Humus bụ ihe na-agba ọchịchịrị-agba aja aja, amorphous, ihe organic na-agbasasị agbasa nke nwere ịdị arọ molekụla dị elu nke na-emebi emebi. A na-etolite ya site na ndakpọ anụ ahụ, kemịkalụ, na microbial na ngbanwe nke anụmanụ na ihe ọkụkụ. Ya mere, ọ dị n'ọtụtụ buru ibu na ala, peat, lignite, mmiri na sedimenti. Isi ihe na-arụ ọrụ na humus bụ humic acid na fulvic acid, ma nwee obere humin. Ebe humic acid na-agbaze na alkali ma ọ bụghị na acid, fulvic acid na-agbaze na acid na alkali, na humus na-adịghị edozi na acid na alkali, na HM na-adịghị edozi na acid na alkali. , n'ihi ya, ha nwere ike kewaa ma dị ọcha ruo n'ókè ụfọdụ site na solubility. Humic acid bụ organic acid macromolecular nke nwere aromatic na otu dị iche iche na-arụ ọrụ. Ọ nwere nnukwu mmeghachi omume ma na-ejikarị arụ ọrụ ugbo, ọgwụ na nchekwa gburugburu ebe obibi na mpaghara ndị ọzọ.