COMPOSTING GUIDELINES FOR SCHOOLS IN
Congratulations! You have now joined the growing number of
schools in
1. IMPORTANT - BEFORE
YOU START!
1.1 You must only compost food waste which arises on site and you must use the resulting compost on site. You cannot ‘import’ any food waste for composting nor take the finished compost off site.
1.2 No ruminant animals or pigs are to be kept at the school premises and if poultry is kept at the school premises the material is to be composted in a secure container which prevents poultry having access to it during decomposition.
1.3 The school is advised to modify the job description of the main person responsible for the composting, usually either the caretaker or a teacher (preferably both) so that their duties include time spent maintaining the composting (and recycling).
1.4 Involving the children as much as possible is desirable to ‘embed’ the system into the school ethos.
1.5 Training must be given to all those who are going to work with and handle the compost particularly in regard to Health and Safety. You should write you own health and safety policy, use the template provided as a guide.
2. KEY TIPS FOR
ACHIEVING A GOOD COMPOST SYSTEM
Follow the four point composting mantra – food, air, water, warmth
2.1 Food – balanced
diet
The food you add to the composts has to be the right balance of carbon to nitrogen. Food wastes are predominately nitrogen rich which means there has to be a supply of carbon brought in, this is also vital for the air element, so sawdust and woodchip fit the bill perfectly (see later notes for quantities).
Food must be added fresh every day as it arises. If you leave it festering in a bucket it will go anaerobic (without air), get very smelly and then it is much more difficult to get composting properly.
Fruit waste is pretty acidic and the first hot stage of composting needs to be neutral or slightly alkaline. Woodchip and plenty of air helps balance the pH and some shredded up cardboard is good as that is also alkaline (see later notes on quantities).
2.2 Air
Air is provided by the woodchip and/or sawdust that you mix with the food waste. This is preferably to softwood and must not be sawdust from MDF or other composite wood with glue materials or tanalised timber etc.
2.3 Water
Raw fruit and veg is mostly water so it is rare that you need to add more, however the 2nd stage composter (or maturation system (e.g. a Scotty’s Hot Box) can dry out especially if paper towels and cardboard are added – if this is the case add water, preferably rainwater.
2.4 Warmth
The Jora, Scotspin, Ridan and Hot Box and are all insulated to maintain warmth.
3. HOW COMPOSTING
WORKS
Composting goes through four stages
3.1 First it gets warm,
3.2 Then, if the mantra has been followed properly it will rapidly progress to being hot. Turning daily to mix and aerate as new food waste is added will maintain the temperature and will accelerate the composting process as long as fresh materials are being added.
3.3 Cooling. As long as the materials have heated up and started to break down in the tumbler they can be added to the maturation container. At this stage the material is only partly composted and it can vary enormously. It can be rather wet and smelly depending on how much your school is putting through the system and how well you are following the composting mantra. It is an opportunity to rectify problems, for instance you can layer in paper towels or cardboard to soak up excessively wet materials or conversely to add moisture to a dry mix use fresh green garden clippings or sprinkle with (preferably) rainwater.
3.4 Maturation. Over a long period of time the compost can now mature.
4. Starting a new
compost system from scratch
4.1 Jora and Scotspin
tumbler composters
1. When you first start a new composter from scratch it is always advisable to add a good dollop from another compost heap in order to get a starter culture of bacteria and other micro organisms. Don’t worry if this is not possible.
2. The aim is to ¾ fill the composter over a period of time (remembering to leave enough space for the materials to tumble). Starting from scratch add a bucket of dry woodchip/sawdust* (a mix of both is fine) and a bucket of fresh ‘greens’, fruit and vegetable peelings. Also add a bucket of composting material from an active heap if at all possible to kick start the microbial populations, a bucket of finished compost is also good. Keep adding and tumbling on a daily basis during the week, don’t worry about the weekends, it’ll be fine. Each day the volume should reduce leaving more space. You will notice that the Joras have two compartments, if you only have one Jora it’s advisable to (almost) fill one side first before starting to fill the other side. If you have two Joras fill one whole Jora before filling the second one but tumble both daily.
3. Normal ratios of ingredients:
i) for cooked food, plate scrapings and left over unserved food follow the rule of thirds: One bucket fresh raw peelings etc to one bucket of cooked food and one bucket of dry woodchip/sawdust (you may need to add extra woodchip/sawdust if the cooked food is particularly dense, wet and heavy).
ii) for mostly raw fruit and vegetable peelings etc follow a 50 /50 ratio roughly equal volumes of fresh materials with woodchip/sawdust
4. During the start up phase – for the first few weeks or month, it’s best to make sure that the air supply, in the form of woodchip/sawdust is higher than is needed rather than less. If you start a system with not enough structure it can easily go airless and start to smell and then it’s difficult to get it back on track.
5. When you first start composting it is also advisable to limit the materials as far as possible to fresh peelings rather than tackling the cooked fraction, introduce this element gradually as and when the compost is steaming away nicely.
6. Cardboard is also a good substance to add in small amounts at the beginning of the composting process as it helps balance the pH, cardboard dust is even better if you can get it or cardboard shredded for bedding. Be careful of adding too much that it balls up and dries the composting material out too much.
NB these are just guidelines and you can augment food waste composters with garden clippings just balance the ‘browns’ and ‘greens’ as much as possible.
The Joras 125, 270 and 400 and the Scotspin are all batch system tumblers. When your tumbler is about ¾ full you don’t want to add any more food or it will not tumble and mix effectively. Without fresh materials being added, after a few days the temperature will start to drop and the cooling phase will be entered. So, you will need to empty it and place the contents into your maturation bin before you can add more fresh material. The final stages of cooling down and maturation takes much longer and is best carried out in this maturation bin.
The Jora does have two chambers which means you can alternate between them. If you have two tumblers you simply have more capacity but they will both still need to be tumbled.
Using the Jora 270
When the second compartment or the second Jora is full you must empty the first compartment or Jora and transfer the contents to the maturation unit (usually a Hot Box)
Depending on the volumes you are putting through the system
(and this will vary from school to school and even week to week) the material
coming out will vary in its degree of decomposition but as long as most of the
material has started to break down it’s fine to transfer to the Hot Box – see
below. See Smartsoil website at www.smartsoil.co.uk.
Using the Scotspin
The Scotspin is very similar in use to the Jora, so follow the instructions above as for the Jora 270, except that it only has one chamber, this means that the most recent materials added will have hardly started to break down when the whole chamber needs emptying, unless you have two Scotspins or an additional system of some sort. It doesn’t matter that not all the materials are composted, the uncomposted materials are well mixed in and can be layered into a maturation bin which becomes in effect a large wormery. See instructions provided.
4.2 Ridan
The Ridan differs from the two systems above in that materials are harvested every time fresh materials are added and the mechanism turned.
When starting to add materials to the Ridan include a good bucketful of active compost and also some more or less finished compost if at all possible. Add a really generous amount of dry wood chip too. When starting up a good proportion mix is for each bucket of wood chips have one bucket of fresh peelings.
When you are getting some high temperatures generated (50 – 60 degrees Celsius) then you can start to add cooked foods too. One bucket of cooked should be mixed with a bucket of fresh raw peelings etc and two buckets of dry wood chip.
Chopping up whole vegetables and fruit with a spade in a bucket is advisable otherwise they tend to emerge relatively unscathed from the machine.
The first materials to emerge from the Ridan can be recycled through the front end again, this helps to boost the pH and to get all the right bugs multiplying. Sieving the materials through a coarse sieve into the maturation bin enables you not only to reuse some of the woodchip but helps the pH and microbe mix.
The proportions above are only a guideline and if you don’t have as much fresh raw peelings you can substitute with fresh green materials from the garden.
See the Ridan website for more advice www.ridan.co.uk
4.3 Using the
Scotty’s Hot Box (or other maturation system )
Materials added to the maturation bin can be in any stage of decomposition, although with food waste the whole point is for the materials to have been through a rapid hot phase which kills off pathogens and renders the material unappealing to rats. Take the materials from the Jora, Scotspin or Ridan and tip into the Hot box, rake the contents level.
This is also a good time to check the moisture levels. If it is wet and sloppy still you can layer in paper towels, (the unbleached cream coloured ones are best, if your school gets blue ones consider procuring these unbleached ones) you can also add some cardboard to mop up excess moisture. If it is too dry then you can add fresh garden greens in layers, such as grass cuttings or fresh weeds etc or you can add water, through a sprinkler (or rose on a watering can) is best.
If you only have one Hot box then when it’s full you will have to scoop off the top layers and put them to one side. You should find plenty of worms under the top section, put them with the top layers too. The bottom section should yield plenty of finished compost after six to nine months or so. This can either be used immediately on the gardens or bagged up until needed.
If you have two or more hot boxes then as you fill them move
onto the next one when all are filled empty the first to be filled and the
whole bin should be ready. If you are not happy with the look of it try sieving
it. Any lumps, sticks or stones are quickly sifted out and can be tossed to one
side. See instructions provided.
5. Top Tips
1) Add fresh materials daily – do not leave waste hanging around in buckets/caddies getting smelly and attracting flies
2 ) Line your buckets/caddies with some paper and or card to soak up liquids and make cleaning easier
3) Always make sure you have the right mix of wet to dry materials – fresh raw and cooked to dry woodchip/sawdust and mix well together
4) It’s easy to store dry woodchip, just cover it up in a bay or use a container
5) There’s plenty of woodchip around, you could ask if any parents or governors have a tree surgery business and could supply you. Alternatively wood pellets are easy to use.
6) Wherever possible chop up whole fruit and vegetables or large items
7) Tumble and mix every time you add fresh materials
8) Leave enough space for tumbling to occur
9) Keep records of what you are doing e.g. amounts, weights, volumes, types of materials, observations of moisture, temperature and odour. This can be linked to curriculum work and some real understanding of the biological processes – pH monitoring using simple litmus tests at different stages of the composting would also be interesting. This monitoring can inform other schools as to how to develop better practice.
10) Cardboard and paper should not be added to tumbling systems in any large quantity as they tend to absorb too much moisture, do not offer structure allowing air flow and tend to conglomerate into balls.
11) Observe what is going on and take steps to rectify any problems as soon as possible, this generally means adjusting the moisture levels or emptying the tumbler into the maturation bin.
12) It’s rare for the compost to be too dry but if it does seem to be too dry it’s better to try and add fresh green material than water.
13) Don’t panic! Compost happens!
6. Troubleshooting
If you are troubleshooting then the guidelines have probably not been followed carefully enough.
Flies – a few are quite natural but swarms are more tricky. Fruit flies like fruit obviously so frequent emptying into an active system on a daily basis it the best thing to do. Getting the mix right is essential. Blow flies are attracted to fresh meat, you shouldn’t have this in your system except perhaps in very small quantities, a hot active system is essential. If you do get large maggots in the compost or lots of blow flies around, try and find some laurel leaves and add them to the composter.
Other insects, ants, woodlice, beetles – these are all perfectly fine, ant colonies can sometimes take up residence.
If you really need
help! Please ring our expert, Nicky Scott, Community Composting Coordinator for
