Rabbit Manure In Worm Composting

“How good is rabbit manure for worms? I would like to use rabbit manure and moss and newspaper and grow them in a bin. Will this work?” ~ Woody Miller

“We have rabbits and an abundance of earthworms – I know these are harder to raise due to slow growth – but I would like more info on growing these common earthworm” ~ Rebecca Cecil

Two somewhat related questions that will allow me to cover a couple of different topics.

Firstly, rabbit manure can be an excellent food source (and bedding material) for worms with the proper precautions and strategies.

Compared to many of the other manures, rabbit manure tends to be quite high in nitrogen. Due to the enclosed rearing methods commonly used, it also tends to have a high concentration of urine mixed in. Urine in fact is usually the primary source of nitrogen in animal waste (but often not really considered since it gets mixed in with feces). Urine can also be a significant source of soluble salts – something else we need to keep in mind when it comes to worm health.

In its freshest state, rabbit droppings (like most manures) won’t be ideal for food or bedding (especially not the latter), since its high soluble nitrogen content (primarily in the form of ammonia) and salts from the urine will be toxic for the worms.

Fresh manure also has a high potential for heating up if there is a decent amount of it in one location (such as a heap or large worm bed).

As I’ve mentioned in a previous newsletter, a great strategy for prepping manure for worms is to ‘pre-compost’ it thermophilically (meaning it should be allowed to reach 130-150 F internal temperature) for at least a few days (longer would probably be better). This is especially important if you want to use the material as the primary bedding for your worms since it will be their habitat.

One thing I would definitely recommend for everyone trying out different foodstock and bedding materials is setting up a test bin to see (on a small-scale) how your worms will respond to a given material. This is a good way to test if a pre-composted material is ready for your beds. Simply place some of this aged manure (or whatever it happens to be) in a small tub and add a handful of your worms.

Start by putting a lid on the bin (once they have all buried themselves) and leaving it sit for 15 minutes or so. If you open it up and the worms are all over the lid and sides of bin (or balled up together in one location) it’s a good indication that your pre-composted material needs to be aged a little longer.

If they remain buried however, simply let them sit for longer (24-48 hrs), periodically opening up the bin and checking on them. Don’t be alarmed if you see a few worms up on the lid – this is very common even in a completely healthy bin. Using this technique will spare you the grief of having a large-scale worm crisis on your hands!

Due to the high N-content in rabbit manure, I would highly recommend you mix it with some sort of carbon-rich material to help balance out the C:N ratio. I think a lot of rabbit breeders use a variety of bedding materials (in the cages) such as shredded newspapers, wood chips, straw etc – these should really help (and if you are using this type of bedding you likely won’t need to add anything else). If on the other hand you are using a bare bottom cage or open area, and simply collecting all the rabit waste (or even letting it drop down onto a worm bed or soil), you should probably add some straw or peat moss to help balance things out.

Speaking of which, this might be a good time to address the question about ‘common earthworms’. As I’ve mentioned before, your normal ‘garden variety’ of soil-dwelling worms are not ideal candidates for worm farming – or at least not worm farming using enclosed (sometimes indoor) beds. That being said, if you are really keen to produce a thriving population of soil worms and potentially even attracting some ‘wild’ composting worms, there are some ways to do this with an outdoor plot.

What I would do is set aside a patch of garden (any sort of exposed soil would work fine), lay down some straw (couple inches thick), brown leaves (if you have them), maybe some grass clippings if you have them, plus some of your rabbit droppings. Add another layer of straw over top, then water it down. If you leave this to sit (watering it periodically), over time I guarantee you will start to see lots of earthworms congregating in the soil below since they will be attracted to the moisture and the organic matter. This is also a fantastic way to create a rich garden bed over time.

Jumping back to the topic of prepping rabbit manure…

Aside from pre-composting piles of rabbit manure/bedding, another strategy that helps is leaching with water. If you leave your heap of manure outside for extended periods (assuming you receive rain showers) or simply use a hose (with a sprinkle nozzle), water will percolate down through the material and remove a lot of the salts etc. and make it better suited to be used for worm food. I would still recommend mixing it with a decent amount of bedding afterwards (so it’s not a slopping mess) and letting it age for at least a little while longer.

One other thing to mention quickly – if you already have large, thriving worm beds with a carbon-rich bedding (shredded newspapers, peat moss etc), adding thin layers of fresh rabbit manure to the surface should not be a problem at all. Just keep an eye on it – making sure it doesn’t pile up to much. As it ages the worms will start to consume it readily. If you have more manure than the beds can handle simply pile it (with c-rich materials) and let it compost as described above.

Hope this helps.

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