noun
Refers to organic matter decomposed for use as fertilizer. In agricultural contexts, 堆肥 often implies composted material, while 厩肥 (きゅうひ) specifically means barnyard manure.
家庭菜園で使う堆肥を作っています。
I'm making compost to use in my home garden.
堆肥を畑にまいて土を豊かにする。
Spread compost on the field to enrich the soil.
Compound of 堆 (たい, 'heap, pile') and 肥 (ひ, 'fertilizer, manure'), literally 'piled fertilizer'. The term reflects the traditional method of piling organic waste to decompose into compost.