I-Humus insundu ngokumnyama, i-amorphous, i-polydispersed organic substance enesisindo samangqamuzana aphezulu okonakaliswe kanzima. Yakhiwa ngokubola komzimba, amakhemikhali, kanye ne-microbial kanye nokuguqulwa kwezinsalela zezilwane nezitshalo. Ngakho-ke, ikhona ngobuningi enhlabathini, i-peat, i-lignite, amanzi kanye ne-sediment. Izithako eziyinhloko ezisebenzayo ku-humus yi-humic acid ne-fulvic acid, futhi iqukethe inani elincane le-humin. Njengoba i-humic acid inyibilika ku-alkali kodwa hhayi ku-asidi, i-fulvic acid iyancibilika ku-asidi ne-alkali, kanti i-humus ayincibiliki ku-asidi ne-alkali, kanti i-HM ayincibiliki ku-asidi ne-alkali. , ngakho-ke zingahlukaniswa futhi zihlanzwe ngokwezinga elithile ngokuncibilika. I-Humic acid iyi-macromolecular organic acid eyakhiwe ngamaqembu anephunga elimnandi futhi ahlukahlukene asebenzayo. Ine-reactivity ephezulu futhi isetshenziswa kabanzi kwezolimo, imithi kanye nokuvikelwa kwemvelo kanye neminye imikhakha.