Living Materials
Living Materials
Many thanks to my friend Bentley “Compost Guy” Christie who really introduced me to and got me fired up about optimization with living materials… much of what I’ve included here is inspired by his excellent work in these topics for vermicomposters. Check out the article on optimization as well which goes hand-in-glove with living materials. A little additional effort in preparing your bin’s inputs yields dramatic returns in speed of processing, preventing things like pests and odors, and having a thriving bin population of happy worms!
Living materials are dark, aerobically-composted, stable materials, mostly carbonaceous, that are rich in microbial communities. Examples in nature are bedded animal manure that’s no longer heating up, or leaf litter/grass thatch like you’d find on the inside of a pile that’s partially broken down. Mature forest duff is another example. If you’ve ever pulled apart a straw bale that’s been outside in the rain and weather for a few months, that rich dark broken-down stuff on the inside is what we’re talking about. It needs to smell earthy (not sour or foul), and will usually be dark, partly-composted, and have a coarse crumbly texture.
Aged manure is kind of a “gold standard” for living material and worm bedding, composting species are even called "manure worms" for this reason. But many of us that vermicompost either don’t have reliable access to it, don’t have a way to transport or store it, or are concerned about possible contaminants like de-worming agents, persistent herbicides, or other treatments. So instead we can approximate manure pretty effectively by making our own “living materials”. So where, you ask, do you find this magic living material? Never fear, it’s pretty easy to source and just make your own. There are a couple ways to bring them into your vermicomposting.
For an established vermicomposter the simplest living material is the screenings from your last harvest! The chunky, not-quite-broken-down pieces are just loaded with microbes and can go right back in to the bin to complete their processing. It's like recycling your recycling!
"Living" bedding
The easiest for those without access to a traditional compost pile is to prepare your bedding well in advance... as a living material! By moistening it and adding a little something to allow it to begin colonizing microbially, you’ll have a MUCH richer material to colonize your scraps when you mix the bedding in to your scraps. You can do this in as small a batch as a 5-gallon bucket with your moistened bedding and something to feed microbes like coffee grounds, fresher grass clippings, alfalfa pellets, or the like. Use a small amount of these: we’re not trying to do a hot-compost but rather to start a gentle colonization of your bedding. If it does heat up a little that’s OK since it’s not going to the worms until that thermophilic (heating) phase has run its course. Allow it to mature in the bucket with moisture and airflow just like you would for the worm bin; oxygen is critical to these aerobic processes. As you use your bedding and start to get low, use a couple handfuls of it to inoculate the next batch of bedding when you make it up! This culture will continue to mature and be cultured forward into your vermicompost just like good sourdough or kombucha. Tom Perkins has a good video on his pre-made bedding procedure here.
Producing living materials for the bin
As we learned in Feeding and Bedding if you can maintain a compost pile, tumbler, or compost bin in addition to your worm bin you have a potent resource for your wormery! A compost backup is great for slow-to-process materials like woody yard waste, and also allows you to still process food scraps when you produce more than your worm bin can process quickly (remember: overfeeding is the fastest way to kill your bin!). The perfect living material/bedding is compost that has completed the hot thermophilic phase, is stable and earthy-smelling, and isn’t actively heating anymore. This is the phase that it’s most active microbially: in traditional composting you would leave this material to mature for some months yet. We however use it alive and kicking and/or through several months of maturation all the way to “finished” compost, and trust me it will really transform your bin when used as bedding!
A cheap and easy way to provide a “living material” resource is an inexpensive, basic hot-composting pile. Buy a cheap straw bale (which is strongly carbon). Or use shredded dried fall leaves if you have them… any fairly-fine carbon source works well. In a bin, tumbler or a pile moisten the straw and begin with a layer about 4” thick on the bottom. On top of this layer add some nitrogen materials. This can be fresh-cut grass, food scraps, coffee grounds form a coffee shop, I’ve even used (and have come to really like) alfalfa pellets from the feed store that have been rehydrated. Stack these in alternating, thin layers and water it in lightly. Go easier on the nitrogen materials, a little goes a long ways and you can always add more if it doesn’t “kick off”. It should begin hot-composting within a couple days. As it starts to cool, usually a week or 10 days, stir/tumble/turn it to get the outside materials inside. Remember we’re not aiming to complete a full hot-composting process like we would for next year’s garden, we're growing microbes on these nice carbon materials to balance the food scraps that we’ll be adding to the bin. This now-living pile can sit and get gradually used over many months. Once it’s alive you can add “overflow” food scraps easily by burying and mixing them into the pile, they’ll process quickly in this microbe-rich environment.