COMPOSTING

Contents

The basic rules (page 2)

1. Why make compost. (page 3)

A bit of science concerning the Soil and Plant growth and the Workings of a Compost Heap.

2.How to make compost -

2a Understanding the composting process. (pages 4 – 5) temperature oxygen. water / moisture. turning the compost

How this knowledge affects the design and placing of Compost Bins, what to put into a Compost Bin and when and how to use compost.

2b Siting and making the compost bays (pages 6 - 7)

2c What to (and Not to) put into the compost. – including ‘balancing’ the textures of the materials that are put into the compost. (pages 8 - 9)

2d What you get out of the compost bin and when and how to use it (page 9)

3. Making Leaf Mould (page 10)

4. A ‘long term’ compost heap (page 10)

5. Stafford Municipal Compost (pages 10 - 11)

6. The Critical Points Revisited (page 11)

7. Problems, Questions and Answers (pages 12 – 14)

Of course, not every gardener wants to make high quality compost. Most gardeners just wish to remove weeds and crop-waste and do not want to waste good plant nutrients; but unless a worse-than-useless, potentially disease-ridden, smelly, organic rubbish heap is required, there are a few basic rules that should be followed.

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An important aside. The word COMPOST is used to refer to 2 totally different products.

1.Potting Compost2.Garden Compost

It is Garden Compost that we get from a compost heap. It is far too strong (too high in plant nutrients/food) to be used for potting by itself. In order to use it for potting i.e. make Potting Compost from it, it should be ‘ diluted’ by mixing with other components – soil and maybe leaf-mould (see 2c below – What

you get out of the compost bin – when and how to use it and 3 below Making

Leaf Mould ).

The basic rules

1. Don’t let weeds and vegetation dry out before adding to the compost. If it is inconvenient to put them into the compost bin straight away, then, as with the compost itself, ensure that they are protected from the sun, rain and drying winds with a cover.

2. In order to ensure beneficial higher temperatures, cover and confine in a container, ensuring as small a surface/bulk ratio (small external surface with a large internal volume) as possible.

3. Only add inert materials very sparingly – such as peat, old compost or soil.

4. Never add synthetic, man-made materials – such as wire, glass, plastic, etc.

5. The higher the quality of compost you want – the higher the temperatures required and more insulation and/or work (turning) will be needed.

6. Have separate bays, at least 2, preferably 3.

7. Put twigs and other woody growth on a second, ‘long term’ compost.

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8. If timbers have to be burnt, do it on a BarBQ, or better still, convert them into Charcoal, powder it and then add it to the soil via the compost heap – called the addition of ‘Biochar’ (see http://www.carbongold.com/ ). Should you burn the wood, then the ashes can (and should) be added to the compost, provided that you do not add too much (no more than approx. 10 - 20%, evenly distributed).

1. Why make compost. - To retain and replenish the organic matter and plant nutrients in the soil.

By boosting the organic matter in the soil, you increase the potential for plant growth by increasing both

1. the soils fertility 2. the soils water holding capacity.

The Soils Fertility

Organic matter in the soil is the major contributor to soil structure and, all things being equal, the better the soil structure then the more the soil organisms (including your crops) will flourish. It is this flourishing of the life in the soil - the production of waste products through the life and then the death of various and numerous soil organisms that provides the chemicals required for plant growth.

The greater this cycle of life in the soil becomes, then the greater is the soil’s fertility ; and it is the organic matter from your compost that will feed and increase this life.

The Soils Water Holding Capacity

The highly complex internal structure of the soils organic matter gives it the very important ability to hold both large amounts of water and the chemicals required for plant growth.

A sandy soil can be a very free draining soil and be beautifully easy to work. However the high sand content of the soil means that the soil supplies only a small amount of chemicals for plant growth, and these plant foods and water are not held very well. Therefore achieving good plant growth requires a large additional amount of both plant food and water.

Clayey soils, because of their great capacity for holding plant nutrients and water will produce large crops. Unfortunately these same properties mean that they tend to be heavy and hard to work when wet, or rock hard and difficult to work when dry.

The best way to improve both of these soils is by the addition of large amounts of Organic Matter, and the retention of as much of the soils organic matter as possible, by composting and not burning.

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As the facts above demonstrate, the compost heap/bin should always be thought of as the heart of any garden. This is even more important when gardening on any soil that is not a superb, deep loam – and that, of course, is most gardens, especially vegetable gardens.

Composting should be a very important aspect of your gardening.2. How to make compost.

In order that you are producing useful compost and neither evil-smelling gunge nor relatively useless woodlouse-ridden, hay-like rubbish, then it is important to understand how composting works

2a. Understanding the composting process.

A good compost heap should get hot (so hot that you can’t hold your hand in it for a length of time). Any relatively soft or weak organic matter ((leaves and this years stems or roots) should be broken down (virtually ‘cooked’) within

days/weeks. A ‘maturation period’ of months is then required before it is suitable for adding to the soil.

This heat is caused the hectic lives (metabolism) of many billions of decay organisms – mainly Fungi and Bacteria. The compost heap will gradually warm up and as the temperature rises, so the fungal and bacterial population changes. The decay organisms that prefer the warmer temperatures gradually replace the decay organisms that prefer cool conditions. This will continue till very high temperatures (over 160°F[70°C]) are reached. This temperature will be held for only a few days and as the oxygen and food supplies of the organisms are used up the population falls, and with it the temperature and the population alters accordingly. This gradual decline takes place over many months.

Although it is at the time of very high temperatures that the most of the beneficial breakdown of material takes place – by the actual high temperatures as well as by the organisms; the maturation period of many months is just as important for it is during this period that many of the beneficial chemicals are produced.

Using this knowledge of the workings of a Compost Heap, we can make now a list of the essentials required.

TEMPERATURE.

You will be aware of the warming affect of having a lot of people in a room. Thousands of people standing or even running around outdoors will not cause much of a rise in the air temperature. In the room, it was the walls that prevented the heat from leaving.

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It is the same with the decay organisms in a compost heap. It is not of much use to just make a pile or heap. Most of it will be acting as an insulating layer.The surface/bulk ratio (small external surface with a large internal volume) has to be reduced and this is best done by confining the material in a large container with an insulated cover.. The period of maximum temperature will only last for a short period but the compost will continue to be gently warm throughout the many months of maturation.

OXYGEN. The organisms that create the high temperatures require Oxygen. There is sufficient within the air that is trapped amongst the plant material that has been placed into the compost – provided that it is not firmed down or rammed in – implying that you should never ‘make more room’ by treading down or compacting. The gentle compaction caused by the addition of more matter serves to remove much of the air and unless turned the compost will gradually cool down after the initial intense heat. But turning is not essential – see Turning the Compost below.

WATER / MOISTURE . The decay organisms need not only warmth but also damp conditions in which to live. The necessary high populations can only be achieved if the conditions are ideal – not too dry or too wet. The high temperatures attained in the compost will cause the evaporation of most of the moisture in the heap and unless prevented, this drying-out would cause the death of the decay organisms and your compost heap will be turned into heap of very poor quality hay. So as well as the cover having insulating qualities, it also has to sufficiently waterproof that the steam will condense and not be lost. Whenever a large quantity of material is added to the compost, then giving a few gallons of water will be beneficial. My ‘rule of thumb’ is to add 1 watering can (2gallons) for every wheelbarrow load of compost material.

The insulating cover and waterproof cover are both essential for the production of high quality compost from garden waste – on the scale that is found in the average garden or allotment.

Turning the CompostIf a sterile weed seed free compost is desired, then the compost has to be turned, putting what was on the outside (and therefore has not yet been ‘sterilised’ by having been subjected to high temperatures) into what will be the centre of the heap where it will be sterilised.This turning introduces a fresh supply of air (and therefore oxygen) and permits the composting process to continue at high temperatures for a longer period. This extended period of maximum temperatures also enables less

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degradable matter (such as slightly twiggy or woody vegetation) to be broken down.

Since I can’t be bothered to go to the trouble of turning my compost and the resulting composts lack of sterility is not a problem, then I ensure that no twiggy or woody vegetation is put in my compost bins.

2b. Siting and making the Compost Bays

Often, a gardens composting area is at one end of the garden. But the fact that material and compost has to be transported to and from there suggests that a central site would be a lot better.

There are 2 major considerations when designing the compost bay(s).

1/. Size. Only a relatively large (greater than 2½ft square [750mm2]) bin will give a sufficiently large central mass that heats up sufficiently to kill weeds.

Wooden pallets are an ideal size for making large (with bays 3-4ft. across) compost bays. Make the bins out of 3 pallets. (These are quite large compost-bays. Excellent for someone who composts a lot of material from a large allotment [Cotonfields allotments are approx. 10yds.x100yds]). But for smaller ones,32x32ins, excellent compost bays can be made using sheets of shuttering ply (8x4).

Construction using pallets.

1 pallet for the back and 2 for the sides, with the top of the pallets facing inwards – whenever possible (this gives a more even internal surface that is easier to line with cardboard). The front of the bay is best made with movable boards to facilitate the addition and removal of compost. The pallets are best wired together rather than nailed or screwed . The addition and removal of compost will cause movement of the bays and wiring the pallets together will allow give and flexing, whereas the use of nails or screws will cause splitting. The compost bays are best constructed on bare soil which will provide a supply of soil organisms and a safe refuge for them from the heat, although standing the pallets on a single course of bricks will help delay their rotting. Treatment with a ‘wood preservative’ (aka ‘biocide’) is NOT recommended.  

But they will need insulation, since most pallets are not solid but slatted and will allow too much cooling. The thin ply-wood or hardboard sheets that most modern interior doors are made from is good and so is the heavy-duty corrugated cardboard used for packaging ‘white-goods’ and other large consumerables (if the cardboard is thin, then use multi-layers). This should be used as a lining to provide insulation. Since it also acts as a barrier to decay organisms, it serves to protect the pallet wood from decay – so do not skimp on its use.

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The use of polythene/plastic/plasticised sheeting to line the wooden bays is not recommended, since its impermeability will hasten the decay of the pallet timber and have a negative affect on the composting. I also put an insulating layer on top. Wet insulation does not work and therefore this insulation layer has to be protected from rain above and condensation from the heap below – in other words, the composting material is covered with a sheet of plastic and then a piece of carpet (if the carpet is pileside down,it will provide better insulation.

Construction using shuttering ply (12mm or 18mm).

(For a series of 3 joined bays, each approx. 31ins x 32ins.)This is usually sold in 8x4ft (metric equiv. = 2440 x 1220mm).1 sheet is used for the back, a 2nd sheet is sawn into thirds (32ins) and is used for 3 sides. The 4th side is made of ‘whatever’, and the fronts are movable boards. Insulate and protect the wood with cardboard as above.A 3rd sheet can be used for making each bay an individual hinged lid.

These much smaller bays are much more convenient, the smaller size makes filling the bays (the covering and uncovering of the compost in particular) so much easier.

For a single person with a very small garden, even smaller bays might be applicable. I once constructed a 2 bay compost, each bay being 2ft x 2ft and 2½ft tall. The second bay was rapidly emptied at the beginning of the growing season and used for putting compost material in. The compost that was produced was good but not perfect.

2/. Number of Compost bins/bays. If you’ve made compost in order to use it (as opposed to simply making compost in order to dispose of waste vegetation), you don’t really want to be digging out the old mature compost from under the younger not yet matured compost.

For this reason, I always have at least 3 bays. (Having only 2 bays is still manageable, but having only 1 bay is not very successful/practical). Each bay is used (filled with compost material) for one year, it is then left to mature for a year, and then gradually used in the 3rd year.

Bay 1. Filled in year 1 - Left to mature through year 2 - Used in year 3.Bay 2. Filled in year 2 - Left to mature through year 3 - Used in year 4.Bay 3. Filled in year 3 - Left to mature through year 4 - Used in year 5

By having the bins/bays next to each other, they provide extra insulation/protection. Should a roof (possibly of individual hinged lids) be put on, then the rain could be run off and collected in a water butt.

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An alternative arrangement could be four bays sited as in the cross-section of a Battenberg cake – which give excellent mutual insulation.

Adjacent bays also give structural support. Unless there is adjacent bays containing compost, the sides will tend to splay out as the compost settles) and the movable front boards will fall out. Movement of the base of the sides can be prevented by either

1. driving metal poles into the ground or 2. securing opposing sides with rope.

2c. What to (and NOT to) put into the compost.

The composting process can be used to breakdown any formerly living material. It is the amount of work, the scale of the operation, the desired quality of end product and the time spent in the compost that defines the type of material that will be broken down.

A relatively accurate rule of thumb for what can/cannot be put into a well maintained average garden compost bin is ‘Any vegetation will break down easily if it has not lived through a winter’ .

WeedsMost living things will be killed by the intensive heat at the centre. This means that all and any perennial weeds (couch grass, docks, dandelions, even horsetail [aka ‘Hosepipe’]) and the seeds of seed-bearing weeds will be killed and can be put into the compost. These plants really should be put into the compost because they contain such a high proportion of valuable plant nutrients. BUT THEY MUST GO INTO THE CENTRAL, HOTTEST PART (unless you will be turning the compost).

It is important to ensure that bacteria and/or fungi have easy and quick access to the whole of whatever you put into the compost – i.e. the skins of fruit, roots and stems are serious barriers to those organisms (they’re designed to be so!), so cut open or break up apples, potatoes and thicker stems (sweetcorn, brassicas etc.).

When adding weeds to the compost, an easily made mistake is to put in too much soil. Soil is virtually 100% inert matter and its insulating properties mean that even small quantities will cause harm. Larger amounts will prevent heating which eventually will lead to anoxic conditions and ‘kill off’ the compost. Always remove as much of the soil as possible from any weed roots. Obviously, no man-made materials (such as glass, plastics, metals and synthetic fibres) should ever be put into the compost.Meats will attract the attention of vermin and are best avoided. But cooked vegetables are fine – the heat from the compost will ‘cook’ them anyway.

Balancing the textures of the materials that are put into the compost.

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If all the materials put into the compost bin are dry – straw, paper, sun-dried vegetation, dried leaves, dry roots, etc., then the composting process never really happens and all that emerges from the compost bin is unaltered straw, paper, etc. On the other hand, if all of the materials put into the bin are of high water content – freshly cut grass and vegetables, vegetable waste and pairings from the kitchen, the remains of meals, etc., the ‘compost’ becomes too wet and may compact and exclude air causing anoxic conditions that result in a smelly gunge. To successfully make compost a balance between the two has to be found, and it is through experience that this is achieved. I’ve been composting for over 40 years, and I’m still learning. It is only in recent years that I have fully realised the importance of adding water. As I stated earlier - (page 5) - whenever a large quantity of material is added to the compost, then giving a few gallons of water will be beneficial. My ‘rule of thumb’ is to add 1 watering can (2gallons) for every wheelbarrow load of compost material.

When masses of weeds and particularly crop foliage (Haulm) are produced, if it is not convenient to put it into the compost straight away and it has to be left in a heap, then ensure that it is covered and protected from the drying and bleaching of the sun, wind and rain.In the latter half of the season, a large amount of drier, less sappy, material becomes available and after this is put onto the compost, it is important to ensure that extra amounts of water are added.If space allows, it might be a good idea to put some of this dry, stemmy material to one side for mixing with the excess of soft, sappy weeds of next years spring/early summer.

2d. What you get out of the compost bin and when and how to use it

After 1 year maturation the resulting compost should be dark brown, relatively moist, friable, containing virtually nothing that retains any sign of its original structure and containing great plant growth enhancing potential.Because of its high plant food content, it is best used when the plants are actively growing – ie the late spring or summer. If used in the autumn or winter, most of the plant foods will be washed out by the autumn/winter rains before the plants have had the opportunity to use them. The best method of application is to use as a top-dressing or to lightly rake into the soil among the plants. I use the incompletely rotted material from the top surface and corners of the bin as a mulch on my brassicas beds. This helps with the prevention of the Club Root disease of Brassicas.

Garden Compost makes an excellent ingredient in Potting Compost. I use it mixed with equal parts of soil and leaf-mould - ⅓ of each.

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If a stronger compost is required – as for tomatoes or cucurbits; then I use 1part soil, 2 parts garden compost and 1part leaf-mould. If a weaker compost is required – as for seed sowing : then I use 2 parts soil, 1part garden compost and 2 parts leaf-mould (leaves that have been decayed for more than 1 year.

When potting Brassicas an alkaline compost is required, and therefore I add a little lime to the mix – before mixing.

3. Making Leaf Mould

As stated earlier, leaf mould is leaves that have been decayed for more than 1 year. Simply put in a pile and leave. If the leaves are picked up off grass using a rotary mower, the addition of cut grass will hasten the process (if the portion of cut grass is higher than 50% then the result will be a quick and high quality compost).

4. A ‘Long Term’ Compost Heap

Because of the limits on what will break down quickly enough to make good compost, it is a wise idea to have a secondary ‘Long Term’ compost. This is merely a heap that becomes extended into a windrow by adding from one side only. Onto it is thrown anything too woody for the ‘quick’ compost – stems and roots from overwintering brassicas, twiggy winter prunings from the fruit bushes (sappy summer prunings will go into the ‘quick’ compost), old bamboo canes, fruited canes from the Blackberries and Raspberries, small rotten timbers, etc.Because the material in this compost heap is woody and takes years to rot (3 – 6), it is not protected from the rain – the water is required to help the slow decay. As the windrow rots down, the resulting rotted organic matter is removed from the opposite end, and is used as mulch. In order that the windrows siting does not move; as rotted material is removed, so the whole windrow is also moved along – and in the process, decay will be aided by the physical breaking-down and mixing-up of the pile – into the now empty space. The resulting compost is excellent surface mulch for permanent plantings – such as perennials, bushes and trees.

5. Stafford Municipal Compost.

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Stafford Borough Council has recently introduced a scheme whereby householders put most organic waste into a brown wheelie bin and this is collected fortnightly for composting. This composting of 72,000 wheelie bins (12/14,000 tonnes per year) is carried out near Eccleshall. The resulting compost is sterile and of high quality (although it contains a a lot of small woody bits and a small quantity of plastics and metals). It can be bought loose by the ton and it is delivered by tractor and trailer. The minimum order is 4 tonnes @ £10/tonne (1tonne = 2-3 cu.m) and each full trailer load is 10 tonnes (2010 rates). Delivery is free in the Stafford and Stone area. But there is a small surcharge if the route has to pass through Stafford (ie delivered to South east Stafford, it is being transported from near Eccleshall). Enquiries about availability and delivery – Rob Ainsworth 01785 850722 robert.ainsworth4@btinternet.comI have found it best used by adding as a surface layer in the late autumn and leaving through the winter.

6. The critical points - Revisited

Those of you not wishing to gain the satisfaction and reap the benefits of making such growth promoting compost or perhaps merely unable/unwilling to put in the work required, should pay attention to the 8 essential basic rules.

1. Don’t let weeds and vegetation dry out before adding to the compost. If it is inconvenient to put them into the compost bin straight away, then, as with the compost itself, ensure that they are protected from the sun, rain and drying winds with a cover.

2. In order to ensure beneficial higher temperatures, cover and confine in a container, ensuring a small surface/bulk ratio.

3. Only add inert materials very sparingly – such as peat, old compost or soil.

4. Never add synthetic man-made materials – such as wire, glass, plastic, etc.

5. The higher the quality of compost you want – the higher the temperatures required and more insulation and/or work (turning) will be needed.

6. Have separate bays, at least 2, preferably 3.

7. Put twigs and other woody growth on a second, ‘long term’ compost.

8. If timbers have to be burnt, do it on a BarBQ, or better still, convert them into Charcoal, powder it and then add it to the soil via the

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compost heap – called the addition of ‘Biochar’ (see http://www.carbongold.com/ ). Should you burn the wood, then the ashes can (and should) be added to the compost, provided that you do not add too much (no more than approx. 10 -20%, evenly distributed).

7. Problems, Questions and Answers.

Problem. I don’t have the time/space for making compost.

Answer. Composting takes very little more time/space than having a fire, and the resulting ‘benefits’ of a fire are inferior and most are soluble minerals that the rain will wash away – unless the gardener takes appropriate action.

Problem It doesn’t rot down properly but dries out and becomes hay/straw like.

Answer. It sounds as if the composting material wasn’t covered properly (see Water/Moisture on page 5 . Or, perhaps it had already dried out before it was put to compost and wasn’t sufficiently wetted. (see Basic Rule 1) .Page 2

Problem The result is a horrible, slimy, smelly and fly-ridden mass.

Answer Most probably caused by too much wet and/or ‘sappy’ green material and too little drier, ‘stemmy/strawy’ material.

See 2c. What to put into the compost paying particular attention to Balancing the textures of the materials that are put into the compost – Pages 8 - 9

Question What about putting seeding weeds and invasive perennial weeds (such as dandelions, docks, couch grass and bind weed).

Answer. These things really should be put into the compost because they contain such a high proportion of valuable plant nutrients. The compost should heat up sufficiently to kill them. If not killed by the heat, then they will be killed by the fact that they will be covered (and therefore without light) for between 1 and 3 years. – See 2c. What to put into the compost. Pages 8 – 9.

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Question Can I put cooked food into the compost ?

Answer. I think this originated from the fear of attracting rats. I agree about large quantities of cooked meat/bones, but since uncooked plant material will be ‘cooked’ by the compost anyway, I don’t agree.

See 2c ‘What to put into the Compost’ Pages 8 - 9.

Question What about ‘compostable’ polythene bags ?

Answer. No to actual polythene even if marked compostable/bio-degradable, but presumably alright if the bag is made from vegetable starches.

Question. What about turning the compost ?

Answer. Turning is only necessary if a sterile, very high quality compost is required, OR if you’re in a hurry (ie not prepared to wait the 12months+) (also see – 2a Turning the compost, page 5 .)

Question. Why not dig it in ?

Answer. You can. But that is a bit a waste of both nutrients and soil conditioner. Let the worms and rain take the material and nutrients down. By applying to the surface/near-surface (it can be lightly raked in) the soil structure and soil health will be improved. This means that you will get larger crops from healthier plants. Healthier plants mean fewer pest and disease problems. See 1.– Why make compost , pages 3 & 4, and 2d – What you get out of the compost bin and when and how to use it , page 9.

Question. Can I add pet bedding (straw/hay/litter from a rabbit or hamster cage).Answer This makes excellent compost!

Question. Can I add cat or dog or even human faeces ?

Answer. Although coming from carnivores/omnivores, this will also be converted to excellent compost. However, it would be advisable to add this to the centre/hottest area. Since the compost is left for 1 year to ‘mature’, there will be no health/safety problems. For further details see – All the reasons for

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doing so and the methodology is to be found in Humanure Handbook: A Guide to Composting Human Manure (3rd Revised edition) – Joseph C. Jenkins (2006) ISBN-13: 978-0964425835. Web site – you will find some excellent advice on this site. http://humanurehandbook.com/store/THE-HUMANURE-HANDBOOK.html

Question. What about the smell ?

Answer. When a ‘Compost Heap’ smells unpleasantly, it is because anaerobic decay (Anaerobic – lack of oxygen) is dominant. This shouldn’t be the case. If the compost is properly made and maintained this will not happen. See 2 – How to make compost ; 2a – Understanding the composting process , pages 4-5.The true smell from a compost heap is pleasant. I enhance mine by adding the vegetation of herbs.

Question Is there a danger of attracting rats ?

Answer The shelter and warmth provided by a compost will attract many insects, animals and birds. Rats being so common (it is estimated that there are about 7 million in Great Britain), it is quite likely that at some stage a rat would be one of the animals to be attracted to the compost heap. Should you be worried about the possibility of them nesting in your compost, then covering the floor with wire netting should prevent their entry.

Question. What about those Dalek like, plastic commercial compost containers?

Answer. I’m not a fan – not only do you have to pay money for them, you have to be pretty good at making compost in order to get decent stuff out. The wooden ones are O.K., but it can be difficult to produce good compost using the plastic ones. Because of the impermeability of the plastic, the balance between dry and wet materials that are put into the bin has to be very exact. Also, the fact that they are not particularly well insulated does not help.

John Gale (last revised and updated 9.09.2013)

Tel. 01785 214894 E-mail john_gale@phonecoop.coop

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If you feel that you would like some further advice, my Coton Fields Allotments plot number is 39

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