As bin charges increase and households try to be more environment friendly we are seeing a corresponding increase in home composting. We have been interested in domestic composting for a long time now and stock some very effective solutions which have a number of unique selling points to suit various applications.
We are often asked to weigh up the pros and cons of each solution so I thought it might be helpful to cover the key differences today and explain how they work. So, here goes…..
Carbon, Nitrogen and Oxygen
It may be obvious but it’s probably worth pointing out that a compost bin needs three main elements to work; carbon, nitrogen and oxygen. Carbon and nitrogen come from the waste material added to the bin, this is broken down by friendly bacteria. Air is needed for the bacteria to breathe, if there is no air in your compost pile it won’t work.
In general carbon comes from dry brown material (dry leaves, cardboard, wood chip etc..), nitrogen comes from green material (vegetable peelings, grass clippings, green garden waste) and air is introduced by either turning the compost with a garden fork or rotating the compost bin itself. As regards ratio, 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. The most common problem with composting is not enough brown material.
Cold V’s hot composting
Any organic material will eventually break down to form compost but if the material can be made to produce heat it will happen a lot quicker. Heat is produced by the bacteria that break down the compost; the heat can be managed by adjusting the mix of materials, adding air and/or insulating the pile. Apart from the rate that finished compost is produced, hot composting also has the advantage of killing weed seeds and pathogens.
A hot compost heap requires some planning and input from the gardener while a cold heap is built as materials become available so is much easier to do. A cold compost heap takes a long time to break down, a year or more depending on local conditions but will still make perfectly good compost.
Naturally an insulated compost bin will retain heat longer than an uninsulated one. More heat means faster composting; material from an insulated compost system is usually garden ready for use in the garden in 60-90 days.
Worm composting or ‘vermiculture’ uses worms instead of bacteria (but in truth a bit of both) to break down the material. The big advantage of worm composting is the finished product is a highly nutritious compost with a perfect balance of nutrients to feed plants.
Some Key composting Solutions:
Static Compost Bins
Obviously the most basic compost solution is simply a pile of compostable material. The next step up is an enclosure of some kind which will either be a single skin plastic product (the Eco Compost Bin, Be Green Compost Bin, Rotating Compost Bin 200L) or a wooden structure like the ‘wooden compost bin‘.
Plastic bins are the cheapest solution and while they can be used for hot composting they are more likely to be used for cold. The most common issue with this type of system is a smelly bin due to lack of air. This can be easily remedied (but rarely is) by emptying the bin and mixing the contents before re-filling. If the contents are overly wet they should be mixed with a dry, carbon based material.
The wooden alternatives are an open slatted design which allow air to circulate so do not tend to suffer from the problems above.
The New Zealand Box system
The New Zealand Box system is a 3 bay system designed to aerate compost by turning from one bay to another. This is a very effective system which can be made far more effective by paying attention to the C/N mix. The procedure is as follows:
Compost material is added to the first bin, this is the hottest compost stage. Material can be added over a period of time but is most effective (gets hotter) when added in large batches.
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 6-8 weeks the material can be turned into the final bin where it breaks down further and can be used as needed.
The New Zealand box system is the best if you have large volumes of garden waste that need to be processed. This method will not build up sufficient heat unless you have enough material to build a large pile (ideally 4ft cubed).
Thermo Plastic Compost Bins
A new product which bridges the gap between static and insulated compost bins, the ‘thermo’ range are made from a specially engineered Thermolen® plastic. Tiny bubbles in the material improves heat retention and speeds up the composting process.
The Thermo Wood, Thermo King and Thermo Star compost bins are all made from thermolene with the Thermo Wood (pictured) being the most attractive with a smart wood finish. All are made by German company Graf/Garantia and are a high quality product.
This product will compost quicker than a standard plastic bin and will produce finished compost in 16 to 20 weeks in the summer months. Material can still be added in Winter but the composting process will be slow.
The Hungry Bin
The Hungry Bin is a worm composting system designed to be easy to use and to be large enough to cope with household waste (anything smaller is really only a hobby kit). The bin is home to up to 16,000 composting worms which process kitchen and garden waste into highly nutritious compost. Apart from the fun of having thousands of worms eat your scraps it is the resulting compost that is the Hungry Bin’s big advantage, it is a perfectly balanced plant feed. The Hungry bin also produces a liquid ‘worm tea’ which is an excellent liquid feed.
To get the hungry bin going you will need approx 2000 worms (naturally we supply). The population will grow over 6-8 months to the full 16,000 depending on how much food is placed in the bin. The worm population will self regulate in balance with available food so you do not need a very large amount of material to feed the bin. At full capacity the hungry bin can process 2.0 kg of waste per day.
The Hotbin is available in small and large sizes, it is an insulated compost bin which is capable of processing all kitchen waste. Temperatures inside the bin reach a steady 60-70˚C which allows the hotbin to compost meat and fish waste and ensures any weed seeds or pathogens are killed off.
It is important that you add a bulking agent (shredded bark supplied with the unit) to create air spaces in the compost mix. If the contents have cooled down or are not composting correctly the material should be stirred and new material added.
The small hotbin is ideal for smaller households (2-3 people) while the large version will process waste from a medium to large family (4-6 people). Finished compost can be produced in 6-8 weeks and will be fastest in summer but will still continue effectively in winter.
The Joraform is probably the most versatile, easy to use and effective composter available, it is also the most expensive. The Joraform can do everything a hotbin can but is more forgiving for the user. The rotating composting chamber mixes material when turned which makes it easy to correct any imbalance in the Carbon/Nitrogen ratio while also introducing air. The unit is also split into two separate chambers with one batch being filled while the other is closed off to mature.
Made from galvanised steel panels, the Joraform is also fully rodent proof and is designed to last. This compost bin is available in a range of sizes including a 125 Litre (small household), 275 Litre (medium to large household) and 400 Litre (small commercial application e.g guest house or school).
In my opinion the Joraform is the simplest rapid compost bin because the mix of materials can be easily adjusted. Finished compost can be ready in 6-8 weeks and is easy to harvest by opening the hatch and inverting the bin. Like the Hotbin, the Joraform can also process meat and fish waste with the advantage of being rodent proof.
I hope all that is some use if you are thinking of changing your composting method, if I can provide any more information please let me know. I include a link to our composting department below if you would like to view the products we have available.