Bokashi Composting for Urban Homes

Introduction to Bokashi Composting

Bokashi composting, originating from Japan, is an anaerobic fermentation process that uses specific microorganisms to break down food waste. Unlike traditional composting, Bokashi can handle all types of kitchen scraps, including meat, dairy, and oily foods. It's a fast, odor-free method ideal for urban dwellers with limited space.

The process involves layering food scraps with inoculated bran (Bokashi bran) in an airtight container. The microorganisms ferment the waste, preserving it rather than decomposing it in the traditional sense. The end product is a pre-compost material that needs to be buried in soil or added to a traditional compost pile to complete the decomposition process.

Understanding the Science: Fermentation vs. Decomposition

Traditional composting relies on aerobic decomposition, where microorganisms use oxygen to break down organic matter, releasing heat, carbon dioxide, and water. Bokashi, however, is an anaerobic fermentation process, similar to making pickles or sauerkraut. Effective Microorganisms (EM), primarily lactic acid bacteria and yeasts, dominate the process.

These microorganisms ferment the food scraps, converting sugars into lactic acid. This lowers the pH, preserving the material and preventing the growth of putrefying bacteria that cause foul odors. The fermented material retains most of its original nutrients, which become more bioavailable to plants after the final decomposition stage in the soil.

Setting Up Your Bokashi System

Getting started with Bokashi is simple and requires minimal equipment.

1. Choosing Your Bokashi Bin

A proper Bokashi bin is crucial for success. Key features include:

• Airtight Lid: Essential for maintaining anaerobic conditions.
• Drainage Spigot: Allows easy removal of the nutrient-rich Bokashi tea.
• Drainage Plate: Separates solid waste from the liquid leachate.

You can purchase commercial Bokashi bins or make your own using two nested buckets, ensuring the inner bucket has drainage holes and the outer bucket has a spigot and airtight lid.

2. Acquiring Bokashi Bran

Bokashi bran is the key ingredient. It's typically wheat bran or sawdust inoculated with Effective Microorganisms (EM). You can buy pre-made bran or make your own if you have access to EM mother culture, molasses, bran, and water. For beginners, purchasing pre-made bran is recommended.

The Bokashi Process: Step-by-Step

Follow these steps for successful Bokashi fermentation:

1. Prepare the Bin: Ensure the bin is clean and dry. Sprinkle a small handful of Bokashi bran on the drainage plate at the bottom.
2. Add Food Scraps: Chop larger food scraps into smaller pieces (1-2 inches). Add a layer of scraps to the bin, no more than 1-2 inches thick.
3. Add Bokashi Bran: Sprinkle 1-2 tablespoons of Bokashi bran evenly over the food scraps layer. Use slightly more for meat or dairy.
4. Compact the Layer: Press down firmly on the layer using a potato masher, plate, or your hands (wear gloves) to remove air pockets. This is crucial for anaerobic conditions.
5. Seal the Bin: Close the lid tightly immediately after adding scraps and bran. Open the bin only once or twice a day to add new scraps.
6. Drain the Liquid: Every 2-3 days, open the spigot and drain the Bokashi tea. Store this liquid in an airtight container.
7. Fill the Bin: Continue layering scraps, bran, and compacting until the bin is full. Add a final layer of bran and seal tightly.
8. Ferment: Let the full bin sit undisturbed at room temperature for at least two weeks to complete the fermentation process. Continue draining the tea every few days.

Using the Bokashi Products

The Bokashi process yields two valuable products: Bokashi tea and fermented pre-compost.

Using Bokashi Tea (Leachate)

This nutrient-rich liquid is acidic and must be diluted before use on plants.

• Plant Fertilizer: Dilute 1:100 with water (approx. 2 teaspoons per gallon or 1 tablespoon per 5 liters). Apply to soil around plants, not directly on leaves. Use within 24 hours of draining.
• Drain Cleaner: Pour undiluted down drains or toilets to help break down sludge and control odors.
• Compost Accelerator: Add undiluted to traditional compost piles to boost microbial activity.

Note: The smell of Bokashi tea can vary from sweet and pickled to slightly foul. A very foul smell might indicate a problem, but often the liquid is still usable, especially for drains.

Using the Fermented Solids (Pre-Compost)

After the two-week fermentation period, the contents of the bin will look similar to when they went in, but they will have a pickled or fermented smell. This material is acidic and needs further processing before plants can benefit from it.

Methods for Final Decomposition:

1. Burying in the Garden (Soil Factory): Dig a trench or hole about 12 inches (30 cm) deep. Add the fermented Bokashi solids and mix lightly with some soil. Cover with at least 6-8 inches (15-20 cm) of soil. Wait at least two weeks before planting directly in that spot. This method rapidly enriches the soil.
2. Adding to Traditional Compost: Mix the fermented solids into an existing compost pile or bin. The Bokashi material acts as an accelerator, speeding up the overall composting process.
3. Mixing with Soil in Containers: In a large container or bin, mix the fermented solids with soil or finished compost (approx. 1 part Bokashi to 2-3 parts soil). Let this mixture sit for 2-4 weeks before using it as potting soil. Keep it covered to maintain moisture.
4. Feeding Worms (Vermicomposting): Introduce small amounts of fermented Bokashi solids into an established worm bin. The acidity requires caution; add gradually and monitor the worms' reaction. Mix it with bedding materials first.

Troubleshooting Common Bokashi Issues

Bokashi is generally trouble-free, but here are solutions to common problems:

• Foul Odor (Rotten Smell): Usually caused by insufficient bran, too much moisture, or the lid not being airtight. Add more bran, ensure scraps aren't too wet, check the lid seal, and compact layers well.
• Blue/Green Mold: Indicates air exposure. Ensure the lid is sealed tightly and layers are compacted. Scrape off the mold and add extra bran. White mold is normal and beneficial.
• Maggots or Flies: The bin was likely not sealed properly, or flies laid eggs on scraps before they were added. Ensure the lid is airtight. If maggots appear, seal the bin tightly; the anaerobic conditions should kill them.
• Little or No Liquid Drained: This is normal, especially if food scraps are dry. Liquid production varies. As long as there's no foul smell, the process is likely working.
• Slow Breakdown After Burying: Soil might be too cold, too dry, or lacking microbial life. Ensure good soil contact, maintain moisture, and consider adding some finished compost to the burial site.

Making Your Own Bokashi Bran

For the dedicated Bokashi user, making your own bran can be cost-effective.

Ingredients:

• 10 lbs (approx. 4.5 kg) Wheat Bran
• 1/4 cup (60 ml) EM-1 Mother Culture
• 1/4 cup (60 ml) Molasses
• 1 gallon (approx. 4 liters) Dechlorinated Water

Process:

1. Dissolve molasses in warm water. Let cool to room temperature.
2. Add EM-1 culture to the molasses water.
3. Gradually add the liquid mixture to the wheat bran, mixing thoroughly. The final consistency should be damp but not dripping wet (like damp sand). Test by squeezing a handful; it should hold its shape but not release water.
4. Place the mixture in an airtight container or heavy-duty plastic bag. Press down firmly to remove air.
5. Seal the container/bag and store it in a warm, dark place for 2-3 weeks to ferment.
6. After fermentation, the bran should have a sweet, fermented smell. Spread it out thinly on trays or tarps to air dry completely. Avoid direct sunlight.
7. Once completely dry, store the finished Bokashi bran in an airtight container away from direct light. It should last for up to two years.