12 January 2011

composting 101

Photo: Akhila Vijayaraghavan © Mycompost heap .

This year I started a fresh batch of compost. I hadn't composted in about 4 months and was beginning to feel rather guilty about it. Once I started I remembered how totally easy it is. My compost bin is about 10 days old and it smells really really good. This might be a weird thing to say about garbage but a well-balanced compost heap really does smell like a forest.

Composting is confusing for many people and it is understandable but it really is easy. You literally need no special equipment - get started with a plastic crate or a big plastic bucket, with a lid. I repurposed a big plastic crate and covered it with a sheet of thick cardboard. You can also purchase composters like Daily Dump if you fancy but all you really need is something sturdy to put the compost into.

I started with a whole bunch of pea pods, dead New Year roses, banana peels and egg shells on Day 1. Gradually I added vegetable peelings, orange and lime rinds, more egg shells, coconut shells (broken into smaller pieces), corn cobs, corn husks, tea leaves, spinach stems etc. Then I added in sawdust - what I'm trying to do here is to add an equal mix of 'green' and 'brown' matter. You can also add grass clipping, leaves, wood shavings, torn pieces of paper, coffee grounds etc.

As I've mentioned before but will also say here. Composting organisms require four equally important things to work effectively:

  • Carbon ("C" or carbohydrates), for energy - the microbial oxidation of carbon produces the heat. High carbon materials tend to be brown and dry.
  • Nitrogen ("N" or protein), to grow and reproduce more organisms to oxidize the carbon. High nitrogen materials tend to be green (or colorful, like fruits and vegetables) and wet.
  • Oxygen, for oxidizing the carbon, the decomposition process.
  • Water, in the right amounts to maintain activity without causing anaerobic conditions.
So in order to ensure that all these criteria are met in addition to ensuring that your heap is properly balanced. You also would need to stir it everyday to ensure aeration. The pile should not be too wet or too dry - it should have the moisture content of a wrung out sponge. Avoid putting in rotten food, cooked leftover food especially it if contains spices, meat, fat, grease, oil and your heap will be fine.

As you can see from my picture - the older food has already started to compost - the corn husks and onion peels are relatively fresh. It takes about 3 months for the pile to be fully composted. If your pile starts smelling like the forest you know you are on the right track! And as long as you avoid the few "dont's" it most likely will.

The reason why garbage heaps smell is because anaerobic respiration takes place. A compost heap uses aerobic respiration and apart from attracting fruit flies, which are a normal part of the process it does not attract house flies, maggots, worms, cockroaches, rats and other critters. These will appear only if you add meat to your heap (egg shells are fine).

Now that you know that composting is easy as pie, get started and keep me posted on your progress as I would love to know!