden, so I really don't know if I am correct.
@Rascal. I noticed that you joined ATP just a couple of weeks ago.
You may be interested in visiting the Permaculture Forum (
http://garden.org/forums/view/... ), or The Soil and Copmpost Forum (
http://garden.org/forums /view/compost/ )
I think you will enjoy ATP.
