When Is Manure Ready For Vermicomposting?
Interesting question from Katheem:
“…[Are] there any parameters such as colour,
texture, state, C:N ratio etc.. to identify the ideal cow dung/manure
There are definitely some attributes you can look for when it comes to working with ANY type of manure. For starters, it’s important to mention that there is a big difference between using manure as a starter “habitat” material, and using it as a “food” material once that safe habitat as been established.
Generally speaking, habitat material will need more time/handling than the manure designated as food. Fresher manures tend to contain higher salt levels and have a greater tendency to off-gas ammonia (both of these commonly influenced by urine content). Salts and ammonia are very dangerous for worms, even at very low levels.
Starter Habitat Manure – If you plan to actually start up a worm bed containing a significant proportion of manure, you will definitely want to make sure it is really well-aged. Ideally, it will have been sitting in an outdoor location, exposed to the elements, for a month or more. It should be darker in color than fresh manure, and should have NO manure (or ammonia) smell – if anything it should be earthy smelling. It will tend to have more of a uniform appearance, not unlike that of a compost or garden mulch (obviously depending on the type of manure, and bedding materials – if any – that were mixed with it originally).
Food Manure – Once you have an established safe habitat – the larger the better – it won’t be quite as important to age manures before adding them to the system. There are definitely some caveats to mention here, though. For starters, the system will need to be extremely well ventilated – best if completely open in fact. This way, any ammonia that gets released can escape without harming the worms. On a related note, the manure should also only be added in thin layers on top – it should NOT be mixed into the habitat zone. Apart from the potential ammonia concern, mixing the manure in may create hot spots in the system which can also be a hazard for the worms.
Another important consideration will be the salt content of the manure. If it has not been allowed to sit outside exposed to the elements, or at least soaked and drained, there is a good likelihood that there will be an accumulation of salts in your system over time – which will also create issues. Certain types of manure – such as poultry manure – can be especially tricky to work with for this reason.
If you have a fair amount of outdoor space, you might try something like a “walking windrow”. Start by setting up a simple heap of well-aged (“habitat”) manure, and introduce the worms to it. Once they are settled in, simply add fresh manure to one side, gradually extending it out into a windrow over time. If the windrow is exposed to the elements, that’s basically all you need to do (apart from harvesting worms/compost if/when you choose to do so). If protected from the elements, you may want to soak each new manure deposit down really well so as to help flush excess salts out.
Additional Manure Use Tips
- Bagged manures you buy from garden centers etc are typically NOT going to be a good choice, since they tend to be pretty lifeless and can be high in salts.
- Avian manures (from any kind of bird) are very different from farm mammal manures – they tend to give off a lot of ammonia and contain high levels of salts. They also tend to be very dry initially, making it even more important to let them sit outside for a while before use.
- Liquid manures, such as pig and dairy cattle manures, should be mixed with a carbon-rich, absorbent material such as straw, saw dust, shredded cardboard etc and allowed to “pre-compost”, or at least age, for a period of time before use (how long will depend on your intended use, as discussed earlier).
- When using ANY type/source of manure for the first time, always test on a small-scale before going too crazy with it.
- Aside from helping to make manures more “worm-friendly”, pre-composting can be a valuable practice for killing off weed seeds and any pathogens that might be in the original material.
Hope this helps!
Recommended (Related) Reading
How Harmful are Vermicides in Manure?