Municipal Compost: is it a good thing?

 

Food and green waste: ready to begin composting

Food and green waste: ready compost - about 45,000 tonnes of waste is composted every year at the EcoPark

What is municipal compost? How can you use it in your container growing? Is it safe? And is it the answer for the urban grower looking for a good quality, sustainable growing medium? This post will try to answer these questions. My next post will answer more of your questions about municipal compost, posted on Twitter (thanks for all these).

Why sourcing compost is a BIG issue (particularly in cities)

The practical reasons

One of the hardest choices to make when building your container garden is: which growing medium to use. There’s quite a bit to consider. Which will perform best? (And performance does vary hugely). Where do you get it from and how do you shift it? (Particularly if you don’t have a car – I broke two bike axles last year by overloading bike panniers with compost!) And of course there’s the cost.

The environmental reasons

Then there are wider issues. Many growing media sold in the UK still contain peat (unless the bag explicitly says ‘peat free’ it probably contains peat).  This is a problem because peat extraction releases greenhouse gases and damages precious habitats. A separate issue is that many growing media are transported long distances, with associated emissions and fuel use.

 Is municipal compost the solution?

Can municipal compost offer a more sustainable solution? Made from food and green garden waste (like grass and hedge clippings from gardens) it reduces landfill, recycles organic material, and is locally sourced and made. It’s also usually available free or at low cost. But is it any good for growing in containers? And how reliable is it and how safe is it?

I went down to the LondonWaste EcoPark in North London, which produces 12,000 tonnes of compost a year to see it being made and to look for answers.

How is municipal compost made?

Food waste and green waste from gardens – grass and hedge clippings, prunings – is roughly shredded (to a width of 400mm) and then mixed with a small quantity of compost activator (contains micro-organisms and enzymes to promote efficient composting). This mix goes into a large, enclosed tunnel. Fans under the floor, blow air through the waste. The pile heats up as it begins to decompose, and the temperature is carefully monitored with probes.  It must reach 60 oC  for at least 48 hours so that pathogens and most weed seeds are killed. After a minimum of one week in the first tunnel, it is turned and transferred into a second tunnel, where the process is repeated. This helps ensure that the materials are thoroughly and evenly composted. The compost is then transferred out of the tunnel, mixed with other batches (to help minimise  inconsistencies between batches), and left to mature for several weeks. The final step is to sift the compost through a large drum – removing anything larger than 20mm.

Waste is loaded into huge enclosed tunnels, and air is blown in through vents in the floor.

The compost is made to the BSI PAS 100:2011 standard. This means the quality has to be regularly tested, including for heavy metals and other chemical residues.

 

How can you use it in Containers?

 

The compost from the EcoPark, like most municipal composts, is rich in nutrients. It is sold as a ‘soil conditioner’ rather than a potting compost.

Reusing old compost

It is probably most useful in container growing to help you re-use old compost. Rich in nutrients, it will add fertility. Also, as most municipal composts contain a high proportion of large particles, it may help improve structure. To your old compost, add between 20% and 50% municipal compost, depending on how rich a growing mix you want. As a rough rule of thumb you want a richer mix for fruiting crops like courgettes, less rich for leafy crops.

As a potting mix

To use municipal compost as a potting mix, the official advice is that one part compost should be mixed with three parts of a more inert growing medium like leaf mould or coir. The problem is that neither leaf mould or coir are very easy to get hold of in the city!  The good news is that I know several experienced growers who grow in straight municipal compost – and do so successfully. My own (admittedly limited) experiments with neat municipal compost have also been successful (see image below).

 

These salads are growing in 100% straight municipal compost - and doing OK!

Experiment

So the best advice is probably to try experimenting with your own local municipal compost to see what works and what doesn’t. (NB municipal composts do vary both from region to region and also, slightly, from season to season). If you do try it neat, make sure it has been left to mature for a few weeks first – as it will be too rich when fresh.

And watch the watering carefully: it can be prone to dry out quicker than some composts.

If you’re interested,  the nutrient levels in the Eco Park compost are typically (in kg per tonne): nitrogen (N) 13.86, Phosphate (P) 4.81, Potassium (K) 10.36, Magnesium (Mg) 3.48, Sulphur (S) 4.68.

How to get hold of it

Contact your local council to find out how it is distributed in your region. Large quantities (several tonnes) are often distributed free or at low cost. Smaller quantities are often available for sale in bags at local recycling centres.

But arguably the best place to find it in smaller quantities is from local growing projects. If they have received a big delivery, they will often be happy for local residents to bag up some to take home – either free or for a small donation. The challenge is to sniff out a supply local to you – good sources of information include local allotments, growing projects and websites like Transition Towns or Project Dirt in London. In Camden, London, Alara Wholefoods in Camley Street often has a supply it is happy to donate to deserving causes. This is a great service, that also engages more local people in food growing. Its an idea you could replicate if you or your community group have access to space where compost can be dumped and stored until it is collected.

Where it’s distributed to in North London

The EcoPark in North London distributes 60% of the finished compost to agriculture, 40% to community groups and allotments. The normal delivery size is a whopping 15 tonnes, the smallest is 7 tonnes. Plans are afoot to introduce 1 tonne bags this year. This willl be a boon for smaller growing projects.

 

The Last Word

I leave the last words to John Walker, who is a enthusiast for peat free composts. See his excellent website, www.earthfriendlygardener.net, for very helpful trials of different peat free composts.

‘My overall feeling is that if you can get municipal compost then it’s worth using it somehow. That might be as a straight soil improver, mixed (after sieving) with leafmould to make your own potting mix, or mixed with bought-in peat free to make a rich mix for containers. I wouldn’t recommend using it on its own in containers, unless you’ve done a test run and found it works (I think all gardeners should be having fun with their own trials, which would also help build a much clearer picture of how these ‘municipal’ materials are doing). Use it to complement other composts/materials because it helps reduce landfill and has a much smaller ‘footprint’ than say peat-based compost.’

He also advises against using it, ‘straight from the bag –  its going to get wet and slump and disappoint’. This advice highlights how municipal composts vary from region to region: I’ve used it straight from the bag and haven’t experienced this issue.

So probably the final, final word should be: Experiment!

If you’ve tried using municipal compost in container growing – or experiment this year – it would be valuable to hear about your experiences.

25 comments… add one

  • Does anyone know if municipal compost is available near Cranbrook, in Kent?
    Sure there’s lots of horse manure round here, but it has rarely heated up enough to kill the weed seeds, so I’d prefer a ‘cooked’ compost.

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    • HI Peter, if you contact your council’s recycling department they should (usually) be able to tell you. Mark

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  • Just picked 6 free bags up here in Swansea.

    Was wondering how to use it…..Thanks!

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  • Brilliant information – thank you.

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  • What is cheap about recycled household waste at £3 for a 30 litre bag?

    http://www.londonwaste.co.uk/ecopark-compost-for-sale/

    It’s cheaper to buy it from a DIY? superstore, even though they sell it at rip off prices…

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    • Depends where you get it, Tony. Community growing sites in London will often get several tonnes delivered for free for at low cost, and then give it away or sell it a very low price. For example, Alara Whole Foods on Camley Street in Camden often has a stash that people can help themselves to – you just need to leave your name and address so they can track where it is going. You may need to ask around a bit to find low cost source or persuade a local growing project to get a large delivery that can be divvied out. I can’t remember the cost per tonne but I think it is about £20 which is roughly equivalent to 25p a bag.

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      • I’m going by the sack price they quote, Mark, on their web pages. If they can deliver a ton for £20, I’d buy 1 for my plot. Who would you suggest I call for a ton delivered to a plot in Ealing?

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        • Ah, I think the catch might be that you need to order several tonnes in one go… might work if you can get several people on your allotment to club together? I’ll email you a contact number for the site.

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  • Thanks for emailing me every month I do read them with interest

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  • Our local municipal compost in Croydon is excellent despite the cringe-worthy name Croypost. I grow hundreds of herbs to sell and use it mixed with one third homemade compost (we have chickens and ducks) and one third Horizon organic. Brilliant results. Also my best ever crop of garlic on my allotment was in a deep bed topped with 15cm of Croypost. Only hiccup was a crop of Judas Ear Fungus one year.

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  • This article is really interesting. I’ve just bought West Country compost, our local council compost provider and it is lovely stuff – nice and dark and rich. The big disappointment though, is the amount of plastic I’ve found in it. It really shows how much plastic is out there in the environment polluting everything.

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  • My first thought when reading about using municiple compost is that it will contain residues of herbicide and pesticide from the garden and food waste of many people using these substances.

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  • I work for Camden Council and have been helping groups access the municipal compost. Alara (the muesli company) on Camley Street behind Kings Cross gets it delivered in the 15 tonne loads to the front of their premises (where they also host a community garden – with a permaculture forest garden out the back!), and it is free to take for anyone who can cart it away.

    The first time I got some was with a new community gardening group I was helping. I must admit it stank! I got a bit for myself – not much as I had to wheel it home – and I took the back roads home to avoid bumping into anyone, they’d smell me before they saw me!

    I’m happy to say the compost stopped smelling after a couple of weeks although it lingered on my gardening gloves for a lot longer. I just used it as top dressing on my plot, but I’ve been to the new garden where it was used neat, and the plants there are thriving.

    I’ve since been back to the “smelly pile” (as we now call it) and the compost there now smells much less offensive.

    I also understand that it is (or soon will be) available in bags from the Regis Road recycling centre, at a low cost to cover the cost of bagging it.

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  • I know that in the U.S. municipal compost contains Sewage Sludge. This is a highly toxic waste which is being disguised as garden compost. Check and make sure your town or city is not using its sewage sludge to enhance its compost.

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  • Great post Mark,

    Lewisham Council hand off their collected green waste to a parks management company who in turn sells it to a large composting company.

    Ive been lobbying for Lewisham Council to make some of this municipal compost available to residents, but they refuse.

    Its residents own waste after all. I may start a bit of a campaign!

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    • Good plan! It might be worth talking to North London Waste Authority – quite a lot of their compost goes to agriculture but they are trying to get more of it going back into the community. Eg they are reducing the minimumm delivery size and holding events to raise awareness of composting in the community. Let me know if you’d like a contact name there.

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      • Hi, I live in Catford and contacted North London Waste Authority yesterday to enquire about getting a load (7 tonnes) of compost. They said they could only deliver to north east London. It is not possible to get municipal compost in south east London it seems.

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        • Hi Martin, Mmm, I’ve heard of others in South London with the same issue. Might be worth you getting in touch with Anne-Marie at Lewisham Gardens (http://lewishamgardens.webs.com/) as I know she was looking into it and seeing if the council would do anything about it. Good luck! Mark

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  • Hi Mark, I’ve enjoyed reading this. We’ve used Camden municipal compost from the start as it was cheap and readily available. It was bought in bags from the recycling centre and used neat in our raised beds. Three years on, the compost has been taken down into the bark chippings, topsoil and clay that was under the raised beds. I top up each year with more and have always had excellent results across my varied crops. I also use it for container growing on my balcony, again with great results. It’s not all used straightaway so is left in bags until needed. This bagged compost was relatively smooth and a good choice while still available. I’m now using compost donated by Naomi (above comment) which needs to be sieved as it has large twigs, glass, bottle tops etc in it. Looks quite good though so the effort should be worth it. Interesting to hear feedback from others as well!

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  • Here at FOOD from the SKY we have used more than 15 tonnes of municipal compost from Haringey. It is rough, rich and very dark with large bits of wood and sometimes we found knives and forks as well as glass bits. We use it seeved for young plants and on the top of our groing container. The compost that was left for few month was fabulous and if you have time it is worth letting it rest and increase its leaf mold and life organisms have time to move in.
    W ehave grown food, herbs and flowers in the boxes for almost 2 years now. We top up evry few months with new compost as well as feeding with all sort of organic fertilisers. We also had biodynamic solutions spread on the whole roof few months ago. Great stuff as it is local, rich and free. I would recomend to add some sand and leaf mold for seeding and seedlings and some top soil for more mature plants if you can.
    Happy growing, thank you Mark for inviting me to write here, very interesting and valuable post!
    xx
    Azul

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    • Thank you, Azul, your learning offers valuable information – and inspiration. Congratulations on creating such a vibrant and productive garden from London’s waste! Very interesting how you’ve found it improves with time – also to learn how you keep it fertile – and the tips to adapt it for different uses in the container garden. Thanks for so much for sharing! Mark

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  • Hi Mark, We’ve been using undiluted North London Waste Compost for our community veg growing project for the last 2 years (and agin for this coming growing season) and have had great results for all sorts of veg growing. Great for runner beans, courgettes, rhubarb, nasturtiums and tomatoes and we will be trying out carrots and parsnips this year too.Very interesting post. Thanks again. Naomi

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    • Thanks for sharing your experience, Naomi – very interesting and useful to hear your experience. I know quite a few people now who are growing directly in the North London Waste compost, undiluted. It’d be interesting to know if people from other boroughs / regions of the UK have had similar experiences. Anyone?

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