Compost is organic material that is added to soil to help nurture the plants, enhance the moisture retention capability of the soil and assist with the plant growth. Food scraps and yard waste together currently make up more than 28% of what we throw away, and should be composted instead. Making compost keeps these materials out of landfills where they take up space and release methane, a potent greenhouse gas. Thus, composting also forms an essential part of circular economy.
There are primarily 3 components to making nutrient rich compost. They are:
Browns: dry leaves, fallen branches, twigs, coffee grounds etc. These components provide carbon.
Greens: grass clippings, vegetable waste, fruit scraps, etc. These components provide nitrogen
Blue: water to encourage the growth of friendly bacteria and fungi that consume all the browns and greens and converts them into humus.
A common practice is to use the browns and greens in equal proportions with layers varying as per size of the components.
Composting is easy, and with several options available. You’ll want to pick a method based on your needs and the space available. Below we describe each approach in detail along with its pros and cons to help pick the one which is best for you.
Cold composting: The method is best for people who have patience and have very limited space for composting. This approach requires a bin (as shown on the right) which can be covered with a lid to let the compost form in its own time. Often the bins are made from recycled plastic and come in various shapes and sizes to suit the varying space limitations. The table below summarizes the pros and cons of this approach:
Covered lid means no foul odor
Containers only hold fixed volume of material
Bottom less design so compost directly falls on the ground
Extracting compost and turning it is hard. Usually the compost falls off the bottom but the ground clearance is about a foot from soil.
Compact size suitable for space constrained farms
Compost output very slow- six months to one year duration
Overview of cold composting
One potential solution to ease the challenge of being able to turn the compost material is to use a tumbler. This could either be made in-house or purchased from the commercial suppliers who use recycled plastic barrels to better house the material. This is a cheap fix for the problem but still comes with a fixed volume constraint.
If the foul odor is your biggest nemesis and you are not in a rush to get the compost just yet, you can always try pit composting wherein you simply dig a pit in your backyard, throw in the material you like to compost and just sit back and relax. No odor and no fuss. It costs you literally nothing (except for a few drops of sweat while digging the pit once) but it can very well take between six months- one year to yield the compost as it is a cold composting method after all.
Hot composting: For the farmers who like to churn out compost batch after batch at fast pace, this method is optimal. The key aspect here is to control microbial activity such that they churn out compost in much shorter time frames. The “hot” refers to the fact that you would like to heat up the compost pile to facilitate the process which means you need to keep an eye out for the soil temperature and moisture content. Too hot and it may simply kill the microbes. Additionally, the size of the compost pile also makes a difference whether or not you will succeed with this approach. A general rule of thumb, is to make a four feet wide by four feet high pit or wooden frame. Usually, it is advisable to align a few of such bins next to each other such that one bin can be used for fresh raw material to begin composting, the intermediate bin(s) can be used to keep the cycle run and the last of the bins can be used to store the fresh compost ready to be utilized. The table below summarizes the pros and cons of this approach:
Easy to construct
Open composting approach might attract flies or release foul odor
Varies per setup size
Cost increases depending on scale of setup
Easy to turn and harvest compost
Scalable depending on space constraints
Overview of hot composting
Vermicomposting: This method yields compost faster than hot composting and harness the power of red worms. These worms can eat about half their body weight per day speeding up the composting process. The process is simply worms eating the food and excreting humus which is essentially the nutrient-rich compost. The infrastructure is quite simple- some people use moistened bedding material to bury the material for worms to feed on while others use composting beds. The table below summarizes the pros and cons of this approach:
Less manual labor to setup
Moist bedding can attract flies
Works in all weather conditions
Need to prevent overfeeding. If this happens, there will be foul odor, the compost will become acidic, and possibly kills the worms
Works indoors/ small spaces / covered outdoors
Unlike hot composting, the temperatures here are moderate so pathogens can bloom easily with the moisture
No need to turn the pile. Worms naturally aerate the compost stack
Overview of vermicomposting
Bokashi composting: Unlike the aforementioned composting methods, this Japanese methodology ferments the organic matter. To achieve optimal results, the raw materials are inoculated with a microbial starter culture, and placed inside a sealed container. These starter cultures consist of several different species of microorganisms, all of which thrive in anaerobic conditions and churn out compost in as little as eight weeks. The table below summarizes the pros and cons of this approach:
Takes very little space so can even be done inside an apartment
Once fully fermented, the material needs to be buried in the soil. Not always accessible, e.g., for apartment dwellers or during winters when it snows
Considerably shorter process time
Fermented material has high acidity so cannot be used for plants directly. The acidity gets neutralized quickly once buried in the soil but burial is a must.
Odor less composting method
Bokashi Bran required to start the process is hard to be made at home and is going to be a recurring cost for the process
Overview of bokashi composting
Word of caution
Not everything that glitters is gold and not everything organic is compostable. Below you will find a list of few of the items that you should not mix in the compost with reasoning.
Dairy products should not be added to compost material as this will release foul odor and attract pests
Disease or insect infested plants must not be added in the composting material. The insects might survive or the disease might get transferred via compost to the plants where the compost will be used later.
Fats, greases and other similar oils should not be mixed
Yard trimmings treated with chemical pesticides should also be kept away and treated separately
With this we hope you have a deeper and intuitive insight into various composting practices and will be able to pick the method or a combination thereof that best suits your needs. Happy gardening!!