From Waste to Black Gold: A Beginner’s Guide to Composting for a Greener Planet!
Composting is nature’s way of recycling — transforming everyday waste into rich, nutrient-packed compost that fuels a greener planet and showcases the power of the circular economy.
Why do people compost?
Globally, almost half (44%) of the municipal solid waste comes from food and green waste [1][2][3]. High-income countries generate relatively less food and green waste (32%), compared to middle and low-income countries which stood at 53% and 57% respectively [1][2][3].
When organic matter decomposes in a landfill, it does not have access to oxygen and hence decomposes anaerobically. When this happens, it produces greenhouse gases (majorly methane), which escape the landfill and accumulate in the atmosphere. This contributes to the already existing greenhouse gas emissions in the atmosphere, contributing to global warming. According to the World Bank, waste contributes to 18% of all human-driven methane emissions[4].
To put this into perspective, in the US alone, the methane emissions from landfills in 2021 was the third largest emitter of methane emissions in the US. This is equivalent to GHG emissions from ~23 million gasoline powered passenger vehicles driven for one year[5].
Composting mimics how food decomposes in nature. It allows organic matter to decompose aerobically. Thus, composting reduces the waste being sent to the landfills and also reduces the GHG emissions from methane.
What is Composting?
Composting is a natural process of converting organic matter, like food scraps, coffee grounds, and dry leaves, into valuable fertilizer. It is a sustainable waste management practice that upcycles organic waste into a nutrient-rich manure. Compost is the name given to the final decomposed manure. It is also called “black gold” due to its colour and the value it brings to both the soil and plants. It is a 100% organic fertilizer containing important nutrients and trace minerals, vital for plant growth while simultaneously improving soil quality.
Composting accelerates the natural decomposition process by controlling the environment to promote microbial growth that ultimately do the heavy lifting. Adding compost to the soil adds to the organic content of the soil. It facilitates the slow release of nutrients over a few days to years for subsequent utilization by crops, thus improving the soil quality.
Benefits of Composting
1. Composting reduces waste
If food waste is composted, it reduces the amount of waste being sent to landfills. It directly reduces the amount of space and fees a city or town may pay for garbage disposal. Composting at home helps redirect some of the waste from the landfills and turns it into a valuable, usable product for gardens.
If you are someone who owns a farm, there is even more incentive to invest in composting as agricultural waste and herbivore manure can all be recycled back into the soil, making it richer and more nutrient-dense for your next crop.
2. Reduces GHG emissions and leachate.
When organic matter decomposes naturally, it undergoes aerobic decomposition. It is broken down by micro-organisms that utilize oxygen. In landfills, due to sheer volume of waste, compostable waste gets buried under. This cuts off the optimum oxygen supply, making them undergo anaerobic decomposition, where biogas is created as a by-product. It is also called “landfill gas”. This is majorly made up of methane and carbon dioxide, both of which are greenhouse gases. Methane is more effective than CO2 at trapping heat in the atmosphere, causing even more damage. Landfills generate a lot of methane (in the US alone, they are the third largest emitter of methane [5]).
3. It improves plant growth without chemical fertilizer & pesticide.
Plants that grow in soils where compost has been added produced higher biomass[6]. Several studies have shown that compost has the capacity to suppress plant diseases[7] and pests [8]. This eliminates or reduces the need for chemical pesticides and fertilizers, while promoting higher yields[9].
4. Improves soil health
Compost has been studied and has been known to improve soil quality and productivity. It is also important in sustainable agricultural practices as it replenishes the organic matter and nutrients in the soil. Compost has been known to increase soil nutrient availability, plant growth and nutrient uptake[10]. It also has the capacity to regenerate poor soil. Composting feeds diverse life in the soil. The bacteria, insects and earthworms present in compost promote better soil health and support a prolific soil ecosystem.
5. Prevents soil erosion and increases soil moisture
Compost has been shown to prevent soil erosion due to its ability to increase infiltration of water and slow it down, binding soil together [11] and reducing the effect of stormwater runoffs. This prevents pollutants from stormwater runoffs from leaching into surface water resources.
6. Recycles nutrients back to soil
By bringing nutrients back to the soil, composting is a good example of a circular economy. The carbon, nitrogen and other nutrient contents from bio-waste are converted to organic fertilizers for the soil.
Do’s & Don’ts of Composting
Composting requires a balance of carbon and nitrogen along with water and oxygen. The two types of organics, the “greens” and the “browns” are both required to make compost. The greens are materials rich in nitrogen (and generally are wet materials) while the browns are material that is rich in carbon (and generally are dry materials). Very large particle sizes slow down the composting process [12]. So, they need to be broken down into smaller pieces (for example, large twigs, big pieces of cardboard and more).
What to add to a compost pile
Greens: Vegetable scraps, Fruit scraps, spent coffee grounds and tea leaves, flowers, bread, pasta, rice, seaweed, grass clippings, crushed eggshells, manure from cows, goats or another herbivore[13][14].
Browns: Dried leaves, shredded paper, newspaper, brown bags, egg cartons and cardboard, twigs, straw, untreated wood chips[13][14].
What not to add to a compost pile
A few things to avoid adding to your compost pile are mentioned below [13][14].
· Meat, fish, and bones
· Dairy products
· Eggs (eggshells are good when crushed; the white and the yolk are a strict no)
· Oil, butter, and animal fat
· Plants treated with chemical fertilizer/pesticides
· Naturally toxic plants
· Disease or insect infested plants
· Large pieces of yard trimmings (needs to be broken down)
· Treated wood or painted wood
· Pet waste
· Stickers and glossy paper
· Dryer lint
Composting at home
1. Select your feedstock!
Your feedstock needs to contain a balance of the “greens” and “browns” as mentioned above. So, you can start with your fruit and vegetable scraps — this can include the peels, vegetable tops, bits of fruits and vegetable that weren’t used for cooking. You can add crushed eggshells, spent coffee grounds, tea leaves and old dried flowers to the list. Do avoid compostable bags and wipes as they need industrial facilities for complete decomposition and may throw off your home compost pile. For your browns pick any from the list mentioned above — egg cartons, milk cartons need to be shredded before adding to your pile.
2. Store your greens and browns
Collect and store your greens and browns separately. The “greens” can be stored in a closed container under your sink, in your balcony, inside the fridge or freezer. The “browns” as they are mostly dry can be stored outside in the yard or balcony without worrying about rodents.
3. Find space for your compost pile and buy a bin
Depending on your space availability, you can either choose some space in your yard and buy a bin or buy a vermicompost bin (many started kits are available) if you live in an apartment and have limited space for composting. Bins can be made of wood, cinder blocks, earthenware or in some cases even plastic. Choose one that is suitable for your scenario. Ensure that there is a water source near your compost pile and has good drainage.
4. Prepare your compost ingredients
It is important to break down bigger pieces of your ingredients into smaller pieces before adding them to the compost pile. Larger pieces slow down the composting process, while smaller pieces breakdown faster.
5. Build your pile (layering)
First add twigs and straw first, for the first few inches. This helps with drainage and also allows air circulation at the base of the pile. Next, add your “greens” and “browns” alternately. For optimum composting, the right proposition of ingredients needs to be in the pile. A ratio of Carbon: Nitrogen (C:N) of 30:1 is considered ideal for composting [12][15]. From a practical standpoint, it can be considered as 30 parts carbon for each part of nitrogen by weight. You can choose to calculate the C:N ratio of your pile or just estimate by using a combination of “greens” and “browns”. The common C:N ratios of materials can be found here[16] (page 106). Do keep in mind that you should cover the “greens” with a generous layer of “browns” to keep the odour away. You can add some water to the pile to keep it moist and soil to add some microorganisms and to keep the odour at bay.
6. Maintain conditions (temperature, moisture, air flow, etc)
As the organics in your pile start decomposing, the temperature will start increasing. This also helps keeping harmful pathogens and weeds at bay. To improve aeration and speed up decomposition, you can turn and mix the compost pile at frequent intervals.
a. Dry pile: If your pile is too dry, decomposition may slow down and stop altogether. As counter measure, add some moisture or “greens” to your pile and turn it.
b. Wet, smelly pile: If your pile is too wet, it is water-logged or too dense. Your microorganisms may not get enough oxygen and might start giving off a bad odour. This means that your pile needs more air circulation. You can add more “browns” to your pile and turn it.
7. Harvest black gold (final compost)
The final compost will be crumbly, loose, and dark. It smells very earthy and like fresh soil. Most of the ingredients will be decomposed. In case there are pieces that are not yet decomposed like twigs or eggshells as they take longer, you can filter them out from the rest of the compost before use. These pieces can be added to your next compost pile. Use the freshly harvested compost back in your garden and your plants will thank you for it!
Compost indoors or outdoors at home, depending on the availability of space and the amount of organic matter you generate. Vermicomposting is generally preferred if there is a lack of space and the equipment required changes accordingly. If you have yard space, go with backyard composting and trust me, you will not look back.
Happy composting!
References
[1] Trends in Solid Waste Management, The World Bank []
[2]
[3] Global Generation of Municipal Solid Waste, Statista []
[4] World Bank Steps Up Efforts to Address Methane Emissions, World Bank Factsheets, 2023 []
[5]
[6]
[7]
[8]
[9]
[10]
[11]
[12]
[13]
[14]
[15] Cornell Composting, Cornell Waste Management Institute, 1996 []
[16] On Farm Composting Handbook, Northeast Regional Agricultural Engineering Service (NREAS), 1992 []
