Echoing Green Earth

Composting was such an alien concept to me before. I literally had zero knowledge of how it works. Living in the city with a busy lifestyle that was completely detached from nature, my interaction with the natural world was nothing more than taking occasional walks. Food scraps were mindlessly collected in the food waste bin, and my living experience was scattered with pieces of fractional processes.

It was only during the pandemic, when we were all forced to re-examine our lives and our relationship with nature, that I started my home composting journey. This Home Composting Series is where I'll share with you my journey and the knowledge I've picked up along the way. We'll also explore areas that I'm not well-versed with but have learned from other people's knowledge and experiences.

So let's start at the beginning - understanding what actually happens in a compost pile.

I always wondered what actually happens when I toss kitchen scraps and garden waste into a compost pile and how they turn out to be compost. The transformation from banana peels and coffee grounds to rich, dark soil isn't just a happy accident—it's fascinating science at work. If you haven't had a chance to witness this transformation firsthand, you're in for a treat today. Let's peek into the wonderful world of nature's recycling system together. Understanding the 'why' behind home composting not only fascinates but also helps you master the 'how' with confidence.

The Biological Magic of Decomposition

Home composting is a natural aerobic process—meaning it requires oxygen—where microorganisms break down organic matter into simpler compounds. As these microbes (bacteria, fungi, and other tiny decomposers) consume your organic waste, they produce carbon dioxide, water, heat, and eventually, humus—the dark, stable organic material that makes garden soil rich and fertile.

What makes home composting truly remarkable isn't just the chemistry—it's the invisible ecosystem you're creating. When you build a compost pile, you're actually constructing a habitat for billions of organisms that form what scientists call the "compost microbiome." This living community includes:

Bacteria by the billions, including specialized heat-loving (thermophilic) species that can survive temperatures up to 77°C (170°F)
Fungi that extend microscopic threads throughout your pile, breaking down tough materials like lignin (the woody, structural component that gives plants rigidity) that bacteria can't digest
Protozoa that graze on bacteria, releasing stored nutrients
Nematodes and microarthropods that shred materials and prey on other microbes
Actinomycetes that give finished compost its earthy, forest-like smell

Together, these organisms function as a single digestive system, consuming your kitchen scraps and garden waste. Amazingly, you don't need to add these creatures—they're already present on the materials or in the air around us, just waiting for the right conditions to flourish, despite being so tiny that you cannot see them.

Your Compost Pet: The Living Digestive System in Your Garden

One of the most helpful ways to understand home composting is to think of your compost pile as a pet you're raising—a living creature with specific needs that rewards you with valuable "black gold" when properly cared for. (Our pet Pedro, the retired racing greyhound, inspired me with this analogy. As a dog owner, I learned to understand his needs through countless subtle hints and behaviors—a skill that transfers surprisingly well to compost care! Fellow pet owners will understand what I mean here.)

This isn't just a cute analogy—it's scientifically accurate! Your compost pile functions as a collective organism with its own digestive system:

Feeding Your Pet (Biomass Input): Your compost pet needs a balanced diet of "greens" (nitrogen-rich materials) for energy and "browns" (carbon-rich materials) for structure and air flow. More on this in the later section of this post.
Digestion Process (Decomposition): Your pet's "digestive system" (the billions of microorganisms) breaks down this food, generating heat as a byproduct—that's why healthy compost piles feel warm!
Pet "Poop" (Humus Output): After digestion, what remains is essentially the waste product of your compost pet—humus-rich compost that's been completely transformed by passing through the digestive systems of countless microbes.

Like any pet, your compost needs proper care: adequate moisture (not too wet or dry), fresh air (oxygen), and the right diet. When your compost pet is happy and healthy, it generates heat, has a pleasant earthy smell, and efficiently transforms your kitchen scraps into garden gold. (Check out our playful post if you are new to composting: "Gamify Composting: Becoming The Black Gold Tycoon".)

This decomposition journey happens in distinct stages:

Mesophilic Phase: When you first add materials to your home compost, moderate-temperature loving bacteria (mesophiles) begin the breakdown process. Your pile will feel slightly warm as they get to work.
Thermophilic Phase: As decomposition accelerates, heat-loving bacteria take over, pushing temperatures to 50–60°C (122–140°F). This natural heating is crucial—when your compost maintains about 55°C for at least three consecutive days, many pathogens and weed seeds are destroyed. That's why a hot compost pile is self-sterilizing!
Cooling and Maturation Phase: Eventually, the pile cools as easily digestible materials are consumed. In this final phase, the compost stabilizes and matures into a nutrient-rich soil amendment.

Throughout this entire process, microbes use carbon as their energy source and nitrogen to build proteins—essentially constructing their bodies, reproducing, and producing enzymes—as they transform your waste materials into compost.

The end result of all this biological activity isn't just decomposed organic matter—it's humus, a special substance that exists nowhere in nature except as the end product of decomposition. Unlike simple "rotted" materials, humus has been processed through the digestive systems of countless microorganisms, creating complex organic compounds that:

Hold water like a sponge, increasing soil's drought resistance
Bind to nutrients, preventing them from washing away
Form soil aggregates that create ideal pore spaces for roots
Suppress certain plant diseases through beneficial microbes
Release nutrients slowly over time, feeding plants for months or years

In essence, what you're creating in your home compost bin is more than just broken-down waste—it's the biological engine that powers healthy soil and, by extension, healthy plants.

Humus vs Compost: Understanding the Difference

Many people use the terms "humus" and "compost" interchangeably, but they're not quite the same thing:

Compost is the entire end product of your home composting process. It contains:

Humus (the stable, complex compounds)
Some partially decomposed materials still breaking down
Beneficial microorganisms
Minerals and nutrients in various forms
Occasionally small bits of recognizable materials (tiny wood pieces, eggshell fragments)

Humus is specifically the dark, fully decomposed portion of compost—the stable organic compounds that have been completely processed by microorganisms. It's the most valuable component of compost, responsible for many of its soil-improving properties.

Think of it this way: all humus comes from composting (either in your bin or in nature's slower processes), but not all compost is fully humus. Finished compost contains humus along with other beneficial components. So, next time, when you see an instruction to add humus-rich compost for the plants, you'll understand what it means.

Carbon-to-Nitrogen Ratio: The Critical Balance

If you've ever heard composters talk about "browns" and "greens," they're referring to the all-important carbon-to-nitrogen balance. Now, let's talk about food for your garden compost pet! This ratio (how you mix the pet food your compost pet will like) is the secret to efficient composting, both shortening the time it takes and the result of the compost.

The ideal overall C:N ratio is about 30:1 (30 parts carbon to 1 part nitrogen by weight). But since most of us don't weigh our compost ingredients, a practical approach is to aim for roughly 2-3 parts browns to 1 part greens by volume in your home compost bin. I personally got confused with all these numbers at the beginning of my composting journey but soon realised that measuring by volume is an easier way to get my head around this.

Browns (Carbon-Rich Materials): Generally speaking, the browns have the characteristics of being dry, structural and harder to break down into smaller sizes when you try:

Dry leaves
Cardboard and paper
Straw and hay
Wood chips and sawdust
Dried grass clippings
Pine needles

Greens (Nitrogen-Rich Materials): Generally speaking, the greens are those with moisture, fresh and easy to crush/cut/separate into smaller sizes or lumps when you try

Fresh fruit and vegetable scraps
Coffee grounds
Fresh grass clippings
Plant trimmings
Manure from herbivores (animals that eat only plants, such as rabbits, horses, chickens, cows, sheep, and goats)
Eggshells

This balance is what your microbiome likes most. Carbon materials are the energy source (the carbohydrates) for your microbial workforce, while nitrogen provides the protein-building blocks they need to reproduce and create enzymes. When you maintain the right balance, you're essentially creating the perfect diet for your decomposer community.

When your home compost has too much nitrogen (too many greens), you'll know it—excess nitrogen converts to ammonia gas, creating that unpleasant, pungent smell. If this happens, simply add more browns to restore balance.

Conversely, if your pile has too much carbon (too many browns), decomposition slows dramatically due to nitrogen scarcity. The pile stays cool and dry, barely seems to change. The remedy? Add nitrogen-rich materials or even a small amount of organic fertiliser.

As home composting progresses, the C:N ratio naturally drops to about 10–15:1 in finished compost because much of the carbon is metabolised into CO₂. This lower ratio is perfect for garden soil, providing accessible nutrients without tying up soil nitrogen.

Home vs. Industrial Composting: Understanding the Difference

Nowadays, many products labelled "compostable" are actually designed for industrial or commercial composting facilities, not home compost systems. This creates confusion for environmentally-conscious consumers. Understanding the key differences between home and industrial composting is essential for making informed choices about what will truly break down in your backyard bin.

Temperature Management

Home compost piles typically reach moderate temperatures of 30-45°C (86-113°F) during active phases. Well-built piles might occasionally peak at 50-60°C (122-140°F) but rarely maintain those high temperatures consistently.

Industrial composting facilities carefully manage airflow, moisture, and pile size to achieve and sustain temperatures up to 65°C (150°F). These higher temperatures dramatically speed decomposition and enable the breakdown of tougher materials.

Different Environments, Different Capabilities

In your backyard compost, nature works at its own pace. All organic materials will eventually break down, but home systems typically operate at more modest temperatures (30-45°C) compared to their industrial counterparts. This temperature difference becomes crucial when considering what to add to your pile.

Any organic materials from your garden and kitchen are compostable - they'll decompose eventually in any system. However, in a home setup, meat scraps, bones, dairy products, and oily foods might decompose more slowly and may attract wildlife visitors during their extended breakdown period. This is something to take note if you are composting them in your compost pile.

This temperature distinction becomes especially important when considering those man-made "compostable" products on store shelves. Many items labelled "compostable" - particularly bioplastics like PLA (polylactic acid derived from plant starches) - are specifically engineered to break down ONLY under sustained industrial conditions (60+°C with carefully managed humidity). In your backyard heap, these materials often remain stubbornly intact, creating confusion and disappointment for people like us.

The takeaway? Feed your home composting system with natural materials, but those man-made "compostable" cups, utensils and packaging typically need industrial composting systems with their hotter, more controlled environments to fulfil their environmental promises unless "home compostable" certifications are there. The problem is, most of us don't have access to an industrial composting facility. What does that mean? The correct way to dispose of these items is to throw them into your general waste bin. Our current waste system can only either incinerate them or bury them in the landfill (Where they'll take a century to break down! You got the picture.)

Processing Timeline

Home composting is relatively slow—a properly maintained pile might produce finished compost in 3-6 months, while a naturally-tended / hands-off pile could take a year or more.

Industrial operations can complete a batch in just a few weeks by optimising all conditions.

Both home and industrial composting turn waste into soil, but industrial facilities operate under stricter controls and more precisely managed conditions, allowing them to process a broader range of materials more quickly. Home composting requires a bit more patience and careful ingredient management—but the results are just as valuable for your garden.

Why Should You Compost at Home?

At Echoing Green Earth, we believe home composting is more than just a gardening practice—it's a cornerstone of sustainable living and a powerful solution to our household waste crisis. When you consider that up to 80% of typical household waste could potentially be managed at home rather than sent "away" to the landfills, composting becomes not just a hobby but a meaningful environmental action.

The benefits of bringing home composting into your life are remarkable:

Reduces household waste by up to 30% – keeping organic material out of the landfills where it produces methane, a potent greenhouse gas
Closes the loop in your personal ecosystem – transforming what was once considered "waste" into a valuable resource
Maximise the value for what you paid for - did you know that you paid for that 'waste' part too?!
Reconnects us with natural cycles – restoring our understanding of nature's perfect recycling system and improving soil structure, helping it retain moisture and nutrients while supporting beneficial microorganisms
Creates nutrient-rich soil amendment for free, improving garden compost productivity
Empowers personal action – providing a tangible way to address environmental challenges through daily choices
Builds environmental awareness – helping family members understand decomposition and natural processes

When we rethink what we consider "rubbish," we begin to see kitchen scraps, yard trimmings, and even certain household items not as waste to be disposed of, but as resources in transition. This shift in perspective is at the heart of true sustainability—seeing the potential in materials to return to the earth and nourish new life and through this practice, involving ourselves in our activities within this eco rhythm and reconnecting ourselves to nature.

Every kilogram of food waste we compost at home instead of sending to the landfill prevents the equivalent of about 1.3 kg of CO₂ emissions. It's one of the simplest yet most impactful environmental actions we all can take.

By embracing home composting, we're not just making better soil—we're participating in a quiet revolution that challenges our throwaway culture and demonstrates that a significant portion of what we typically discard never needs to leave home at all. Getting Started with Home Composting

Now that you understand the science behind composting, you're ready to begin your own composting journey. In our next post, we'll explore the different composting methods available for homes of all sizes—from sprawling gardens to tiny apartments—and help you choose the approach that's perfect for your lifestyle.

Whether you're a gardening enthusiast or simply looking to reduce your environmental footprint, composting is a rewarding practice that connects you directly to nature's perfect recycling system.

Looking for compostable products to support your sustainable lifestyle? Explore our plastic-free, home compostable collection designed to break down naturally in your home compost system.

Have questions/comments/corrections to make about what I covered in this post? Share them in the comments below, we can all learn from each other!

The Science of Home Composting: How Organic Waste Becomes Garden Gold