Using Worm Castings as Sole Source Compost

I've spent at least 30 minutes on this reply in the Topic "Hello, from the Shenandoah Calley, VA!". I don't want to hijack that thread as this has to do with using worm castings as the only compost source.

I'm too new to be able to comment on worm casting except to use them as one ingredient of the blended compost. I'm just sharing the following experience.

There is an organic farm near Paso Robles, CA, that uses ONLY worm castings. I wish I had saved their brochure. They had a stand at the San Luis Obispo Farmer's Market where we bought a bag of their worm castings and 4 artichokes. The next day, we visited the farm on our way home

No pesticides or weeding. They have a 40-60' long, 3-4' deep, concrete worm bin where they feed the worms with their compost. To harvest, side panels are opened, the bulk compost lifted (with small tractor fork?) and the lower worms and castings removed. Worms are saved and put back with the compost. Major worm operation.

Produce is grown on mounded rows of castings on the ground both outside and inside the long greenhouses. There are weeds but they don't weed. Good and bad insects and bees galore as the doors are left open. I couldn't help but think "Now, if they only had SFG raised beds . . ." The roots of the produce are in both the top castings and the ground soil below. So, I consider their castings as an organic fertilizer and soil conditioner.

Idea for an Experiment - and don't look at me to do it! I have no spare castings!:

If someone out there with lots of worm castings could do an experiment in a 1'x1' box with a weed cloth bottom, using peat moss, vermiculite and only worm castings as the MM, we could find out if castings are a complete compost. I would say the experiment should go for a few re-plantings with only castings used to replenish the nutrients. I personally prefer the idea of using green and brown plant composts and herbivore manure composts with the worm compost. No facts or experience, just a feeling.

Hi sanderson,
I don't have any thing to go on, for I do not know if the worm castings have enough nutrients to support a garden by itself.
All I can say is that there are too many/wrong nutrients for African violets by using worm castings alone. The recipe for Violet planting medium-2 pt. vermiculite, 2 pt. peat moss, 1pt worm castings. I thought I'd be smart and since I had plenty of castings, I used straight worm castings, and the violets wilted bad, and I lost a few before I caught it.
My opinion: Don't try to fix something that's not broke.
Jo

I do believe this question was answered in the 1,000 Worms on the Way thread. If I remember correctly, it was advised that worm castings are a type of fertilizer and not considered actual compost, despite the vermicompost label.

From what I have read, worm castings should be no more than 20% of compost.
There was an experiment using various percentages of worm castings, and the 100% came off the worst. There were pictures of plants for comparison.
Llama Momma is more expert than I, so I am sure she will chip in with the source.
If she doesn't, I will search for it, it is about time I did some work on this forum.  

This is the thread that I had read that my comment in Hello from the Shenandoah Valley thread was based on: Does this Worm Compost count as two of the 5 Mel's Mix Compost sources? about half way down the page you will find a conversation in which Llama momma discussed the salt content of worm castings and a book that quotes the OSU study that her info was based on.