I've posted elsewhere on making charcoal from rice husks, and this year, I made my own.
I took an old petrol can, and using a steel punch and small sledgehammer, cut out a chimney hole and some side-holes. Making round holes with a punch is a satisfying and enjoyable pastime, although inevitably the jagged edges rip bloody holes in one's fingers...
At the height of the harvest season, I went to the local rice mill and asked permission to take some of the husks. "Any time, feel free", they said, and you can see why. In Japanese we say 'yama'.
I was too busy tending the process to take photos this time. You need to be careful making rice husk charcoal. You can leave it unattended for the first couple of hours, but thereafter it needs watching for safety and best results. If you don't put it out carefully when it's done, it'll burn up leaving very little residue. You need to dump rather more water on it than you might think to put it out inside. I thought maybe I could use a chimney of green bamboo, but my friend reckoned it would catch fire, so I sprung for a proper metal chimney. Glad I did, because the bamboo would definitely have burned merrily. 'Hi no youjin' as they say - be careful when you play with fire.
A lot of people don't bother toasting their husks and just apply them straight on their rows. It seems to work OK, but in my experience, the husks take several years to rot down. (When I stopped my bike to take this picture, I put my left foot down 'all wrong' and twisted my ankle so that I suddenly fell, bike and all, off the path and about a metre into a dry rice field. I landed painlessly on my back. If there had been a stone, or a piece of fencing, or some old machinery where I fell, that would probably have been it. All of a sudden, like.)