We have constantly have projects we work on at Kainojuku Farm, and making 燻炭 / “Kuntan” was one we worked on last week.
A brief definition of some terms I’ll be using before I go on:
籾殻 – “Momigara”, or rice husks, are the protective shell that rice grains are covered in, and is taken off after the rice grain is harvested for consumption. Removing the momigara unveils the rice grain in its “genmai” or brown rice form.
燻炭 – “Kuntan” is a kind of biochar (biological charcoal) made from momigara. Japan has a long history of making and using charcoal, and kuntan is no exception. Kuntan is primarily used in soil and has many benefits: If added to acidic soils, it will help balance the pH levels because of its alkalinity. Additionally, the black color of kuntan will help heat up soil in the spring. Biochar has porous characteristics which helps with aeration of soil and increases the soils water holding capacity. That’s not all – because biochar absorbs nitrogen and holds water, creates a stable and moist place for bacteria and fungi to reside and prosper. Biodiversity, from animals to bugs, down to the micro organisms, is key in organic farming.
We are very fortunate to be surrounded by rice farmers, most whom are left with an abundance of momigara after harvesting their crop. A local rice farmer offered to drop off a truck load of it at the farm – which we happily accepted.
Once the fire got going, we covered the cone and chimney with momigara. The momigara touching the cone and chimney started to burn – and the fire eventually spread outwards, leaving charred momigara, which is the kuntan.
The momigara burned from the inside until creating blackened spots on the surface, which we covered with more uncharred momigara. We repeated this until the majority of the surface was covered in kuntan.
We then proceeded to flatten the mountain out, making sure everything was properly carbonized. Water was poured on the pile and kuntan collected into large barrels, which were then covered with a plastic sheet to cut off any oxygen that could fuel the fire.
The kuntan will be spread in our fields over the next few days to prepare for our spring crop.