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Biochar in South Korea: experiences from everyday

by Haiko Pieplow

In South Korea, in spite of rapid industrial growth, the millennia-old tradition of using biochar has been retained. From kimchee production to functional bathroom sculptures, from sauna décor to natural farming, the tradition of charcoal use in South Korea transcends time and inspires anew. Unlike in Western biochar research, the focus is on biochar's involvement in biological processes. Biochar plays an increasingly important role in the closure of material cycles, especially in conjunction with the rich culture of fermenting food and the use of bokashi to ferment organic waste.

In Asia, there is an age-old culture of both food fermentation and the use of charcoal. Every family in South Korea has its own recipe for kimchi and soybean pastes, both of which are produced by lactic acid fermentation. Kimchi is fermented Chinese cabbage, radish, other vegetables of the season and a lot of chili, similar to our finest artisanal sauerkraut. As with sourdough bread, wine or yogurt, the production depends not only on the quality of the ingredients, but on the specific composition of the fermenting yeasts and bacteria. The diversity of the microbial composition is virtually infinite, so that each family has its own fermenting culture and thus its own kimchi, which it passes on from generation to generation. Thus every family builds with time its very own particular flavor of everyday dishes, which also brews a strong sense of family cohesion.

Everywhere in home gardens you can see the beautiful ceramic fermentation vessels, even on the roofs of high-rise buildings (Fig. 1). In kimchi production large amounts of residual liquid arise, thick with indigenous microorganisms (IMO), which the uninitiated in Europe can purchase as a Japanese invention called Effective Microorganisms (EM). EMs are cleverly marketed for a number of uses that the Korean indigenous microorganisms fulfill. Kimchi liquid is used in a wide range of applications in everyday life: as a cleaning agent, as a remedy for skin diseases, in animal nutrition, in conjunction with biochar for plant vigor, and for the sterilization of organic waste (Fig. 2).


Figures 1 and 2: fermentation vessels for the preparation of kimchi

There are more kimchi recipes than families in Korea and you can quickly create your own recipe from the ingredients available in your own garden. An internet search under the term “kimchi recipes” is worthwhile to come up with new exciting ideas for cooking tasty, healthy foods. Kimchi is not unjustly considered the world's healthiest food. The list of health benefits is long and is increasingly attracting scientific attention (Park, Jeong, Lee, & Daily, 2014). Regular consumption of kimchi apparently leads to lower cancer rates, prevents obesity, promotes colorectal health  and prevents constipation. It also lowers cholesterol, dissolves blood clots, prevents premature aging through anti-oxidant effects, increases concentration, boosts the immune system and improves skin health (Park, Jeong, Lee, & Daily, 2014). For some recipe examples, see here and here.

Natural Farming in South Korea: sophisticated climate farming

In 2010, I attended a Terra Preta workshop in Beijing on the Korean method of Natural Farming. This method of farming is practiced in many Asian countries on small-scale family farms, which apparently means that substantially higher revenues and profits are achieved using natural methods than with industrial agriculture and the Western methods of organic farming. The founder of the Korean Janong Natural Farming Institute, Han Kyu Cho, has published a manual based on  his 50 years of practical experience with Natural Farming in the whole of East Asia. In the preface of the book, he states that farmers should use the available resources in nature, rather than make themselves completely dependent on chemicals. Why can agriculture not exist in harmony with nature? Why can farming not be a happy, divine work? Why should farmers no longer be the masters of their farming? Farming is a living art! You can find a copy of Han Kyu Cho’s inspiring book on Natural Farming here.

Whoever reads Cho Han Kyu’s manual will get a feel for how much knowledge we have lost in our Western culture and how much we can learn again about growing healthy food and how to live in harmony with nature. It should be emphasized that it is not enough to deal with only specific practices such as fermentation, composting, charcoal production, soil conservation farming or healthy eating. One should rather have in mind the balance of the whole cycle of food production to food consumption. This relates in particular to obtaining a deeper understanding of the directly linked carbon, nitrogen, phosphorus and water cycles.  When you have understood the basic principles for building on these cycles, there are infinitely many ways that you can find a healthy and fulfilled life. Those who follow in this way, will gain more quality of life from year to year.

I was fascinated in South Korea to find in the mega-cities, but also in small villages,  many Koreans who live sustainably and well, without being able to explain in detail the scientific background of their practices. I must add, of course, that as a guest, one gets shown particular and specific aspects of the country, and of course not all biogeochemical cycles are closed sustainably in Korea. By now most kimchi comes from the supermarket and most of the 70 million South Koreans live in high-rise buildings. But the decisive factor is that both the awareness of the ecological value of tradition and the awareness of the need for closed material loops are widely found in South Korean society.

The Korean culture of charcoal

In addition to fermentation techniques, biochar plays a key role in the formation of Terra Preta soil and the associated development of continuous high humus content. In Korea, there is an age-old culture of wood and plant charcoal production, resulting in a variety of everyday uses for different forms of charcoal.
We visited an impressive charcoal factory with long rows of reactors made of stone and clay, in which oak logs are converted into charcoal in the traditional way (Fig. 3). The reactors are large enough to fit many people inside. After the finished charcoal was cleared, the stone inner walls of the kiln stay very hot for a long time. The kiln walls are coated with mud and augmented with wooden floors and rice straw mats and used for some time as a sauna (Fig. 4).


Figures 3 and 4: Traditional Korean charcoal kiln, which is then used as a sauna (Jjimjilbang).

The produced charcoal is sorted into different qualities. Some of the most beautiful pieces are sold as raw material for sculptures (Fig. 5) and jewelry (Fig. 7 and 8).


Fig.5: Seon-ghi Bahk is one of the most famous and inventive Korean artists working with biochar as main material in his sculptures.


Fig. 6: Have a look to this most beautifull images about the charcoal sculptures of Seon-ghi Bahk.

The largest part of course is marketed as fuel charcoal. The charcoal dust, however, is mixed with rice milk and pressed into briquettes for barbecue or used for bokashi fermentation of waste and for soil improvement. For its restaurant, the charcoal company has its own greenhouse with numerous vegetable species, where both biochar and fermented and composted kitchen waste, as well as kimchi juice (IMO) are used for soil improvement and the closing of material cycles. In this way, charcoal production is even today still celebrated as a social event and as an intelligent commercialized experience, where visitors can stay at a campground designed with Feng Shui principles. It is natural to assume that most of the manufacturing of charcoal in Korea is now done industrially, but still, the connection to tradition has remained.

Fig. 7 and 8: Charcoal is widely used also for jewelry in Korea.

In Korea, no valuable hardwood is carbonized to make biochar for soil amendment; instead, dust is used. You can also see in the fields that rice husks and straw residues are charred and returned to the soil. In the fermentation vessel depicted on Figure 2 one can see swimming in the juice, larger charcoal pieces to prevent faulty fermentation. These are charged with the same microorganisms and nutrients used for soil improvement.


Fig. 9: Hakutan Sculpture. Hakutan is a section of White Charcoal with an extremely high carbon content; this high grade of charcoal cleanses the air naturally and remains active for very long time. It regulates humidity (think bathroom) and absorbs odors (kitchen smells), all while looking like a small natural sculpture. And, if you should ever tire of it, you can dispose of the Hakutan by crushing it and mixing with potting soil.

In everyday life, Koreans encounter almost everywhere a variety of applications of charcoal. Standing on many modern toilets are bizarrely shaped charcoal sculptures for odor control (Fig. 9). The best example I found after sauna sweating in the charcoal kiln. I was led into a quiet room which was completely lined with charcoal (Fig. 10 and 11). There I rested in excellent air and thought of Hans-Peter Schmidt, who also discovered the beneficial effects of biochar in building materials.


Fig. 10 and 11: Entrance and inner wall of the sauna relaxation room lined with charcoal.

Hayasaka S et al (2008) studied and published in a scientific journal the Effects of charcoal kiln saunas (Jjimjilbang) on psychological states. Six factors relating to mood were measured using the POMS: Tension-Anxiety, Depression-Dejection, Anger-Hostility, Vigor, Fatigue, and Confusion. The two anxiety concepts of state anxiety and trait anxiety were also measured. Changes in psychological states before and after sauna bathing were then determined. All mood scales and both manifest anxiety measures were improved after sauna bathing. Charcoal kiln sauna bathing appears to improve mood and decrease anxiety.


 Fig. 12: The charcoal quiet room at Spa Land in Busan, South Korea.

The Korean version of the optimization of small carbon cycle

Climate farming is something you can smell, taste and handle yourself. For sustainable healthy eating you need a healthy soil rich in humus. That this is true not only for agriculture in the country, but also for the gardener in the cities, the Korean government recognized some time ago, and passed a law to promote urban agriculture. In the city of Seoul (pop. 10M), in addition to countless roof, window and terrace gardens, there are also 850 hectares in agriculture and nearly 12,000 professional farmers. A particularly fine example is the community garden on Nodul Island in the Nanham River surrounded by Seoul. At the opening of the park, the Mayor of Seoul put the emphasis on the connection of urban gardeners, climate change and community:  “We expect that, supported by the government and civil society, urban agriculture will become an effective contribution for climate protection and for the cohesion of the urban community in Seoul."


Figures 13 and 14: The community garden on Nodul Island in Seoul and its organic fertilizer production. Let's hope that the gardeners also discover mulching for humus formation and planting hedges to promote biodiversity.

The garden area and the required infrastructure on the island is provided by the city free of charge (Fig. 13). When I visited the island, the planting of small parcels of land was in full swing. The use of synthetic fertilizers, pesticides and herbicides is not allowed! The site for organic fertilizer production was quickly found: It was located right next to the dry separation toilet (Figure 14). Even on closer inspection no urine or fecal odor was noticeable. The toilets are cleaned with IMOs from the aforementioned kimchi. In big brown vats behind the toilet the IMOs are added in appropriate amounts (Fig. 15). These fermentation tanks hold a mix of kitchen and garden waste with 20% feces, combined with climate-friendly converted facultative anaerobes to produce earthworm food (Fig. 16). A perforated pipe in the center ensures the gas and moisture regulation. When you lift the lid, it smells not unpleasantly sweet and sour. After completion of the fermentation, the material then enters the worm composter where worms finalize the production of a highly fertile soil substrate. Everything is explained in simple understandable pictograms where an earthworm tells you which containers are used for what. The kimchi waste, also known by the Japanese term bokashi, is mixed with charcoal dust and sold commercially in sacks. In this city of gardeners, humus-rich substrates are highly sought after as they make high crop yields possible in the smallest space in pots, boxes or bags.


Pictures 15 and 16: Multiplication of indigenous microorganisms as inoculant for fermentation and containers with fermented garden and toilet waste.

Professor Mooyoung Han of Seoul National University has with his students transformed the roof of his 10-story Institute building into a vegetable garden (Fig. 11), complete with many fermentation vessels (Fig. 17).


Pictures 17 and 18: vegetable garden on the roof of the University of Seoul, including mandatory fermentation tanks and compost heap.

It is time in Europe to also convert the roofs on our schools and universities into gardens; air condition our habitats with plants; use the spaces in front of our windows and on the balconies for the production of our food and for the recycling of the waste into humus. Our vision must seek the empty space that can be planted. We should not only vigorously promote the sustainable use of compost, but with what we know already, begin to build it today. There is no lack of knowledge, only of commitment.


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  • Balz Baur, Serbia
    25.11.2014 17:49

    Reminds me of old Europe

    Thank you for this article. It is very interesting. I live in Serbia on the country side. Traditional small farming is the normal case, but slowly tradition gives way to modernity. Sauerkraut (Kimtchi) gives way to Convenience Food. Unfortunately it seem to be a human talent, that we have to loose things in order to find out what is missing.

  • Kelpie Wilson, United States
    10.12.2014 22:38

    Question about charcoal and kimchee

    I would like to know more about how a piece of charcoal in the kim chee prevents faulty fermentation. Would you get the same effect from mixing charcoal dust in the kim chee?

  • Brian D Smith, United States
    26.01.2017 18:28

    Charcoal in Kimchee

    Lumps of charcoal in kimchee are used as fermentation stabilizers. Charcoal sorbs a variety of organic molecules. The molecules provide nutrition for the mixture of microbes (yeasts, fungi, bacteria) that ferment the vegetables. These microbes penetrate the charcoal, being sustained by the sorbed nutrients and become a reservoir of the microbe mixture. Each time the charcoal lump is used, it both adds and releases microbes, ensuring consistency from batch to batch. Charcoal dust being fresh each time, will not stabilize the ferment. However, it will be consumed and provide some benefits in the human gut.

  • John HOFMEYR,
    05.08.2017 09:44

    Aerobic versus anaerobic microorganisms and biochar storage

    1) How are the microorganisms which colonise the lumps of biochar kept alive between one batch of fermentation and the next? (I presume there is no source of nutrients?) 2) In Figure 2, the lumps of biochar are floating. That suggests that the pores of the biochar are filled with air? How are the lumps of biochar stored between one fermentation batch and the next? Must they be kept wet? And in an anaerobic environment? Or can the lumps of biochar just be left to dry out in the air, so that they will float in the fermenting mixture?

  • Pieplow,
    09.08.2017 23:05

    Thanks for your kind comments. Most of the charcoal pieces will sink down with time. Some of them enclose air or other gases that make them float though these are usually only few pieces. Over time, most pores of the charcoal are slowly filled with the nutrient-rich liquid of the Kimchi. It is not yet well understood why biochar promotes lactic fermentation though it is a frequent observation in Kimichi as well as in silage or in cattle digestions. There are only some more or less well found hypotheses reaching from electron buffering to inter bacterial electron exchange. Sorry for not being more precise here.

  • ebenezer,
    30.10.2019 07:41


    please help me to get the contact of places where i can purchase imo

  • Schmidt, Hans-Peter,
    30.10.2019 11:10

    IMO making

    The best is to do them yourself: take 100 l of water, add 3 kg of sugar, add 30 l of fresh green leaves, grass, flower etc. Mix it all well. Cover it for 7 to 10 days. Ready!

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