Humic acid is a kind of natural polymer aromatic weak acid polymer with complex structure. Mainly from leonardite, peat, lignite and biological fermentation.Usually consisting of fulvic acid, brown humic acid and black 
humic acid, called Humic Acid (HA), the main elements: C, O, N, H, S.
Its active groups contain: carboxyl, hydroxyl, alcohol hydroxyl, enol group, sulfonic acid group, amino, quinone group, carbonyl, methoxy and other genes, with ion exchange, complexation, chelation, flocculation, dispersion, bonding and other functions.
1. Soil improvement
Humic acid is a porous substance. Which can improve the aggregate structure of soil. Adjust the water, fertilizer, air and heat conditions of soil, improve the soil exchange capacity. Adjust the PH of soil. Achieve the acid-base balance.
Its adsorption and complexation reaction can reduce the harmful substances in the soil (including pesticide residues, heavy metals and other toxic substances). Enhance the natural purification ability of the soil. Reduce pollution. Meanwhile, due to the colloidal properties of humic acid, the microbial community in soil can be improved. Which is suitable for the growth and reproduction of beneficial bacteria.
2. Stimulate fruit tree growth
Humic acid contains a variety of active genes. Which can enhance the activity of catalase and polyphenolic oxidase in fruit trees. Stimulate the physiological metabolism of plants. Promote the young trees to develop roots quickly, have a large number of roots, have developed roots, strong and luxuriant stems, branches and leaves, strong photosynthesis, and accelerate the transfer and absorption of nutrients.
3. Enhance the effect of fertilizers
Humic acid contains carboxyl group, phenolic hydroxyl group and other active groups. Which have strong exchange and adsorption capacity. Reduce the loss of ammonium nitrogen and improve the utilization rate of 
nitrogen fertilizer. Degraded fulvic acid can increase the distance of phosphorus moving in soil. Inhibit the fixation of water-soluble phosphorus in soil. Promote the absorption of phosphorus by roots.
Also can absorb the storage potassium ion. Causes the potassium fertilizer to decompose slowly. Enhances the quick effect Potassium content. It can chelate with calcium, magnesium, copper, zinc and other insoluble metal ions to promote the absorption of trace elements in fruit trees,so does the microbial growth.
4. Enhance resistance ability and improve fruit quality
Humic acid can reduce the opening of stomata on the leaves. Reduce the evaporation of water on the leaves. Adjust the amount of water. Improve the water condition in the plants. Ensure the normal growth of fruit trees under drought conditions. As amphoteric colloid, it has great surface activity and can inhibit fungus. Enhance cold resistance of fruit trees and reduce pests and diseases.
Humic acid can complex or chelate with trace elements, regulate the proportion of Massive element elements and trace elements, strengthen the synthesis and operation of enzymes on sugar, starch, protein and various vitamins, make polysaccharide into soluble sugar, promote the synthesis and accumulation of starch and protein, increase fruit and sugar content.
