Vermicomposting in the cold-climate apartment- Bacteria

July 15, 2006

My understanding is that the worms don’t eat the food scraps – that bacteria break down the food scraps and that the worms eat the bacteria.

From this flow several implications

Storage

Storing food scraps in the refrigerator is not a good idea. Apart from health issues, refrigeration slows down bacterial growth. We want to speed up bacterial growth, not to slow it down. Faster bacterial growth and multiplication means that the food scraps are converted to a worm-digestible form much sooner.

It is for this reason that storing the food scraps bin under the (warm, moist) kitchen sink makes sense.

Timing

There has to be a delay between the time the food scraps are introduced to the vermicomposter and the time at which the bacteria have multiplied sufficiently to provide a food source for the worms.

Delivering three week’s worth of food scraps once every three weeks would surely places the worms in a boom-or-bust cycle. It makes sense to add scraps as frequently as possible in such a manner as not to disturb the worms too much.

Regular addition of food scraps means regular delivery of bacteria, each batch of bacteria being a constant number of days behind the addition of the food scraps.

Diet

Since worms don’t eat food scraps, but they eat bacteria, the worms diet consists of one or more types of bacteria. I don’t know what types of bacteria exist.

This question arose when I was asked if worms will eat hot peppers. Here in part is my answer:

• If by Hot Peppers you mean those thin ones, who knows? I am revising my ideas on foodstuffs for worms. If they eat bacteria, then the real question of diet becomes (1) what types of bacteria will red wrigglers eat and (2) do I have bacteria that will eat this food.

• Suppose that there are only basic types of bacteria that the red wrigglers can eat. Let's call them "VPB" or vege-peel bacteria (they eat potato, carrot, lettuce) and "GEB" or grain-eating bacteria (they eat boiled rice, watered corn flakes and bread) and "MEB" or meat-eating bacteria (they will get stuck into chicken bones and "PEB" or protein-eating bacteria (they will eat egg white and egg yolk etc.).

• If there WERE only four types of bacteria that red worms would eat, then any question about food (in your case "hot peppers") translates into "what bacteria will eat hot peppers?". If the answer is one of VBP, GEB, MEB or PEB, then you are in luck.

• If on the other hand only "HPEB" (hot pepper eating bacteria) will eat hot peppers, and we know (!) that red wrigglers won't eat HPEB, then the hot peppers aren't good to add. There may be HPEB in the compost, and the HPEB may consume the hot peppers, but the red wrigglers won't eat the HPEB, so they will proliferate and cause a problem.

• This must be going on with, say, dairy products. A small bit of cheese is not good, because "CEB" (cheese-eating bacteria) eat cheese, and red wrigglers don't eat CEB.

• This is a THEORY, but I'd love to get my hands on two lists:

• List 1: A list of bacteria that Red Wrigglers will consume

• List 2: For each bacteria on List1, a list of foods that those bacteria will eat.

• This would settle the "food" question for all time.

• And we should guard against excess. I know that some meat is OK, but too much meat gives me blowflies.

Non-diet

Since worms eat bacteria, they can’t eat what bacteria won’t eat. Plastics, obviously, although I’ve been successful spreading a film of plastic with food stuffs adhering to it, and layering soil over it. The bacteria find and devour the adhered food and the worms eat the bacteria. Don’t screw the plastic into a tight ball. The bacteria will find their way in alright, the worms will follow the bacteria, dine, and then die, lost in the maze.

Bacteria don’t do well on woody stuff, like - well - wood, or apple stalks, or that tough star-shaped green stuff atop the orange. So those things will pass through your vermicomposter.

Bacteria don’t eat bones. We’ve all seen pictures of skeletons unearthed after many years. Flesh gone, bones remain. So I put chicken bones and steak bones in the vermicomposter; the bacteria eat the meat and leave the bones. I can bake and grind the bones for fertilizer. A two-pound chunk of raw meat cannot be digested quickly enough by bacteria; it rots and attracts egg-laying flies. You know what happens next. Don’t do it. Instead cut it up into small one-inch chunks to provide more surface area for the bacteria.

“Worms eat their own weight each two days”

You will read variations on this throughout the literature.

We are talking food-waste here, vegetable and fruit scraps, mainly. A lettuce leaf is what – 98% water? Peach flesh – 95%? Regardless, if we were to weigh our waste before adding it to the composter we might think that we were digesting, say, a pound of matter each four days.

Truth is that the bacteria devour the food waste, and the worms devour the bacteria. The water held in the matter is released during this process and evaporates from the soil (through churning and excretion by the worms) or pools in the bottom of the digester (which leads to toxic goo and the death of the worms).

Either way, it might be true to say “worms DISAPPEAR their own weight” every so many days, but the truth is that most of the mass will disappear by itself.

It’s not wrong to weigh three flats of lettuce before adding them to the digester and stating “sixty pounds of lettuce were digested in one week” or similar, but consider the description of an experiment in which lettuce was weighed (60 pounds), cut and spread out to dry, and weighed one week later – “Virtual worms reduced sixty pounds of lettuce to a scant two pounds in one week”. Not bad for worms that don’t exist, but loss of weight nonetheless, due to good old natural evaporation!

If you are faced with a great mass of material to be digested, you might want to consider pre-drying some of it – lettuce leaves are a good example, but peach flesh would probably attract fruit flies – before adding it to the digester. If nothing else, there’s less bulk (in the form of water) being added to the digester and less water being added, so better control over the moisture of the soil and bedding.

In the end, optimization of digestion is probably a judicious mixture of techniques – reducing water content by drying to the point where addition of bacteria-laden soil starts the bacterial process, followed by the timely addition of the pre-digested mass to the vermicomposter for fast-digestion.

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