Boulder Vermicomposting

Gone fishing

Folks, I’m going to take a break from the worm composting blog for a bit–I am getting married June 5 and things are a bit hectic around here.  So, please forgive the lack of new posts for a couple of weeks.

Thanks!

Add comment May 25th, 2010

The difference between compost tea and leachate

I realized that I had written this a while ago, but only published it on my newsletter, so I thought I’d post it on the blog for the world to read.

I’ve seen several inaccurate posts/articles about worm composting and in particular the uses for the liquid that often comes out of the bottom of a worm bin. This liquid is called leachate. The US Environmental Protection Agency provides us a handy definition of leachate: “Water that collects contaminants as it trickles through wastes, pesticides or fertilizers. Leaching may occur in farming areas, feedlots, and landfills, and may result in hazardous substances entering surface water, ground water, or soil.” The leachate out of the worm bin is not useful, and can be harmful. I know that some of the people I’ve interviewed have used it on their plants, judiciously.  Forest says “I would just dump [it] down the toilet if it was bad. [some of the worm leachate] had sat for a couple weeks and that didn’t have the smell anymore. And that I would mix with water and then water my plants with it.”

But there’s a difference between leachate and compost tea. Compost tea is compost mixed with oxygenated water, creating “a Petri dish: favorable conditions are made for the beneficial soil microbes, already in abundance in worm castings, to reproduce millions of times over in the water culture.” Water running out of the bottom of your worm bin may or not be favorable to these beneficial aerobic microbes. Since it runs through the bottom, it may be collecting microbes that thrive in anaerobic conditions. These microbes, called “obligate anaerobes”, use chemicals other than oxygen to respirate. According to wikipedia, “[t]he most favorable [chemical for respiration] (after oxygen) is sulfate. [Byproducts of which] most of us are familiar with as the rotten egg smell”. This water probably also contains uncomposted organic matter, which is not what you want to apply to plants; otherwise we’d just dump our scraps directly on plants.

In short, what comes out of your worm bin is called leachate and is not compost tea.  Don’t use it like compost tea.  Dispose of it (I’d probably put it back in the worm bin, myself).

4 comments May 19th, 2010

Earthworms used for coffee waste

Via Clean Technica, I found this article about the Rogers Family Company using redworms to process their coffee waste.  Apparently, coffee processing generates a fair bit of organic waste, and this was decomposing and  leaking into groundwater.

So, leveraging techniques used elsewhere, including in Selva Negra in Chiapas Mexico, they set up worm bins on their farm in Panama.  The goal?  Process 5000 tons of coffee pulp and turn that into free fertilizer for independent growers.  The company ended up with “10,000 square meters [of worm bins] filled with a billion worms”.  I asked why they chose E. Foetida, rather than one of the worms more suited to the tropics (as outlined here [PDF]); I’ll be interested to see their answer.

Talk about industrial vermicomposting!  I remember reading a while ago about ‘decompiculture’ (PDF here) which is the idea of “growing or culturing of decomposer organisms by humans”, the same way that agriculture is the growing or culturing of plants and herbivores.  Decomposers, whether redworms, bacteria or mushrooms, can help address some of our most fundamental issues of garbage management by turning waste into useful substances.  This project showcases decompiculture.

Pssst!  You should complete the cycle and vermicompost your coffee grounds.

Full press release here, and full blog post with pictures here.

2 comments May 13th, 2010

Worm Composting Article in The Boulder Weekly

I helped the author of a worm composting article in the Boulder Weekly a week or two ago, and it’s now up on their website.  From “Let Worms Eat Your Garbage” by Charmaine Getz:

Moore, a web developer who once spent two weeks in Australia as a volunteer farm worker, raised the lid and introduced me to his red wrigglers. There was a whiff of plant rot.

“I haven’t been here in a couple of months,” Moore apologized, as he hefted a bag of dead leaves into the bin. “It doesn’t smell when you give it regular attention.”

By that he meant renewing with fresh worm food and removing the compost more frequently. Still, the bin smelled less than my weekly wormless kitchen compost.

Moore pulled out a drawer near the bottom of the bin into which worm castings had fallen. The contents looked like the black gold that I buy at the garden center.

The bin yields about 10-20 pounds of compost twice a year that go to the condominium association for its community garden. Moore started another worm bin recently at the home he shares with his fiancée, Pam Sinel.

Read the whole article here.

Add comment May 6th, 2010