This past Friday, Joanne (a fabulous lady who works part time on projects with us) and I spent an hour and a half picking through 75 liters of Hydroton that was in the last of the AquaBundance grow beds on our deck. This was the second grow bed from our two-bed AquaBundance system development project and it was not going to make it into the greenhouse for the winter because of space constraints. The Hydroton was going to be stored outside for the winter. What were we digging for? In part we were removing roots that had been left behind. But mostly we were rescuing worms.
Worms are an incredible asset to any media based aquaponics system. Watch below and our friend Murray Hallam shows off the worms in his grow beds during a video shoot…
Here are just some of the roles worms play in an aquaponics system:
- They break down the solid waste from the fish, and excess roots and other materials that plants slough off, and make them more bio-available to the plants through their excrement: vermicompost. This additional metabolic layer in media based systems is what allow media growers to avoid both the requirement to filter out solid waste AND the requirement to frequently clean out their grow beds. A 12″ (300 mm) deep grow bed with a healthy population of worms will probably only need to be cleaned out every five years or so, if then.
- Vermicompost, and the ‘tea’ that results from soaking vermicompost in highly oxygenated water (the exact condition found in an aquaponics ebb and flow grow bed), have been studied extensively by the Soil Ecology Lab at Ohio State University. Their studies have concluded that vermicompost and the corresponding ‘tea’ are tremendously beneficial because they:
- Suppress plant disease including Pythium, Rhizoctonia, Plectosporium, and Verticillium
- Suppress plant parasitic nematode
- Suppress plant insect pests, including tomato hornworms, mealy bugs, spider mites and aphids
- Besides helping battle plant diseases, worms have also been shown to mitigate pathogens that affect humans. An April 15, 2010 article in the Journal of Environmental Protection titled ‘Earthworms: Charles Darwin’s Unheralded Soldiers of Mankind‘ stated “The earthworms also release coelomic fluids that have anti-bacterial properties that destroy all pathogens in the waste biomass . They produce ‘antibiotics’ that kill the pathogenic organisms in the waste and soil where they inhabit and render it virtually sterile. It was reported that the removal of pathogens, faecal coliforms (E. coli), Salmonella spp., enteric viruses and helminth ova from sewage and sludge appear to be much more rapid when they are processed by E. fetida. Of all E. coli and Salmonella are greatly reduced .”
Because fish are cold blooded creatures, their waste cannot contain E. coli – that is reserved for warm-blooded creatures only. In fact, the only way that these pathogens can be present in your aquaponics system is if they are introduced from an external source. In a recently issued, drama-filled newsletter, an aquaponics company that specializes in DWC (raft-based) growing and training associated the introduction of worms to a media bed with the introduction of compost that may contain un-decomposed manure which might contain E. coli. “If you introduce compost and/or worms into your aquaponics system, you run the risk of bringing in dangerous or deadly varieties of E. coli such as H0157, 11 of which can kill an otherwise healthy adult human.”
This was followed by “The REAL problem with incorporating worms that may have been in manure and may carryE. coli with them is the very real possibility that your produce (contaminated with E. coli H0157 from the compost and/or worms you added to your aquaponics system) kills someone who eats it uncooked.”
Dramatic indeed! Of course you should exercise common sense with the introduction of anything into your aquaponic system, whether that be a pest control spray (even if it is ‘organic’), new fish (quarantine first!), or a new source of water or media. Introducing manure from warm blooded animals into your aquaponics system would be dangerous and quite foolish. The irony here is that worms are perhaps one of your best chances of dealing with any harmful pathogen that has been introduced to your system!
In addition, I was told by our worm supplier that most responsible vermiculturalists rinse their worms at least twice after removing them from their (USDA certified organic) compost home, and then they use peat moss to ship them. He said that it doesn’t even make sense to ship worms in compost because compost gives off heat and high heat is the biggest risk when shipping worms. Click here to check out our worms.
That said, if you buy your worms from a less-than-professional source, like Craig’s List, or you harvest them from your own compost pile, you should clean the worms of anything sticking to them before introducing them to your aquaponics system. A member of the Aquaponic Gardening Community named Converse, who happens to run a commercial redworm farm, offers this advice “Care needs to be used that when redworms are introduced to an aquaponics system so that they are not carrying any matter sticking to their skin (such as animal manures or rotten veggie matter) that might be harboring bad bacteria. Only after it passes through the gut of the redworm would this be completely safe…So if your redworms are introduced along with a handful of matter that does not get consumed by them, you have in effect just possibly contaminated your aquaponic system. So you need to be sure that redworms that are introduced are not plopped in the aquaponic medium with any of the bedding they were living in. Better yet, purge their systems (guts) by putting them in wetted down corn meal for 24 hours (okay, be sure it is not e-Coli harboring corn meal – or use oatmeal or cream of wheat wetted down). Then wash off the redworms, and introduce them into the aquaponics system.
So, let me net this all out for you. While you should understand where your worms came from, what they were shipped in, and/or how they were cleaned before entering your aquaponics system, don’t let that deter you from adding worms to your system! They are another valuable waste conversion machine, freeing up precious nutrients for your plants. They mitigate the need for frequently cleaning your beds. They help manage plant disease and harmful insects and nematodes, and they work to help render pathogens harmless. They are indeed aquaponics secret ingredient!