THE SCIENCE OF COMPOSTING: WHAT REALLY HAPPENS
Composting is a process that builds on and speeds up the natural decaying process of organic material. We can speed up the natural process by providing the ideal conditions for the beneficial microorganisms to break down the material. If you read our composting 101 blog, but you're still curious about the actual science behind composting, here is a summary.
Beneficial microorganisms, mostly aerobic bacterias in a compost bin, need 4 things to create their ideal environment so they can get to work munching through all those scraps in your compost. They need the right ratios of:
nitrogen
carbon
air
water
Nitrogen is provided by green matter, like kitchen scraps, weeds, grass clippings, garden trimmings, etc. Carbon is provided by dry and woody materials, like dried leaves, wood chips, or small branches and twigs. Air is introduced by turning or aerating your compost pile, and you may also need to add water to keep the compost moist.
With the right ratios of these key ingredients, bacteria can get to work on the 3 phases of composting and transform your pile of kitchen scraps and dried leaves into a beautiful nutrient-rich humusy soil.
THE STAGES OF COMPOST
There are 3 stages to the composting process: mesophilic, thermophilic, and maturation.
Mesophilic is the beginning stage, where the pile has started to build up a bit. In the first few days, mesophilic organisms begin to chow down on the organic materials in your compost pile, breaking them down into smaller pieces. In doing this work, they create heat which raises the temperature of the compost pile. They work best when the temperature in the compost is between 68-113ºF. The bacterias physically break down the biodegradable compounds; this creates heat and the temperature quickly rises to over 104ºF
In the second stage, when the temperature rises, thermophilic bacteria organisms take over and break down the organic matter into finer pieces. The higher temperatures during this period help to break down proteins, fats, and complex carbohydrates. This stage can last from a week to several months.
The higher temperatures in stage 2 are important but need to be managed. If the temperatures get too high (over 149ºF), it will kill all the microorganisms and basically stop the process. You can manage this by turning or aerating the compost. Aerating the compost and turning it keeps the temperature from getting too hot, and helps to provide essential oxygen for the microorganisms so they can keep working.
In the 3rd stage, maturation starts when thermophilic organisms have used up their supplies, and the temperature begins to come back down. Once it hits the range for mesophilic bacteria, they take over again and finish breaking everything down. This stage usually lasts for several months.
If you have the right balance of ingredients, the composting process can be pretty fast, delivering that black gold humusy soil in as little as 3 months. Without the right elements though, it can take much longer for everything to break down.
WHAT ARE THOSE MICROORGANISMS?
Most of the organisms found in compost are aerobic bacteria, which need a minimum of 5% oxygen to be effective.
Aerobic bacteria are the most efficient and important microorganisms for composting. They consume organic waste and excrete the chemicals that our plants need to live, like nitrogen, phosphorus, and magnesium.
Anaerobic bacteria are not as efficient, and they don't require oxygen to work. But, they can cause compost piles to stink since they release hydrogen sulfide, which smells like rotten eggs.
There are also fungi, molds, yeasts, critters like pill bugs, worms, and centipedes, which help break down organic matter. Some people add red wiggler worms to their compost, which can speed things up even more. These worms can tackle up to 10 pounds of food waste in a single day.
A COMMON COMPOST PROBLEM…
Most people who compost add their kitchen scraps, weeds, grass clippings, etc., as they are available. This means that the compost bin or pile is regularly getting green material, but often not enough brown matter. Compost needs a ratio of approximately 25:1 brown to green matter in order for the bacteria to function properly.
You can solve this problem by keeping a stockpile of brown matter to add to your compost pile. Brown matter includes any plant matter that has been thoroughly dried out. Things like fallen leaves, wood, branches from pruning, wood chips or bark mulch, cardboard, paper, hay, straw, or dried corn stalks. Anything large, like corn stalks or branches, will break down fastest if it is shredded or chipped first. Otherwise, large woody chunks can take up to two years to break down completely. Ideally, you should add a brown layer over every layer of green, to keep down flies and other unwanted bugs.
If you haven't started composting yet, what are you waiting for? Stop by the garden center and get yourself set up to start making your own black gold soil.