Dynamic Accumulator Sock

One of the things I love about my job is being able to indulge my creative urges and get into some product design from time to time. This idea came to me whilst I was dividing up comfrey roots last winter.  Comfrey (as no doubt most of you will know) is what permies refer to as a dynamic accumulator.
As I am in the business of nutrient cycling, I feel it is an obligation to minimize the amount of nutrients and particulate matter I create from entering waterways. This item helps achieve this nicely by trapping the sediment and accumulating the nutrients from it as well as slowing down water in rain events.

Now seeing as my neighbour at home is one of those lovely old ladies who likes to sweep her concrete front yard, backyard and path with a hose, she manages to sweep a load of sediment through onto my side of the fence (thanks!) this combines with the chookpoo from my chook run and chooktractor to flow down into one of my veg beds but I would rather it didn’t quite so directly… “Bing!” (sound of lightbulb inside my head) how about using a “sediment or silt sock” to trap the soil and sand and plant some comfrey in there to harvest the nutrients from it?

Here are some of the key things I like about the Dynamic Accumulator Sock concept:

  • It gets no love – I don’t water it, it gets by on overflows alone
  • It captures what I once lost: nutrients and sediment/soil
  • It helps protect waterways
  • You can move it when you need to
  • You don’t have to worry about getting comfrey where you don’t want it as the roots go deeeep! (Which is why comfrey can be awesome but not if you don’t want that)
  • When you want to divide up the roots just open the bag – no digging required!
  • Harvest whenever you need to make some tea or just chop and drop
  • Look at the list, you can plant other things if you want – give it a go and tell us all in the comments how you go

First I tried using an old coffee sack but frankly it was more hassle than I was prepared to get into (especially considering it would rot before the summer was out) so instead I wandered down to the local hardware store where I discovered they were selling the small ones for about $2.75 each. If you want you could make them out of geotextile fabric – I don’t have easy access to a sewing machine so hand stitching the off-the-shelf model it is! You could even use an old green shopping bag – anything that isn’t waterproof, that won’t rot too quickly will work.

What you will need to make your Dynamic Accumulator Sock:

  • a sediment sock from your hardware store (or geotextile fabric if you are making your own)
  • a sack needle which you will find at a sewing or craft shop
  • polyester thread
  • sharp scissors
  • old potting mix/dirt/gravel/sand remember this is to fill the bag hold it in place don’t waste $ on good soil
  • root pieces of comfrey or your chosen accumulator
  • optional: a short length of plastic trellis to act as barrier to grazing animals and also makes for a great handle

Assuming you have opted for an off-the-shelf sediment sock:

  • Step 1: mark where you want the holes. I made 2 slots for ease of stitching but you could make circles or whatever
  • Step 2: choose where you want your plants and make the holes accordingly then sew to prevent fraying – a quick bit of needlework to create a couple of sealed holes
Sew the edges of the incision to prevent fraying of the fabric
Sew the edges of the incision to prevent fraying of the fabric
  • Step 3: filling – I used old used potting mix with some scraped up sand from the neighbour and poked the plants in as I went. Once you have filled it just use the ties to tie it all off. Don’t overfill as you want a decent length to tie and carry the item once complete
If using plants rather than roots, it's easiest to stand the sock up and insert the plant material as you get to the right level. Make sure you leave enough space to tie off the end.
If using plants rather than roots, it’s easiest to stand the sock up and insert the plant material as you get to the right level. Make sure you leave enough space to tie off the end.
  • Step 4: cage – this is optional. As I had hungry chooks, they were very happy to have fresh comfrey salad as part of their diet. This didn’t suit the experiment so I just put some plastic trellis around it – this kept them away and also makes for a handy carry handle.
  • If you are making your own using geotextile bag you are only limited by your imagination and can create something that will fit into whatever space you have where you have nutrient and sediment runoff. Ie. Triangle for a corner.
The before and after pics of an accumulator sock at Timbah Rooftop Garden. This gets maybe an hour of sunlight in the height of summer.
The before and after pics of an accumulator sock at the Timbah Rooftop Garden. This gets maybe an hour of sunlight in the height of summer.

It’s been about 10 months since I deployed my socks and they are doing pretty well and I’d have to say it’s one of my better ideas. As I’ve said you can plant anything you want especially if you have an automatic irrigation system that tends to cause a runoff. Go forth and harvest that escaping goodness!

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