Some tips on composting
We’ve had a few questions on composting recently so I thought I would add a few tips this week. Making compost is not difficult, it is constantly happening without any help from us whenever organic material dies and begins to decompose. Whatever mix we put on a compost heap will eventually break down anyway but we can control the speed of the process and, to some extent, the quality of the finished product. Any issues which may arise (bad smells, slow composting, wet compost etc..) are usually easily remedied by changing the ratio of ingredients or adding some air.
The most important ingredient – air.
Air is a crucial ingredient to your compost. The micro organisms that break down your kitchen and garden waste need oxygen to breathe and do their work. If they have plenty of air they multiply faster, work harder and produce more heat. You can create air spaces in your compost by layering in bulky material like hedge trimmings or bulky cardboard (e.g.egg boxes) as you fill. You can also introduce air into a compost heap by turning the compost with a garden fork. If you live in a wet area you should also cover your compost heap as water fills up the air spaces in the material and will prevent your pile from working properly.
The New Zealand Box System
The New Zealand Box system is generally accepted as the best method of creating top quality compost. The system works by adding air as the material is moved between the 3 bays shown above.
Compost material is added to the first bin where it completes it’s first stage, this is the hot compost stage that generates the most heat. After 6-8 weeks the hot compost pile is turned into the second bay which mixes it and introduces air. This triggers a secondary compost cycle that does not create as much heat as the first but breaks down the material further. After 4 weeks the material can be turned into the final bin where it can be used as needed.
The second and final stages of the process will likely be full of composting (brandling) worms. Worms add the icing to the cake by digesting the compost and producing highly fertile wormcasts or ‘vermicompost’. At this point you have achieved compost perfection!
You can see me build a New Zealand Box system by watching the video below. This is very similar to the one we sell (including the our unique bracket system) but our new model does not need to be dug into the ground.
Hot composting means getting your pile up to 60°C which has the advantage of speeding up the process and killing off any weed seeds and pathogens. To create a hot compost pile without an insulated container the size of your structure will need to be 3ft x 3ft x 3ft, anything smaller will not generate enough heat. You can only really do hot composting in the Summer as it is the green material that provides the heat and it is unlikely you will have enough in the Winter months.
As we’ve said any compostable material will eventually decompose no matter what ratio it is added to your pile but hot composting will require the right mix of material to get it up to temperature as follows:
Nitrogen/Carbon ratio – weight not volume
In general green or soft kitchen and garden waste is nitrogen rich while brown waste is high in carbon. You will see a lot of conflicting information about the ratio they need to be mixed which is usually due to confusion over weight and volume. I find the best mix is 2 parts green x 1 part brown by weight. In volume this will look more like 50/50 as the brown material weighs less than the green.
In practice you can always correct a problem by adding more of either material and/or turning your heap. If your compost is wet and smelly add carbon (brown), if its dry and slow to break down add nitrogen (brown).
12 month hot composting
It is possible to hot compost year round by using an insulated compost bin which can retain the heat when outside temperatures fall. Apart from the usual hot compost advantages of killing off weed seeds and pathogens the insulated compost bin also has the added advantage of being able to handle meat, fish and cooked food waste. Clearly, expanding the amount of waste you can deal with makes sense especially with increasing bin charges; this helps justify the cost of the unit which, to be fair, is not cheap.
An insulated compost bin also composts much quicker (a full cycle takes 6-8 weeks) so can handle a lot of material over the year. You have 2 main options to choose from, the Joraform rotating drum compost bin (which is available in 3 sizes) or the Hotbin which looks more like an insulated wheelie bin.
The advantage of the Joraform is it rotates so it is easier to correct your mixture if required and to introduce air into the mix. It is also galvanized steel so completely rodent proof.
The Hotbin just looks like a standard wheelie bin but is made from thick insulated foam. It makes compost just as quickly and is easy to use once you get the hang of it. This option is significantly cheaper than the Joraform but works on the same principle.
As we know air is crucial in your compost heap so you need to make sure you allow air spaces in the material when filling a Hotbin. The company provide a bulking agent for your first cycle (this is bulky shredded bark) which is layered between dense, nitrogen rich material. We can provide this material in bags if you need it but hedge prunings or anything else that creates air spaces will do just as well.
All three of the above solutions produce excellent compost but are suited to different situations depending on the size of your garden and household and the amount of waste you produce. If you need any help or advice on any aspect of your composting project we are always happy to help.
This week I thought I’d end with a nice big picture, I took this one on the walk to work this morning. I wasn’t looking forward to it as I left the warm kitchen and pulled the door behind me but then walked down the lane and saw this. There’s always something beautiful just round the corner…….