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Each year an average of 150 liters of kitchen waste is produced per person. Composting is also possible in the city. Not only do you get wonderful fertilizer for your balcony and houseplants, but you also close the natural cycle by returning nutrients to the soil. For city dwellers, bokashi and worm composting are particularly suitable.

What is Bokashi and worm composting actually?

With bokashi, kitchen waste is fermented with the help of Effective Microorganisms into a preliminary stage of humus. Subsequently, the Bokashi is humified and completely decomposed.

In worm composting, compost worms (Eisenia Foetida) and microorganisms in a so-called worm box process the organic waste into ready-to-use humus.

„EM“: Effective Microorganisms (EM) are a concentrated blend of beneficial microorganisms, bacteria and fungi that activate soil life, promote root development and strengthen the plant.

„Humus“: Inanimate organic soil matter composed of dead plants, roots, and soil organisms, which is constantly, rebuilt and decomposed.

What are common features of both "composting" systems?

  • Suitable for urban dwellers without access to gardens
  • Organic waste should be chopped before „composting“
  • Provide liquid fertilizer during the conversion process
  • Are odorless when used properly

What are differences?

Bokashi

Worm composting

B. = Bokashi

W. = Worm composting

Process

B.

Fermentation

W.

Worm composting

Process

Fermentation

Wurmkompostierung

Type of degradation

Anaerobic (without air supply), by means of yeast and lactic acid bacteria.

Aerobic (with air supply), by means of worms

Type of degradation

B.

Anaerobic (without air supply), by means of yeast and lactic acid bacteria.

W.

Aerobic (with air supply), by means of worms

Ingredients

Raw and cooked kitchen waste, tea and coffee grounds, dairy products, bread, slightly moldy food

80 % Raw vegetable kitchen waste, tea and coffee grounds; 20 % Cardboard shreds, newspaper

Ingredients

B.

Raw and cooked kitchen waste, tea and coffee grounds, dairy products, bread, slightly moldy food

W.

80 % Raw vegetable kitchen waste, tea and coffee grounds; 20 % Cardboard shreds, newspaper

Smell

B.

Acidic

W.

Slightly musty

Smell

Acidic

Slightly musty

Maintenance

1-2 Mal pro Woche Bokashi-Saft abzapfen

Add a mineral mixture 1 time per month to regulate the pH; Air regularly

Maintenance

B.

1-2 Mal pro Woche Bokashi-Saft abzapfen

W.

Add a mineral mixture once per month to regulate the pH; Air regularly

Ready after

B.

approx. 2 months

W.

approx. 5-6 months

Ready after

approx. 2 months

approx. 5-6 months

Temperature

8-30° C 

15-25° C

Temperature

B.

8-30° C 

W.

15-25° C

Costs

B.

approx. 50 €

W.

approx. 200 € (Worms can also be acquired through allotment clubs)

Costs

approx. 50 €

approx. 200 € (Worms can also be acquired through allotment clubs)

Bokashi

  • Suitable not only for vegetable waste but also for cooked food, bread and (solid) dairy products
  • Takes up little space
  • Very easy to maintain; well suited for people who like to travel for longer periods of time
  • No nuisance from flies and insects
  • Fermentation creates additional vitamins and enzymes
  • By-product Bokashi juice is a great fertilizer and can also be used in the household (e.g. as a pipe cleaner)
  • Bokashi juice can smell a bit
  • Effective microorganisms has to be purchased
  • After fermentation, Bokashi mass has to be mixed with soil first
  • Bucket has to remain closed during fermentation; 2 buckets make sense for continuous use
  • Additional container for collecting organic waste recommended

Wurmkompostierung

  • Worm box is also available in wood
  • Humus can be used immediately
  • Worms multiply, hence there is no need to buy more
  • More demanding in terms of feeding and environment
  • Worms are not everyone's thing
  • Not all bio-waste can be recycled (e.g. garlic, onions, ginger should not be added and coffee grounds only in moderation)
  • Fly (e.g. fungus gnats, fruit flies) and insect infestation occurs more frequently
  • Requires cardboard supplies (20% of the filling consists of cardboard)
  • If more than 3 weeks of vacation, someone must be assigned to care for the worms

With bokashi, you can utilize your organic waste more effectively and have less effort in maintenance. While worms can flee the box or perish if fed incorrectly, microorganisms are very tolerant and also take slightly moldy or non-organic foods, etc. You can even utilize (small amounts of) meat and fish if you’re not put off by the thought of rodents that might be attracted to the smell of the bokashi. And all you have to do is just add a bit more Effective Microorganisms and possibly sprinkle zeolite over the waste. With the worm bin, there are some do’s and don’ts that you should know before you start using it. However, you get ready-to-use humus and not a preliminary stage of „compost“ that you have to mix with soil first like with bokashi.

Both, bokashi and worm composting are two great alternatives to traditional compost, and ultimately you have to decide for yourself what suits you better.

„Zeolite“: Volcanic mineral with tiny pores, whose large surface area can bind pollutants very well.

Basic information about the worm box

There is a separate article on bokashi and its historical background. Therefore, for the sake of completeness, worm composting is explained in more detail here. 

Basically, there are the following two versions of the worm bin.

Vertical worm box

  • Consists of several „floors“
  • Over time, the worms move higher and higher, while humus settles in the lower part of the box
  • Liquid seeps down into a collection tray and can be taken out as worm tea
  • Vertical worm bins are largely made of plastic due to the seeping liquid

Horizontal worm box

  • Consists of a two-chamber system, in the middle of which there is a grid as a partition wall
  • One chamber is filled after the other
  • As soon as the first chamber is composted, the compost worms will move on their own and you can take out the soil
  • There is no worm tea and you have to take care yourself that the content does not get too wet
  • Horizontal worm bins are made of wood, which can breathe well and provide the worms with oxygen.

How do I properly cake care of my worm box?

  1. Add a 3-4 cm layer of moistened cardboard pieces or mix the cardboard pieces with unfertilized substrate.
  2. Fill the substrate with compost worms (as a rule of thumb: 150 g of worms for a worm box with a volume of 10 liters).
  3. The worms have to acclimatize first and hence, are not allowed to be fed for the first 3 days. At night, place the closed worm box under a light source for the first 5 days to prevent worm escape.
  4. Feed the worms. Start with 100 g of food/day and increase the dose in small steps. The chopped worm food should be placed loosely and should not form a compact mass. If it starts to smell, you may have fed too much.
  5. Cover the content of the box with a hemp mat and periodically check for humidity. You do this by taking out a handful of material (without worms) and squeezing it in your fist. If water comes out, the inside of the worm box is too wet and you should mix in dry cardboard shreds. If you feel no water at all, the worm bin is too dry. Spray the content with water or add moist cardboard shavings.
  6. Air the worm bin regularly.
  7. After 3 weeks, start adding 1-2 tablespoons of mineral mix monthly to adjust the pH of the content and provide minerals to the worms.
  8. For the vertical worm box, check the liquid level in the collection tray about 1 time per month and remove worm tea as needed. 
  9. Depending on the design and size of the worm bin, you can harvest the humus after 3-6 months.
  10. Clean the separation membrane of your vertical worm bin to maintain its permeability.
  11. Mix the humus with soil substrate in a ratio of 1:15 or 1:20.

„Substrate“: Usually industrially produced mixture of various mineral and organic materials used for growing and cultivating plants. 

How do I use the worm tea?

  • Worm tea is rich in nutrients and due to the many microorganisms soil revitalizing 
  • Dilute the worm tea in a ratio of 1:10 with water and water your plants with it

What are the C/N ratios of the ingredients?

A good C/N ratio is important for both Bokashi and worm composting. If the ideal C/N ratio of 25:1 shifts, the working speed of the microorganisms changes and with it the quality of the „compost“. By mixing as versatile as possible, deficiencies can be compensated and one-sidedness can be avoided.

„C/N ratio“: Ratio of carbon (C) to nitrogen (N) in an organic mass. The closer the C/N ratio, the more nitrogen is present compared to carbon, and the faster is the decomposition. A good C/N ratio is 1:25.

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