noun
rice husk ash; rice husk charcoal
Agricultural material made by smoldering rice husks; used as a soil conditioner, often called 'kuntan' in gardening contexts.
くん炭を土に混ぜると、通気性が良くなります。
Mixing rice husk ash into the soil improves aeration.
家庭菜園でくん炭を使っています。
I use rice husk charcoal in my home garden.
もみ殻 is the raw rice husk, while くん炭 is the carbonized ash product made from it.
炭 is general charcoal, often from wood; くん炭 specifically refers to rice husk ash.
Compound of 燻 (kun, 'smolder') and 炭 (tan, 'charcoal'), referring to charcoal produced by smoldering rice husks.