rice husk ash; rice husk charcoal
Agricultural material made by smoldering rice husks; used as a soil conditioner, often called 'kuntan' in gardening contexts.
Mixing rice husk ash into the soil improves aeration.
I use rice husk charcoal in my home garden.
Standard kanji spelling combining くん (smolder) and 炭 (charcoal).
Alternate kanji spelling using 燻 (smolder) instead of the kana くん.
Compound of 燻 (kun, 'smolder') and 炭 (tan, 'charcoal'), referring to charcoal produced by smoldering rice husks.