Whenever you get into a conversation with anyone about making compost you will hear the term ’browns’. This will be referred to in conjunction with the term ‘greens’ with equal enthusiasm. You will also hear about getting the right balance between nitrates (from nitrogen) and carbon.
So, what is brown material in compost? Examples of brown material would be shredded paper, cardboard, leaves or sawdust. All of these have an abundance of available carbon which is required when making compost. In the general ecology there is a natural carbon cycle. A significant part of this cycle is played out during the making of compost.
When making compost it’s important to aim for a balance of inputs to get a quality result. The nitrate input will be from any green vegetable waste from the kitchen for example lettuce and cabbage leaves. In general, anything that you add to the compost bin from the kitchen that has the potential to turn into a soggy mess will be high in nitrates. This will be the ‘greens’.
What is brown material in compost? Anything that contains carbon.
This has to be balanced with enough carbon based material. This will be the browns. For carbon think cardboard and anything else like it. This would include newspaper dead leaves or sawdust if you can get it. If you you are lucky enough to get hold of dead leaves you will find that they work best if they are shredded. When dead leaves become damp in compost they tend to stick together in lumps. Shredding will avoid this.
Dead leaves can make some of the best compost that you will ever make. They have a very high carbon level having been fixed through photosynthesis. We have a post explaining how dead leaves can produce a natural, truly organic fertilizer. You can see it at ‘How to make organic fertilizer from leaves’.
What is green and brown material in compost?
The ‘green’ material is what we discussed earlier, that is anything that is actually green. This would include discarded leaves of any kind, vegetable trimmings and peel. When you peel a potato or carrot the peelings are considered to be ‘green’ and ideal for making compost. The ‘green’ portion can only successfully convert to a passable compost if it is balanced with an adequate inclusion of, what are known as, browns. This usually refers to cardboard or newspaper but don’t forget dead leaves when they are available and sawdust.
About brown material in compost
Compost Brown to green ratio
There is a recommended ratio of 1 unit of ‘green’ material to 20 units of brown material. In practice, however, it’s possible to monitor and assess this as you are going along. If the compost is looking wet and soggy then you need to add more brown material. It’s usually the browns that will be in deficit but this isn’t a problem because if extra is clearly needed you can add it at any stage and it will begin to improve the composting process from then on wards.
If you haven’t got the ratio mix anywhere near to where it should be, there will be a number of tell-tale signs. You will probably notice a sour smell and flies turning up from maggots that may have hatched from the compost. You can enhance your composting by simply adding hydrated lime. This will lower the acidity and encourage aerobic digestion which is what composting is all about.
Compost green brown list
There are two categories of waste that go together to make successful compost. These are the ‘greens’ and the browns. A basic identification list can be presented as follows:
For the ‘greens’ include lettuce leaves, cabbage leaves, potato peelings, carrot peelings, trimmings from any other fruit or vegetable that you can mention. Fruit or vegetables that are showing signs of ‘going off’, that is starting to go mouldy. You will often see fruit-flies around when this happens. The ‘greens’ category will also include left-over food which will include scrapings from plates after meals. In general any products that are food to us and, therefore, has the potential to go mouldy and rot, can be placed in the ‘greens’ category.
For the browns list, this is much more simple. If you have a regular supply of newspaper or cardboard then that’s all you need. Shredding the paper and ripping up the cardboard into small pieces will help with the mixing and general conversion into compost.
You can also add to this category dead-leaves which, ideally, should be chopped and sawdust if there is any going.
Remember that the process involves getting a balance between these ‘greens’ and browns. The rule-of-thumb is that you need to aim for 1 unit of ‘greens’ to 20 units of browns. As a general rule to make good compost always be ready to add extra from the browns list.
Is cardboard good for compost?
Cardboard is an ideal example of brown material. Rip it into small pieces and mix it into the forming compost. This is easy in a tumbler type composter. For a static bin you can either mix in cardboard pieces with each delivery of fresh waste or it may be more convenient to make thin layers. This will then gradually become incorporated with the rest of the compost over time.
Cardboard is one of the best sources of the, much needed, carbon that will balance the nitrates in the kitchen waste portion that we want to convert into compost. So when an empty cardboard box turns up, don’t throw it away to landfill. Just flatten it out and store it somewhere dry to be ripped up and used later.
What items can and cannot be composted and why?
Only items that are food to us and have the potential to go mouldy can be turned into compost. Microbial bacteria will feed on all foods, whether we want them to or not. This is why it’s a constant battle to preserve food items for us to eat rather than the, ever-attacking, range of moulds and mildews that would get it first if they could.
It is, however, highly convenient that there are these moulds, mildews and microbial bacteria around in the environment when it comes to making compost. They are everywhere, we will never get rid of them, the have always been a part of the planets natural ecosystem so we may as well make use of them.
There are some things that just won’t rot. If you put plastic wrappers into compost it will just sit there and do nothing. If there are worms in the compost they will make a good job of licking it ‘clean’ but they can’t consume it because the microbial bacteria can’t break it down and make it ready for them. Focusing on plastic, it’s worth noting that conventional plastics are, in the main, made from oil.
Whatever you may think about oil as a pollutant or not, we must be mindful that it is actually naturally occurring. It is also in the category of being organic, that is in the true unadulterated sense of the word. The definition of organic being carbon based and once living. This means that in the fullness of time plastics will break down but they won’t do so in the short time frame of making compost.
There are some modern plastics that are made from corn starch. These are being used, with considerable success, for making compostable plastic bags which line kitchen waste bins. This means that the bag with all the messy contents can be put in the compost bin without having to empty it. The bag and contents will rot down together.
It’s no good putting tin cans in compost, these are not compostable items. That is unless you want to allow 10 to 20 years for your compost to be made. Tin cans will rust and, in the acidic environment of forming-compost, they will rust quite quickly. It is possible for most steel based metals to rust completely away over time but this is not practical for an average 12 month time-frame for making compost from kitchen scraps.
Tea bags don’t appear to break down in compost, just the tea inside the bag. If you analyse compost when it’s ready to use you may have noticed empty tea bags. This, I have to say, came as a surprise to me because I always thought that tea bags are made of paper. The fact that they come out of a lengthy composting process very much intact suggests that they are made of something more durable. I suspect that there is a plastic element in there somewhere.
We have a post that looks at how to make compost from tea bags. See it at ‘Composting tea bags’.
What are some examples of composting?
There are three basic ways of making compost. The most basic of all is to make either a wire framed box or wooden box in the corner of the yard or garden. You then load it with waste from the kitchen until it’s full. Then just leave it to rot down over time. For this you will need at least two containers so that when one is full you can start filling the second and then, perhaps, a third. This is the long way of doing it and will suit some people.
Another way is to load the kitchen waste into a ready-made compost bin. These are uncomplicated plastic containers which have no base. You just put them down somewhere out of the way and start filling. The have an outlet door at the bottom of the bin. You won’t open this until the bin is almost full by which time the compost at the door should be fully formed. The idea of this is that as you remove compost through the door, the material above will drop down making more room for fresh waste to go in. This is an in-the-top and out-at-the-bottom system. If you have a lot of waste to dispose of it may be necessary to have more than one bin.
Then we have the compost tumblers. These will deliver a finished sample of compost much more quickly. The action of turning the barrel upside down opens up the compost and allows air into the mix. Composting is an aerobic digestion process. The microbial bacteria need all the oxygen that they can get. This process is not so suitable for worms because they don’t like being disturbed by the trauma of having their world turned over and over. So, what you can do is to empty out the tumbler barrel and load it into a static compost bin where the worms can get to work without being disturbed.
The main thing that you need to remember about compost tumblers is that there will come a time when you won’t be able to load in any more waste because it’s full. So, what do you do? You have two choices. Either get an extra tumbler and start loading it and carry on rotating the first tumbler until the composting process is complete or empty out the tumbler into a static bin and just leave it there to fully convert to compost in its own time.
Conventional compost tumblers can only manage one batch at a time. At the point of being full there will be a mix of waste that is fully converted to compost, fresh waste that hasn’t started to convert and every stage in between. This makes it awkward because the old material will be mixed with the new.
We have a post that compares static compost bins with compost tumblers. You can see it at ‘Tumbler composter vs bin’.
There is an alternative system of compost tumbler that completely removes this problem, it’s called the Rolypig. See more bellow.
The Rolypig needs brown material
The Rolypig composter is like no other tumbler style composter. It does not operate as a batch process. It’s an in-one-end and out-the-other system.
Feeding the Rolypig is easy to do but you still need to make an effort to get the balance right. If you just feed in ‘green’ waste and nothing else you will see all the signs of the acidic stagnation that this will lead to. There will be a foul smell and, in the summer months, there will be flies.
Adding brown material will balance this out. Ripped up pieces of cardboard and shredded paper will absorb a significant amount of surplus moisture. Removing the moisture will help to dry out the mass allowing air into the mix which will promote the composting process.
The Rolypig composter is a composting barrel that sits on the ground. The rotation is achieved by rolling it over. This only needs to happen when you feed waste. Rolling it over makes more room at the mouth-end as it moves towards the rear. Find out more about the Rolypig at Rolypig.com. Leaves are categorized as browns, see: how long does it take to compost leaves?