My red wigglers survived the winter in a cold garage, on a diet of mostly coffee grounds and shredded newspaper. And the occasional banana peel. I was expecting the end result to be crumbly - like good, humus-rich soil; but instead I find the castings to be rather sticky, like clay. There are no "off" smells that I can detect - I don't think it went anaerobic. Is this a cause for concern? Did I not harvest soon enough? Thanks in advance for any input.
I've been bin vermicomposting for four months, feeding a lot of vegetable scraps, bananapeels, yerba mate, coffeegrounds, juicer pulp, and pulverized eggshells. My finished bin vermicompost is also kind of clayey and, though it smells fine, clumps in big balls and doesn't mix well into soil, or have the instantaneous magical rejuvenative effects of outdoor earthworm compost. I'll be happy to return to the earthwormed compost, unless I'm doing something wrong.
1. The type of system you use will have a dramatic effect on the texture of the overall product. Flow through systems produce the best texture, allowing for a 100% aerobic environment, while plastic bin systems often lean toward anaerobic environments.
2. The materials you use to vermicompost also have a significant effect on the texture of the overall product. Most commercial producers prefer horse, cow, or pig manure to produce their vermicompost, and those materials will always make the best castings (in terms of texture and effectiveness). Food waste is often toward the "low end" of materials.
That being said, a plastic bin system fed with food scraps will still make excellent vermicompost! But might require some extra post-processing to get the nice crumbly texture you're used to from commercial growers. I'd suggest drying out the castings, and optionally screening them depending on how much you care about the texture. To dry them, spread out the castings in a shallow tub and break them up every couple of days with a hand fork. You don't want the castings to get dry, so you want this to be a slow process. You're just looking to remove excess moisture. Once they reach a wetness somewhere around a lightly damp sponge, you can screen them. To do this, staple on some 1/4" hardware cloth onto a square frame and dump some castings on top. Shake back and forth, and the vermicompost that falls through the hardware cloth will be a nice, uniform texture.
You won't see any negative effects from using clayey castings, but the effectiveness of the vermicompost will definitely improve if you allow them to dry out and reach a more aerobic environment.
You might also look into removing excess moisture from your bin system. The worms can tolerate a very wet environment, but the best castings come from an entirely aerobic environment. It might be as simple as removing the lid and replacing it with cloth, or drilling some more drainage holes (especially toward the bottom), or just adding more bedding (more bedding never hurts!).
My vermicompost worms have been going for five years now and have never made crumbly textured material.
I think commercial producers make a product that looks a certain way because that's what consumers expect. Kind of like red delicious apples, only they make black and delicious looking compost. (Though the vermicompost probably tastes better than red delicious apples.)
Commercial producers also have to be able to label their vermicompost with nutrient levels. That means it needs to be fairly consistent. And those labels have to meet consumers' expectations and look good lined up against the competition.
All that means they do things a certain way to get that commercially viable result.
Compare what comes out of an old manure pile to bagged up and sold "composted ruminant manure" and you see something similar. The bagged up manure is crumbly and spreads easily. The bagged stuff is much less lumpy and chunky than the natural stuff, and very consistent throughout. That's the result of processing and addition of material to achieve a result.
As Kyle says, there's nothing wrong with using your clayey textured vermicompost. When you put your vermicompost on your garden, it will melt into to the soil as the organic material breaks down further. Then your plants will thank you.
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