Humic acid is a mixture of natural organic macromolecular compounds. It exists widely in nature, and the proportion of humic acid in soil is the largest. Soil humic acid is a heterogeneous complex mixture of physical and chemical properties. The molecular weight is polydisperse. The mixture is natural, high molecular weight, yellow to black. , Amorphous, colloidal, aliphatic and aromatic organic polyelectrolytes, which cannot be represented by a single chemical structural formula.
