What is compost?
Compost is the humus-like product resulting from the controlled decomposition of organic matter by micro-organisms.
Ingredients, good things to compost
How to site and build a compost heap
Compost FAQ’s – info, tips & troubleshooting for composters
The kinds of composting systems that people build
Why compost?
To reduce the volume of waste ending up in landfill.
As much as 50% of the waste that is picked up at kerbside in the wheelie bin is organic and readily compostible at home. This waste takes up valuable space in a landfill and ties up a lot of your money in waste collection and landfill charges. If you compost your household’s organic waste then you’ll need only the cheaper, smaller wheelie bin and you’ll help free up ratepayer’s money for more important things, like roads, footpaths, street lighting, parks and community health care.
Because it produces a valuable resource from rubbish.
Sadly we tend to treat organic waste with contempt. Saved from the waste stream and turned into compost it becomes a hugely beneficial product. Compost is a way of concentrating the nutrients in the food and green waste we throw out. In soil, compost encourages better plant growth and reduces our dependence on fertilisers. Furthermore, increasing the amount of organic matter in soil, enhances the soil’s capacity to retain water, so composting can reduce our use of water!
Who should compost?
Before you start you need to ask yourself why you want to compost your household’s organic waste in the first place. Is for gardening? Or is it primarily to reduce the amount of waste ending up in the wheelie bin? If it’s the former and you would like a ready supply of compost you might want to consider a home made or commercial bin. If the emphasis for you is simply to do your bit and reduce the waste load on landfill, without necessarily wanting to generate copious quantities of compost, then a heap that decomposes slowly and without interference in a corner of the backyard with or without a bin might suit you. If you are wanting to manage kitchen waste alone then you might consider a wormery.
Composting basics: what are the processes involved during composting?
When you mass together a pile of kitchen scraps, lawn clippings, garden waste and waste paper micro-organisms present on the waste and on the soil surface start to colonise the pile and use it for food. This process is variously called fermentation, digestion, rotting or decomposition and it leads to the transformation of the waste pile into compost. Broadly there are three stages that a heap of this sort will precede through as it breaks down:
1. Mesophyllic or moderate temperature stage (-18-40°C).
Courtesy of mesophyllic bacteria. These bugs hang around in the top soil and get to work on the soluble, readily degradable components in the young heap like the simple sugars. They eat and reproduce and as their numbers build and more and more fuel is consumed, things start to heat up.
2. Thermophyllic or high temperature stage (40-65°C).
Eventually things get too hot for the mesophyllic bacteria and the numbers of a tougher breed start to increase. These thermophyllic bacteria digest more complex, insoluble molecules that have stronger chemical bonds such as proteins, fats and complex carbohydrates. The temperature continues to build and at 65°C and over human and plant pathogens are destroyed. However at these temperatures some microbes that aid the decomposition process are destroyed also, and this is one reason why a compost heap is turned, but more about that later.
3. Cooling and maturation stage (can take several months).
As these fuel molecules run out, the temperature falls and mesophyllic bacteria increase in number again to finish off the process.
Making good compost: the dynamics of a compost bin.
The aim here is to help you to become intuitive about composting. There is little doubt that knowing something about how a compost works as an ecosystem will help this process. Compost heaps have some basic requirements and if you are particularly interested in reducing the pong factor or getting your compost to break down fast it is definitely worth considering the following:
1. Oxygen.
Air won’t penetrate very far into a compost heap without some form of ventilation. When you build a pile there is an initial period where air is plentiful. As the number of microbes in the heap increase so too does the demand for air, inevitably the oxygen runs out and, depending on the composition of the heap, microbes that can survive without oxygen get to work and they start to produce rotten egg gas and methane (anaerobic fermentation) -charming! The supply of oxygen around each particle can be renewed, however, by regular turning or by building the pile around either some PVC pipes that have aeration holes drilled into them or just some large twigs.
Tip: Hot air leaves the compost through the top and cold air enters from the bottom so it’s a good idea when you are composting to build the pile on top of some small branches to really help the fresh air get through.
Tip: Lazy or just can’t dig? No-worries just get some PVC pipes and drill lots of holes into them. Use them to make a kind of Tee-pee frame and then build the compost around this. This way you’ll get the air flowing in and around the compost permanently.
2. Balance of Carbon and Nitrogen materials.
There are two broad groups of food molecules that composting microbes consume, those that contain a lot of the carbon and those that contain a lot of the nitrogen, in composting parlance these have become known as browns and greens respectively. You get browns from dry stuff like autumn leaves, straw, dried grass clippings etc, greens tend to be moister, and smellier like manure, fresh weeds, fresh grass clippings and food scraps. Getting the carbon/nitrogen (or brown/green) balance right is as important to compost microbes as a good balance of energy and other nutrients in the diet is to you. To a bacterium (indeed to any living organism) carbon is an energy source and the major building block of practically all biological molecules. Nitrogen is required to make protein and nucleic acids which are fundamental to all cellular processes. In the case of compost microbes, too much nitrogen can lead to the excess being released as ammonia. Too much carbon (relative to nitrogen) can cause microbial growth to be retarded slowing the pace of decomposition. It is generally accepted that the correct starting ratio of Carbon to Nitrogen is around 30 parts carbon to one part nitrogen by weight. As it is impractical to weigh all ingredients as you build a compost it is recommended that you use the rule of thumb that compost should be made up of approximately equal volumes of carbon and nitrogen (or brown and green) materials.
Tip: To strike the right balance of carbon and nitrogen, you should include roughly equal volumes of browns and greens in your compost.
3. Water.
Obviously microbes are living things like us and for this reason need water. However you can over do it. Too much water has a similar effect as waterlogging on the roots of plants, essentially they can’t breathe and an anaerobic or oxygenless environment results. This may lead to anaerobic fermentation and the release of rotten egg gas. A general rule of thumb is that compost should be about as wet as a well wrung sponge. When squeezed, you don’t want your compost to dribble water, if it yields a drop or two then that’s OK.
Tip: Kitchen scraps contain a lot of water. You will not need to add as much water to a mix that contains lots of them.
4. Dimensions of the pile.
The correct dimension of the pile is a compromise, really, between the need to get air into the system and wanting to limit the amount of water and (in the case of a hot heap) heat loss at the same time. If your pile is too small it will dry out rapidly and it won’t heat up. Too large and you are struggling to keep it aerated. For a hot heap the correct dimensions for a pile is around 1m cubed. Cold heaps range in size much more as heat isn’t important, they will just start off small and increase in size as waste accrues.
5. Particle size.
Throw a whole broccoli stem into the compost and leave it for a week. It probably won’t compost down much. On return it will be softer and smellier but probably more or less whole. If you were to cut it into smaller pieces first, you would find it composted down perfectly along with all the rest. The moral? Small particles will compost down quicker than large because small objects offer relatively more surface area to hungry microbes and so get eaten quicker. However it is important to bear in mind that exceedingly small particles will tend to compact together thus reducing the level of aeration in the pile. It is good to have a mix of particle sizes to ensure there are plenty of air pockets throughout the heap.
Tip: If you are using a tumbler style compost bin you don’t have to worry about compaction so you can use extremely small particles. In fact with this system small particles will compost down very quickly providing you remember to tumble it!
How to site and build a compost heap
Finding a location for the pile
How to prepare weeds for composting
Turning for even composting (cold heaps):
For moisture (hot or cold heaps):
Knowing when the compost is properly broken down and ready to us
Hot heaps versus cold heaps
There are, broadly, two types of compost heap you can build: hot or cold. As can be assumed from the terms hot heaps are those systems that heat up (60 degrees Celsius or more) and cold heaps don’t heat up much if at all. Hot heaps break down very fast and to some extent through their heat, sterilise the contents. As a general rule if you want to build a hot heap you need to be aware of the correct carbon/nitrogen ratio, dimensions of the pile and level of aeration. Cold heaps on the other hand require less fuss, but the product is less reliable. For instance, it can, depending on the ingredients sprout weeds when put on the garden. However, a cold heap is by far the best option for people who don’t want to spend a lot of time in the garden building and maintaining compost bins. Generally, you add to them all the time, let nature take its course and eventually you harvest the compost.
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Finding a location for the pile
You can situate the bin anywhere you like, more or less. Some authors suggest that you avoid locating the bin near wooden structures and housing, due to the possibility of insect infestations or of these structures simply rotting. It is probably better from the point of view of aeration that the system is away from a solid structure like a fence. Keeping the heap out of the direct sunlight will help to reduce water loss, especially in summer. Under a tree is good. Close to the area where you intend to use the final product is another good idea, especially if you haven’t got a wheel barrow.
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Preparing the ingredients
If you compost with large pieces of organic material, they will break down, eventually. If, however, you want compost fast you will need to process the raw materials into smaller pieces.
Materials suitable for composting are all included in the ingredients section. There are a number of ways in which you can chop up materials. A whipper snipper used like a bamix in an ordinary plastic rubbish bin chops up browns that are too large, like soft plant stems and vines, dried reeds, or dried large leaves. Alternatively if you have the equipment and the space you can shred these types of materials and even dampened newspapers by running over them with a lawn mower. For harder materials like canes, grape vines etc a mulch maker is ideal, these can be hired. For those of us who don’t have the luxury of motorised garden equipment, the options are to cut up waste as it is generated either with secateurs or strong scissors, if this becomes habitual it relieves the drudgery of having to process an enormous heap just before building the pile. If you want to use kitchen scraps they should be chopped as much as possible before adding, again this is a habit that could be adopted in the kitchen as waste is generated.
Tip: When cooking get into the habit of roughly chopping up large pieces of vegetable waste like broccoli stems with a knife before throwing in the scrap bucket. It doesn’t take long and speeds the process of decomposition.
Tip: Keep a jute bag hanging on a nail in the toilet to collect ripped up toilet rolls and always buy toilet paper that has paper packaging so you can compost it as well.
Tip: With a cold heap that isn’t turned much, it’s good to have a mix of particle sizes as this helps to keep the mix open and aerated.
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How to prepare weeds for composting
Weeds present a problem as seed, nodes and other propogules can survive the composting process (even if the pile does get hot) and go on to produce a new generation of weeds in the garden bed. One method of killing weeds involves drowning them. Simply place the weeds in a drum or garbage bin and cover completely with water. Place a close-fitting lid on the bin (this mixture can pong after a while) and leave for at least 4 weeks (I leave for 6-8 to be sure). After this time, you can use the water as a weak fertiliser while the weeds go into your compost to finish breaking down.
Monitoring the system: when to turn, when to add water.
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Turning for heat (hot heaps):
If you are composting with a hot heap you will need to check that the system is heating up. A day after constructing the pile, plunge a length of metal pipe or thick wire into the centre of the pile, leave for a minute or so then remove. If it is feeling hot to touch then the pile is progressing through the high temperature stage and will need to be turned soon. You can’t really turn compost too much, turning helps get air into the system and stops bacteria being killed off by rising temperatures. Stop turning when the system heats up no longer.
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Turning for even composting (cold heaps):
Turning is also relevant to cold heaps. Whilst it isn’t absolutely necessary, if you turn a cold heap you will facilitate more even composting. Really you can turn as often or as rarely as you like. Ensure that materials that were on the outside and which, by virtue of this, were poorly composted are incorporated into the centre of the new pile.
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For moisture (hot or cold heaps):
Check the moisture level of compost inside of the pile, it should be as wet as a well wrung sponge, yielding just a drop or two of water if it were squeezed. If you need to apply water then you need to ensure that the water gets through to the middle. Poking a metal pipe or broom handle in a few times should help.
Tip: Not really keen on the idea of squeezing compost? When assessing the moisture level you don’t have to touch it. Look at it, it shouldn’t look wet, it shouldn’t ooze or be squelchy when you poke it with a stick. Imagine the cool humidity of a rain forest floor, that’s what you are trying to emulate; everything covered in a thin film of water rather than drenched.
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Knowing when the compost is properly broken down and ready to use
Be it from a hot or cold heap, you will know when the compost is ready by the colour, texture and smell of it. Compost is dark and crumbly with a sweet, earthy smell and nothing recognisable in it. The quality of the finished product will depend on the quality of the materials used and the attention to preparation as well as the extent of maintenance during the composting process. It defeats the purpose to dig unevenly composted material into your garden. Partly composted components go on breaking down due to the action of soil microbes and these bugs monopolise soil nitrogen, robbing you plants in the process. Uncomposted materials found in the mixture should, therefore, be returned to the heap to continue breaking down. You can however apply partially composted material to the surface of the garden as a mulch.
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The kinds of composting systems that people build
The ‘just chuck it in the corner of the yard and forget it’ pile
The ‘bag it and forget it’ compost system
Composting with a commercial bin, simply.
The Hot Heap: getting technical with a system of corrals or bins.
The Gedeye Bin as an example of an anaerobic compost system.
The ‘just chuck it in the corner of the yard and forget it’ pile
Nothing to be ashamed of at all. Suits busy people or those not physically disposed to hard labour down to a tee. It is also the best option if you are more concerned with reducing waste than producing compost. It’s a cold heap so it will need plenty of time to break down (as much as 2 years). This system can either accumulate organic matter as it comes to hand (probably the most likely), or you can build it all at once and walk away. Remember, anything that is not turned will not only take longer to break down but will not break down completely. There will always be material on the outside that will stay whole. When harvesting, take what is composted, from the middle and the bottom of the pile, and chuck everything else back to continue to rot down. Important also is the need to add a range of waste materials to the pile as adding food scraps alone will result in a slimey, foul smelling mess. Try to include grass clippings, leaves and shredded cardboard or paper like envelopes, non-glossy junk mail, egg cartons and toilet rolls.
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The ‘bag it and forget it’ compost system
Actually an anaerobic system that works fine, requires little equipment and is quick to prepare. When you have some garden waste to deal with, such as weeds (that haven’t gone to seed), autumn leaves, etc, you simply place them in a garbage or supermarket bag and seal the opening. Leave and forget about them for a few months while they break down. If you use fresh plant material you probably will not need to add water, but if you are using something that is drier like leaves you will need to add some water (or rake up and bag just after rain).
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Composting with a commercial bin, simply.
This is a simple, relatively low labour, cold system that stays aerobic, manages garden and kitchen waste and which can be harvested after 6 months. Good for people who are prepared to do some initial work when constructing the piles but are not interested in constantly attending it.
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Aeration
To really get the air flowing you place the bin on several bricks so air can travel upwards. A piece of PVC that has had aeration holes drilled into it is then placed up the centre of the bin and some old branches are placed at the bottom inside the bricks to ensure air can enter from below.
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Construction
The object of this system is to facilitate the management of waste as it becomes available: as the kitchen scrap bucket fills, when you mow the lawn, weed the garden etc. When green materials are added to the top, browns, such as shredded paper, straw or dried leaves are spread over this both to protect it from roving insects and to provide some carbon/nitrogen balance. As the stack progresses branches are again added to avoid the compaction that would stifle the aeration process and produce anaerobic (air-less) pockets. Water will need to be added if the pile dries too much so monitor the moisture level of the pile it should be about as wet as a well wrung sponge.
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Management
You can operate several bins in parallel so that you are adding fresh material to one bin as the other (or others) are breaking down. You can harvest when the compost is dark and well broken down. When harvesting, anything that is not properly composted is thrown back into the current bin to continue breaking down. You can also recycle the branches.
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A simple home-made bin
Really just a piece of chicken wire that is fashioned into a large cylinder. Wonderfully open, so plenty of air over the entire surface of the pile. With this system you can be as lazy or as energetic as you like. The frame just sits on the ground and you build up the pile inside it. When it comes time to turn the pile you just lift off the chicken wire (it’ll need some shaking), place it on the ground next to original pile and shovel the partly decomposed material in, making sure that you give the material that was on the outside a chance on the inside of the new pile where the bulk of the microbial action is.
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The Hot Heap: getting technical with a system of corrals or bins.
The most efficient systems in terms of producing a pathogen and weed free compost fast involve a hot heap system of 3 corrals. Cobbled together out of anything at hand (corrugated iron, wood, old pellets and wire etc) corrals allow material to be systematically transferred from one to the other until composted. If you have the space this is the most efficient way to go. All corrals should allow for an initial pile size of 1 metre cubed and should be in a line for easy transfer.
The first corral is for collection, garden waste such as grass clippings, leaves, and weeds are added as they arise, see recipe section. You build the pile all at once in the second corral. Start by wetting the ground under the pile. Layer the materials fairly thinly, watering as you go. The thing to note here is that layering is really only second best, the ideal is a homogenised mix of materials, so making the layers too thick moves you away from this ideal and will lengthen the decomposition process. Cover with damp hessian or a similar material that can breathe if you wish at the end.
Monitor the pile in the usual way and once the pile has cooled transfer the mixture to the last corral, watering between layers if necessary and cover and leave again to finish rotting down. Repeat the last step again, if you can. As a general rule, the more you turn the quicker it will break down and the better the quality. It is recommended that you let the compost mature for a couple of months before using. This process can be incredibly quick, one author’s father can produce an evenly decomposed product within 3 weeks, incidentally this composting maestro of a guy routinely mows other people’s lawns just to get enough raw materials for his brew. Now that’s dedication.
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The Gedeye Bin as an example of an anaerobic compost system.
Some systems are designed so that the contents break down more or less anaerobically or without air! They do produce methane and rotten egg gas but as long as you don’t disturb the contents too much when adding food or garden waste the smell isn’t too bad. Because they are intended as oxygen-less systems there is no need to aerate them using PVC pipes or twigs in the bottom etc. The Gedeye bin is a good example of a readily available anaerobic system and if you are not keen on constant maintenance it could be the system for you. You can use it simply to compost food scraps adding the occasional layer of either compost, garden soil, straw or shredded paper if it gets too wet and slimy. Add waste materials until the bin is filled and then leave it to break down while you fill another bin or use another system. You will need to wait as long as 12 months for the compost to completely break down after filling. If you need the bin before the compost is ready just lift it off, cover the compost with plastic or hessian and leave the compost to mature.
Did you know humans share an interest in composting with a group of birds? Called the Mound builders these ground dwelling fowl use large mounds of fermenting earth to create warmth for their eggs. The bird controls the temperature of the mound by scratching and adding materials (in much the same way, one presumes, we turn our composts and control the addition of browns and greens). Examples in Australia include the Scrub Fowl and Brush Turkeys of the tropics and the Mallee Fowl of the dryer inland regions.
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Ingredients, good things to compost
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A
Animal products. OK in compost or wormery in the quantities generated at the kitchen table. In very large quantities animal products may attract rodents and blow flies and stink as they rot down. The fats in some animal products, like butter, cream and roast drippings, actually coat compost particles cutting off the air supply so adding large amounts encourages the smellier anaerobic form of decomposition.
Annuals (spent). Eg. Forget-me-nots. Watch out with these as they may have viable seeds. Check with your nursery as to whether they are likely to self seed or not. If they are and you don’t want them popping up every where (some people might!), treat them like weeds and drown them.
Apple peels and cores. For nitrogen. Great in a wormery or hot or cold heap. Large pieces of fruit (such as whole apples) should be chopped roughly before being added.
Aquatic weeds. For nitrogen. Suitable in a wormery or hot or cold heap.
Ashes. Not carbon or nitrogen. Ashes from chemically treated wood or glossy magazines are not suitable at all for wormeries and should be added very sparingly to compost heaps. Tends to be alkaline so will increase the pH of the heap. Coal-ash should be avoided.
Autumn leaves. For carbon. Suitable in hot or cold heaps. Be careful to make sure they are well mixed in as leaves have a tendency to mat together and in so doing resist decomposition.
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B
Banana skins. For nitrogen. High in calcium, phosphorous and sulphur. OK to compost in hot or cold heap as they decompose rapidly. Great too in a wormery.
Bamboo leaves. Green for nitrogen. Dried for carbon. Shred leaves, whether green or dried; see preparation of ingredients for tips. You might have too much at a time to expect the worms to process it but some of it would be a good bedding material. Great in a hot or cold heap.
Bamboo stems/roots. Noxious weeds. Not suitable to compost.
Bark. For carbon. See saw dust.
Beer and brewing wastes. For nitrogen. Suitable for hot or cold heaps. Try it in the wormery if you want to, in small quantities. Could also just throw on the garden, lawn or under a tree.
Bird cage cleanings. For nitrogen. Small amounts will help to activate a compost. Large amounts can get very hot. Not suitable for a worm farm on account of the heat.
Black walnuts. Debatable. These plants have evolved highly aggressive chemical warfare with which to compete with their neighbours. They produce a toxin called juglone, which destroys plants within metres of them. Juglone will break down eventually (it may take 2 years) so if you compost with any part of the Black Walnut you would be wise not to spread it out until weeds start to grow out of the compost (indicating that the juglone has bio-degraded).
Blood and bone. For nitrogen. An alternative to dynamic lifter and an easy way to inject nitrogen into your compost heap.
Bracken ferns. OK in a hot or cold heap. Worms might struggle with these – best not to.
Bread. OK for compost or wormery but may attract rodents if left uncovered.
Butter (rancid). OK in a hot or cold heap or wormery in small quantities, but it is inadvisable to add in large quantities, like whole blocks. See fat.
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C
Cabbage. For nitrogen. See apple peels and cores.
Cardboard. For carbon. Absolutely fantastic for wormery bedding providing it’s free of coloured ink. Soak overnight before adding. Also suitable for composting in a hot or cold heap, especially if you have some high nitrogen materials to compost – shred before adding.
Carrot peel. For nitrogen. See apple peels and cores.
Cat litter. Suitability for compost bin or wormery varies. See cat poo.
Cat poo. Cats are subject to infestations by Toxoplasma gondii. This microbe has the potential to cause brain damage to the unborn child and it is recommended that pregnant women, small children and those with impaired immune systems not handle cat faeces or litter. Toxoplasmosis produces varying symptoms in other people and is often asymptomatic. Many authors say that while it is unwise to put compost containing decomposed cat poo on vegetable gardens, it is OK on other parts of the garden. This may be good advice, but as anyone who has a cat and a vegie patch can attest, keeping them away from freshly dug earth is nigh on impossible. There is, therefore, a fair chance that if you have a cat which is infectious (and it seems this is by NO means all of them) the soil in the vegie patch will already be infected. None of the authors can be bothered collecting cat poo to compost. If you must compost it, make sure you wear gloves at all times, always thoroughly wash hands after contact with cat poo, compost and soil, even if gloves have been worn, and always wash thoroughly any vegetables harvested from a backyard vegie patch. You could also use a Pooperator (trade mark).
Celery tops. For nitrogen. See apple peels and cores.
Chaff. For carbon. If you have access to it it’s a very concentrated source of carbon and so may be excellent for people who want to compost kitchen scraps and need a lot of carbon on a regular basis to do this.
Cheese (mouldy). OK in a compost or wormery in small quantities. See fat.
Chicken carcass. OK in compost or wormery in small amounts. Will take a long time to break down in a wormery, return to compost if necessary. See animal products.
Chilli. OK in a compost bin, not suitable in a wormery.
Citrus peel. For nitrogen. Suitable in hot or cold compost heap. Not suitable for wormery, citrus oil is too strong for worms.
Coffee grounds. For nitrogen. OK in a hot or cold heap. Really good worm food.
Coffee filters (paper). For carbon. Suitable for hot or cold heaps if shredded or for wormery.
Comfrey. For nitrogen, potassium, calcium and phosphates. Because of its high nutrient content it is supposed to act as a starter, helping to get the composting process going.
Compost Starter (commercial). Nitrogen, essential nutrients and compost bacteria. Starters are what they say they are, starters! They get the composting process going. No-one in our group has used any of them, we all seem to get things to compost down without needing to import any products. If, however, you need to compost down a large quantity of browns, compost starters might be the answer. See dynamic lifter.
Corn cobs. For carbon. Very slow to break down in a compost. Shredding or cutting with a sharp knife will help before throwing it into the kitchen scrap bucket. Can be composted, but might need to be sifted out and returned to next batch when compost is harvested. Worms might struggle.
Corn stalks. For carbon. Suitable for hot or cold heaps. Must be shredded.
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D-E
Dairy foods. OK in a compost or wormery in small quantities, but it is inadvisable to add in large quantities. See animal products.
Diseased plants. Not suitable for composting. Goes for insect-infested plants as well. Home composting is unreliable as a means of sterilising diseased plants. Need to consult your council about the approved methods of disposal for diseased plants.
Dog poo. OK in a compost bin or wormery. There are a lot of specialised products on the market, like the Pooperator and the Tumbleweed pet poo converter, that are designed specifically to handle pet waste. You might like to consider these or simply use your existing bin. Worms would be a helpful addition whatever system you choose. Remember when handling compost (ANY compost) it is important to: wear gloves, wash hands thoroughly after contact (even when gloves were worn) and thoroughly wash any vegetables harvested from your garden.
Dynamic lifter (trade mark). Commercial manure product. For nitrogen. Great if you don’t have enough nitrogen in your compost mix and this may be the case if you only have autumn leaves or dried lawn clippings to use. Will get things heating up nicely. Not suitable in a wormery.
Egg cartons. For carbon. See cardboard.
Envelopes. See office paper waste.
Eucalyptus leaves (dried). For carbon. By the stage of being shed, dry eucalyptus leaves have yielded most of their nitrogen to the tree and therefore are considered to be mostly carbon. Some say that eucalyptus oil is too toxic to be added to compost but there are others who seem to have no problem. One author’s father always includes the gum leaves picked up when mowing the lawn, with no adverse effects. Gum leaves tend to be high in lignin so shredding will definitely facilitate faster break down.
Eggs (yolks and whites). For nitrogen. OK to put in a hot or cold heap or wormery.
Egg shells. Will not really break down when added to compost whole. You can dry and crush them into a fine powder before adding to compost (they will contribute some calcium) or add to a worm farm (the worms take them into their gizzards and use them to macerate their food). If you are lazy add them as they are, who cares if the compost has the odd bit of egg shell in it anyway? One author noticed worms seeking refuge in them.
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F-G
Fabrics. In small amounts can be composted providing it consists of natural fibre from wool, cotton or hemp (not synthetics or blends).
Fat. OK to put in compost or worm farm in small quantities. Fats, oils, roast drippings, butter, ghee, cream and cheese will tend to coat particles in the compost and cut off their supply of air. If you are disposing of table scrapings then a little fat is fine. Larger quantities should be buried in the garden. Choose a site where you are not likely to be digging regularly and bury about 30cm (1 ft) deep. Do not under any circumstances dispose of fats or oils down the sink.
Feathers. For nitrogen. We have never composted with them, however some authors suggest that they should be shredded and put in a cold composting heap.
Fish bones and prawn shells. OK to put in a hot or cold heap or a wormery in small quantities. See meat and bones.
Flowers. For nitrogen. Suitable for hot or cold compost heaps. Good for prettying up the wormery too.
Food wastes. Suitability varies. Meat products, fish, eggs, dairy foods, butter and oils, as already mentioned, are OK in small quantities but you should be careful when adding large amounts. Try leftovers in a worm farm and see if your worms go for them (they might like your cooking!). For vegetable matter like peelings and other fresh vegetable and fruit wastes, a wormery or a hot or cold compost heap are all OK. If you compost in a backyard heap be careful to add enough carbon to balance the high nitrogen and water content of the food scraps or else things could get pretty slimy and smelly.
Garlic. Not suitable for a wormery. OK in a hot or cold compost heap.
Grape stalks. Carbon. See apple peels and cores.
Grape vine canes. Carbon. Best put through mulch maker first. Suitable in a hot or cold heap. Leave plenty of time to break down.
Grass clippings (fresh). For nitrogen. Great in a hot or cold heap. Composed of fine particles that compost down quickly. Note: a lawn that is well watered and well fed will have higher nitrogen than lawn which is dry and straw coloured. Many authors suggest that leaving the clippings on the lawn returns valuable nutrients to the grass and acts as a mulch. However do what you like, if you value compost on your garden more, then make compost!
Grass clippings (dried). For carbon. OK to compost in a hot or cold heap.
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Hair. For nitrogen. Use sparingly in hot or cold heaps and mix well with the other ingredients. Pet hair can also be spread out on the grass (make sure the cat is inside) for birds to use (they LOVE it).
Ivy. Absolutely, positively must not be put in the compost. All you need is for one node to survive. Don’t trust that the temperature of even a hot heap will rise enough to kill all the plant tissue, not with ivy in any case, it just isn’t worth the risk.
Kitchen scraps. Mostly suitable for hot or cold heap or wormery. See food wastes.
Leaves. For Carbon. Suitable in a hot or cold heap. You will probably have too many to deal with at one time to put in a wormery. If you want to compost leaves quickly, combine 5 parts leaves to 1 part manure.
Lettuce. For nitrogen. See apple peels and cores.
Lucerne hay. Probably too valuable as a mulch to waste putting in your compost. But it is fine if you do. Even when dry, lucerne is high in nitrogen.
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Magazine paper. Probably not suitable to compost. Inks used during printing tend to be of metallic origin. OK if printed with vegetable based inks. Check with the publisher if in doubt.
Manures. For nitrogen. Highest in nitrogen when fresh. Suitable to compost in hot and cold heaps where it helps to activate a compost. The heat given off by many bird manures during decay tends to be too high for a wormery.
Mayonnaise. Only likely to be available for composting in small amounts so no need to worry about the fat or vinegar. Chuck it in.!
Meat and bones. Bones won’t break down in a hurry and will probably still be intact when you go to use the compost. Meat will break down but it may stink and attract flies and possibly rodents. It is up to you really, we don’t waste much meat but have found that the occasional meat trimmings or leftovers compost down fine. Remember to cover the compost or wormery with plenty of dry stuff to repel the flies, see worm section.
Milk. OK in a compost bin in the proportions that an ordinary household will generate.
Newspaper. For carbon. Suitable for hot or cold heaps and wormeries. Very high carbon so needs plenty of nitrogen to compensate. Shred to facilitate mixing and avoid matting.
Nut shells. For carbon. Depending on the nut, shells will break down to varying degrees. Macadamia nut shells will finish breaking down sometime during the next geological period and coconut shells several eons after that.. Peanut shells will break down the quickest. Even though they take a long time to break down there is no reason really why you can’t put them in the compost, so what if there are a few nut shells in your compost when you spread it out on the garden! Worms might struggle!
Office paper waste. For carbon. Suitable for hot and cold compost heaps or as wormery bedding. Great if you can access a source of it as it comes pre-shredded. Try your local school, if they can off load this waste for free you will be doing them, as well as yourself, a favour.
Oil. Oil has a tendency to coat compost particles, blocking out the air in the process. This may lead to the compost turning sour or anaerobic and smelling bad. Small amounts of oil, however, shouldn’t present a problem. If disposing of deep frying oil or more than a few tablespoons at one time, it is a better idea to bury it. See fat.
Onion peel. For nitrogen. See apple peels and cores.
Pasta. For carbon. OK in a hot or cold compost or wormery but may attract rodents.
Peanut butter. Mainly fat but OK for a hot or cold heap or wormery in the small amounts likely to be generated at home.
Pear peelings. For nitrogen. See apple peels and cores.
Pea shells. For nitrogen. See apple peels and cores.
Pea straw. For carbon. OK in a hot or cold heap or wormery. Adds nitrogen if green.
Pet food. See meat and bones.
Pigeon droppings. For nitrogen. Small amounts will help to activate a compost, if you can be bothered to scrape it off some public sculpture. Large amounts can get very hot. Not suitable in a wormery.
Pineapple tops and peel. For nitrogen. See apple peels and cores.
Pine needles. For carbon. Quite high in carbon and tend to be acidic so will take time to compost down and will need to be teamed up with a good nitrogen source. Might be a good ingredient to team with a little wood ash which is alkaline.
Pita crusts. See bread
Pizza crusts. See bread.
Potato peelings. For nitrogen. See apple peels and cores.
Prunings. For nitrogen. Suitable for hot or cold compost heaps. Needs to be shredded and shouldn’t include ivy or other nuisance plants that propagate freely from nodes, unless you really like them!
Pumpkin skins and seeds. For nitrogen. See apple peels and cores.
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Rice hulls. For carbon. Suitable for hot or cold compost heaps. Make sure that hulls are fully composted before adding to garden. Unevenly composted hulls behave like a barrier to water and it becomes impossible to water the garden.
Rice (boiled). For carbon. OK in hot or cold heap or wormery, but may attract rodents.
Saw dust. See woods.
Seaweed. For nitrogen. Suitable for hot or cold compost heaps. It is better to collect seaweed fresh and wash in freshwater. As it dries it absorbs salt. Harvesting it after a storm is a good idea. The large kelps, like bull kelp, will take longer to break down than the smaller leafy varieties and you would need to shred the former. Packed with plant minerals.
Soil. It’s good to add some soil at first as a means of innoculating the compost with microbes. Some soil on the surface of the pile after you have added kitchen scraps and especially meat, might lessen the problem of insect infestation.
Squash. For nitrogen. See apple peels and cores.
Straw. For carbon. Suitable for hot or cold compost heaps. Breaks down easily, so if you can get hold of it, it’s an excellent source of carbon for home composting. Try local stables.
Table scraps. OK to put in a hot or cold heap or a wormery in the proportions that are generated at home. See food wastes.
Tea bags. For nitrogen. Suitable for hot or cold compost heaps and wormery.
Tea leaves. For nitrogen. See tea bags.
Toilet roll cardboard. For carbon. See cardboard. Tear them up in the toilet as they become available.
Tomatoes skins and seeds. For nitrogen. See apple peels and cores.
Turnip tops. For nitrogen. See apple peels and cores.
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Urine. Good for nitrogen and potash. Can be added to compost. With respect to methods of application, use your imagination. Some authors suggest diluting it….the mind boggles!
Vacuum cleaner dust. Worms love it and it’s suitable for hot or cold compost heaps as well.
Weeds (prior to flowering). For nitrogen. Suitable for a hot or cold heap, as long as they are pulled before going to seed. Weeds that propogate by way of rhizomes or stolons should not be composted after pulling. Even if you have a hot heap, you cannot be sure that all nodes (propogules) will spend enough time in the centre of the pile (where it is hottest) to be killed. Furthermore, chopping up fresh plants like these often leads to more vigorous growth (as is the case with couch grass). You must kill these types of weeds before adding to heap. Drown your weeds by leaving in water for 4 weeks to rot, then add drained weeds to compost and use the liquid as a fertiliser. Alternatively, you can compost them down anaerobically by sealing in a plastic bag for a few months. Plants to be very careful of include: Ivy, Couch Grass, Tradescantia (Wandering Jew) etc.
Weeds (post flowering -with seeds). Not suitable to compost as they are. You cannot be sure that all seeds will spend enough time in the middle where it is hot enough to kill them. Can be drowned see weeds prior to flowering.
Yoghurt. OK in a hot or cold heap in the proportions you are likely to generate at home. See animal products.
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Compost Recipes
Tried and tested ways of dealing with household waste
Grass clippings, newspaper, a hot heap and a healthy weekly work out!
If you have access to grass clippings then you might be interested in setting up a hot heap. Build it about one metre cubed and layer the grass clippings (some of which will be dry by the time you go to build) and newspaper with a light sprinkling of dynamic lifter between layers. Water lightly between layers and turn every week with a shovel. You can prepare the newspaper by damping down and then running over it with the lawn mower. Heats up and breaks down fast. Yummy!
Tip: There is no better an aerobic activity than turning a compost pile. It’s good for your respiratory health and your upper body strength. Considered a moderate activity, you’ll burn off 20-30kj/min, so you can expect to work off an average serve of chocolate (600kj) in about 20 minutes.
Tip: Ever wondered what happens to your grass clippings after your garden has been mowed by a professional? They are taken to the tip and dumped. Let the gardener know that you are a composter and set up a chicken-wire bin or some other container to receive clippings.
Autumn leaves
Autumn leaves have yielded up their precious nitrogen to the tree and so are a carbon source. They therefore need to be combined with a nitrogen source such as fresh grass clippings, manure, dynamic lifter etc. The biggest problem with leaves is their tendency to form tight layers that quickly exclude air and become anaerobic and smelly. Add some twigs to the mix, especially at the bottom, build around a PVC pipe with air holes drilled into it, or get into the habit of turning it once in a while. Good in an open system like a home made chicken-wire bin.
Tip: To the lazy composter a few PVC pipes are absolutely indispensible. Drill them full of holes and use to increase the aeration through your heap by building the heap around them.
Kitchen scraps and household cardboard
Use any bin to build a cold heap that includes the household’s kitchen vegetable scraps, finely torn toilet rolls, egg cartons and other shredded waste paper, making sure that you include plenty of carbon to mop up the moisture and offset the nitrogen. Keep it aerated as you would autumn leaves (above).
Tip: Get into the habit of tearing up small cardboard items like egg cartons and toilet rolls as they come to hand. It only takes a few seconds to do, is great for compost and drastically reduces the amount of waste going to landfill.
Tip: A jute bag hanging on a nail in the toilet is perfect for receiving torn toilet rolls.
Tip: Just as a guide the authors weighed the vegetable waste produced over 20 days. One family which consisted of 4 adults were found to produce about 675g of vegetable waste per day.
Pretty short recipe book eh! Email us your recipes and (if we can) we’ll try them out in our test garden and put them on the site.
Compost FAQ’s – info, tips & troubleshooting for composters
My compost bin stinks, what should I do?
How do I get the carbon/nitrogen balance of my compost right without all the fuss?
If I use compost can I then stop using fertilisers?
I’ve heard compost is a soil conditioner. What is a soil conditioner?
I really can’t tolerate rodents, how do I keep them out of my compost?
How do I control insect infestations in my compost heap?
What is a hot heap and when should I use one?
What is the best size for a hot heap?
My hot heap won’t heat up. What am I doing wrong?
What is the difference between anaerobic and aerobic fermentation?
Is it OK to compost with wood?
Legionnaire’s Disease and compost -how does home composting effect my health
My compost bin stinks, what should I do?
Properly made compost shouldn’t stink. It should smell like freshly dug earth or forest humus. If it reeks then it may have become sour (with a characteristic ammonia odour) or sulphurous (characterised by the odour of rotten eggs):
- Ammonia odour
Too much nitrogen (greens) -layer your heap with more browns (carbon) like dried leaves, dried grass clippings, shredded paper or finely torn cardboard.
- Rotten egg gas
Too wet (not enough air)-too compact (not enough air)-layer your heap with more browns (carbon) like shredded paper, dried leaves or even soil to absorb the excess moisture,
If very wet it may pay to spread it out flat for a while to dry in the sun. Initially you may need to turn it with a shovel to get air back in and reverse the effects of compaction.
Rebuild the pile with PVC pipes (that you’ve drilled aeration holes into) running through the centre or incorporate twigs, branches or plant stems into the mix to create lots of air pockets.
Drill more ventilation holes into your compost bin.
Add compost worms, they’ll mix up the compost and prevent compaction.
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How do I get the carbon/nitrogen balance of my compost right without all the fuss?
Achieving the right balance of carbon and nitrogen materials in your compost will reduce both the time taken for it to break down and the incidence of foul odours. As a general rule of thumb, having approximately equal volumes of carbon and nitrogen materials in your mix will help ensure carbon and nitrogen are available in the proportions that compost microbes prefer. This is a guide only, however. Ingredients can differ markedly in the amounts of carbon or nitrogen they contain and so the equal volumes rule can fall down. Actually when it comes to striking the right C:N balance, one of your best friends is your nose. Consult My compost stinks, what should I do? in this section, for ideas about correcting C:N imbalances. As you become experienced at composting you will become better at assessing the need for carbon or nitrogen. Whilst the processes that go on inside a compost heap are complex and hard and fast rules are rare, with experience you will gain a feel for the right balance of browns and greens. Be attentive, monitor your compost, smell it and don’t be afraid to experiment.
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If I use compost can I then stop using fertilisers?
The short answer is no. Compost is a relatively poor, slow release source of nitrogen. It has been estimated that the nitrogen, phosphorous and potassium (NPK) values of some compost are 1.5%N, 2% P and 1% K respectively (The Ohio State University Bulletin). Compare this with Miracle-Gro™ where the N, P and K percentages are 15, 13.1 and 12.4 respectively. Compost may have the edge over inorganic fertilisers, however, by being less subject to nutrient leaching, and by having the full complement of trace elements which commercial preparations generally don’t. As a general rule if you are growing vegetables and need a short burst of fertilizer it is best to supplement compost with manure or, perhaps, smaller quantities of commercial preparations. It seems that compost has greater value to the home gardener as a soil conditioner.
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I’ve heard compost is a soil conditioner. What is a soil conditioner?
A soil conditioner is a product that improves the quality of the soil with respect to plant growth. Compost is a soil conditioner. It improves soil tilth, making it more friable and therefore more aerated and less susceptible to water-logging. Because compost is humus, it enhances the water holding capacity of the soil. Furthermore, erosion is reduced in a well conditioned soil and the tendency for nutrients to leach out is greatly lowered.
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I really can’t tolerate rodents, how do I keep them out of my compost?
Really the only solution is prevention. Make it a habit not to compost with the kinds of foods rodents like ie. dairy products, meat and eggs. Sadly, high carbohydrate food scraps like pizza crusts, bread and pitas may also attract rodents. If you are composting with these or kitchen scraps keep them covered using damp hessian, newspaper, carpet or underlay and, perhaps, aim for a system that heats up so they break down quickly. Turning the compost regularly should also create conditions unfavourable for nesting. Probably the best way of proofing against rodents is to choose a system that is already rodent proof. Worm farms that consist of stackable units are completely enclosed and will not permit the entry of rodents. Hot heaps tend not to attract rodents, presumably it’s too hot!
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How do I control insect infestations in my compost heap?
Fruit fly larva actually assist the decaying process so you could just learn to live with them. If, however, they are really getting to you, here’s some combat strategies. To bar access, cover the compost with several sheets of damp newspaper, hessian or carpet underlay. To remove fly eggs, wash fruit well before eating (even bananas and citrus). Keep kitchen scrap bucket covered. If they are already in your compost, set traps. Fruit flies like cider vinegar and the colour yellow. The simplest trap is, therefore, a yellow container with some cider vinegar and a drop or two of detergent (to reduce the surface tension and make them fall in). If you place this in the bin you’ll need to be very careful not to tip it over. Frustratingly, many flies seem to be wiley enough to escape. A better trap imprisons the flies. Create a funnel from paper (preferably yellow) that has a tiny opening at its pointy end. Place this funnel pointy end down into a glass jar that has some cider vinegar and a drop of detergent in it. Make sure the tip is as close to the liquid as possible. Secure the upper edge of the funnel to the top of the jar with tape and hang the trap in the bin. Refresh the vinegar every 2 weeks.
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What is a hot heap and when should I use one?
A type of compost heap that breaks down largely by the action of thermophilic bacteria (bacteria that prefer hot temperatures). Heat is given off by the bacteria as they metabolise the waste. Because these thermophilic bacteria are aerobic or oxygen loving, it is often important to turn the compost to counter the depletion of oxygen in the pile. Piles often heat up if manure or manure based products are added to them. In addition to having a good source of much needed nitrogen, manures are a concentrated source of bacteria and so, for this reason, have a stimulatory effect. The most efficient hot heaps have a Carbon:Nitrogen weight ratio of 30:1. Hot heaps are compost systems that suit people who want compost fairly quickly, are prepared to put in the time and effort in turning them and who have a large amount of materials to build the pile initially. Use hot heaps to compost autumn leaves or large amounts of carbon waste that you have on hand. The initial dimensions of a hot heap should be 1 metre cubed.
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What is the best size for a hot heap?
A hot heap that is about 1m cubed represents a compromise between wanting to limit the loss of heat from the system and the need to get air into it. If the heap is very small, it will be well aerated, but any heat that is generated will quickly diffuse to the outside and be lost. Increasing the dimensions of the pile insulates the inside so the thermophilic bacteria, that carry out the bulk of the decomposition during the high temperature stage, can multiply. The down side is that as these microbes process the waste the oxygen does eventually become depleted, forcing the need to turn the compost to aerate it.
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My hot heap won’t heat up. What am I doing wrong?
There are three main reasons why a hot heap stays cool and they all relate to some of the basic principles outlined in the making good compost section. First, big heaps retain heat, small ones lose it. If the heap is too small (less than a 1metre cubed) then any heat that is generated is quickly transferred to the outside where it dissipates and is lost. Second, compost microbes like a good balance of nitrogen and carbon organic matter. If you don’t add enough nitrogen to the mix then the heap is not likely to get hot; try adding roughly equal amounts of greens and browns. Third, the mix is too dry. Yep, just like us, microbes need water and if you don’t apply enough water, especially when the heap is first constructed, then there will be little microbial growth and therefore little fermentation.
Tip: When adding nitrogen in the form of manure or dynamic lifter to your compost it’s important to bear in mind that compared with fresh lawn clippings manures are very high sources of nitrogen and that a large handful per layer (6 inches, 15 cm) of carbon matter is quite sufficient.
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What is the difference between anaerobic and aerobic fermentation?
Aerobic fermentation is performed by oxygen loving bacteria. It is the preferred method for backyard composting as the products are sweet smelling (relatively). The bacteria that perform anaerobic fermentation, on the other hand, can tolerate an oxygenless environment, and their activity is characterised by the release of methane and hygrogen sulphide (rotten egg gas). Anaerobic fermentation is what goes on in a landfill.
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Is it OK to compost with wood?
First, it is not OK to compost with treated pine as it contains toxic chemicals. Other types of wood are OK however there are problems. Wood is made up largely of a very strong substance called lignin. Highly resistant to breakdown by the kinds of bacteria in a compost pile, lignin is decomposed largely by fungi during the latter stages of the composting process. Bacteria can break down some of the molecules in wood (such as cellulose) but their access tends to be barred by large numbers of bulky lignin molecules that literally get in the way and cover up the cellulose. Where does this leave the home composter? Providing you include enough nitrogen to offset its high carbon content, there is no reason why you can’t put wood in your compost bin. Saw dust will break down quickest as it presents the largest surface area to microbes. Chips will break down much slower. Perhaps exercise some restraint, adding a great deal of wood to compost will necessitate a longer breakdown period and the addition of a very high nitrogen source like dynamic lifter.
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Legionnaire’s Disease and compost -how does home composting effect my health?
Legionnaire’s disease is a bacterial infection transmitted via air-borne particles such as those delivered by airconditioning systems and sometimes dust from dry compost. The symptoms of Legionnaire’s disease include headaches, fevers, chills, muscle aches, respiratory problems and pneumonia. People at higher risk of infection include males aged over 50, heavy smokers, heavy drinkers, diabetics and people with chronic lung diseases or impaired immune systems. It is recommended that you never handle dry compost – dampen it down with water first. Always wear gloves when handling compost and be gentle when handling to avoid creating dust. After handling compost always wash hands, even when you have been wearing gloves, to avoid hand to mouth transmission.
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Glossary
Get up to speed with composting and worm farming terms
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Aerobic bacteria: bacteria responsible for breaking down organic matter in the presence of oxygen releasing carbon dioxide in the process.
Ammonia odour: caused by a pungent alkaline gas formed by the decomposition of protein, nitrogenous bases and urea (from urine). The smell of ammonia in your compost tells you that the mix is too high in nitrogenous materials like manure, kitchen scraps or fresh lawn clippings. A compost like this is said to be sour.
Anaerobic bacteria: bacteria responsible for the breakdown of organic matter in the absence of oxygen, releasing hydrogen sulphide and methane in the process.
Bacteria: ancient, microscopic single celled organisms found in soil or water or which are parasitic on plants or animals. They have cell walls and reproduce asexually simply by splitting in two. There are two broad groups of bacteria relevant to composting – aerobic (oxygen loving) and anaerobic (oxygen hating).
Bedding: the material in a wormery where worms may retreat to escape the heat or to shed capsules. Usually situated under the food, bedding can simply be castings or material such as shredded paper or straw.
Blues: (Perionyx excavatus), a species of composting earthworm being red-purple at the anterior end, changing to a brown-red at the tail-end with a cream under belly, they have a creamy coloured unraised clitellum and a tendency to thrust their bodies about when exposed to light.
Browns: shorthand for all those compostible materials that are high in carbon as opposed to nitrogen. Usually includes dry plant matter such as straw, chaff, dried leaves and lawn clippings. Compare with greens.
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C
Capsule: the cocoon from which a small number of worms hatch. Secreted by the clitellum of a worm, it collects sperm and eggs as it is shed. Fertilisation occurs inside the capsule with young hatching within 3 weeks. When you see them in the soil they look somewhat like granules of Osmocote™.
Carbon: the key atom that contributes structure to all organic molecules. For the composter, carbon rich materials or “browns” include straw, paper and dry grass clippings or leaves. Compare with nitrogen.
Carbon / nitrogen ratio: the weight for weight ratio of carbon to nitrogen materials in a compost heap. The generally accepted ideal C/N ratio for composting is 30:1. If a hot heap is desired then it is fairly important to keep the ratio around this ideal; however, organic material will still compost down if the ideal is not upheld.
Castings: material which has passed through the digestive tract of a worm. There are two types of castings – Vermicompost, which will still contain worm capsules and possibly live worms and Vermicast, which is pure castings with no worms.
Cold heap: a compost heap that never heats up beyond 60°C. Usually cool enough to contain earthworms and not requiring as much attention as the hot heap.
Compost: the humus-like product resulting from the controlled decomposition of organic matter by micro-organisms.
Compost Starter: a commercial preparation consisting of manure and various nutrients which is said to hasten the composting process probably by boosting the level of bacteria in the mix. Manures, dynamic lifter and even blood and bone will, to varying degrees, have the same effect. Not absolutely necessary if you want to compost but could be useful if you want to compost a large amount of material that is extremely nitrogen deficient.
Corrals: often used when making a hot heap. Three corrals are constructed in a row the first being used to collect garden waste as it is generated, the second to build a pile and the third to receive partially composted material when the second pile is turned.
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Decomposition: broadly the break up of dead material into smaller and smaller particles. In biochemistry the splitting of large molecules into smaller ones by enzymes.
Dynamic lifter: has become such a mainstay in the garden these days that it warrants an explanation. It’s a processed chicken manure product extremely high in nitrogen (all bird manures are because they contain both faeces and urine). Good if you want to compost down a lot of carbon material that is highly nitrogen deficient.
Earthworms: segmented, hermaphroditic invertebrates of the subclass Oligochaeta (from the Greek ‘few hair’). Especially noted for their influence on soil health. Earthworm burrowing breaks up the soil and their muscular gizzards grind soil particles to create a fine tilth. They are also responsible for improving the nutrient availability to plants. Compost earthworms differ from native Australian species in their preference for environments rich in organic matter and this makes them ideally suited to composting food scraps. There are three types of composting earthworms of note: Reds, Tigers and Blues.
Fermentation: decomposition occurring in organic compounds often carried out by micro-organisms resulting in the production of other compounds and the release of heat and gases.
Fertiliser: a preparation that supplies plant nutrients, can be of organic or inorganic origin. Does not normally mean manure or compost.
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G-J
Gizzard: that part of the worm digestive tract that is muscular and responsible for pulverising soil particles. The reason why soil with worms in it is soft and friable.
Greens: shorthand for compostible materials that are high in nitrogen as opposed to carbon. Includes things like: kitchen scraps, manures and fresh lawn clippings and leaves. Compare with browns.
Hot heap: a compost heap that heats up to and beyond 60°C. Usually requires attention in the form of correct C:N ratio, moisture levels and aeration. Has the potential to kill plant pathogens. Compare with cold heap.
Indian Blues: (Perionyx excavatus) often just called ‘Blues’, composting worms of a bluey-red colour.
Juglone: a toxin produced by Black Walnuts which has evolved as chemical warfare against competing plants. Will break down eventually but if black walnut leaves are composted an extremely long maturation phase must be observed (as long as 2 years or better still wait until weeds start to grow in the compost).
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L-N
Lignin: extremely high in carbon and composed of very strong molecules that are highly resilient to decomposition. The main component of wood. Breaks down very slowly in compost, only soil-based fungi have the enzymes capable of breaking down lignin. Takes a long time to compost down and requires a lot of nitrogen to do so.
Maturation phase: the period after the bulk of the composting has been completed during which compost continues slowly breaking down and maturing to become a more stable product. Can take a few months. Compost that has not matured could go on breaking down in the garden, robbing plants of valuable nitrogen in the process.
Mesophilic bacteria: bacteria whose optimal temperature range for growth is 40-65°C (moderate temperatures). Their numbers are high at the start of composting (when the compost has just been built or new materials have been added) and they tend to digest the soluble, readily degradable components of organic matter like simple sugars. Compare with thermophilic bacteria.
Mulch: a protective covering given to soil around plants. Generally consisting of uncomposted or partially composted plant matter such as straw or immature compost but can also take the form of wood chips or even gravel and metal filings. Mulch slows the rate of evaporation from the soil surface and encourages the presence of earthworms.
Nitrogen: like carbon a key element in all biological molecules. Proteins are nitrogenous compounds as are nucleic acids (DNA, RNA) and many other molecules such as anti-bodies in animals. For the composter nitrogens or “greens” are most abundant in fresh organic matter like kitchen scraps, manures and fresh lawn clippings and leaves. Compare with Carbon.
Nucleic acids: polymers of nucleotides forming the two major molecules of genes and gene expression DNA and RNA respectively.
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O-R
Organic material: for the purpose of composting, any material that was once living; usually of plant or animal origin. Could also be a by-product of a living organism such as manure or worm castings.
pH: a scale of acidity. Spanning pH 0.0 (the most acid) to pH 14.0 (the most basic or alkaline). The ideal pH range for worm farms and composting is in the neutral range pH 5.5-8.5. Compost undergoes a natural change in pH as the breakdown products of microbial action (including organic acids) accumulate. Low pH favours the growth of fungi which digest lignin during the last stages of composting.
Plant pathogens: any biological agent of plant disease. Can be bacteria, single celled eukaryotes, fungi or invertebrates.
Protein: any of a number of nitrogen rich compounds consisting of linked amino acids. Proteins are important structurally (think muscle, ligaments and cartilage), biochemically (enzymes, chlorophyll) and to animal immune systems (anti-bodies etc).
Reds: (Lumbricus rubellus) a species of composting earthworm of a deep red colour with a clear, raised clitellum and measuring about 7.5 cm in length as adults.
Rotten egg gas odour: a pungent sulphurous smell arising from the fermentation of nitrogenous material in an anaerobic environment. It releases hydrogen sulphide gas in the process. Rotten egg gas from your compost tells you that it is not aerated enough.
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S-T
Soil conditioner: something you add to soil to improve its structure. Soil conditioners will make soil friable, more aerated and improve drainage whilst facilitating wetting. Compost is an excellent soil conditioner.
Soil microbes: refers to the community of bacteria, other single celled organisms and fungi found in the soil and which are largely responsible for the decomposition of dead organic matter.
Souring: caused when a compost system or worm farm becomes anaerobic. Acids accumulate causing a dramatic drop in pH.
Tigers: (Eisenia fetida) a species of composting earthworm which have a brown body with distinctive yellow banding, a raised clitellum and a tendency to exude an unpleasant liquid when threatened.
Thermophilic bacteria: bacteria whose optimal temperature range for growth is 40-65°C (high temperatures). Thermophilic bacteria breakdown molecules that are fairly stable chemically and have relatively strong bonds such as proteins, fats, and complex carbohydrates. Their numbers generally build in a compost heap after the numbers of mesophilic bacteria start to decline. Compare with mesophilic bacteria.
Toxoplasma gondii: a microbe found in cat faeces which is responsible for Toxoplasmosis in humans. Can also be transferred in raw meat. Advisable for people not to touch cat faeces and not to put same into compost if it is to be used on vegetable gardens. Always wash hands well after contact with compost or garden soil. The wearing of gloves is advisable.
Trace elements: those elements required by plants in minute or trace quantities. The trace elements are boron, iron, manganese, copper, zinc and molybdenum. Deficiencies in trace elements can cause a wide range of plant diseases.
Turning: the periodic mixing of a compost heap in order to cool it down, replenish the supply of air and ensure even composting. Particularly important when using the hot heap method.
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V-W
Vinegar flies: the tiny flies that seem to swarm from the compost every time you lift the lid. Attracted to compost by acids in rotting plant material.
Wormery: a worm farm.
Wormettes: a term we use to describe newly hatched earthworms.
Worm farm: a system of housing and breeding worms generally used to perform the function of organic waste disposal. Worm farms can be commercial bins or improvised structures. Usually they have the capacity to allow drainage of moisture away from worm bedding and a division which facilitates the separation of castings from live worms when the former is harvested.
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Upper Yarra Valley Garden Club Inc 