Friday, September 29, 2017

Fixing a hole with Red Clay: repairing charcoal kilns in Niiharu

Last winter, Charcoal Making Club of Niiharu Lovers struggled to bake bamboo charcoal. We lit the fire at 6:00 for the charcoal kilns, and they could not be hot enough at 20:00. Later, when we opened the kilns, we found out the bottom of the metal barrels had huge holes which made it impossible for the kilns to cook bamboos efficiently. This summer, Charcoal Making Club did a major overhaul for kilns by replacing the broken metal barrels with high spec oil drums provided with the courtesy of one of the world majors. There are many designs for modern charcoal kilns in Japan. (Photos can be seen here.) Niiharu’s kilns are made of a drum of 57cm of diameter and 90cm tall, buried in red clay. The bottom of a drum has a hole of 11cm diameter. The bottom wall of the drum also has 4 holes each of which is connected with a pipe of 5cm diameter. The top of a drum is a lid with a hole for a Ø3cm pipe. The drum is then put on a U shaped concrete gutter as its Ø11cm hole is over the trough. The drum and gutter are held by red-clay loaded in a space surrounded by four 150cm*120cm metal walls. The clay holds the drum and 4 pipes by piling up the square tightly to the rim of the drum. When we see the kiln from a side, it looks like a metal box situated on a clay mount with 4 pipes sticking out from the top.

A sectional view of Niiharu’s charcoal kiln
It’s a view from the above of the kiln.
The Lovers took out the metal barrels
from the structure.
The new kilns.
I didn’t know there were several kinds of metal barrels.
My seniors said the new barrels had thicker wall
so that it can keep the heat well.

The science of charcoal making is, when we add heat on logs slowly but continuously in an almost sealed-up space, they start to heat up themselves and release volatile substances their cells hold. If we keep burning them by firewood, they will eventually become ashes which are the materials, such as metals, that cannot evaporate with the energy created by camp fires. In contrast, if we stop adding external energy, but create tightly sealed environment for the heated logs, they continue to burn themselves slowly with very limited supply of oxygen and discharge unstable oils from their body as much as possible. Though, without new fire supplied, the closed structure eventually cools down and the self-combustion of logs inside also stops. The logs burned in this way end up as a chunk of carbon. They are now charcoals which are incompletely combusted logs in a shut room. When a charcoal is very close to pure carbon, they do not contain volatile element much. Unlike firewood, they can burn for a long time without creating flame. In other words, a charcoal kiln intends to let the logs free the unstable elements completely during combustion. Niiharu’s kilns are designed to do that just by burning firewood in the concrete gutter. As this is for weekend forest volunteers, it’s not for cooking wood charcoal for days, but for one day making with bamboos. Even though, the inside of the kilns must reach around 700ºC that made the previous metal drums porous, and the concrete slab that sealed the U-shaped gutter with the metal drum crumbled when we removed the red clay to take out the metal drums. The power of fire and heat …

The difference between completely burned woods and charcoal.
One of my senior Lovers showed me how different they were.
Completely burned woods looked like a charcoal,
but they were very fragile and easily became ashes
just by rubbing them between the fingers.
In contrast, our bamboo charcoal maintained its form
and emitted metallic sound when we gently tapped them.
The dug-out metal barrel, upside down.
It was surely worn out.
The side wall of the barrel.
No wonder the kilns could not heat itself up well.

I now know the pipes at the bottom wall of a drum were not welded but inserted to the hole and stabilized by clay. The pipes are for volatile substance inside the bamboo free to evaporate. The red clay is typical soil in Kanto region especially where the volcanic ashes from Mt Fuji fell. I asked if we can just burrow up the land wherever allowed in the Niiharu Forest to replenish the stock. “Huh? Of course not. Niiharu is rich forest with lots of fallen leaves and the other organic materials. When we use the top soil, those organic materials will be burned during the charcoal cooking, and the mud cannot seal the kilns tightly.” So, we’ve been to a place in the forest where we can harvest the clay beneath the top soil. We have to DIG deeply. I also noticed the difference in red clay between “before” and “after” of charcoal cooking. When we dug out the drums from the structure, the “clay” was hard by tapping, but could crumble easily into very fine grains with a strike of spade. We needed face masks to operate to avoid coughing. In contrast, freshly procured red clay is dense. By adding water, we can make mud balls easily. I understand why a desert is desert … The tierra of desert was exposed to direct sun light continuously. It must have turned into the “after” clay of Niiharu’s kilns. I guess the organic richness of the soil is definitely greater in Niiharu than those places in desert in China …

Red clay in Niiharu
We dug a hole to harvest the clay.
You may say there are lots of red clay
in our charcoal making hut.
Actually, we used up almost all of them during the repair.
My seniors said this winter we have to procure more
before baking charcoals in order to seal the kiln.
Hmmm, it may be difficult to see in this photo
the difference between the “fully-baked clay” and newly procured one
... I hope you sense the texture of before-baked clay
in the bucket by comparing the baked clay surrounding it.

The red clay was in full-operation during the renovation. After replacing the crumbling drums and slabs, the mud balls were applied to seal the gaps and holes of the metallic materials, to act as a plaster for bricks and U-shaped gutters to stay together, and to attach tightly the pipes at the bottom wall of a drum. Hmmmmm … playing with mud balls in kindergarten must be something in order to learn the basic technology of human settlement. Hey, moms in the world, don’t stop your kids to play in mud. Certainly their garment could be damaged beyond repair, but that’s an important experience to understand human history! The mud-pasted structure is next stabilized by piling dry red clay within the 4 metal walls. … In the end we worked reticently to fill the once emptied space. Digging the thing out, and digging the thing in. Zen ...

The walls were temporarily removed to work in the kiln.
The worn-out walls were replaced by new metallic panel.
But …
Lovers noticed the newly procured panels have holes.
So, they were sealed by mud balls.
“Hey, I’m a city boy of Yokohama,
and have never done indecent things of
soiling my pants when I was a kindergartener.”
“Well, so you have to do it now.”
Preparing mud balls
Plastering the bricks was also with mud balls.
Before setting the barrel
First, situate the marble …
Then, seal the space with the clay,
Put the marker for the Ø11cm hole,
and seal the remaining gaps with more clay …
And set the metal barrel.
“Watch out for the direction of the 4 holes.
They must be on the diagonal line of the space.”
Next, we inserted the pipes
and adjusted the direction of the kiln in diagonal.
It’s because when we bake the charcoal,
long bamboo chimneys will be attached to the pipes
which go out from the holes of the walls of the hut.
The diagonal direction of the pipes is determined
by the locations of the side holes.
An operating kiln with chimneys should look like this.
At this stage, we made it sure
the mouth of the pipes inside the barrel smooth.
Otherwise, when we load bamboos to be baked,
the ledge created by a pipe impedes packing.
When we cook charcoal,
inside of the barrel should be tightly filled as much as possible
so as to make the circulation of the heat efficient.
Now the pipes were provisionally stabilized with a hemp line.
Then the gaps between the pipes and the barrels were
sealed by mud balls from outside.
All in all, sealing the space inside of the barrel is very important.
Now cover the bottom of the barrel with red clay a bit
and stomp it over to make the closure for sure.
And pile the clay up, up, up …

Now the new charcoal kilns have pretty red and blue lids in Niiharu. We hope this winter we can finish our baking within 8 hours. Fingers crossed.

If you find a problem in Niiharu Forest, please make a contact with

Office for the Park Greeneries in the North 北部公園緑地事務所
Yokohama Municipal Government Creative Environment Policy Bureau 横浜市環境創造局
Phone: 045-311-2016 (I guess in Japanese only)
FAX: 045-316-8420 (I hope there is somebody who can read English …)

Niiharu Administrative Office / Satoyama Exchange Center 新治管理事務所・里山交流センター
Phone: 045-931-4947
Fax: 045-937-0898

Friday, September 22, 2017

Baby trees in Mad Max 3: planting trees in the place of Neon Genesis Evangelion

Kanagawa Green Trust かながわみどり財団 has a year-round program for anybody to join forest management in Kanagawa Prefecture.  Once to three times a month, they organize a field trip to a forest for planting, mowing, thinning, pruning … you’ve got the idea, haven’t you? The majority of event-dates are during weekend + the place is mainly a public land that is normally off-limit.  It’s a good weekend getaway from urban life. The Trust arranges a free bus tour to the site from a commuter train station of Odakyu Line 小田急線. And so, your transportation cost is minimized. Volunteers make an online reservation (; you can reserve your seat for an event here), then, on the reserved day, wear mountaineering gear (a pair of work gloves is a MUST), carry your lunch and lots of drinking water, and go to a meeting place normally within 5 minutes’ walk from a designated train station. The rest is taken care of by the Green Trust and Kanagawa Forest Instructors. The forest activity is for the morning. After lunch in the forest, many events are over and the Trust brings you back to the commuter train station. Sometimes additional program is arranged such as meeting with local forest volunteer organizations, or free spa in Hakone 箱根. Actually, if a forest is in Hakone, it is a HUGE bargain to visit a forest of Hakone! They say the program is gaining popularity these days and seats for some date become rapidly full. The purpose of this tax-payer funded fun is to provide opportunities for urbanites to know forest management hands-on, and to manage vast water catchment forests of the prefecture in whatever way. As such, the forests chosen for the program is often for water conservation in Tanzawa and Hakone. For the water source forests in Tanzawa, I’ll post you my experience there soon. Today, I tell you my experience with continuing afforestation efforts in Sengoku-hara 仙石原 of Hakone. Although the area ceased to be the water source for the City of Odawara 小田原, the place still provides water to the community in northern Hakone. A weekend forest activity concluded with relaxing free spa is, I tell you, gorgeous.

The gate of off-limit prefectural forest in Hakone.
It’s open only for the time of forest management.

Hakone is one of the most prestigious resort towns in Japan. Inevitably, there are several golf courses. Among them, Hakone Country Club in Sengoku-hara is the place for rich and famous in Japan to enjoy their weekends. In the premise, they have several ponds, of course, but one of them, the largest, is not for golfers.  Its name is Itari Pond イタリ池. It is one of the remnants of a marsh spreading in the northern Hakone area until some 70 years ago before the place underwent a massive resort construction. In 1959, another remnant, the Sengoku-hara hygrophyte meadow was designated as a National Natural Treasure of Japan. The meadow attracts lots of visitors, contributing to the tourism business of the town. Aside from being scenery of rich golfers, Itari Pond too is sustaining the economy of the area in a very practical way. The people in Sengoku-hara area pump up the water of Itari Pond (about 700m ASL) to 2.5km south of Owakudani 大涌谷 (about 1050m ASL) and let it through the well of volcanic steam. The H2O becomes mineral rich boiling water and comes down to northern Hakone to be spas. So far, it never fails to provide lots of lots of spa water. No wonder. The area is the source of Hayakawa River 早川 pouring to Sagami Bay 相模湾 in the south of Odawara City. It is the river supplied water for some 400 years to Odawara, although since 1936 Odawara is using water coming from Tanzawa Mountains.

Over there is Hakone Country Club.
According to Neon Genesis Evangelion,
this is the place for Neo Tokyo-3.
At least for now,
the majority of strollers in the premise are not millennials,
but their parents or grandparents.
(In any case, we have survived 2015 …)
Hakone Yumoto 箱根湯本 and Hayakawa River

The reason why Odawara switched its water source was, Hayakawa River could not fulfill the demand any more. There was population growth of course, which made even the rich marsh of Hakone could not satisfy people’s satiation. You may say Sengoku-hara is right next to Lake Ashinoko 芦ノ湖 that is the source of Hayakawa River anyway. The lake can take care of the matter, can’t it? Well, yes and no. The water right of Ashinoko Lake is held by Shizuoka Prefecture 静岡県, not Kanagawa, because of historical reasons originated in the 17th century. Based on the present-day law, the civil engineering maintenance for the lake is under the jurisdiction of Kanagawa Prefecture, but the water of Ashinoko Lake must go to Shizuoka via Fukara Canal 深良用水 which holds the title of International Heritage of Irrigation Facility, designated by International Commission onIrrigation and Drainage. So, Kojiri Watergate 湖尻水門 in Sengoku-hara leading to Hayakawa River is permanently closed. That’s that. In any case, I suspect one of the reasons for the 20th century water shortage from Hayakawa was environmental. Here is a photo, borrowing from the homepage of Hakone Shrine. It shows how Sengoku-hara area was in 1949 when the Emperor Hirohito came to hold an afforestation ceremony. The marsh was not that much wet but more of dry grassland. Water retention was definitely lower in 1949 comparing with 2017 when the area is fully-afforested.

In Itari of Sengoku-hara meadow, spring 1949.
Actually, Japanese Emperor presides over
the annual afforestation festival since 1934,
importing the American idea of Arbor Day.
The festival could not be held in 1944 and 1945,
but otherwise it has been one of the most important
official duties of the Emperor
This year, the event was held in Toyama Prefecture.
Sengokuhara meadow, in summer 2017

For more than 70 years of continuous afforestation, the former grassland is now a forest (and 2 golf-courses).  First, people planted coniferous trees there. They are now matured cedars and cypresses many of which are harvested for funding nature management programs of the Prefecture. This spring, in the forest management tour we planted next generation trees to the newly created vacant plots in Itari area of Sengoku-hara. The site is now managed by Kanagawa Water Supply Authority 神奈川県内広域水道企業団 in order to supply water to the northern Hakone area. The chosen seedlings this time were deciduous trees, nurtured from the local seeds of Stewartia monadelpha (Tall stewartia), Acer palmatum (Japanese maple), Cerasus jamasakura (Japanese hill cherry), and Cornus kousa (Kousa dogwood). Before we arrived, The Water Supply Authority cleared the place and marked the place with a bamboo stick for the seedlings to be planted. Although, Hakone area does not (yet) suffer deer problem, the place was enclosed by sturdy wire mesh to prevent deer lunch, just in case. Everything was ready when we went there. We simply dug at the indicated point holes deep and wide enough for the roots of seedlings to be covered with 2-5 cm of soil and applied gentle stomping around the root to stabilize the soil (; it’s a maneuver similar to a dance around a small poll, which I loved). Then, each baby tree was loosely tied to the bamboo cane with a hemp yarn. The fastening of the seedling is important to prevent the weak babies to be knocked out by strong winds and rains. The point to apply yarn is at 2/3 of a seedling from the bottom.  We put the string in 8-shaped loop around the marker-stick and tied the end at a seedling, not so tight but secure enough for the fastener to stay at the point. The baby trees grow taller and spread their branches from their growing point, normally at the tip. The trunk 2/3 from the root will not have a new bough anymore, but only get thicker. So, gentle tying with a yarn will not hamper their growth.

The underground reservoir that gathers water in Itari forest
A tag attached to a seedling.
 There is an interesting story about such switch in afforestation
from coniferous trees suitable for mass market
locally procured broad-leaved trees.
I tell you about it in my later post
together with the thing of grassland and the forest;
they are related.
It’s the water purification plant for northern Hakone.
Not that huge, isn’t it?
After the planting we had a tour in the water purification plant.
The water from Itari forest is not contaminated,
but the plant is to make it sanitary.
Bacteria, poops of wild animals, etc, etc., you know?
the purified water is slightly acidic
due to volcanic activity of the area.
In order to make the taste
acceptable for the majority of the tourists,
the Authority adds baking powder
for neutralization before distribution.

Our senior Forest Instructors said, “What fascinating in afforestation is, we imagine how these babies grow. Here, the sun light comes from this direction so that these thin branches near the growing point will take a shape to receive the max energy from the sun in such way (he explained by body language). The direction of the tree to get taller will also be affected by the direction of sun. Then, there will be a race for survival not only among these seedlings we planted today, but also with weeds and wild seedlings now dormant in the soil but will come out sooner. All compete for the max sun shine, and water and nutrients underground. Taking care of the planting site is watching a gradual change of the natural community where we brought the seedlings. Sometimes, our first expectation will be completely off target because some seedlings could not survive for their first few years. Others could have a shape we did not expect originally. Some became spectacular, another just mediocre. We know we cannot live long enough to make it sure how the most successful baby tree becomes in hundreds of years. That’s the best part of afforestation, realizing such things by attending the same forest for a long time.”

They are about 70 years’ old trees in Itari.

In the event of forest management by the Green Trust, we returned the same place during summer for mowing. Certainly, the seedlings we planted were surrounded by tall weeds and in a competition with wild seedlings such as Japanese pepper (Zanthoxylum piperitum). “Please mow all except the planted seedlings!” OK. When I cut the pepper tree, the air was filled with the pure aroma of Japanese pepper … piquant and a hint of fresh mint. Do you think mowing them wasteful? Well, I’m sure when we return the same place next summer, another wild Japanese pepper trees are establishing themselves no matter what. The caged afforestation field in Hakone is the place for the survival of the fittest.   Very Mad Max place. Welcome Aunty Entity.

The afforestation site in August.
The wild weeds are dominating the place.
After mowing.
The baby trees can take a breath now.
In the established coniferous forest of Itari,
in August wild Hydrangea macrophylla had very large buds everywhere.

If you find environmental problems in Hakone, please make a contact to the Visitor Center of Hakone National Park
Hakone Visitor Centre, Ministry of Environment 環境省 箱根ビジターセンター
164 Motohakone, Hakone-machi, Ashigara-shimo-gun, Kanagawa, 250-0522
250-0522 神奈川県足柄下郡箱根町元箱根164
(TEL) 0460-84-9981
(FAX) 0460-84-5721