Humus yog xim av-xim av, amorphous, polydispersed organic tshuaj uas muaj qhov hnyav molecular uas nyuaj degraded. Nws yog tsim los ntawm lub cev, tshuaj, thiab microbial decomposition thiab transformation ntawm tsiaj thiab nroj tsuag. Yog li ntawd, nws muaj nyob rau hauv ntau qhov av, peat, lignite, dej thiab sediment. Cov khoom xyaw tseem ceeb hauv humus yog humic acid thiab fulvic acid, thiab muaj me me ntawm humin. Txij li thaum humic acid yog soluble nyob rau hauv alkali tab sis tsis nyob rau hauv acid, fulvic acid yog soluble nyob rau hauv acid thiab alkali, thiab humus yog insoluble nyob rau hauv acid thiab alkali, thiab HM yog insoluble nyob rau hauv acid thiab alkali. , yog li lawv tuaj yeem sib cais thiab ua kom huv mus rau qee qhov los ntawm kev solubility. Humic acid yog macromolecular organic acid uas muaj ntxhiab thiab ntau pawg ua haujlwm ua haujlwm. Nws muaj reactivity siab thiab yog dav siv nyob rau hauv kev ua liaj ua teb, tshuaj thiab Environmental tiv thaiv thiab lwm yam teb.