Wednesday, November 30, 2011

Harvesting Domestic Worm Farms Made Easier

article contributed by Ken Reid

One of the activities in working with worms in the domestic set-up which tends to put off all (except real enthusiast) is harvesting the worm castings (poop.) This is because of the time it takes and the fact that the “worm farmer” has to get his/her hands into the vermicompost—and the really passionate wormer doesn’t want to lose any of his worms in the process! The result often is that the wormer gives up on his worm farm and it falls into disuse. This is a great pity because these domestic worm farms do have a very important role to play as every family who has one working is contributing in a positive way to slow down the impacts of climate change and soil degradation.

We should also look at the reasons for harvesting. The most obvious and commonly used reason for the domestic wormer is to remove the worms from the vermicompost, so that it can be used for conditioning or improving soil. But there is another one and that is when it is necessary for the worm population in a wormery to be reduced, in which case the target for harvesting becomes the worms. Usually in the latter case the worms are taken from one wormery to be placed in another, given to friends or used for a weekend’s fishing! (I personally prefer fly fishing to fishing with my friends!)

To illustrate just how important these small contributions are, I often fall back on the following example. Research has shown that the average family of 3 generates between 500 and 1 000g of worm-friendly kitchen waste every day. Taking it at the lesser of the two, this means 3.5kg per week or 14kg per month. Now it does not take a mathematical genius to work out how much this amounts to every year, or how much a community of 20 000 such families or 1 million (similar to some of our bigger South African cities) would be generating. Then consider how much of this would be going on to landfills were it not for people who see the advantages of using worm farms which convert this waste into very beneficial vermicompost.

Being aware of this tendency to avoid harvesting, I have been actively looking for ways to make it cleaner, easier and more fun. The best methods that I have been able to come up with so far are confined to rectangular or square wormery units only, i.e. the ones that one comes across most often at hardware stores and garden centres. The biggest problem with the round, multi-level bin systems lies in the fact that each tray must lie firmly on top of the tray below it. So if you have a round bin, I am open to your suggestions as to how to make your task easier.

The solution I have found for the rectangular bins (whether they are single or multi-layered) came in part from Charl Pienaar’s excellent little book Goodbugs, Little Workers and in part from my constant search for making the job easier and less time-consuming for myself.

What you need
I have found these items really make my life a lot easier when harvesting:
  1. To buy a rectangular plastic fruit tray (obtainable from most plastics warehouses or catering suppliers) which will fit easily into the worm bin; or
  2. To use a rectangular (or square) seedling tray (I have found the big ones work great in my 70lt bins, in spite of the fact that these only have holes at the bottom. Whichever of these two containers you use, the steps are the same. )
  3. A pair of kitchen gloves as I truly believe that it is easier to handle the worms with gloves than with bare hands—and also a lot cleaner should you be called to the phone or anywhere else while you are in the middle of harvesting;
  4. A few large flat plastic basins, one to contain water for rinsing and another for carrying the basket to be harvested from the bin to the work surface, which should be in good light, but not full sunlight. This helps to reduce loss of worms “in transit.”

Start the process at least one week before you actually harvest. This is to give the worms time to “migrate” into the basket.

How to do it
You fill the tray/basket with kitchen peelings (preferably those which have been “ripening” for a few days). Open out a space in the vermicompost in one end of the bin which will allow this basket to fit in neatly) and fit the basket/tray into this space.

Once you have done this, cover the tray with a thick layer of damp paper or cardboard, but leave the rest of the castings exposed to the light. Instead of replacing the bin lid, cover the bin with either clear glass, clear Perspex sheeting or heavy-duty clear plastic sheeting, which must be well secured so that no unwanted predators get in.

After a few days you can remove the basket, which will be full of worms which have migrated into the new food source and away from the light. Put the basket gently into a large basin for carrying to the work area.

Tip the contents out onto a flat working surface and catch worms in large numbers!

You will find that it is very easy to collect the worms in this way and place them where you want them to go, which might be into another bin.

Repeat this process a few times until you find that your basket no longer attracts large numbers of worms. By this time, the vermicompost that you want for your garden can be removed from the bin and prepared for use in the garden. All the unprocessed material goes back into the system for the worms to carry on their good work.

I have found this method speeds up the harvesting process considerably, as I can now harvest 1kg of worms in about the same time that it used to take to harvest about 250g. This means that I am able to do the job about 4 times faster than with the old “dump and sort” method.

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