Wet Worm Casting

I have noticed that when a worm bin gets too wet the casting get muddy and smelly. Harvesting the castings then becomes quite difficult. If you leave them out to dry they become hard. If you have had a similar experience than you can relate to the following reader question:

My worm castings is very wet and doesn’t crumble. it seems more like paste. How do I get it to mix with the soil? I tried letting it dry for a while and it just became hard.

The best answer is to make sure that your bin doesn’t get too wet in the first place. An overly wet bin causes anaerobic bacteria to grow, which will cause the bin to smell and detracts from the effectiveness of the castings. The castings get muddy and when dried they get hard. The castings will be more difficult to work with and less beneficial to your soil and plants.

Below are a few tips to keeping the right amount of moisture in your bin:

• Have adequate drainage holes at the bottom
• Have holes in the top of the bin as well to allow proper air flow
• Make sure your bin has the appropriate moisture content from the start and try to keep the correct balance
• Pre-soak bedding before starting a bin and wring the water out by hand
• Add dry bedding whenever wet feed is added (like fruit scrapes)
• Generally there is no need to add water to your bin, other than a mist to cool it in the summer

Keeping the right moisture content in your bin will make the worms happy, the bin should then be relatively odorless or pleasant smelling, and your castings should be rich and crumbly.

Harvesting Worm Castings

Worm composting is not only a great way to reduce waste, but it also provides a valuable byproduct: worm castings. Worm casting make a terrific soil amendment, improving soil structure by providing tons of beneficial micro-organisms.  The castings also increase water holding capacity of the soil, attract earthworms already present in the soil, and work to ward off pests and disease from nearby plants. Now that we now that this is REALLY great stuff, the question is how can I harvest the castings easily?

There are several ways to harvest casting (i.e. separate the worm poop from the worms and non-composted materials).  A few suggestions include: sorting the worms and non-composted material by hand, the pile and light method, using a tray system or flow through reactor, a worm tumbler, or any number of variations. I will cover each method in a little more detail below.  Choosing which method works best for you depends on the amount of time, effort, money, and size of worm bed you have.

Hand Sorting

For those of us with a small quantity of worms either hand sorting maybe the best bet as it is the cheapest (FREE).  This method involves dumping out your worm bin into a pile, then sifting through the pile for worms and non-composted material. After emptying the contents of the bin I would recommend starting with some fresh bedding and then adding back worms and non-composted material as you sift through your pile.

Another similar approach is dumping out the contents of your bin and using a light to encourage the worms to burrow down into the pile.  After you have given the worms a couple minutes to burrow down you can scoop off the top layer of material (which by that time should be clear of worms).  Keep scooping until you reach the worms.  Give them a couple minutes to borrow down away from the light again and repeat the process.

Both of those methods require a little patience to sort the worms from the compost, but the end result is worth it.  Also, if you don’t do a perfect job separating the worms from the castings that’s OK (worms mixed in with the castings can goto work in the garden).

Now for a couple easier approaches: a multi-tray worm bin or flow through reactor.

Worm Bins

The idea behind the multi-tray worm bins is that the worms and the food waste start in the bottom tray, as the worms start to turn the bottom tray into compost more food can be added to the tray above it.  Once the worms are done with the food on the bottom tray, they will migrate up through holes in the tray above.  The worms will always follow the food.  That will leave the bottom tray full of worm castings.  This method makes it very easy to harvest the bounty.  Having a few trays allows you to have room for more worms and doesn’t require you to harvest the system as often.

Flow Through Systems

A flow through reactor applies a similar methodology to harvesting casting. The idea goes like this: you start with a container and add food waste and worms, as the worms turn the waste into castings you add more food on top. Eventually the container fills up with worm castings and food waste and worms, with the bottom being all castings and the food waste and worms near the top.  The castings are then harvested through a hole in the bottom of the container and everything in the container slides down a bit opening more room on top to continue the process of adding more food.

Tumblers

The last method that I will describe today is a worm tumbler.  This is a common method used by large worm farmers.  The tumbler is a large cylindrical apparatus made of a metal mesh like material.  The worms and the compost are dumped into the cylinder which is constantly spinning.  The castings drop through the holes in the mesh cylinder, while the worms travel the length of the cylinder and are collected on the other side.  Don’t worry, while the worms may be a little dizzy they come out unharmed.

Those are a few of the most common ways to harvest your worms and worm castings.  If you have a better way to do it I would love to hear about it and I’m sure all the other readers would too.

Shrinking Vermicompost

We have another reader question:

Hi – I have had a wormery for 11 months now. I was careful in researching what to feed the worms beforehand, and think that I have done this. My concern however, is that the vermicompost seems to be compacting as opposed getting bigger in volume. I mean in 11 months, my worms are not even 1/2 way up the bottom bin yet (and I am wondering how long it will actually take to fill a bin). Should I be aerating the vermicompost in the bin with my hands, or is this “normal”?

Thank you – I look forward to hearing from you.

Thanks, Samantha

Samantha,

The short answer to your question is YES!

Your composted material will seem to shrink overtime for several reasons. One of which is that when you put in your foodscraps, they are usually large and funny shaped. When you pile them on top there is a lot of gaps and holes. Once the worms eat all this material, they turn it into tiny castings. Castings are very small and they don’t leave these gaps.

Another reason why the compost seems to shrink before your eyes is that most of the material you are putting in your bin is probably water! All of your fruits and veggies are probably over 70% water. Once they start to break down, a lot of these juices will evaporate. This also leads to much less compost.

I know it can be very frustrating if you are really excited to use your castings in your garden and you feel like you are making very few castings. But the good news is that a little can go a long way. You really wouldn’t want to use 100% castings on your plants as it might burn the roots, and would just be a waste of good castings. Castings will do great for your plants with just a 5% mixture of compost. Any more and you are just wasting your castings since the increased benefit is marginal.

Good luck with your vermicomposting Samantha. Keep the questions coming guys.

Vermicompost – The Other Black Gold

What is vermicompost?

- Vermicompst is using worms (particularly red worms) to turn rotting vegetation, manure, or any other organic material into a nutrient rich compost through the natural breakdown and processing of this material from worm digestion.  The end product, castings or worm poop,  is an organic fertilizer and soil conditioner containing an abundance of beneficial water-soluble nutrients and bacteria.

What are the benefits of vermicomposting?

- There are countless benefits to vermicomposting, but some of the most important and obvious benefits include:

Soil
* Improves its physical structure
* Enriches soil with micro-organisms (adding enzymes such as phosphatase and cellulase)
* Microbial activity in worm castings is 10 to 20 times higher than in the soil and organic matter that the worm ingests
* Attracts deep-burrowing earthworms already present in the soil
* Improves water holding capacity

Plant growth

* Enhances germination, plant growth, and crop yield
* Improves root growth and structure
* Enriches soil with micro-organisms (adding plant hormones such as auxins and gibberellic acid)

Economic

* Biowastes conversion reduces waste flow to landfills
* Elimination of biowastes from the waste stream reduces contamination of other recyclables collected in a single bin (a common problem in communities practicing single-stream recycling)
* Creates low-skill jobs at local level
* Low capital investment and relatively simple technologies make vermicomposting practical for less-developed agricultural regions

Environmental

* Helps to close the “metabolic gap” through recycling waste on-site
* Large systems often use temperature control and mechanized harvesting, however other equipment is relatively simple and does not wear out quickly
* Production reduces greenhouse gas emissions such as methane and nitric oxide (produced in landfills or incinerators when not composted or through methane harvest)