Co/ Prof. Stephen Joseph, from his work in Vietnam with Mai Lan Anh, May 2016

1. Draft For Comment
Producing Biochar in the Kontiki in Monsoon
Season With Wet Feed Stock
Mai Lan Anh and Stephen Joseph
May 2016
675.5
420
1200
Volume = 375 L

2. Context
• Main biomass feedstocks in monsoon season are sawmill
waste wood from acacia plantations, twigs and
branches, bamboo, manure and very small amount of
straw and rice husks
• These feedstock have moisture content above 25%
• Biochar needs to be made just before harvesting as
farmers are busy when harvesting starts and then they
will prepare soil for the second crop
• Farmers only want to spend 4-6 hours in one day to make
biochar.
• They were prepared to make about 50kg of biochar/clay
straw manure mixture

3. Getting Started
Kontiki made in local
metal shop out of small
sheet of metal and
transported by motorbike
to farm
Small cone made
in damp clayey soil

4. Straw and waste wood
Twigs and stick
Twigs and stickTwigs and stick
Loading and Starting the Kiln
Put small wood and
twigs at bottom of kiln
Add straw and waste wood Start Kiln by Lighting Straw
Add Twigs

5. Straw husk manure and red clayey soil
Twigs and stick
Biochar
and Ash
Operating the Kiln
Slowly Add
Wood so Fire
not too Hot but
there is No
Smoke. Keep
adding wood
until the kiln is
nearly 70% full
Make a mixture
of equal parts
by weight of
straw rice husk
manure and
clayey soil

6. Quenching the Kiln With Clayey Soil Manure and Straw
Quickly add the
mixture. There will
be a little smoke
for one minute
Add more clayey
soil and allow the
mixture to stand
overnight.
Temperature of mixture near
wood biochar after 1 hour

7. The Kiln Is Allowed to Cool for 24hrs. The Kiln is tipped on its side.
Then the Mixture is Quenched with Urine
Wood biochar

8. The Biochar from the bottom of the kiln is mixed with the
clay straw manure and the mixture is applied to the
manure that is in the cattle pen to eliminate odours and
soak up more nutrients.
The straw manure and biochar is composted for 20-30
days before applying to the field