The color of castings

[mikej]

I was looking at my harvested vermicompost yesterday and realized it was brown, not the rich black color I would expect. I'm not sure what this means. Did I harvest it too soon? I harvest when there are no recognizable remains of the original bedding and the bin seems full of fairly dense, almost mud-like material that I have been assuming was castings.

My bins are rubbermaid totes. My bedding is a mix of shredded leaves and shredded cardboard. I put food scraps on the surface and cover it with sheets of damp newspaper. I replace the newspaper as the worm eat it.

[Darryl]

Mike, personally I have never ran across that situation but then again, I am not holding my breath either as dealing with worms definately produces some odd results and unexpected circumstances at times. The quality of vermipost is in direct proportion to the types of feed that the worms ingest, including bedding. I have closely watched bins process before and as time goes on I notice the castings becoming darker and darker. I have harvested lots of castings in my day and they are always a rich black. Someone other than myself, with more knowledge of worm byproducts should reply to this post.

[theinfamousj]

For what it is worth, I'm on my first bin ever and it is approaching harvest time. My castings are most definatley a nice gray color. I figure that's because soldier fly larvae (who do produce gray castings, I've noticed) have dominated this bin, though my worms are quickly catching up.

[mikej]

I was working in the yard and found a couple of trash bags with some of my older castings. They were darker than my more recent castings which are more the color of mud.

So, thinking back, I realized that the recent castings were made with a bed of a 50/50 mix of garden compost and shredded cardboard. Previously I had used a bedding mix of compost and shredded newspaper. Last summer I put a bunch of cabinets in the garage and had tons of cardboard. I shredded it and started using it in my bins.

Is it possible the change in bedding material made such a noticeable difference in the color of the castings? I need to experiment. I need to start 2 bins at the same time, one with the cardboard/compost mix and the other with the newspaper/compost mix.

[theinfamousj]

Mike,

If you do that, I think you will become our resident expert on casting color.

[JudyA]

In the very first bin I ever had with redworms, they were so pleased with the newspapers in the bedding that they made gray fuzzy castings. For while I thought they were just shredding it finer. Have never had papers do that since.

[redhen]

The ENC's I have had came originally in pulverized paper bedding that was a light gray color. The castings in those bins were a gray color..at first. After some time (being fed produce and with shredded newspaper for bedding) the castings in the lower bin have darkened. All my other bins of EF's have always been fed produce and shredded newspaper/junk mail for bedding. Those castings are dark and also get darker with aging. If I put Starbucks in there, those castings are almost black. I am thinking it's like my Gma said.."you are what you eat!"

[mikej]

The experiment is on!
I harvested 2 bins yesterday and restarted them with fresh bedding. One bin has all cardboard bedding, the other has all shredded newspaper. Both bins also got several large handfuls of compost that I skimmed off the top of the harvested bins. The skimmed compost contains castings plus the remaining kitchen scraps that the worms didn't get to yet.

I surface feed my bins and cover the scraps with sheets of dampened newspaper. This means there will be some newspaper added to the cardboard bin but it will not be enough to affect the outcome. I base this on the fact that this is the same procedure I have used all along, including the bins that came out with mud colored castings.

Also, I will not add coffee grounds to either bin. Grounds seem to darken the castings and I want to isolate this to just the affects of the main bedding ingredient.

I'm sure the true scientists out there could find several faults with my setup but that's OK. This is just a hobby for me. It will answer my question and satisfy my curiosity.

[redhen]

I love experimenting and will look forward to an update

[Jay Blair]

Casting colors depends on the feed mix used. I have found grass wastes produce the lightest color castings. leaf mold produces a darker hue and vegetable , meat and manure slurry produces the darkest castings.

By pre digesting all wastes through a methane gas digester, the resulting feed sludge I put into the bins of newspaper and leaf mold bedding yields dark castings.

Here are some free online plans of methane digesters. The plans and photos the author provides below are nicely detailed and can be size customized to your requirements.

biorealis.com/digester/construction.html


You can use PVC glue and screw fittings to avoid the need of a plastics welder.

The Journey to Forever Project has the following text in their online reference library on methane digestion on a larger scale.

journeytoforever.org/biofuel_library/MethaneDigesters/MDToC.html




* Please note, I edited this post to remove my reference to use of a now unavailable furniture stripper as a possible plastics fusing agent. See post #14 for detailed explanation.

[mikej]

My wife doesn't actually understand my interest in worms but at least she seems to have resigned herself to it. I don't think she would be so understanding about a methane digester in the back yard. I'm sitting here chuckling as I picture the look on her face as I try to explain the idea.

I don't think we can eliminate the bedding composition as a contributor to the final color. I have been using kitchen scraps for quite a while as my main feedstock. About 2 batches ago I switched from shredded newspaper to shredded cardboard as the primary bedding material. There is a definite difference in the color between the recent castings and the older castings.

Unfortunately I can't say what else might be a factor. For example, over time I have also added coffee grounds, steer manure (bagged from the hardware store ), shredded leaves, etc. So this is my first attempt at a somewhat controlled experiment.

As a final thought - I am the only user of my castings so I don't really care about the color. In the back of my mind I have the idea that some day I might expand a little and start to sell bags at the local farmer's market. I suspect that from the perspective of potential customers, a darker casting will be more appealing than a lighter casting. Jay, you sell castings, don't you? Do you have any thoughts on this aspect of castings?

[tt]

just bagging casting now -got a home bag sealer to start with and it is working well. looks quite good actulally

[Jay Blair]

Mike ,
As you mentioned, the darker the castings the more appealing they are to most users.

I now only generate small quantities for my own use from the 8 bins I have and feed household scraps and scraps that are harvested from my garden mixed with water oak leaf mold .

I only use about 20 % by volume of shredded paper. This I add as a visual finishing indicator.

While worms will re consume their own waste as opposed to starving to death, they also will consume processed paper as the last edible thing in the bin.

Another factor in darker castings is the insects that share the bedding with the worms.

I did an experiment two years ago where I put all outdoor harvested amendments such as leaves, grass clippings and insect infested vegetables through a crockpot to pasteurize them of all insect and microbes. I then predigested them in an open bucket for 3 weeks until the soup resembled sewage.

I then pasteurized it again and added it as feed to a bin stocked with 500 worms while preventing any infestation of spring tails, rovers or spring tails.

The castings formed by only the worms digestion and gullet microbes were brown, not black.

I now allow insect population in my bins to remain active also and my harvested castings are black, not brown and my worm stock shows better development.

I now only eradicate insect populations from castings I use in indoor potted planting mix and do so by pasteurization of the castings befor mixing with sand and kitty litter.

Castings used in the outside gardens are used with the insect populations intact.

[tt]

Looked a the links for digestors, mine are not quite that up to date but they sure work well. Have them at the landfill and nothing is frozen yet really quite amazing. Everything else is frozen around them.

[Jay Blair]

Further info on building a methane digest container.

I spoke today with the coworker who taught me to use the methyl ethyl ketone furniture stripper as a plastic fusing agent and he said it is no longer available for sale. He told me he thought it was removed from the market due to respiratory and cancer concerns.

He also said the furniture strippers that will degrade plastics for crack fusing cannot be neutralized at the fuse point with washing as MEK could and will totally destroy the plastic.

With this added information, I would not advise use of this type of stripper if you have it.

Use only screw type PVC fittings and PVC cement or a plastic fusing electric tool as the website listed in post #9 of this thread advises.