Smallholder Composting: Can I Compost Alpaca Manure?
HOTBIN owner Clare has a smallholding with 50 chickens, 6 alpacas and is now about to open a cattery (www.clarescattery.co.uk). Following her success with her first two HOTBIN compost bins, she has asked us a number of “smelly based” questions over the past couple of months, the latest of which is HOTBIN’s ability to compost alpaca manure.
Clare asked us:
- Can I compost alpaca manure?
- Can I compost chicken poo with my food waste?
- Can I compost cat poo?
- Should I have separate compost bins for the alpaca, cat, and chicken/food waste?
Let’s begin with a cute picture of an alpaca before getting down and dirty with the issue of composting alpaca manure and other animal waste. Hopefully you are not feeling queasy and are ready to read on!
Can You Compost Alpaca Manure? (or Llama poo – its related cousin)?
The answer is yes. All animal poo (including dog and cat poo) can be composted. Clare has been successfully composting alpaca poo for 6 months in a HOTBIN compost bin. She reports just how easy it is: “The alpaca manure is largely free from any bedding additives, save for a bit of hay. I find that alpaca poo composts in no time at all, in fact many people say they use it neat, shall we say, as alpacas are ruminant animals and therefore poo is almost compost as it comes. However, I still prefer to compost it for a short while at least.”
Can I Compost Chicken Poo With My Food Waste?
Yes, chicken poo makes great compost fast. However the addition of bedding from chicken coops/houses can slow the composting process down so you may need to watch the amount of wood shavings added.
Different bedding materials compost at different rates: paper is the fastest followed by straw, sawdust and wood shavings. If you are using ‘pellet bedding’ – this can be either paper pulp or sawdust based. If you want to know more about the science of how lignin and surface area affect the speed of composing visit our woody material post.
Chicken poo is so fast to compost it acts as a compost accelerator and is more cost effective than commercial accelerators.
Can I Compost Cat Poo?
Yes, although many compost websites categorically say no to cat poo composting. There are however some health and safety issues to consider, but in our opinion with a correctly operating HOT home composting bin the risks are small. We do however broadly agree that adding cat poo to a cold compost heap should be avoided.
Should I Use Separate Compost Bins for Each Type of Waste?
We see no reason to separate the different wastes into different compost bins however the options below will give you some advice to make you own decision:
For a smallholder such as Clare we have two options to consider:
1) Separate the wastes into different HOTBIN’s, one each for food waste, alpaca manure, chicken poo and finally cat poo. This is essentially what Clare does now.
2) Mix all wastes together and fill the bins in rotation (e.g. bin 1-day 1; bin 2-day 3; bin 3-day 5; bin 4-day 7; bin 1-day 9 and so on).
We favour option 2 because it is easier to keep the temperature high (60C) with a mixture of wastes (soft, hard, green brown, etc). The easy to digest waste (e.g. alpaca manure and chicken poo) will help the harder waste (shavings and pellets) to rot down. There will also be less wood in one bin so it’s more likely each bin will compost at the same rate. You could set up a ‘square’ of four bins and ‘fill by rotation’, which would keep all the composting in one place and help reduce the heat loss as there will be less wall area exposed to wind chill cooling.
Method 1 would be better if you wanted separate compost, for example just “alpaca compost”. This option also suits separate locations – e.g. (for Clare) a bin by the cattery, chicken pen, alpaca field, and one near the kitchen door.
Whichever method is chosen keep an eye on the temperature and if they are not getting to 60C regularly then adjust the mix.
10 Interesting ALPACA FACTS
- The alpaca is a ruminant with three stomachs; it converts grass and hay to energy very efficiently, eating far less (as a percentage of its body weight) than other farm animals.
- Alpacas do not eat their afterbirths. Clare added 3 into the compost bin and they sent the temp dial spinning! No need to be squeamish about these things, it is what nature is giving us – thanks mother nature!
- Alpaca poo benefits from the addition of a bulking agent to improve its porosity. It is too heavy and dense to allow air to flow evenly through the mix.
- Raw (non composted) Alpaca manure is lower in organic matter (most of the plant cellulose id digested) than the manure from most other farmyard livestock (cows, horses, goats and sheep). Alpaca manure can generally be spread directly onto plants without burning them. Like all manure it is best to hot compost it as this reduces faecal pathogens and converts the organic matter to humic substances.
- The nitrogen and potassium content of alpaca dung is comparatively high, an indication of good fertilizer value. Nitrogen, phosphorus and potassium are the major plant nutrients. (They are the familiar N-P-K on fertilizer bags.
- South American Indians use the alpaca waste for fuel and local farmers apply alpaca’s droppings as a fertilizer when growing fruits and vegetables.
- A herd of alpacas consolidates its waste in one or two spots in the pasture, thereby controlling the spread of parasites, this also makes them popular pets and easy (ish) to housetrain (allegedly!).
- Alpacas originate from South America and have a life expectancy of around 20 years.
- Alpaca fibre lacks the roughness of some other types of wool, so is a popular material for making jumpers, socks, gloves and many other forms of clothing.
- The Alpaca is classified in the same animal group as Camelids, with Camels and Llamas as close family relatives.
Can I Compost…?
Got a question on what you can and can’t HOT compost? The HOTBIN composting team get all sorts of questions on what can be composted and how best to go about it – View our What Can I Compost Lists.
Composting Human Hair and Orange Peelings in Sunny Spain!
We had an interesting enquiry today from a new user about to set up the HOTBIN in Spain on how to compost human hair and orange peelings.
“I have just ordered one [HotBin] for southern Spain. My hairdresser is happy to provide bags of hair. Is hair in large quantities ok? Also a juice bar has offered bags of orange peel. Again is this ok in large quantities? I want acidic compost. Thanks for your help. I am really quite excited about moving from cold to hot composting”
With the first snow of winter falling today, sunny Spain sounds great.
Here is a summary of the tips:
Hot Composting Human Hair
You can hot compost human hair. As with most things in composting, it tends to work better when mixed with other items. We do not have specific experience, but for a few months check it does not form into a dense thick layer that might affect airflow. Remember to give it a stir and mix in less if it does.
Hot Composting Orange Peelings From Juicing
Orange peelings and pulp from juicing will be a challenge for hot composting. They are very high in water content and an item often “too wet for hot composting”. You may need lots of shredded paper or to air dry the peelings in the sun for a few hours. (Also your dry hair might be a good balance – it really depends on how much of each you have). You will need to experiment but give a call any time if you need help to get the recipe right.
You mention ‘acidic compost’ – presumably you are trying to tackle an alkaline soil. I am not sure attempting to make acidic compost is the best route. Bacteria in the heap work best at neutral Ph. If the bin goes acidic (due to organic acids found in all plants, but high in orange peel), the compost will turn anaerobic, stink and slow down to a halt.
I think you will be better leaving the compost to work at neutral Ph and tackle your soil Ph either slowly by adding ‘neutral’ compost which will eventually bring the soil Ph down, or by adding a natural acidic mineral to the soil (eg sulphur or iron sulphate). You may know this, but just in case, take care because if you add too much you will cause issues. Best to get an exact Ph reading from the soil and then match this to the exact quantity (in grams) of the acidic mineral. The RHS has a good article on soil acidification: http://apps.rhs.org.uk/AdviceSearch/profile.aspx?PID=82
Sourcing “Trade Waste”- Do a Quick Check
I do not wish to put a damper on your ideas, but please check with your local traders and you will not get into trouble with the local Environment Agency or waste disposal officer. All waste from businesses within the EU is classified as ‘trade waste’ and rightly, each business is subject to rules to ensure the waste they generate is disposed off safely. As daft as this might appear, they might not legally be able to give you peelings or hair for home composting! Hopefully, your local agencies will be enlightened and see small quantities and home composting as a good route, but these things can get very sensitive depending on interpretation of the rules.
Permaculture Review the HOTBIN Compost Bin – They Love it So Much….
John Adams and Maddy Harland at the Permaculture Magazine review the HOTBIN compost bin. They loved it so much, they decided to add it to their green shopping supplement.
Over the years I have tried most ways of making compost but I have never found one that really suited my requirements until Maddy showed me her Hotbin. I was really impressed that it worked even in winter, how quickly it made compost (about 90 days) and that it could even cope with cooked food scraps. I just had to have one.
The Hotbin certainly gets hot. Last summer it was positively thrumming (up to 60ºC). There is never any smell from the bin and the process is fast. There were also no flies as their eggs cannot survive the heat in the bin.
We both love this product so much we have added it to our Green Shopping catalogue.
Download and read the full review here.
Buy your HOTBIN compost bin online today.
DOES HOME COMPOSTING BENEFIT THE PLANET?
Does each small piece of home composting positively benefit the environment and planet Earth?
To understand how and why, you need to look closer at the role of soil (dirt) and its critical role in mankind’s survival. This 30 min Radio 4, ‘Shared Planet’ broadcast hosted by Monty Don has a good overview: http://www.bbc.co.uk/iplayer/episode/b03cmt4t/Shared_Planet_Soil_Science/
When you add compost to soil you add “organic matter”. This organic matter is vital to soil fertility and carbon sequestration.
Think of it as a pyramid of stacked blocks, at the top:
Humans require food, therefore
We need plants and animals to eat
Animals need plants to eat
Plants need soil to grow (+water and sunlight)
Plant growth is determined by soil fertility
Soil fertility is a based on complex interactions of nutrients, water, air pores and soil compounds such as humus
Soil micro-organisms (bacteria, fungi, worms etc) manage soil fertility (eg the release nutrients to plants)
Soil microorganisms require organic matter (food) to survive
You need to ensure soil organic matter is replenished. If not, soils degrade and eventually they stop being productive and the pyramid collapses.
The HOTBIN team has blogged on the impact compost has on soil fertility. We try and focus the debate away from what compost looks like and onto how much humeric substances your compost contains.
Composting wood preservatives?
Can I compost wood that have been treated with wood preservatives?
Many think the answer is no, but in most cases it is YES you can!
We have done our best to distal the facts, read the comments below and note we can only act as an information source not a guarantor of safety. With that said, what we found is: modern preservatives supplied in the EU/Can/US to the general public during the last 10 years are biodegradable and compostable.
The golden rule: follow the manufacturer’s label.
By the time the wood is no longer usable – you will have most likely have got rid of the tin! Look at the problem logically. The purpose of the preservative is to kill bacteria and fungi that rot wood – they contain biocides and fungicides that kill bacteria. Hopefully you are not throwing ‘good’ usable wood on your compost heap – it is more likely your wood is rotting/decaying. If the bacteria are already decomposing the wood -the chemical that was preventing bacterial growth is no longer working! Composting merely accelerates and completes the process.
The question now is where are the leftover chemicals and is the compost safe?
Why do so many composting sites advise not to compost wood treated with preservatives
This relates back to toxicity –10-20 years ago ‘heavy metal’ wood preservatives (see table below) were nasty, dangerous and were banned. This toxicity issue appears to be applied to all wood preservatives!
It is right to be concerned about toxic chemicals many mistakes have been made – but I also advise, whenever you see toxicity cited as a reason not to do something, step back and ask: toxic to what (plants, humans, animals?) at what level (parts per billion or gallons of the stuff? and how is it toxic (when it touches the skin, ingestion, inhalation)?
10-20 years ago ‘heavy metal’ wood preservatives (see table below) were found to be nasty, dangerous to both marine life and workers exposed to heavy doses of fumes and liquids – they were banned.
Heavy metal preservatives & old wood
The arsenic and chromium would remain in your compost/soil – even in small quantities, the risk of them entering the food chain is unacceptable. Do not compost old wood treated with old arsenic or chromium based preservatives.
Newer organic and organic+copper preservatives
The organic (carbon) fraction is used by the bacteria. The copper ions are most likely to be left in the soil/humus matrix. Most soils already contain metal ions – the quantity looks small and non copper is not a problematic metal (our water system run through copper pipes).
If your wood has been treated with a newer version and is rotting – the preservative is already gone/well on way out – composting bacteria will decompose the wood and any copper ions will return to the compost/soil.
Brief History – 2000 years of wood preservative use
||Olive-oil, linseed oils to help protect woods
||Coated their ships hulls with tar
|Creosote – the dark brown stinky stuff
||A natural product from wood or coal. Will fully biodegrade with time. Became common place to treat railway sleepersAll types of creosote are composed of phenol derivatives (as found in wood). For its useful effect, wood-tar creosote relies on the presence of methyl ethers of phenol, and coal-tar creosote on the presence of naphthalenes and anthracenesToday, creosote is manufactured from the distillation of coal tar. Creosote is regulated as a pesticide, and is not usually sold to the general public – but it is still used
|Heavy metals compounds 60-90s
- CCA (Chromated Copper Arsenate) green tinted
- ACQ (Alkaline Copper Quaternary)
|The bad period – nasty chemicals started being used to treat wood without the knowledge of hazards. Typically arsenic, copper, chromium based compounds.These were banned in late 90’s as they were found to be toxic to marine life (small amounts) and caused problems for factory workers via inhalation and ingestion (exposed to large amounts)
- Copper azole & Other copper compounds
- PTI – – Propiconazole-Tebuconazole-Imidicloprid
|They all have incredibly long chemical names like tebuconazole or propiconazole – but I did note these same chemicals as used in food production – so safe? CuHDO used in EuropeCurrently limited to above ground applications such as decks (why – because below ground it decomposes! (Note: all three of the PTI components are also used in food crop applications)
Wiki has a very informative section on wood preservatives http://en.wikipedia.org/wiki/Wood_preservative
We have done our best to distal the facts. As always with H&S – you are the guardian of you own safety. We can only act as an information source not a guarantor of safety.
Can I Compost Egg Shells And Eggs?
Can I compost egg shells and even ‘out of date’ eggs?
You have missed the box of eggs in the back of the fridge – they are 3 weeks past the USE BY date – you are not going to eat them… what do you do with them?
Here is the HOTBIN composting ‘egghaustive’ review of the topic!
Let’s agree we are going to gently chastise ourselves, plan better and monitor the fridge more often so it does not happen again. Maybe next time we buy too many and it looks like we are going to have wastage, we can arrange a “Bake OFF” with the children….
But right now that still leaves us with a box eggs unfit to eat –
- We could chuck box and eggs in the waste bin and they will go off to landfill
- We could crack them open, tip the egg down sink and put the shells in the compost bin (messy!)
- OR In a HOTBIN – we could just crack the eggs into the bin and compost them.
Are we sure – yes – the eggs are just protein and water.
As long as your bin is working between 40-60C, and you add some shredded paper and bulking agent (as normal with food waste) the egg and yolk will be broken down and ‘invisible’ within a few days. The shells will take a lot longer – but all that calcium carbonate in the shell will go back into the soil it’s just a version of ‘lime’ for gardeners.
OCD HOTBIN users, sad but true…
We do know at least one person has fried an egg inside the HOTBIN composter – we stress this was more out of inquisitiveness than with any intent to eat the fried egg!
Did you know 1: in the UK we eat 32 million eggs a day, a staggering 11 billion eggs every year. Over 85 per cent of these are produced domestically by 29 million laying hens each laying an average of 314 eggs each. (source: British Egg Information Service, website).
Did you know 2: The UK throws out an estimated 19,000 tonnes of eggs a year, costing us about £60 million pounds (WRAP – the food we waste, 2011). The average egg weighs 40g, so we have 25 eggs per Kg, 25,000 eggs per tonne, or 475 million eggs thrown out a year.
There are ~30 million UK homes, so on average, each household throws out ‘a dozen eggs a year’.
Cross check – an egg costs 14p, £0.14 X 475 m eggs = £66 million = WRAP figure
Please note our first paragraph – we are not suggesting composting eggs is a good thing – your goal should be to avoid wasting them and any food. Given that accidents happen – sending eggs to landfill does not seem a positive step.
Please let us know if you have more creative options for what to do.
Did you know 3: Although we are not sure how accurate this is in terms of H&S aspects like listeria: you can test an egg and get an approximation of its age by gently dropping the egg into a bowl of cold water:
- sinks to the bottom and stays there, it is about three to six days old.
- Sinks, but floats at an angle, it’s more than a week old.
- Sinks, but then stands on end, it’s about two weeks old.
- Floats, it’s too old and should be discarded.
If it sinks, it’s good; if it floats, it’s too old.
Eggs act this way in water because of the air sac present in all eggs. As the egg ages, the air sac gets larger because the egg shell is a semi-permeable membrane. The air sac, when large enough, makes the egg float. Eggs are generally good for about three weeks after you buy them – and this should be the USE BY date – the red stamp date on the egg.
Did you know 4: to test if your egg is hard boiled, spin it on a flat surface. If the egg wobbles, it’s fresh because the insides are moving around. If the egg spins smoothly, it’s cooked.
I think we have now ‘egghausted’ this topic! But if you have a HOTBIN that is HOT COMPOSTING you can COMPOST out of date eggs!
Composting Leylandii, Conifer and Pine Needles – HOTBIN
Composting Leylandii, Conifer and Pine Needles – Can I Compost Them Or NOT?
You can compost all forms of confer
Some composting advice state: ‘do not compost leylandii, pine needles or other conifers as they create acidic compost and soils’. Below we set outline whether this is a myth or fact.
Will leylandii compost in the HOTBIN? Yes.
Leylandii and pine needles can be hard to compost – but they obey the same rules as other wood based material. The speed at which they compost is linked to the size of the bits (surface area) and temperature (cold, warm or hot). Where it would take 2-5 years to cold compost them at 10C, hot composting at 40-60C it would only take 1-3 months.This explains why some people say report compost in 30 days and others that they still have leylandii in their heap after 5 years.
Small shredded pieces and pines needles will compost quickly in the HOTBIN – typically 90 days. Do not add large non shredded bits of conifer to your HOTBIN – they will just come out the other end partially composted.
Conifers create acidic SOILS that kill plants? Myth
Acidic soils are formed over millennia by weathering of rocks and minerals and the close interaction these minerals with organic matter that falls on the ground. Over time these reach equilibrium and you get soils that vary from acidic, neutral and alkaline (see soil classification). Most conifers, pine, leylandii and evergreen species grow in cold temperate climates on mildly acid soils – this is their natural habitat. The soil is acidic by location.
“You cannot grow anything under a pine tree due to acidity”
Most gardeners agree it is hard to grow anything under a pine tree. Research studies have shown there is no significant change in soil pH after years of adding pine needles to soil (ref Manynard et el). There are many acid loving plants – these would colonise the soil below the trees if acidity was the only problem – see below.
“CONIFERS release acidic chemicals when they fall to the ground”
True – but misplaced relevancy. Pine trees (like all woods and plant life) contain organic (carbon based) chemicals that chemists would class as ‘weak organic acids’. Plant life is made up of hundreds of these chemicals – turpenes, phenols, even the smell of ‘pine trees’ is an organic acid.
Organic acids are broken down during composting and return back to carbon dioxide. Think of it this way “acids in a pine needle are just bacteria food to be eaten”.
(It might be possible that “acid rain” that fell on many Scandinavian conifer forests has got muddled into this. Acid rain is caused by sulphur dioxide and nitrous oxide from coal burning power stations reacting with water to form weak sulphuric and nitric acid – which then kills the pine needles).
Lack of plant growth under pine trees is more likely a combination of three factors. A) Pine needles create a thick mulch layer (we define mulch is a dense layer of actively composting material). The bacteria in the mulch rob the soil below of nitrogen and hence prevent plant growth – typically mulches are used to prevent weed growth). B) Conifer roots are shallow – they out compete other plants for water and nutrients so plants struggle to grow around conifer roots. C) Conifers create dense shade which makes it difficult for plants to grow. All these factors create the ‘no growth zone’ rather just acidity.
“Leylandii are acidic – I get a SKIN burn when I cut the hedge”
Many people suffer skin rashes when leylandii clippings touch bare skin. The rash is a reaction to the weak organic acid – it is a ‘burn’. Some skins will be more sensitive than others – it is wise to wear gloves and clothes that cover bare arms and legs when cutting leylandii hedges. (Please see above – these acids are broken down in the soil via composting bacteria).
COMPOSTING HEAT – CAN I USE HEAT FROM HOTBIN COMPOSTING
Can I use the heat from the HOTBIN composting to heat my house, water or greenhouse?
Several customers have asked questions about heat recovery and using the heat from HOTBIN composting to heat water or heat the greenhouse. Here is a quick summary of the answers:
Can I recover the heat from the HOTBIN and use it to heat water? Yes, but three problems make this impractical.
1) An easy way to extract the heat would be to wrap a plastic or copper tube around the inside of the walls, circulate cold water through the pipe and the water inside the pipe heats up (just like a small immersion heater). This would collect the heat – but as soon as you remove heat from the waste, your waste will cool and stop hot composting – it will go cold and stay cold. Basically the HOTBIN will no longer be HOT!
2) You could extract the heat after it has left the bin (ie collect the steam from the valve) and then condense the hot steam via a heat exchanger. This is complex and the heat exchanger systems are expensive. It would only be worth it if the cost was offset by the energy saving.
3) A typical HOTBIN burning about 1-2Kg of waste a day equates to the heat output from a 30 to 60 watt bulb. A central heating systems typically is pumps out 2Kw (2000 watts) of heat. There is not enough heat to make an impact.
There are large community composting schemes that recover heat from compost heaps. They tend to have a large tonnage of waste – at least 10 times that of a normal house/garden. The theory and engineering of hot composting are covered in R. T. Haug, Practical Handbook of Compost Engineering. I don’t believe the heat output and cost of equipment to support ‘heat collection’ from a domestic composting bin is really a worthwhile option.
CAN I PASS THE HOT GASSES INTO THE HOUSE to HEAT IT? NO!
As above there is not enough heat energy to heat the house. But the bigger issue is health. The hot gas leaving the valve is carbon dioxide and hot water (ie steam). If you pipe this into the house, the water will condense on walls and within weeks you will have a black mildew mould all over the house. We need to breathe oxygen and hence need fresh air in the house. Pumping carbon dioxide in is a bad idea – although we doubt you could create a serious issue, elevated CO2 levels are to be avoided as they cause nausea and dizziness. (THE release of gases outside is different – they are quickly dispersed and diluted as soon as they leave the HOTBIN).
CAN I USE THE HOTBIN to HEAT THE GREENHOUSE? YES!
The heat is not enough to warm a greenhouse over winter, but there should be enough to keep the frost at bay. Also the gas leaving is a mix of steam and carbon dioxide – just what any plants inside the greenhouse need. With a few hours of daylight – the plants should have a slightly enriched growth environment.
PS: if you do want to move you HOTBIN into the greenhouse this Autumn – please ensure you empty the waste out first. Do not attempt to move your HOTBIN when full – the bin can weigh over 100Kgs. This is unsafe to move – think of your back, the recommended max lift is 20Kgs. You will undoubtedly damage the hot weld seal between the upper and lower halves too. This can only be repaired by an expensive trip back to the factory repair shop.
HOT composting food waste
Waste “Too Wet” to Hot Compost
Occasionally it can be a struggle to get the HOTBIN up to 60C. One of the most common issues is the waste is “too wet” for hot composting. In this post we explain what this means and how to fix it.
What does ‘too wet’ for hot composting mean? You have more water in the food waste than energy (calories/heat) available to evaporate the water as hot steam. If you do not balance a wet mix, the waste will not get above 40C, it will turn smelly and a lot of leachate will drain from the base.
We appreciate not achieving 60C can be frustrating and no-one wants a smelly bin. You bought the HOTBIN to resolve these issues. The answers are for HOTBIN hot composting. The advice might not match your past composting experience. Please stick with us – the advice works, it is based on the fundamental laws governing hot composting. Once grasped, you will find the HOTBIN easy to use for ever.
When is my waste “too wet” for hot composting? It is a challenge because it relates to the water inside the food waste. The waste does not need to be “dripping wet” to be ‘too wet’. As a rough rule of thumb:
- Garden waste is OK (it is usually 40-60% water)
- Vegetable peelings are OK (about– 70% water)
- Food waste is too wet (averages 80%). Always balance food waste
- Foods like salads, juice pulp and cooked food are excessively wet (90% water)
What are the signs my waste is ‘too wet’ for hot composting?
- Lots of leachate (brown water) leaking from mesh plate, (Check the water is definitely seeping from behind the mesh plate and ignore condensation and lots of water dripping off the inside of lid when you open it)
- The waste in the HOTBIN smells putrid, rancid or drain like (ie it is anaerobic)
- The temperature in the top layer will not increase above 30-40C. (Poor aeration and lack of new waste also prevents temperature rising above 40C – so check these as well).
Tip: Always investigate and fix excess water issues – the sooner you address, the easier it is to fix. Sorting out an anaerobic smelly mush of partly composted food waste is just about the worst composting job there is.
How do I fix (balance) waste that is too wet? By adding a dry ‘easy to digest’ waste into your mix. The easy and available material to add is shredded office paper and/or chopped up corrugated cardboard.
Tip: avoid adding newspaper or cereal packet card for this task. They are not easy for bacteria to digest and will just end up as a mushy lump in your final compost.
How much paper do I need to add to food waste? 30g of dry paper per 1Kg of wet food waste. This is one part shredded paper for every two parts of food waste. See the table below:
Full food waste container (by volume in litres)
||Kitchen measuring jug
||Small plastic kitchen waste caddy
||Medium kitchen waste caddy
||Full carrier bag, plastic bucket, or large food caddy
|Measure of paper
|Add this many hands full of paper per full container
|Ratio by volume
||For every full container of food waste, add half the same container of shredded paper. (The volume ratio is 2 parts food waste to 1 part shredded paper).
To fix top layer, you may need ½ a carrier bag of paper/cardboard pieces (360g).
To rebalance a ¾ full bin, you may need 2 full carrier bags (1.4Kg) of paper.
Do I need to add bulking agent if using paper? Yes, ALWAYS add bulking agent with food waste. The bulking agent will form a supportive structure that maintains airflow.
Remember: In hot composting, paper fixes wetness, wood chip helps aeration. You cannot balance ‘wet waste’ by adding wood chip bulking agent, nor can you fix ‘poor aeration’ by adding paper. You need to check how much bulking agent has been added.
How much bulking agent do I need to add to my waste? Add 1 part bulking agent to 5** parts food waste. See table:
Full food waste container (by volume in litres)
||Kitchen measuring jug
||Small plastic kitchen waste caddy
||Medium kitchen waste caddy
||Full carrier bag, plastic bucket, or large food caddy
|Add this many hands full of bulking agent per container
|Ratio by volume
||For every full container of food waste, add a one fifth of bulking agent. (The volume ratio is 1:5)
Your top 10 cm layer of food waste should have 4 litres (two measuring jugs or 6 hands full) of bulking agent in. A ¾ full bin of just food waste should have a total of 16 litres (just short of a full carrier bag) of bulking agent added to it over the filling weeks.
(Note** if you read the earlier version of this post, it was changed from 1:10 to 1:5 on 24/09/13. The amount of bulking agent depends on the waste mix going in, ie how much other woody waste is being added from the garden. We need to reflect a more cautious ratio to cater for those using only food waste).
How do I ensure all food waste is balanced in future? With practice you will spot which food wastes are “too wet” and which are OK. Until then the safe way is to add paper every time. Tip: half fill your food collection container with paper. Now add the waste on top. The paper will squash down.
HOW do I fix ‘wet waste’ already in the HOTBIN?
| Step by Step
|1) Check if waste is too wet. Do you have:
- Lots of leachate (brown water) leaking from mesh plate
- Waste that smells putrid, rancid or drain like (ie it is anaerobic)
- The top layer will not increase above 30-40C.
|2) Fix the top layerMix in 8 hands full (half a bucket or half a carrier bag) of corrugated cardboard (or shredded office paper). Check you have added at least 6 hands full of bulking agent (wood chip) to the food waste over past couple of weeks. If not, add now.Leave 48 hours. Check if temperature has risen above 40C. If not, move to step (3)
|3) Check the base layerTake off the door panel and look at the waste in the base. Match how the waste ‘looks’ and ‘smells’ to one of the four options below. Follow the actions for your match. If you are unsure, send a photo to firstname.lastname@example.org
|3.1 Base layer Aerobic & active
- Leaking water but does not smell putrid
- Has yellow/green non composted material with recognisable pieces of waste.
- Temperature below 40C
Your waste is still active. Typically this will be the case when the waste is less than 6 weeks old.
||If the waste in the top does not rise above 40C within 2-3 days, the base is probably suffering from restricted airflow.Mix in 1 to 2 carrier bags of paper into the base layer. Did you add at least a carrier bag of bulking agent during filling? If not, top up now.You may find it faster and easier to mix by emptying it out onto a plastic sheet, mixing then adding back.
|3.2 Base layer anaerobic & active
- Leaking water
- Some yellow/green waste in base, but also brown/black with slimy partially digested waste
- Smells putrid
- Temperature below 40C
Your waste needs action to remove the smell and return to aerobic state.
||Take out the base layer and leave on sheet of plastic to aerate and dry. (This may take a few hours).Mix in 1 to 2 carrier bags of paper with the base layer. Did you add at least a carrier bag of bulking agent during filling? If not, top up now.
|3.3 Base layer aerobic, not activeIs it mainly brown, sticky pieces, cold (below 20C), very wet/soggy and claggy, no odour or an earthy odour(Typically this will be the case with waste over 12 weeks old).Your waste has composted and is now “stable”. It is unlikely to reheat to 60C
||This is ready to take out and use. If you leave it longer it will compress further and eventually airflow will be severely restricted which will prevent the upper layer in the HOTBIN getting above 60C. If you are worried the compost looks lumpy and too rough – please visit the post on ‘looks can be deceptive’.
|3.4 Base layer anaerobic and not activeIs it black sludge, leaking water and has a pungent drain like odour.Your waste has anaerobically composted. It is now “stable” and unlikely to reheat to 60C
||If you leave this waste in the base it will compress further and eventually airflow will be severely restricted which will prevent the upper layer in the HOTBIN getting above 60C. There are two options:a) Take it out and leave it to dry. Occasionally turning with a fork will help aerate the waste and remove residual odour. Once dried, break it up with a fork. Use the smaller bits as mulch, add the larger bits back into the HOTBIN gradually as a substitute bulking agent (it must be dry!)b) Dig it in to soil. (Before digging in – double check it is not active by looking at step 3.2. (Active waste will attract vermin and ‘rob’ soil of nitrogen due to ongoing bacterial activity.
|If you are unsure which description fits your waste, please send us a photo of the top and base layer and we can look at it for you.
|5) If you have removed any material from the base, wipe around the door joints, replace door and tighten cam belts. Gently push the waste down into base to form a new base layer. Add more new waste as soon as possible.
|6) Close the lid and ensure valve plate is set to minimum position (ie just 2mm open). The HOTBIN should lose all putrid odour and rise into hot zone within 48 hours. Once back to 60C, continue as normal for 3 months then empty.
Why does the bin turn anaerobic and leak water? The HOTBIN simplifies the composting science to allow fast hot composting. Aerobic composting breaks down the waste to release water and carbon dioxide. Food waste can be 80% water so a 5 litre caddy of food waste has 1.5 litres (a measuring jug) of water in. This water has to go somewhere. In hot composting, most of the water is removed out the top (through the valve) as hot steam. If this is does not happen, water drains down and seeps out of the base as ‘leachate’. A wet base layer restricts aeration and leads to a smelly compost bin. Removing the water relies on a piece of science known as the energy / water balance.
What is the composting Energy-Water balance? A scientific equation to balance the amount of water that needs to be removed from the waste with the amount of energy (calories, heat) needed to drive the water off as steam. We can determine exactly how much dry waste (energy) needs to be added to balance any wet mixture. The tables above are a simplified summary that will suit most needs. If you have a special mix we can assess and advise.
What if I have no shredded office paper or cardboard available? What if it is too much hassle to add paper/card each time? There are three options:
1) Do not add excessively wet items (eg juice pulp, salads) to the HOTBIN
2) Drain / dry excess water – eg squash and then strain water out before adding.
3) Continue to add wet items and accept it will not get above 40C and will generate lots of leachate. (You will need to stop adding meat, fish and cooked food).
We can’t change the laws of chemistry and physics. The HOTBIN will only get hot and drive off water as steam when you have waste with more calories than the calories needed to vaporise the amount of water in the waste
Why do I add corrugated cardboard and shredded paper in the HOTBIN? Dry corrugated cardboard and shredded office paper is easy for composting bacteria to digest and they are also very ‘dry’ (ie have very low water content, typically less than 5% water). They balance wet food waste to ensure there is enough heat to drive off excess water as steam. If you want to learn why we specify the paper type (office paper rather than newspaper, please read our post on woody and lignified materials.
How do I create lots of chopped up cardboard quickly? Everyone tends to have corrugated cardboard boxes, but tearing them up can be tiresome. You can quickly cut into strips using a craft / Stanley knife – but you need to take care to avoid taking your fingers off! A safer way is use a ‘multi sheet’ cross cut paper shredder. Most 8-sheet units will shred cardboard boxes. (Note if you put too much strain on a low sheet feeder it will just overheat and conk out!).
What is the water leaking from my HOTBIN? Water is released during composting. When the waste is ‘too wet’ for hot composting, this water drains down to the base and eventually leaks out as leachate.
Can I completely avoid leachate? No. The HOTBIN will occasionally seep water and it is not possible to prevent some leachate at some point in time – water is released in all composting.
There tends to be more water seepage in winter and more water seepage on first use of the HOTBIN as there is no compost in the base to absorb water.
Is the leachate just water? No, as water drains down two types of leachate can be formed:
- A brown odourless liquid
- A light yellowish liquid, often with a pungent smell.
Can I collect the leachate and use it as a fertiliser on the garden? Yes if it is a brown odourless liquid you can collect it and pour it on to your soil. It will have nutrients in and humeric acids.
If the leachate has a pungent odour and is light yellow, it is still active and potentially phytotoxic (bad for plants). Leave the liquid in a container to rest for a few weeks until the odour goes – ie bacteria have completed decomposition.
How can I collect the leachate? We are developing a collection spout. A temporary way to collect is to take a small plastic tray, set this on the ground and push tight to the mesh plate. Connect the two using putty (or another waterproof flexible membrane), ensure the joint is at the bottom of the mesh plate (see this post).
The mesh grill appears blocked and no water is coming out: It is very rare for the plate to be fully blocked. This would require a huge amount of silt to build up in the reservoir behind the aeration mesh plate. The design of the base reservoir and mesh grill means any small pieces of silt sink to the bottom and water flows out the mesh plate above the silt. If you find the plate is fully gunked up and the water line very close to the top (20-25mm), then dab the plate with a cloth/sponge loaded with neat bleach. This will kill the bio film (removing the gunk) and the water will flow out.
Normally there is about 5mm of wetness below and about 15mm of dry mesh above – creating a clear water line. The air flows in above the water line.
If the mesh plate is constantly fully blocking, please check your HOTBIN is level. When tipped forward, the water and silt will collect behind the grill not in the reservoir.
Do not worry if the mesh plate looks rusty – it is a galvanised mesh. It often looks a rusty colour as the brown leachate dries on grill a rusty colour. If in doubt – clean with bleach as above.
HOTBIN COMPOSTING IN AUTUMN
Autumn is Coming –
Here are a few tips for managing your HOTBIN after your garden clear up!
Time for the big autumn tidy up which means lots of waste. Unlike a traditional heap the HOTBIN will not freeze and continues to work over the winter providing you with a nice batch of spring compost.
To get HOTBIN composting in autumn here are a few tips to help you manage the tidy up.
Tip One: Shred waste where possible. A pile of hedge trimmings that fill a barrow will be a few cm high when well shredded. If you do not have a shredder, careful use of your hedge trimmer or lawn mower can suffice:
- Hedge Trimmer – pile up the waste on soft grass, cross cut repeatedly.
- Lawn Mower – pile waste on the lawn and run over it repeatedly with the mower.
We do not recommend either technique if the twigs are more than 5 mm thick.
Tip Two: If you have lots of brown fallen leaves and the grass is not too damp for one last cut, it is worth spreading the leaves on the lawn and cutting and shredding both in one go. The grass/leaf mix will compost super-fast in the HOTBIN.
Tip Three: Where you have too much, ensure your stock pile is protected from the rain. A large bag of wet cold leaves will be significantly harder to get hot than a dry cold bag of leaves. You will be amazed how quickly a mound of waste can be composted if you maintain 60C using the “little and often” technique.
Tip Four: Do not be tempted to add or squash everything in. Fast composting requires heat and heat requires airflow. If you compress it too much airflow will be restricted. Adding bulking agent (particialy composted woodchip) helps maintain airflow throughout the waste. If you add a lot of cold waste it will take longer to reheat. You are better off adding a 20-30cm (one foot) layer every 2 days over one 50 cm layer in one go.
Tip Five: If your HOTBIN is already full, then check your base layer to see if it is worth removing now. Even if the base does not look like perfect compost, it might be better to remove and use it as winter mulch or for digging in. This is not always easy to assess – if you need help view how does HOTBIN compost look and feel.