Here is a good question from Jillian:
We use a rabbit bedding made from recycled newsprint and it
contains some baking soda. I was thinking about saving the used
bedding, manure and all, to feed our worms. During the summer months
I could hot compost outside, though in the winter it isn’t really
possible. Do you think that the baking soda used for deodorizing the
rabbit’s bedding would cause problems with the ph in the worm bin?
Rabbit cage bedding (containing manure) would be an excellent ‘worm food’ – it’s the baking soda that makes me a tad nervous. I’ve faced the same dilemma myself with my compostable cat litter – I was thinking about adding some baking soda to help with odor reduction, but then it suddenly dawned on me – baking soda (sodium bicarbonate) contains a LOT of sodium.
I just grabbed a box of it from the back of my fridge for reference purposes. This “pure baking soda” contains 164 mg of sodium per 0.6 g (600 mg). A quick calculation tells me that this material is basically 27% sodium by weight. So, say you decide to add 50 grams of the powder to your bedding – that would be 13.5 grams of sodium.
In all honesty, I’m not exactly sure what effect sodium itself has on worms, and wasn’t able to track any more information down. As I told you via email, worms tend to be extremely sensitive to inorganic salts – so for example, it definitely would never be a good idea to add inorganic fertilizer to a worm composting system (if you were trying to boost nitrogen or something like that).
Even if the sodium doesn’t harm the worms (which I still suspect it will), it is definitely known to be harmful to plants when present in high enough concentrations, so the castings you end up producing might not be all that great for growing anything.
If you are really keen to vermicompost your rabbit bedding (again, highly recommended) perhaps you can try something like peat moss as an additive to help reduce ammonia odors, rather than the baking soda.
NOTE: I just noticed that you mentioned that the bedding already contains baking soda, so I guess the first thing to do is determine how much there is in the material, and perhaps think about trying a different bedding material (again, if you are really interested in vermicomposting with it).
Hope this helps!