‘Worm Juice’: the difference between leachate and worm cast extract

3 min read

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We’ve likely all come across those bottles on the side of the road or at the local farmer's market, below a handwritten sign reading "Worm Juice” or even "Worm Wee" and wondered if that mysterious brown liquid was really all it is chalked up to be.

While the idea of a suburban squeezed liquid worm fertiliser sounds like nature’s bargain, you must be very careful to understand the origin and process used to produce the aforementioned ‘bargain’ product.

First up, worms don’t actually wee, so we recommend mentally crossing out the words ‘worm wee’ for all future use. If you’re curious, worms release their water waste through pores on their body, (the way we sweat) but it’s not the same as urine. The product often referred to as ‘worm wee’ or ‘worm juice’ is simply the excess liquid drained through a worm farm environment from inputs and watering. It is more accurately known as leachate. If you’re a worm farm user, you’ll be familiar with leachate; it’s the liquid that passes through your worm farm and pools at the bottom to be drained.

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While leachate may likely have picked up some beneficial microbes on its way down your worm farm (as it’s passed by some of that magic worm cast), it has also passed through decomposing matter and therefore may contain microbes that are not so beneficial.

In our vermicomposting vs conventional composting article, we talk about the difference between aerobic (what you want) and anaerobic (what you don’t) which also applies here. Depending on how long the leachate is left to pool in the bottom of your worm farm, it may become anaerobic (if it smells bad, ditch it). Therefore, as leachate can contain phytotoxic compounds it’s best to be cautious with your applications and avoid using it on your edible gardens. It can be used on ornamental gardens, but we recommend the most appropriate use for it is to put it back into your habitat to assist in maintaining appropriate moisture levels. This way any beneficial microbes that are in there will be compounded and any bad guys that hitched a ride will be eliminated when they pass through the worm’s gut.

A well-functioning worm farm should also not have a significant amount of leachate – this can indicate your worm farm is too high in moisture. Worms thrive in an environment that is moist but not wet, so getting an abundance of leachate is not your goal!

Worm Juice Watering

So, what’s this incredible worm liquid people are talking about then? What you’re really after is the worm cast. This soil-like substance the worms leave behind after processing your waste is supercharged with an amazing diversity of beneficial microbes, enzymes & growth promoters. Worm castings can be used to prepare worm cast tea or worm cast extract.

When we prepare our commercial liquid Worm Cast Extract (WCE) we age, aerate and ‘feed’ the microbes in our worm cast to maximise the beneficial properties, particularly mycorrhiza fungi. We then utilise a proprietary method of extraction to harvest the microbes, fulvic acids, humates and nutrients into a pure rainwater solution for our farmers and gardeners. The extract encourages microbiological activity and speeds up the growth rate of bacteria, fungi, protozoa, and nematodes, helping plants compete with other pathogenic organisms – now that’s a quality brewed tea. Our Worms Downunder farm is peppered with ongoing experiments and perfecting the recipe for our Worm Cast Extract has been one of our greatest triumphs, so we definitely recommend investing in a couple of litres for your garden

So now you know, avoid the ‘wee’ and focus on nature’s ‘black gold’ (worm cast). Trust us, your soils and plants will thank you.

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