Closing the Loop


By Ivan Hawkes
October 5, 2018


I’m a couple of months into my attempt to make fertile soil from unwanted waste material now, so here’s the update no-one asked for or wanted.

Still being dirt poor (ironic, since I have no actual useful soil / dirt) I scoured the internet for ways to turn unwanted materials into a soil I can grow my plants in. My chief concerns are it should be really cheap, but also as organic and natural as possible.

I ingested all the local ads I could to find out what material was available for free or very cheap and found two contenders:

  • horse manure
  • hardwood sawdust

It’s very important to note, this is actual sawdust from hardwood trees created as a waste from making wooden stakes. It’s not the chemical laden garbage you would get from the cutting station at the local hardware store. That is full of poison from chipboard and laminates.

Now, there are many articles stating outright that using sawdust or wood chips for a garden is a bad idea because it leaches nitrogen from the soil. What most of them don’t mention is that it is only on the top of the soil, and only during the composting process. It will actually release the ingested nitrogen once that process is completed.

Good news everyone, horse manure is naturally rich in nitrogen and actually has an NPK ratio that is almost ideal. You can nearly use it immediately in the garden. Mix that with the sawdust, and apply a handy nitrogen amendment and that should in theory cancel out any reason to not use sawdust.

Soooo, I grabbed a couple of massive bags of sawdust for AUD $4 each, and 25 bags of horse poop at AUD $2 a bag. Just one thing missing, the extra nitrogen rich fertiliser needed to help it all break down. I bought a funnel and a watering can, and you can guess where this is going. I ahem, closed the loop :grin:

There’s a good chance you are pissing about 1.5 litres of urine into a perfectly clean supply of water and flushing it with 50-100 litres of water every day. That’s incredibly wasteful, both of pure drinking water, and your nutrient rich previously bottled Fuji water.

I collect most of my urine in the watering can via aforementioned funnel and store it until it’s full. I’ve been depositing it onto my pile of manure and sawdust, along with a decent spray of water to keep it all moist (it’s super dry here).

The roughly 8:1:1 mix of NPK from the urine (yes, that’s right, that’s how good it is fresh from the tap!) is helping break down the piles of sawdust and manure.

It’s worked so well so far that a bunch of pumpkin I didn’t plant is fighting it’s way out of the compost pile. I’m actually going to just let it fruit, even though the soil isn’t quite ready yet….pumpkin…uh, err, finds a way.

The compost isn’t quite a soil yet, it doesn’t hold together when squeezed, but for just a few months it’s going great. I have actually already, through necessity, potted a few plants into it, including a couple of banana plants, and they are all doing very well. Not quite as good as a store bought potting mix, but good enough to get started.


Use whatever you can find around you on the cheap to make your dreams come true. I dream of a beautiful and bountiful garden, yet live on a steep hill with sand and clay instead of soil. Dreams aren’t wishes, they are just hard work, perseverance and innovation…or money if you have that, money trumps everything.

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