Composting is a controlled and accelerated rotting down of organic matter into nutrient rich compost. Aerobic Composting uses the natural processes of rotting and decay by microorganisms in the presence of oxygen and produces heat and hence it is sometimes called hot pile composting. Whereas Anaerobic or Bokashi composting is the job done mainly by microorganisms in the absence of air which is more like fermentation process.
Aerobic Composting requires 4 things: Carbon, Nitrogen, Oxygen and Water in just the right amount for proper composting. Out of these, we need to provide Carbon and Nitrogen in the right ratio, what is known as the C:N ration or Carbon Nitrogen Ratio. Things that are rich in Carbon are called the Browns and those that are rich in Nitrogen are known as the Greens.
To be correctly composted, a material needs to have the following two important characteristics: 1. The waste material must be organic and biodegradable.
2. The waste material must contain things that are liked by micro-organisms to feed on.
So what types of waste can we can use in aerobic composting method. Firstly, let’s start with what we should NOT put onto our compost bin or compost heap. So let lists the Don’t’s First:
- Glass, metal and plastics are obviously prohibited in both types of composting.
- Oil, fat, meat, fish or dairy products are avoided because of their tendency to attract insects like flies and rodents. But these products are allowed in Bokashi composting.
- Hard woody branches, stems or roots which take a very long time to decompose.
- Rubber bands, Latex condoms, diapers and other obvious stuff like metallic objects like for example safety pins.
Having looked at the things to be avoided, now let’s look at what we can add, and there are literally thousands to choose from. The micro-organisms and even macro-organisms like earthworms need to have a balanced diet and just like animals or humans they need “energy” in the form of food to survive. This energy is supplied to them by carbohydrates which contain Carbon. But micro-organisms also need proteins in the form of Nitrogen and also Phosphorus. Aerobic composting works best if these organisms are fed a mixture of carbon rich materials known commonly as “Browns” and nitrogen rich materials known commonly as “Greens” in proper ratios.
Let’s List the Browns First: Browns are mostly dried woody materials which are high in carbon. Without the browns your greens will decompose too quickly and turn into a smelly pile – that’s called putrified pile. Here’s the List of Browns:
like dry fallen leaves, dried flowers, wood chips, twigs, straw, shredded paper, shredded card board or paper cartons, like this and also the toilet paper rolls, toilet paper or used napkins or facial tissues, coffee filters and tea bags, cotton, sawdust, pine needles, Pencil Shavings, dried grass clippings, peat moss, cocopeat or coconut fibers, used paper plates, nut shells, wine corks, toothpicks, paper cupcakes, used match sticks, wood ash or ashes from the fireplace, coal, etc.
Now Let’s List the Greens: Greens are mostly wet materials like waste kitchen scraps mostly vegetables scraps, fruit scraps, fresh grass cuttings, animal manure but not your cat or dog poop, bird or poultry droppings and feathers, fleshy plants and leaves, flowers, tea and coffee waste, egg shells, nail clippings (if no nail polish), human and animal hair, etc.
Having said that, now lets look at the Greens Vs Browns Ratio and the Carbon:Nitrogen Ratio. The right mixture of greens and browns, known commonly in the gardening world as the Carbon-to-Nitrogen ratio or C/N ratio, is important for proper composting. We want Composting and not Putrefaction or rotting.
So what is the ideal C/N ratio for an aerobic composting? Most experts suggest a CN ratio of 25 to 30:1, which means 25 to 30 parts carbon rich material to 1 part nitrogen rich material. High Carbon may result in too slow composting whereas high nitrogen may result in foul smelling putrefaction.
HOW TO USE THE C:N RATIO? Do not misinterpret this CN ration! This ratio describes the chemical composition of a material and does not mean that you need a volume of brown materials that is thirty times greater than the amount of green matter! Don’t make this mistake! Here comes the Green to Brown Ration to our rescue. You have to understand this carefully. The Ideal Green to Brown Ration is 2:1 but it can also be 1:1 for those who are starting to compost. This means for one bowl of greens, you can add one bowl of browns. Let me explain this. Every material has its own C:N ratio, like for example Food Scraps has a Carbon:Nitrogen Ratio of 17:1, meaning 17 parts Carbon to 1 part Nitrogen). Saw dust has very high C:N ration of 500:1. Hence this calculation depends on what you add to your compost bin and it gets more and more complicated. You can store this table for reference of C:N values of various materials.
For Ideal Composting – Do Remember these 2 Golden Tips:
- A 2-to-1 ratio of Greens to Browns is your best bet when creating a Batch Pile. This will aid you in creating about a 30:1 C/N Ratio. Adequate enough to get a hot pile.
- A 1-to-1 Ratio works well with the Add as You Go Pile as well as for the Batch Pile and is safe for beginners. This will aid you in creating about a 50:1 C/N Ratio, adequate enough to get a warm pile.
In our Next posts of this composting series, we will demonstrate how to do Aerobic and Anaerobic or Bokashi composting at home.
WHAT IS COMPOSTING?
Composting is a natural process of breakdown or decomposition of various organic materials otherwise regarded as waste products and finally produces a nutrient rich product which is known as the compost.
WHY SHOULD YOU COMPOST?
Most of the solid wastes in our cities comprises of our yard waste and kitchen or food waste. By composting or recycling these items, it makes it possible to reduce the overall amount of waste being sent to landfills and mass-burn incinerators. The final compost, is nutrient-rich and can be used to amend poor soils and fertilize gardens instead of using chemical fertilizers which are hazardous to all organisms on earth.
TYPES OF COMPOSTING:
There are three types: aerobic, anaerobic (like Bokashi’s composting), and vermicomposting. Each one has its own pros and cons.
- AEROBIC COMPOSTING: In aerobic composting method, air or oxygen is introduced to help break down organic materials. The composting pile needs to be turned for aeration every other day. This can accomplished by using a fork tool or using a tumble style or barrel composter. We will discuss and demonstrate how to easily do aerobic and also anaerobic or bokashi’s composting later, after we discuss some fundamental concepts of composting.
- ANAEROBIC COMPOSTING: This is exactly opposite of aerobic composting. Actually some do not include this in composting and rather call it a fermenting process. Japanese method called Bokashi composting is the best example of anaerobic composting. Anaerobic composting takes almost no effort at all. Just add scraps into the composter, and leave it air tight for many days. Many people think Anaerobic composting stinks like hell but this is not true if done properly and this can be avoided with the use of Bokashi method which we will demonstrate and discuss later.
- VERMICOMPOSTING: Vermicomposting uses earthworms, oxygen and moisture to safely break down organic material with very less odours. Basically, worms do most of the job along with the bacteria. This method is the most preferred method due to its many advantages.
FUNDAMENTALS & REQUIREMENTS FOR COMPOSTING:
These basics are really important and please do not skip these points.
Well, Composting requires the following three components: 1. human management, 2. aerobic conditions, and 3. development of internal biological heat. Composting Process by organisms require four equally important components to work effectively:
- Carbon — for energy. And the microbial oxidation of carbon produces the heat. High carbon materials to be added to compost bin are generally brown and dry stuff like dried leaves, twigs, saw dust, charcoal and so on. We will discuss on the materials that can be added and those prohibited in the later episodes of this composting series. Well, the second ingredient is
- Nitrogen — which is essential to grow and reproduce more organisms to oxidize the carbon. High nitrogen materials generally tend to be green like the wet scrap from your kitchen like fruits and vegetables. We will also discuss on the importance of Carbon:Nitrogen ratio later on.
- Oxygen — for oxidizing the carbon and for the decomposition process. This is supplied by good aeration of the bin and also by turning the compost pile every other day.
- Water — All life needs water – that’s for the microorganisms and also the earthworms if you are vermicomposting. And Water in the right amounts is very important for decomposition process and to keep the temperature regulated. Too much or too little water is bad for composting.
The Composting microorganisms are introduced into the pile to start the process of decomposition by either adding a good quality garden soil or a manure like vermicompost or even cowdung manure. You also have many commercially available compost makers for this job.
Well, In our next postswe will list out the materials that can be added and those that are prohibited along with the some basics on the C:N or the Carbon:Nitrogen Ratio. Then we will demonstrate easy methods for both aerobic and Bokashi composting methods for home gardening.