Composting II Three Bin
Anyone can compost. When we think about composting, most people imagine great big industrial units full of dump-trucks processing what everyone left over from dinner that week. But composting is dead simple – it’s just the controlled decomposition of dead stuff. It’s happening in your black bin bags right now. However, when you compost at home, you’re capturing the good stuff from the waste and recycling it into growing new things, as opposed to letting it rot and clog up landfill and adding to pollution and global warming. You’re plugging into a circular system taking from the earth and returning to the earth.
Today I’m going to cover the first basic composting system – just piles of stuff in the open that you turn over until it becomes compost. For this system you need a bit of space or a garden. I will cover other systems for those of us that have less space in later blogs. I’m also going to be making my gardening screen debut – I did a few videos to run with this blog. I’m not expecting a nomination from the Academy any time soon though.
All kinds of things can be adapted to make a compost bin. The only limits are your space, your imagination, the materials that you can get hold of and your DIY skills. I’m going to show you a system I put together with seven pallets that made three containers. Pallets are good to use as basic infrastructure, as they are sturdy, double-layered, so they stand up easily, and can be lashed together with twine, or screwed into posts driven into the ground. They’re also often just thrown away - any Tesco Metro, Sainsbury’s Local or small grocery store will have plenty from deliveries that they just have to dispose of - so using pallets is fairly cost-effective.
I made three boxes: one for new material, one active pile that I ‘work’, and one for finished material to mature and as storage. Dependent on your craft skills, you can make a sliding front, lids, liners.
The advantages of making your own are:
- Materials are cheap or free;
- Fun to make;
- Will last for years.
However, there are disadvantages. They’re a bit hard to vermin-proof, so unless you feel that you need to feed the local rats and foxes, be careful what you put in – especially food items. They can also be a bit ugly, dependent on your DIY skill. That said, I’ve seen some lovely home-made compost bins, that look like a piece of garden furniture.
Just a quick note on the waste food content in a bin. Don’t put in cooked food, meat, fish, oils or dairy produce. Do put in spoiled vegetables and fruit, tea and teabags, used coffee grinds, crushed eggshells, stems, vegetable peelings and cuttings. Be careful though on the amount of citrus fruit, onions and garlic. They can change the acidity of your pile, and worms (your best composting friend) don’t like too much onion and garlic. I guess they are sensitive about their breath. Also tear up your cereal boxes, kitchen roll tubes and eggboxes and compost them too.
In making compost you need a mix of materials. I’ll divide them into ‘Browns’ and ‘Greens’. Your Brown materials include dry woody stems, wood chippings, cardboard (the centre of loo rolls and Amazon boxes are good – as long as you peel off the tape and stickers), paper, dry plant stems, hay, straw, dry leaves. Your Green materials are your kitchen peelings, scraps of fruit, spoiled veggies, salads, fruit – fundamentally anything that is fresh and green (nettles are brilliant, as they are an activator and speed up the compost process), weeds, plant cuttings, grass clippings.
You need to get a mixture of these items. Too many Browns, and the pile will be dry and will not compost, too may Greens and it will become clogged, wet and smelly and will not compost. The importance of the Browns is that it gives the pile structure and creates tunnels for air and water and crawlspace for invertebrates – the three factors that turn waste into compost.
Composting is an aerobic i.e. with oxygen process. Air and water react with fungi and bacteria and create an environment for decomposition. Worms and other insects break down the fibres in the material and allow the bacteria and fungi to do their work. A compost heap is like a living organism. When it works, it will create heat (when a compost heap is working efficiently, it will be between 49oC and 77oC (120-170oF) and on a frigid day you’ll see steam coming off it. This will cook any seeds so that they don’t sprout and kill off most harmful bacteria. In an efficient system you can break new material into usable compost in about four weeks) and liquid.
When I start off a new compost pile, I try to layer it like lasagne. I create a cardboard base, cover this with a layer of Browns and then a layer of Greens and so on. How thick you make a layer depends upon how dense and wet your materials are. Fresh cut grass needs to be added in a thin layer of about 2cm and mixed with Browns, or else it will clog.
Follow this mantra, and you won’t go far wrong:
They are the basic requirements for life – applicable equally to compost heaps and human beings. By constructing your pile, you are creating an environment for billions of micro-organisms to help make composting happen. You need a happy mix of air and water – a balanced pile will be about as moist as a squeezed-out sponge. If the pile becomes too dense and sloppy, you are starving the aerobic bacteria (with-oxygen) and the pile will go anaerobic, and the bacteria that will move in will make the pile smelly and decompose (or ferment) the material into substances that will kill your plants. That’s why you need a good mix of Browns.
If your pile gets too dry, the good bacteria will die of thirst. If you have this problem, run your hose over the pile for a bit. I’m not recommending this, but an important accelerator is urine (especially male wee. It’s wet and has nitrogen and enzymes in it that feeds the bacteria). Some systems use urine to speed up the process.
The food you add will include a good balance of proteins, carbohydrates and dietary fibre – same as what I’d recommend everyone to consume. The two types of micro-organisms in the pile are bacteria and fungi. The bacteria consume the nitrogen, and the fungi eat the carbon. As long as you add a good mixture of material balancing wet and dry, structure and absorbency, Green food and mix them together your compost pile will work. In cold weather, try and cover the pile with a bit of tarpaulin or old carpet, otherwise the water will freeze, and the process will stop.
Once you have created your heap, you can then work your heap in a second bin. This involves turning the compost over every few days, to introduce oxygen and keep the temperatures high. This can be carried on for three weeks. After this period, transfer to your third bin for maturation and cover.
Leave me any questions in the comments below.