Christmas Food Waste
Before dealing with winter composting techniques please read this section on Christmas Waste, how to reduce food waste and composting diferent seasonal waste.
Each year we in the UK throw away about one third of all the food we buy at least half of which could have been eaten. It is hard to believe but the average UK household is estimated to throw away about £325 of edible food every year, and about £20,000 worth in a lifetime.
The total household Christmas food bill is estimated to be about £170 with a third of us confessing to having helped ourselves to “an excessive amount” of food over the festive season. This would be bad enough if it was all eaten but 35% admit to throwing away more food at Christmas than at any other time of year.
It is estimated that almost 10% of every Christmas meal is wasted. This the equivalent to the UK chucking £64 million in the bin each Christmas.. Waste on this scale should not be caused by individuals, we have a government to do that for us.
It is estimated that we celebrate the festive season by wasting the equivalent of :
- 17.2m Brussels sprouts
- 11.9m carrots
- 11.3m roast potatoes
- 10.9m parsnips
- 9.8m cups of gravy
- 7.9m slices of turkey or 2 million turkeys,
- 7.9m cups of stuffing
- 7.1m pigs in blankets
- 7.5m mince pies
- 7.4m slices of Christmas pudding or 5m Christmas puddings
This is an incredible amount of unnecessary waste, all of which could be avoided by careful buying, food storage and cooking leftovers with any food being home composted using the appropriate food composting equipment e.g, a Hotbin, Green Johanna, Jora 125 or a Bokashi system if space and the amount of wasted cooked food is limited
Composting food waste
Despite the planning and good intentions there will be some food waste, including cooked food, so I you do not have one add a food composter to the Christmas list .
All of the items of food listed above can be composted in a Jorra 125 (which is specifically designed to compost food waste) or a multipurpose hot composting systems such as a Hotbin or Green Johanna.
Not mentioned in the lists of food waste above are gravy,and sauces. Normally it is not advisable to add liquids to compost bins but they will take “plate scrapping” quantities of gravy, cranbery sauce, etc. if mixed with shredded If adding large amounts of food waste to a compost bin add plenty of bulking agent (wood chip, wood pellets or sawdust). Uneaten nuts e.g. chestnuts can be smashed with a hammer and composted with the other food. Natural corks can be added but will take a time to break down and might need returning to the bin for a second session when the compost is harvested.
It is often said that orange, satsumas and clementine peel should not be added to composting bins but while these are not suitable for wormeries they can be composted in a convention bin as part of a balance diet with peelings from winter vegetables and carbon rich “browns” such as cardboard packaging from Christmas gifts as, Christmas cracker inners. Christmas wrapping paper (non metallic/glossy/plastic/waxy) can be scrunched up and added to the mix.
For the Hotbin absorbent browns such as shredded paper should also be added at the rate of two or three generous handfuls per 5 litre caddy of food waste.
With the Green Johanna add one part garden waste to two parts kitchen waste in layers stirring the top garden waste, or shredded paper layer with the aerating stick provided. While the Hotbin is made out of insulated material the green Johanna needs additional insulation to keep it operating in cold weather Great Green Systems sell a winter jacket or it can be insulated with layers of bubblewrap.
The Jora is, what I call a tombola style, tumbler which turns/.aerates easily and is designed as a food composter. It is recommended to use compressed sawdust pellets as the bulking agent at a ratio of 1 caddie of pellets:10 of food waste. This absorb the liquid, provide a carbon source and does not add much to volume in the bin.
If there is only a relatively small amount of food waste this can be dealt with using an indoor Bokashi system which will ferment the food to a material that can be added to a” normal” garden compost bin
Real Christmas trees can be shredded and composted, although the needles may take some time (C:N ratio of pine needles 80:1) so some recommend composting them separately, or that they be used as a multch. Some use the needles on muddy garden paths.
If the branches are to thick to shred using a garden shredder they can be used to form a blanket to protect plants that are susceptible to windburn, plants that are marginally hardy in your area, and those susceptible to early frost plants.
Most Councils will collect Christmas trees for composting
With the coming of winter most composting processes slow down or stop as a result of the cold weather but there is no reason to stop feeding the compost heap or bin in preparation for an increase in microbial activity when spring eventually puts in an appearance. However you may like to try to keep the composting process working over the winter to increase your yield and as a challenge to show your composting skills.
The use of a commercially available insulated bin, such as the Hotbin or Biolan, will mean that while the composting process may slow a little it should continue during the cold weather.
Alternatively with a little work ordinary bins can be insulated so that they continue the composting process over the winter months. If you continue feeding the heap or bin with the right mixture of greens and browns the rotting process will continue generating its own heat all that is required is that as much as possible of the heat is retained.
One of the keys to success is the size of the bin, or heap, it needs to be at least 1 cubic metre (1.3 cu yards) to provide the critical mass for thermophilic organisms to keep working. Unless insulated to a very high standard a smaller bin or heap is likely to be frozen while one that falls to near freezing will not remain active. The first approach to prolonging the working period is therefore to increase the size of heap to encourage the composting process continues longer into the winter season. It will also be advisable to site the heap or bin so that it is in full sun to take advantage of any external heat.
Covering the compost heap with a tarpaulin or carpet avoids it becoming waterlogged with cold rain and may slow the loss of heat generated but this is not enough to keep the bin working, insulation is necessary to keep the bin functioning during the colder months.
Old carpet, flattened sheets of cardboard or polythene sacks filled with straw or loft lagging ( sealed in a plastic bag to keep it dry) or layers of bubblewrap will help retain the heat if wrapped round a plastic bin or wormery.
Wooden bins can be lined with layers of corrugated cardboard with a layer of polythene (old compost bags?) on the inside where the cardboard would come into contact with the compost. One of the points to be considered when buying or making a wooden bin is whether to opt for solid or slatted sides. The slatted slides offer improved aeration during the summer but are more difficult to insulate during the winter. Bales of straw or hay can provide a quick and easy means of insulation but will some need to be removed to allow waste to be added to keep the composting process working though the winter. An outer wall about six inches bigger than the original sides can be built of wood or blocks round the bin, to provide a space for further insulation to increase heat retention. Wall insulation material is excellent, as is loft insulation but items such as cardboard or bubble wrap can also be used. If a pallet bin is being converted cardboard or other insulating material can be stuffed in the gaps in the pallet to further increase the insulation
The top of the bin must also be insulated. Some sources suggest using a thick layer of bedding, loose straw or leaves, while these will help retain the heat they are not practical if waste food material is to be added to the bin during the winter. A layer of loft or wall insulation sandwiched between wooden boards from pallets or polythene sheeting cut slightly larger than the top of the bin and sealed to keep the insulation dry provides an insulated lid that can be easily removed
While cold weather will slow the compositing process the insulation should maintain the crucial microbial activity inside the heap or bin. The microbial action of the bacteria, fungi, and actinomycetes causing decomposition of the material in the bin will produce heat as a by-product of the chemical process. The bin insulation should mean that this heat is retained.
During the winter fresh waste materials must be added continually to keep the bin at working temperature. It is also recommended that more care is taken to layer the browns and greens. The layers help insulate the heap and retain heat. Shredding or tearing the materials to less than two inches in size has been shown to assist in heating the heap uniformly.
The correct mix of Greens (nitrogen rich) and Browns (carbon sources) is more important during the winter than in the summer months as there will little external heat to assist the composting process. This will be dependant of the heat generated by the process itself. It is suggested that this material needs to be well balanced with C: N ratio between 20:1 and 40:1
Straw, fallen leaves (saved in sacks), shredded newspaper, or sawdust can provide a source of carbon. In addition small amounts of wood ash can are added to increase the calcium, phosphorus, and potassium content of the finished compost.
The main source of nitrogen rich materials during the winter is likely to be kitchen scraps as little will be available from the garden. A good supply of vegetable and fruit peelings is essential. It may be possible to supplement your kitchen waste with some from neighbours. Used Coffee Grounds, provide an additional boost and may be obtainable from a local cafe.
Chickens and rabbit manure also provides a good source of winter nitrogen. Black treacle (Molasses) used at a ratio of 1 part molasses to 20 parts water to soak absorbent material such straw or shredded paper or the manure /animal bedding is a useful addition. As those who make aerated compost tea will be aware black treacle is good source of bacterial nutrients and will help raise the compost temperatures
Moisture is one of the key factors in the composting process and winter winds and low humidity can dry the compost heap or bin. During warm spells warm water could be added to dampen but not soak the compost if it appears to dry. Aeration and turning the compost is not recommended by some sources during the winter as this will interfere with the insulation that you’re careful layering of the bin has produced and let cold air into the material. However others recommend aeration as a means of getting air into the heap which should activate the aerobic micro-organisms and producing heat to maintain the composting process. Rather than using an aeration tool it might be better to empty and refill the bin to ensure a god mix. If a two or three bin system is being, for what in the spring and summer would be hot composting, when moving the compost from one bin to another ensure that the material at the side of the bin is added towards the the middle of the new bin so it composts evenly.
As an alternativeto continuing to use the compost bin Trench composting, in which a trench is dug and filled with kitchen scraps over the winter offers a simple method of composting over the winter months. Although it has fallen out of favour as a composting method, other than for creating a bean trench and for marrows etc, it is still worth considering as a means of composting uncooked kitchen waste.
Bokashi Bin or wormery One of the indoor methods of composting such as a Bokashi bin or a wormery will reduce the need to venture into the garden during the winter. This of course assumes that the wormery is moved into a shed, garage or outhouse for the winter and not wrapped in insulation and left in the garden.
We have kept wormeries working at Compost Corner at Snibston Discovery Museum during the winter insulating them with loft insulation in polythene bags and bubblewrap. The insulation round the lid needs to be removable so that the Worms can be fed and access should be provided to the tap to enable the Worm Wee to be harvested