Composting is a natural process that transforms kitchen scraps and yard waste into valuable, nutrient-rich soil. While traditionally associated with suburban or rural settings, composting is increasingly accessible to urban dwellers—even those with limited space. This comprehensive guide will help city residents start and maintain effective composting systems that reduce waste, create valuable garden material, and contribute to a more sustainable lifestyle.
Why Compost in the City?
Urban composting offers numerous benefits that extend beyond waste reduction:
- Reduced Waste: Food scraps and yard waste make up approximately 30% of what Canadians throw away. Composting diverts this material from landfills, where it would otherwise generate methane, a potent greenhouse gas.
- Resource Creation: Compost is often called "black gold" by gardeners for its ability to improve soil structure, add nutrients, and enhance plant growth—a valuable resource for urban gardens and houseplants.
- Cost Savings: By creating your own compost, you reduce the need to purchase commercial soil amendments and fertilizers.
- Community Building: Community composting initiatives can bring neighbors together around shared environmental goals.
Understanding the Composting Process
Before starting your urban composting journey, it's important to understand the basic principles behind the process:
The Science of Decomposition
Composting is essentially managed decomposition, where microorganisms (bacteria, fungi) and larger organisms (worms, insects) break down organic materials into simpler, stable compounds. This process requires:
- Carbon-rich materials ("browns"): Dry leaves, paper, cardboard, wood chips
- Nitrogen-rich materials ("greens"): Food scraps, coffee grounds, fresh plant material
- Oxygen: For aerobic decomposition
- Moisture: Ideally, the consistency of a wrung-out sponge
- Microorganisms: Naturally present in the environment and organic materials
The Carbon-to-Nitrogen Ratio
A successful compost pile needs the right balance of carbon and nitrogen. Aim for roughly a 3:1 ratio of browns to greens by volume (not weight). Too much nitrogen (greens) can lead to odors and a soggy pile, while too much carbon (browns) will slow down the decomposition process.
Composting Methods for Urban Settings
Several composting methods are suitable for urban environments, each with different space requirements and management needs:
1. Vermicomposting: The Apartment-Friendly Option
Vermicomposting uses red wiggler worms (Eisenia fetida) to process food scraps into worm castings—a rich, odorless soil amendment.
Setup:
- Container: A plastic bin with a lid, approximately 40-50 liters for a household of 2-3 people.
- Bedding: Shredded newspaper, cardboard, or coco coir, moistened to the consistency of a wrung-out sponge.
- Worms: Start with about 1,000 red wigglers (approximately 1 pound) for a standard bin.
- Location: A dark, quiet place with a stable temperature (15-25°C), such as under the sink, in a closet, or in the basement.
Maintenance:
- Feed worms about 250-500g of food scraps per week, burying them in different spots each time.
- Add bedding materials as needed to maintain moisture and carbon balance.
- Harvest castings every 3-6 months by moving contents to one side and adding fresh bedding and food to the empty side. Worms will migrate, leaving castings ready for harvest.
What to Add:
- Fruit and vegetable scraps (avoid citrus in large quantities)
- Coffee grounds and filters
- Tea bags (without staples)
- Crushed eggshells
- Small amounts of plain, cooked grains and pasta
What to Avoid:
- Meat, dairy, and oily foods
- Onions and garlic (in large quantities)
- Pet waste
- Diseased plants
2. Bokashi Fermentation: The Odorless Indoor Option
Bokashi is an anaerobic fermentation process that uses specific microorganisms to pre-process food scraps before they're added to soil.
Setup:
- Container: A specialized Bokashi bucket with a tight-fitting lid and spigot for draining liquid.
- Bokashi Bran: Carrier material (typically wheat bran) inoculated with effective microorganisms.
Process:
- Add food scraps to the bucket, sprinkling each layer with Bokashi bran.
- Press down to remove air pockets and close the lid tightly.
- Drain liquid (Bokashi tea) every few days for use as a plant fertilizer (diluted) or drain cleaner.
- When the bucket is full, seal it for 2 weeks to complete fermentation.
- Bury the fermented material in garden soil or add to a compost bin for final decomposition.
Advantages:
- Can process meat, dairy, and cooked foods
- Takes up minimal space
- No odor when properly managed
- Works year-round indoors
3. Balcony Bin Composting: The Compact Outdoor Option
Small-scale compost bins designed for balconies or patios allow urban dwellers with outdoor space to compost more conventionally.
Setup:
- Container: A small tumbler or dedicated composting bin (30-100 liters) with ventilation and a secure lid.
- Location: A sunny spot on a balcony, patio, or small yard.
- Initial Mix: Start with a base layer of browns (dry leaves, shredded paper) and a handful of garden soil or finished compost to introduce microorganisms.
Maintenance:
- Add greens and browns in roughly equal volumes.
- Mix or turn the contents weekly to aerate.
- Monitor moisture levels, adding water or dry materials as needed.
4. Community Composting: The Shared Responsibility Option
Many Canadian cities now offer community composting options for residents without space for individual systems:
- Community Garden Composting: Many community gardens maintain shared compost piles where members can contribute materials and use the finished product.
- Neighborhood Composting Hubs: Some neighborhoods establish shared composting facilities where residents can drop off organic waste.
- Municipal Green Bin Programs: Many Canadian cities offer curbside collection of organic waste, transforming it into compost at centralized facilities.
Troubleshooting Common Composting Issues
Even well-managed compost systems can encounter problems. Here are solutions to common issues:
Odor Problems
- Ammonia smell: Too much nitrogen (greens). Add more carbon materials like dry leaves or shredded paper.
- Rotten egg smell: Poor aeration causing anaerobic conditions. Turn the pile more frequently and add coarser materials to improve airflow.
Pest Issues
- Fruit flies: Cover food scraps with browns or bury them in the center of the pile.
- Rodents: Avoid meat, dairy, and oily foods. Use a rodent-resistant bin with a secure lid and small ventilation holes.
Slow Decomposition
- Cold weather: Decomposition slows in winter. Insulate outdoor bins with straw or bubble wrap, or use indoor methods during cold months.
- Too dry: Materials should be moist but not soggy. Add water while turning the pile.
- Pieces too large: Chop or shred materials into smaller pieces to speed decomposition.
Using Your Urban Compost
Once your compost is dark, crumbly, and earthy-smelling, it's ready to use. In urban settings, finished compost can be used in many ways:
- Houseplants: Mix compost into potting soil when repotting or use as a top dressing.
- Container Gardens: Blend compost with potting mix for balcony or windowsill gardens.
- Raised Beds: Incorporate compost into garden beds to improve soil structure and fertility.
- Compost Tea: Steep compost in water to create a liquid fertilizer for plants.
- Share with Neighbors: Offer excess compost to neighbors or community gardens.
Conclusion
Urban composting is not only possible but increasingly practical for city dwellers concerned about sustainability. Whether you choose worm composting in an apartment, Bokashi fermentation in a condo, or a small outdoor bin on a balcony, you can successfully transform kitchen waste into valuable compost. By closing the loop on organic waste in your own home, you contribute to a more sustainable urban environment and connect with the natural cycles that sustain our ecosystems. Start small, experiment with different methods, and discover the satisfaction of creating "black gold" from materials that would otherwise be thrown away.
