compost

Reworking our Aerobins

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One of our two Aerobins, alongside our worm farm
One of our two Aerobins, alongside our worm farm

At present, we have three Aerobins and one worm farm. The thing that makes the Aerobins special is the  patented lung ® or aeration core inside. This is a series of connected pieces that provides greater levels of circulation, and therefore faster decomposition.

The pieces of the Aerobin "lung", mangled through use.
The pieces of the Aerobin “lung”, mangled through use.

 

At least, that’s the theory. In practice, the pieces often get mangled when turning over the contents of the Aerobin, and several of my hat-like structures have been damaged beyond use. I know I’m not the only one to experience this.

A replacement aeration method, made of out 90mm pipe
A replacement aeration method, made of out 90mm pipe

Taking a suggestion from my dad, I emptied out each of the Aerobins, and removed the aeration core pieces. To replace this, I drilled holes in a length of 90mm polypipe, adding a cap on the end. (These are standard plumbing items that can be obtained from the nearest hardware or plumbing store.)

The result is a more robust source of air circulation, that should be resilient against day-to-day use. Touch wood, it should still give me the faster aerobic breakdown of compost.

The Aerobin refilled, with its new home-made air spike
The Aerobin refilled, with its new home-made air spike

We’re now up to two compost bays

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Two compost bays in action.
Two compost bays in action.

A little while back, we cleared some space behind our house, and snuck in a proper compost heap. This has been cooking down nicely, and is just about ready to spread on the guerrilla gardened food forest.

Following on the success of the first compost heap, we expanded to a two-bay system. The second bay is currently composting down a mix of chicken poo, wood shavings (from the chicken coop), and used coffee grounds.

There’s something very satisfying about turning waste products into valuable garden ingredients 🙂

This is what 3 cubic metres of compost looks like

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Now that's a big pile of compost!
Now that’s a big pile of compost!

I recently ordered a large delivery of compost, to be mainly used in the guerrilla gardened space behind our house. Much of that soil is heavily depleted, and I wanted to give our fruit trees the fastest rate of growth this year.

Why order such a big pile? For the simple reason that it cost $51/m3 to buy in bulk (plus a delivery charge), compared to $9 (or more) per 40L bag if purchased at a garden centre (or Bunnings for that matter). And a it takes a lot of 40L bags to make up a cubic metre of compost. That’s a big saving!

This time around, I purchased the compost from Australian Native Landscapes, who have a nice range of recycled products.

We ordered “RE-CARB® ESSENSE”, which is described as:

Humus rich, 100% organic compost is specifically designed to build soild carbon levels and soil microbial activity.  Apply 75mm and dig into tired, nutrient poor soils. Suitable for all plants, this compost is particulary beneficial for phosphorous sensitive Australian natives.

That matched exactly what we needed! In general, I really like the idea of using recycled coffee grounds, Sydney sewage, wood chips, etc to make compost. Much better than going into a tip…

Finally, we have a proper compost heap

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A proper compost heap, out the back
A proper compost heap, out the back

For a long time now, we’ve had two compost bins (Aerobins) and a worm farm. Which have been great, particularly after I gave them more solid foundations to sit on.

That still left me with a hankering for a proper compost heap, to supply organic material for our guerilla-gardened food forest.

Some space has finally opened up at the back, giving the me opportunity to construct the first of several compost bays (at least, that’s the plan).

Creating a square metre of compostable material wasn’t hard, between the piles of fallen leaves, weeds galore, and other green materials. I’ve turned it once already, and it’s starting to build up some heat.

Onwards to compost!

A wheelbarrow full of coffee grounds

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A wheelbarrow full of coffee.
A wheelbarrow full of coffee.

It’s not every day that you end up with a wheelbarrow full of used coffee grounds, but I’m looking forward to making it a regular occurance at Lewisham House.

A little while back, a new cafe opened up just down the road, The Pig & Pastry. Other than their passion for great food, they also have a real interest in environmental issues. This includes some lovely raised garden beds set up in their backyard, for vegetables and herbs.

A week ago I approached them with a strange question: “what do you do with your used coffee grounds?”. Nothing as it turns out!

Coffee grounds are much loved in the permaculture community, as a source of free fertiliser for the garden. Apparently they deter (or hopefully kill?) slugs and snails, and the grounds are a particular favourite of citrus trees.

Online there are a number of long conversations about the relative merit of coffee grounds, including whether they’re too acid, and their effect on chickens. The general consensus is that when they break down, they become more neutral, and they don’t appear to be too toxic for chickens.

So I’ve left several plastic buckets down at the cafe, and I’ll drop down every week with a wheelbarrow to pick up the grounds. This saves them rubbish fees, and keeps my compost bins happy. A win all round!

Built (not) to last

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Stripped down to its simplest form, this worm farm should now last
Stripped down to its simplest form, this worm farm should now last!

As a novice gardener, it’s hard to think and design for the long term. Things going into the garden need to last not just for months, or even years, but perhaps decades. Our consumer society also tends towards fancy solutions that aren’t robust.

Our worm farm is a perfect example. I’ve had it for years, and it was a lovely solution. It sat on my balcony, resting on four legs. Sliding doors gave access to the vermicast, and there was a tap to draw off the worm juice.

It wasn’t to last.

  • The tap was the first thing to go, when it clogged up and stopped working.
  • When shifting the worm farm on the balcony, one of the plastic legs broke off.
  • Then when moving it to our new house, I discovered that the bolts holding the sides together had rusted into a mass of iron.

When we got it to the house, I abandoned the three remaining legs, and sat it on a row of bricks. But over time, the whole thing sank into the ground, at an angle, so the lid didn’t go on properly.

So with my new-found renovation skills, I made a small concrete pad for it, as shown above. The base, with its broken tap, was finally discarded.

The result: four sides and a lid, sitting on concrete. This will last!

It’s a lesson that’s hard to learn, and it highlights why we should always listen to our grandparents when it comes to gardening. They’ve seen and done it all, and have long since settled on solutions that work for decades…

Choosing the right inner-city compost solution

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A little while back, a very good friend of mine approached me with a simple question:

What compost bin should he choose for their household?

While it’s a simple question to ask, there are many possible “right” answers, depending on the circumstances.

This post outlines a few of the options, and explores how the decision was made.

The situation at hand

  • Classic two-parent, two-kid family, with both kids still quite young.
  • Located in inner-west Sydney, living in a free-standing house on a fair-sized block of land.
  • Due to the demands of the kids, there is no time for either adult to garden, beyond a few pots of hardy herbs.
  • Existing ornamental garden beds and a number of trees, as well as areas of grass.
  • A single lemon tree of some age, not well fed and producing few lemons.
  • A general interest in “saving the environment”, but are pragmatic about what they realistically have time for.

So, what composting solution would fit?

Option 1: full-sized compost bin

One of our two Aerobins, alongside our worm farm
One of our two Aerobins, alongside our worm farm

The classic composting solution is, well, a compost bin. The idea is simple enough: you put a mix of “green” and “brown” material into the bin, keep it moist, and give it time. In due course, it decomposes down to rich compost that can be used in the garden.

There are many options, from fancy (and expensive) Aerobins, all the way down to simple one-piece bins with a lid. The advantage of fancier options is typically two-fold: they claim to decompose the scraps quicker, and they typically give easier access to the compost without having to wait for the whole bin to compost down.

One of the challenges for compost bins, however, is that they work best when full. Ideally, “hot composting” involves at least a cubic metre of material, making it less suitable to top-up-as-you-go situations.

And in this situation, there is the one big problem: what to do with the compost?

It’s all very well to be creating lovely compost, but without a vege patch, what’s it needed for? The decorative garden beds would benefit from the compost, but not to the extent that you’d go to the year-long effort of running a compost bin.

Option 2: worm farm

On the surface, worm farms are very similar to compost bins, but they work on quite different principles. Instead of composting via bacterial processes, worm farms use … worms … to break down scraps.

The worms are regularly fed of things such as kitchen scraps, which they munch through to create vermicast (worm castings) and “worm tea” (liquid fertiliser). This is truly wonderful stuff, which plants love.

There are an incredible range of worm farms of every size and shape, each suited to a different circumstance. Worm farms thrive on small, regular feeds which is a good match for a household’s worth of kitchen scraps.

Care, however, needs to be taken about what goes into the worm farm (no citrus or onion, for example). And again the big problem: what to do with the output of the worm farm?

Option 3: in-ground composting

A "Little Rotter" in-ground compost bin, in one of our garden beds
A “Little Rotter” in-ground compost bin, in one of our garden beds

The last option considered was an “in-ground composting”. This comes in many forms, from the “Little Rotter” compost bin shown above, through to a simple length of pipe embedded into the ground (the favourite approach of permaculture folks).

In all cases, the principle is the same. Drop kitchen scraps into a container that’s embedded into the ground and open at the bottom. The worms that naturally live in the garden are attracted to the scraps, which they munch through. The nutrients then leach into the surrounding soil.

(My grandma still uses the simplest version of this approach: dig a small hole in the ground, drop in the scraps, cover it back over with soil. Her vege patch results speak for themselves!)

In the end, the in-ground composting was the chosen option.

The lemon tree was the key: by placing a number of in-ground compost bins around the drip line of the tree, kitchen scraps could find a better purpose, and the lemon tree would thrive as a result. With the in-ground option, there was also no upkeep or pressure, and it’s well suited to regular small feeds.

Your mileage will vary

In all cases, the natural processes of composting work best when they’re in sync with the human processes of the household. And bigger (and more complex) isn’t necessarily better!

So there isn’t one right solution, only the solution that best fits the circumstances.

Happy composting!