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Sustainability Pathway 2024 June – Composting


We may have got to that point in the year where you’ve generated a load of grass cuttings and trimmed the bushes and there’s no way it will all fit in the green bin. Alternatively, you might not have a garden at all, but you’ve had a clear-out of all that paperwork that you no longer need to keep, and you’ve got a pile of vegetable peelings from last night’s dinner. Composting isn’t just for people with gardens. There are a wide range of domestic items that can be composted, and some forms of composting can even happen indoors!

Why compost at all? Soil is a rare, precious resource. It keeps us alive by enabling us to grow food and plants that provide oxygen, lock up carbon from the atmosphere, provide habitat for animals, and by providing building materials, provide habitat for us! The soil itself is a colossal ecosystem and a powerful store of carbon. Healthy soil takes a very long time to develop naturally and it is being destroyed ten times the rate that it is being created – hence dwindling crop yields, soil erosion, “dust bowls” in formerly fertile areas, and ultimately desertification. Phrases like “as common as muck” show how little humanity values this natural wonder.

Composting is a way of returning organic matter to the ground to keep soils healthy and fertile and promoting biodiversity.

Why not simply use the Council’s green bin? After all, they compost the contents! First of all, composting on-site reduces the need to transport compostable material off-site, and to transport compost and other soil additives on-site, and hence avoids the emissions associated with this transport. Secondly, there are far more items that can be composted than you’d put into your green bin (e.g. food-contaminated paper and kitchen scraps). It’s also a process that brings us closer to nature; one of the magical things about composting is that the composter constantly makes more space as the process reduces the bulk of the material.

How to compost?

Reading all of the well-meant advice on composting is a sure-fire recipe for never getting anything done for fear of getting it all wrong! Remember that Nature has been successfully composting unaided by humans since the dawn of plant-life. This was a pretty random process of plant and animal materials landing on the forest floor in whenever order, and gradually breaking down into nutritious mulch that would support future growth.  Human involvement has made this process more efficient by taking some the randomness out of it (and also made it more complex by introducing non-natural materials such as plastics!) but the random approach still works, more slowly. When faced with a fervent compost enthusiast telling you that you need to use this particular type of compost aerator, or exactly what you can put in, or that you’ve got your mix of “greens” and “browns” all wrong – just remember that Nature managed just fine before humans came along!

The term “composting” covers a range of processes:

  • “hot” composting, where well-mixed compostable materials with the right amount of water and air encourage microbial activity to the extent that the compost heats up causing rapid decomposition; the heat also sterilises many of the seeds that are in the compostable material, preventing them from unexpectedly germinating when the compost is used.

  • “cold” composting, where less control over the mix of the compostable materials means that there isn’t as much microbial activity, but other minibeasts (worms, slugs, beetles etc) still break the material down over a slightly longer timescale. Deliberately composting with worms is called vermicomposting.

  • Fermenting – technically, this is isn’t composting at all, but can be combined with composting to help speed up material processing (and to deter pests!) A suitable microorganism is introduced to the compostable material (often through a sprinkling of waste bran “inoculated” with that microorganism) and the material is left to be broken down for a few weeks; it can then either be used directly or added to a conventional composting process. A key difference from composting is that fermenting works best with minimal air, whereas regular composting seeks to introduce air.

It’s perfectly fine to mix these types of composting. Many people aim for “hot” composting and yet there are periods of “cold” composting. Others aim for cold composting and are occasionally surprised when the compost pile heats up!

Council facilities are well-equipped for hot composting – they can mix the garden material in green bins with food waste and process it in large quantities ( to create a good-quality compost out of a wide variety of input material. Some councils go further with huge steel composting vats with computer-controlled aeration, mixing and watering! The heat from this process ensures that all of the seeds from weeds that people put in their green bins are inactive when the compost is used.

Some people will go for hot composting by investing in an insulated “hotbin” (see but this isn’t necessary. We’ve got several standard  (uninsulated) compost bins that work perfectly well:

We lined them with chicken wire to prevent rodents getting in – this upgrade has proven successful over several years:

… and then filled them with grass cuttings, kitchen waste, shredded tree clippings and shredded paper:

After an unexpected initial period of hot composting, things slowed down and the worms and other minibeasts moved in – and I can assure you that you can tell when worms are really enjoying their food!

And (after regular turning to keep the aeration up) we were eventually left with a respectable-looking compost!

The local bird population had clearly caught on that we’d created a high-end abode for well-nourished worms, and would come and demand feeding whenever we went out to add to or stir the compost bin.

We’re now on first-name terms with our local robins – we’d not expected to be involved in this part of the ecosystem!

What goes into the compost?

  • Kitchen waste (this is fermented first – see below!):

    • food preparation offcuts

    • uneaten food

    • teabags, coffee grounds

  • Other domestic organic matter (e.g. dust bunnies, cobwebs, nail clippings, leaves from pot plants, hair from the hairbrush.

  • Waste paper and cardboard (including packaging material with the sticky tape removed!) ideally put through the shredder.

  • Food-contaminated paper wrappings (NB this isn’t allowed in green bins or orange bins so would otherwise have to go into the black bin for landfill/incineration!)

  • Compostable magazine wrappers

  • Garden waste:

    • lawn clippings

    • trimmings (including branches) – ideally passed through a garden shredder

  • If you use a wood burner, uncontaminated wood ash is permissible in moderation.

Weeds and other plant matter than might put viable seeds into the finished compost are disposed of in the Council green bin rather than the compost pile; this ensures that they will get composted at higher temperatures than our amateur composting will achieve.

People who want to maximise hot composting will talk about how you need to get the right ratio of “green” (high in nitrogen) and “brown” (high in carbon) materials in compost. Aim for two parts of brown to one part of green. For further details, see

  • Green materials are typically “wet” organic wastes such as fresh grass clippings and plant cuttings, fruit and veggie scraps, and fresh manure (but only use manure from herbivores!)

  • Brown materials are typically “dry” organic wastes such as fallen leaves, branches, wood chips, sawdust, shredded paper, and cardboard egg boxes.

What if I don’t have a garden? Fermenting kitchen scraps

A Bokashi bin (see is a means of collecting and preparing food scraps for composting – or for rendering them down into a liquid fertilizer. It uses a fermentation method (triggered by adding a special inoculated bran – although you don’t need to add as much as the people who sell the bran recommend!) and can therefore handle items (e.g. meat) that would not usually get added to compost. This makes it a lot easier to use in a busy kitchen as virtually all preparation and food scraps can be placed in the same bin with little thought! You can see that the process is working well as the fermentation is accompanied by a slight “pickle” smell and the contents of the bin being enveloped in small quantities of white mould. (The better you are at excluding air, the less white mould you’ll get.)

These bins are supplied in pairs so one can be fermenting while the other is being filled; then the contents of the first bin can be used and the bins swapped over – we typically do this once a fortnight. They’re designed to be used internally (ours lives in the cupboard under the kitchen sink) and the lids are an effective barrier against smell. There is a tap at the bottom that enables the liquid from the fermentation to be drawn off; this can be diluted and used as a plant food, or even used neat as an organic drain cleaner!


For those of you running a conventional compost bin, the advantage of fermenting the food scraps before adding them to the compost is that it accelerates breakdown of some food types, and it renders the food unappealing to pests.

What if it all goes wrong?

Relax. It will go wrong – there’s no “if” about it! However, composting is a very forgiving process and virtually all issues can be fixed!

  • In a lot of cases, composting slows down because the level of moisture or air isn’t right. Make sure that the moisture level is such that the material will clump together under gentle pressure, and turn it over with a suitably-sized garden fork to introduce more air. (I did try a bespoke compost turning tool and decided the form was more effective – it’s not worth the money!) An eggy small is a good indication that there isn’t enough air in the compost pile (the smell is caused by anaerobic decomposition rather than that aerobic decomposition we want) so turn the compost, and possibly introduce more shredded cardboard which helps to trap air as it it mixed into the pile. With experience you’ll know that compost is healthy from an earthy smell.

  • Foreign matter – it’s inevitable that something non-compostable will go into the compost. Unless it’s actively toxic, you might be best leaving it in place, as it is far easier to spot these items and pick them out once everything else has turned into a brown mush! We have an old trampoline with a green plastic cover which is slowly shedding – spotting these pieces in green grass clippings is near-impossible but it’s very easy picking green plastic out of brown compost!

  • Pests – in some cases these are beneficial. Slugs and snails are doubly useful as not only do they help to digest the compost, when they die, they are themselves compostable! Rodents are more of a challenge, as their urine can cause Weil’s disease (see so you might wish to handle affected compost carefully and avoid using it on edible crops. The best approach is defence – the chicken-wire lining to prevent rodents getting into the compost, and either fermenting food waste (our preferred approach) to make it sour to rodents, or being more selective in what we compost (both wasteful and too much thinking to do each time you create kitchen scraps, in my view!)

What compost can be used for

The finished compost can be used:

  • for surface dressing pot plants and flower beds – as well as proving nutrition, this keeps weeds down

  • for digging into soil (e.g. in preparation for planting vegetables).

  • as a potting material (one part compost to three parts soil for seeds, one part compost to two parts soil for seedlings)


For best results, the compost should be sieved before use, and any large pieces of material that haven’t fully broken down can be put back into the start of the composting process.

Other forms of composting

  • Leaf mould: A small amount of fallen leaves can go into the compost pile, but in autumn, you might have more than you can deal with while keeping the composition of your compost balanced. The answer is to divert these into making leaf mould. Gather the leaves up and leave them somewhere with air and moisture until they turn into a wonderful dark mulch – this might take several years. Unlike compost it’s not got a lot of nutritional content but it is great at building soil structure, so can be mixed with compost when treating soil. For further information, see

  • Composting toilets: these are less gross than they sound, and are more commonly used in areas where there is no sewer connection (including remote buildings, on boats and in camper vans). The idea is that the solid and liquid waste are separated at source (this minimises smells!) and the solids are mixed with sawdust (to help absorb residual moisture and smells) and then allowed to rot down over about a year to form a powerful fertilizer; this is recommended for use on flowers, hedges and other ornamental (non-edible) plants. For further information, see

  • Composting funerals: One of the most sustainable options for leaving this world is to choose eco-burial, where the body breaks down naturally, often with new forest growing above. This is far more sustainable than cremation (which is very energy intensive) or traditional burial (which prevents natural breakdown through the materials used.) The St. Albans Woodland Burial Trust is at Keysoe, about 9 miles from our parish, and St. Andrew’s Church has assisted in tree planting here. It may be appropriate to review whether your last wishes could be more sustainable and to discuss your thoughts with your next of kin. For further information, see

Composting at St. Andrew’s

In the past year we’ve set up a composting system at St. Andrew’s. It’s designed around the types of waste that we create, and to avoid complexity for the people who create the waste. We have Bokashi bins in the kitchen for all of the food scraps and plate scrapings from our catering, and this mixes with waste paper (and cardboard from children’s activities) and garden trimmings. We have a rotary composter which mixes the compost when a handle on the side is rotated (this allows aeration without using a garden fork – this encourage “little and often” mixing) and a static compost bin for the finished compost to rest in until it is required.

Further reading:


What’s coming up this month?

  • Discussion: Those interested are invited to an informal discussion of this month’s topic during post-service refreshments on Sunday 16th June at 11.15-12.15 in the corner of the hall. Please come along and share your questions and your experience of and issues encountered investigating composting; you can share as much or as little as you wish about what you have learned! (It’s Father’s Day – why not use this to mug up so you can talk to him about compost over lunch? He’ll like that!)

  • “Six Inches of Soil” film: this new film looks at the sustainability of food production and the impact on soil – see There is a free screening at Stevington Village Hall on Sunday June 16th at 2pm, followed by a discussion with the film director and co-author. Further details and booking are at

  • “UK Earth Overshoot Day” was on 3rd June (see Mark this with due reflection, as its the day where our country used up its share of sustainable ecological resources for the entire year, so all resource use past that date to the end of the year is unsustainable. There is some better news – last year this date was May 19th, so the work that is being done to improve sustainability is having some impact.

  • Great Big Green Week ( s being held between 8-16 June. The events local to Bedford are summarised at – these include a comedy shows aimed at youngsters (age 6-11) called “Don't Panic! We CAN Save the Planet” at the Quarry Theatre on 8th June ( and a range of walks, litter-picks and other events.

  • TeenTech are hosting a webinar on the art and science of sustainable and ethical design aimed at 11-19-year-olds ( This event can be watched live on June 10th 1600-1630 (Note date change since last month’s announcement!), but those who register for the event can also watch the recording until the end of July. TeenTech run an amazing range of high-quality technology events for younger people; if any of you remember watching Maggie Philbin on Tomorrow’s World or Multicoloured Swap Shop, she’s the driving force behind them!

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