> As I understand it, earthworm castings produce a reliable, well-balanced tea > and also facilitate homeopathic herbal and mineral additions. Isn't this > compost a good, somewhat easy to replicate material that would make it > easier to test out the effectiveness of various additions to the mix? Any > problems surfacing with using earthworm compost tea? > > Thanks so much Allan for setting this opportunity up!
I too thank Allan for setting this up. I enjoy the opportunity. Do you mind if I get into worm compost debates a bit deeply here? What is "worm castings", versus "worm compost"? To be a stickler, castings are ONLY the material that is processed by the worms, through their digestive system. No matter how many worms you have in a bin, you CANNOT be assured that every bit of that material was processed by the worms through their guts. Only if you sieve the material coming out of a worm bin, such that you have only the little poops, would you know that you have pure castings. So, what is sold is really worm compost, not pure castings. What makes worm castings (I'm focusing on the poops right now, not along with the other stuff that isn't processed) such wonderful stuff? The earthworm gut is a quite interesting place. The evidence I have seen is that worms themsleves do not make the enzymes to break down organic matter. Worms do not contain the DNA to make the enzymes to break down organic matter. Therefore, what is it that worms are eating? The muscles of the earthworms grind soil particles together in the digestive systems, and crush, grind up and otherwise physically break open the bacteira, fungi, protozoa, nematodes and microarthropods in the soil the worm consumes. Do they crush ALL the bodies. No. Alot of them? Yes. The really susceptible populations of bacteria and fungi appear to be the human pathogens, probably because they are typically large cells with delicate cell walls and membranes. Fungal pathogens appear to be quite susceptible to being destroyed by passage through the earthworm gut. But that's not the best part of the worm digestive system! The worm absorbs the crushed cells of all these organisms, but then in the back end of the worm, we have some really super bacteral and perhaps fungi species that hang out there, and inoculate all that wonderful food stuff, so the castings are chock full of beneficial bacterial and fungal species. What goes in the front end of a worm is modified and improved in many ways. Clive Edwards at Ohio State is trying to show that there are lots of plant growth hormones, or plant growth promoters (PGPs) in worm castings, but he has yet to do a really well-controlled sicentific experiment that demonstrates that worm castings have these material in high concentration. I have no doubt that they are in worm castings, but, the science must be well-done to show that worm castings and thus the worm compost, contain significantly higher amounts of growth promoters than soil itself. If you have a really healthy soil, are the same growth promoters made? So why fuss with worms? Ah, but is it easier to get lots of PGPs when high numbers of worms are present? Probably. So..... Well, you can see where this would be of interest to plant people. Worms are merely ways to control the beneficial populations and get rid of the bad populations. Now, lets move on to the other stuff that isn't processed by the worms, i.e., does not actually go through the worm gut. That could still have pathogens in it, right? Ah, but because the worms move through the material, even though that material is fairly wet, they leave behind them air passageways. Worms are little, itty, bitty mixers, teeny-tiny plows, if you will. They aerate the material quite well. What is the minimum amount of aeration needed? It depedns on how much high nitrogen-containing, simple sugar food resources you have thrown in the bin. The higher the juicy, easy-to-use N and sugars in the bin, the more worms you need to keep up the aeration so the bacteria and fungi don't use up the oxygen in the compost and drive metabolism into the anaerobic range. Anaerobic means all kinds of plant toxic compounds being made, and the possibility that human bacterial pathogens and plant fungal pathogens are going to grow and out-compete the beneficial organisms. How wet can a worm compost be before it starts to go anaerobic? Depends on the number of worms, and how fast the bacteria and fungi are growing. I've seen worm bins at 80% moisture that make great worm compost, and some at that moisture that make terrible compost. I've seen worm bins at 30% moisture that make terrible compost. Not enough moisture and the worms just won't do their job. Too few worms at high moisture and the "compost" stinks to high heaven. So, balance is the key. A few factors that you have to keep in mind - moisture, food quality, presence of good bacteria and fungi, worm density. The more worms, the faster the processing, the more food you can add to the bins and the wetter you can keep it. What causes worms to die off? Oh boy, there's a complex topic. The wrong kinds of foods added to the bins, not enough "chunk" to the foods so air does get limiting, not enough paper or cardboard, too little water, etc. Temperature plays a part only in that there is a top range and a minimum range. The worms work faster as temperature increases, up to the point they start to die when it gets too hot. So, please understand that worm compost can be really good, and it can be really bad. No panacea here. You must pay attention to the quality of the product, how it was produced, the way it feels, smells, and insist that the producer show you the biological data and the chemical data. If the manure going into the worm bin is high in salt, the compost will be high in salt. The manure will be high in salt if the animals are being fed pelletized foods, so use small amounts of that kind of manure. You can use normal amounts of manure from animals that are fed grass, grain (be careful of high protein coming through if fed too high grain content however, you have to balance with high paper, cardboard, stalk and stems of plants) . Can worm compost be as variable as thermal compost? Yes. It's just less likely to be as consistently variable. Thermal compost varies from batch to batch because hte starting materials going in are quite variable. If the starting materials are exactly the same, but percentages of the different materials are varied, the results can still be variable. We have data from a big study with the City of Eugene, OR that we'll be publishing soon. (there's a relative term for you - what do you mean by soon? I mean we'll start the publishing process in June or July, after analyzing the data, writing up the paper, and you could expect to see the pub in about 2 years. That's why I have the e-zine. I can talk about results before they ae officially published). But your implied question is relative to thermal compost. Is worm compost more consistent than thermal. Yes. So, given a source of good worm compost, use it. I tend to mix 10 - 50% thermal compost with 50 to 90% worm compost to make tea, so I increase the diversity of organisms in the tea. Hope this answers your question! If not, try again! Elaine Ingham
