I just added a generous serving of greensand and Azomite. Not sure if that counts as adding grit. I think it does. My population went from a pound to five pounds without any. I feel the greensand an Azomite and rockdust if I had some would be better able to share it's goodness if it was incorporated into the worm castings. A better use of it might be in the animal feed or as bird dust bath or a bit in the stall bedding mix. Same with biochar. But I do not have animals or birds. We will see if Miracle's happen. ... ... ... How long do I have to wait?

"My population went from a pound to five pounds without any." Without any what......?

If it went from 1 to 5 pounds it's doing real good without it.

This is some of what he had to say in the email...

Hi David,

Some of our vermicompost producers use it in the bedding while others mix it in with the finished product (and some do both). I would encourage you to try some controlled experiments with it either in the bedding and/or finished product vs. non-mineralized castings to note any differences in germination rates, foliar development, root development, pest resistance, etc. You may also want to see if you notice any improvements in reproductive rates among the worms as well. I also appreciate your offer to spread the word if you like how our Andesite performs.

Andesite is rock dust mineral. I was just wondering if anyone here has tried it in their bins.

I add some rock dust with each feeding. Since I feed composted cow manure, I want to make sure the little guys have some grist for the digestion process. I'm sure it would be helpful to the final product, but my interest is the health of the worms.

We feed pulverized eggshells for the calcium, but the rock dust is consistently finer and I think that matters for grist material. I started the rock dust add after reading "Worms Eat My Garbage". UC Davis recommends a handful of soil every couple of months for grist, but I still like the rock dust for consistently small particle size. A back of envelope calculation is that the rock dust adds about 10 cents to the cost of each cubic foot of finished castings.

I too am curious about rock dust in the worm bin. I know more of the nutrients and elements and microbes as they interact with specific bacteria in the dirt or rhizosphere of the plant root, but far less about how the elements/nutrients interact with microbes in the worm bin or in the worm. I have found that azomite makes a big difference in the taste of tomatoes and other plant health when added to the soil, but is it safe? I've heard critics said that its somewhat radioactive and therefore carcinogenic. I have no idea of the degree of truth to that. The azomite website says that it does contain a fair bit of lead. I generally like the idea of feeding what I can through the worm bin rather than adding it directly to the soil. I generally try to only add aerated worm compost tea and worm castings to my soil and plants... and it seems that the quality of the worm compost is directly related to the diversity of the microbes in it, which is directly related to the quality and diversity of the materials those microbes feed on. So it stands to reason that perhaps the added minerals and elements from azomite could be useful to the worms and the microbes they interact with. Unless there is something harmful or inhibitive in it. But I seriously don't know and haven't read studies on it.

I sure would like to know more.

Sweetland....Did "Worms Eat My Garbage" recommend rock dust? If so did it give any recommendations about what kind, quantity and frequency? Or information about which elements were useful or counterproductive?

Yes. The book recommended rock dust but did not give any information on rate or quantity to feed, nor on a specific brand. I chose rock dust from a glacial source assuming that would give the maximum of trace minerals - found it on Planet Natural web site. I use a baby food jar and feed 1/4 of a jar to every 6 bins (bins are 4'x4') along with 1/4 of a jar of powdered limestone (calcium carbonate) with a feed rate of every 2 weeks. I am following the "sounds good, let's try this" theory.