In one of my last posts, I exposed my lack of understanding of composting and inability to create good compost (despite assurances that any idiot can do it). I did conclude that part of this was because the two chambers of my composting tumbler just didn’t give me enough space for the amount of kitchen scraps I was producing. From here came my idea of turning our old coal bunker into a compost bin.
The coal bunker was surplus in our garden. It was one of the many pieces of junk that the previous owners of our house left behind for us to either get rid of or repurpose. It did have some coal left in it at the time, but this is long gone by now. We’re onto using wood for our multi-purpose stove. This would be our preference anyway, but it was further sweetened by the 2 years’ worth of wood my father-in-law had hoarded from when he had a wood stove about 10 years ago … Honestly their level of hoarding makes me feel very stressed but it has given us 2 winters worth of free wood so I shouldn’t really complain. This is a trait my husband has definitely inherited. I tried to get rid of 2 egg cups we have because neither of us have ever eaten boiled eggs and don’t even eat eggs at all anymore. As you can imagine, he was completely distraught at this suggestion because they might possibly be useful once one undetermined day in the far future.
I hate throwing things away, but this hunk of metal had been taking up space in our garden, unused, for the best part of 2 years. One of the hinges on the lid was broken so it wasn’t something anyone else would really want. We have a woodshed to store all our wood, another thing that was inherited from my in-laws. It was dismantled at their home nearly an hour away and then reassembled in our back garden; bear in mind, this was an old woodshed that was never designed to be dismantled and reassembled once it had been built. The level of commitment from all involved should be commended. This is due to a mix of my unwillingness to throw things away, my husband and his family’s unwillingness to spend money, and the hoarding traits of my in-laws that have led them to have 2 of everything. Yes, they still have another woodshed that they do not use back at their house ….
I realise I am slowly descending into using this as an opportunity to rant about hoarding, so I’ll move on! You might recall from my previous blog post, that one of the key reasons for my selection of a compost tumbler was fear of rats. The rats living under our shed can chew through anything and everything, including the shed floor. I didn’t want my new compost bin to become another place for them to get free food and accommodation. Somehow, I felt that they would struggle with chewing through the metal of a coal bunker, leaving my compost bin out of their list of local hotels and restaurants.
The process
Preparation
I started off by washing out the coal bin. It is unusual for something like a coal bin to really need a bath. After all, it’s going to get grubby straight away! The same applies to this as a compost bin because it’s going to be filled with dead plants and vegetable scraps straight away. Why bother?
The main reason I elected to bathe the coal bin before I started anything was because of the coal remnants. Like everything, there is conflicting information on the internet about whether coal or coal ash can be used on plants and in compost. Some blogs say go ahead. Others say a little bit won’t kill you. And the final camp says that coal ash will kill everything in your garden and your family.
Coal and charcoal ash contain substances that are harmful to plants such as sulphur, arsenic metals, and other chemicals that the coal has been treated with. This can make the compost produced too acidic for most plants to thrive. However, as one blog pointed out, the earth already contains some of these trace metals. The problem is that you can have too much of a good thing. Therefore, in small quantities, it stands to reason that coal ash shouldn’t do any harm.
As much as I want to recycle, I don’t want to be poisoned which I think is fair. Whilst I concluded that a small amount was probably fine and wouldn’t do any harm, I was left wondering whether some composted coal ash would actually have any benefit for the garden. Probably not. I decided to err on the side of caution and just wash away the potentially hazardous but also potentially fine, material. The more “official” and more universally recognised sources like Recycle Now and the Royal Horticultural Society forbid the use of such material. Thus, I decided that, like a good citizen, I would follow that advice.
On the other hand, the cousin of coal ash, wood ash, can be added to the soil assuming the wood was not treated prior to burning. It is a good source of plant nutrients, such as potassium. This is all laid out in the RHS article linked above. However, wood ash should be only added occasionally or it can create compost that is too alkaline. This is useful if a soil is too acidic, but not if the soil already has the perfect pH of 6.5. It does kind of make sense to me that wood ash would be ok because wood has already grown from the ground, using the nutrients of the soil. Alternatively, coal is just an ugly diamond, created by intense heat and pressure over hundreds of millions of years. Composting wood therefore feels like a nice circle of life moment where the nutrients are returned to the soil. I remember how chuffed my mum was after we had bonfires when I was younger as she could spread the wood ash over the vegetable patch.
Drilling holes
Using a special drill bit purchased just for this occasion, I drilled lots of holes in the bottom and sides of the metal bin to allow for adequate air flow. You do need a specific High-Speed Steel (HSS) bit for drilling into metal as you need something that will cut through. The biggest drill bit I had was 6mm in diameter, but really I think I could have done with a slightly bigger bit for this purpose. I worried that the bigger decomposers, like the worms, would not be able to get in through the holes or that they might cut themselves on the sharp metal edges! I tried to file down the sharp edges on the inside to prevent such workplace accidents, but this was with limited success.
As I mentioned in my previous composting post, the key features that the decomposer union requests for its workers is good quality food, oxygen, and an environment with goo air flow to be able to do their work. Without holes in the bin, there would neither be the access to my good pile of decomposing scraps, or air flow to create a comfortable work environment that allowed them to prosper.
Without oxygen and therefore without these holes, the compost pile could become anaerobic. If you can go back to your GCSE science lessons, you should remember that anaerobic simply means without oxygen, and therefore without airflow. It is a legitimate method of composting and is something that continues to be used today with nitrogen rich materials like manure. You can also use anaerobic composting through a compost trench where you dig a trench in the earth, fill it with organic matter, and then cover it over. All the decomposition happens underground without decomposers that require the oxygen that aeration brings.
There are several reasons to choose aerobic composting over anaerobic. As I found in my mistakes of a beginner composter, anaerobic composting really smells! I have therefore accidentally practised anaerobic composting. This often happens due to a poor balance of nitrogen and carbon materials and poor aeration. Therefore, unless the compost is kept in a sealed container that the air cannot escape, an anaerobic heap is thoroughly unpleasant to be around.
Additionally, it takes longer, needing at least a full year to mature. On the one hand, this might not matter as it requires less effort from the gardener with no turning and aeration efforts that would introduce air into the heap. On the other, it is a closed process. The bin I wanted to create would be a circular process where I could continuously add waste to the top and take the finished product from the bottom. A closed process would require more space and a minimum of 2 large bins; one full bin would need to be left alone for the year to decompose whilst the other was filled.
If you want to read more about anaerobic composting and how to do it at home, click here. It might be something I explore more if I get more space or if I want to. Right now, aerobic composting suits my needs and is the first skill that I want to learn.
The final touches
I really am over-exaggerating this by calling it a “process”, as all it really involved was drilling holes. But still, I like to think that my decisions are well thought out. As a further bit of “upcycling”, I stood the finished product on top of an old wine or beer bottle plastic crate that was, again, left over from the previous owners of the house.
The reasoning for this was threefold:
- I was locating the bin on a paving slap, not the earth. Worms and decomposers get access through the earth when the compost bin has no bottom. There would be little point drilling holes in the bottom of the bin if these were not going to be accessible, so creating some open space between the bottom of the compost bin and the ground allowed access. But I definitely had the thought of the need for a stand first. Yes that idea came first … it wasn’t just a way to make sense of what I had already done …
- I wanted to be able to open the bottom hatch to let compost fall out. As I explored above, I wanted to be able to create a circular system that I could continue adding to whilst also taking rewards from. This would take up less space and (hopefully) only require one bin.
- A hole punched base for the bin along with a stand would allow adequate drainage. Since I was not placing the bin on the earth with no base, there would be nowhere for the compost tea to go or for the larger decomposers to gain access. Excess moisture would typically drain into the earth where decomposers would also access the material from. If I put holes in the base of the bin but placed it directly onto the concrete, the excess moisture would have nowhere to go and would only settle at the bottom of the bin. It would have to therefore be raised for the purpose of drainage to be met.
Conclusion
I hope you enjoyed this little “upcycling project” and I hope it inspires you to look at any of your old goods that might have a new life in a new role. Not all upcycling needs to be incredibly creative or complicating, involving redesigning clothes or repairing and painting old furniture. It could just be a matter of drilling some holes.