What are the differences between humic acid, fulvic acid, potassium fulvate, and humic acid?

I. What is the difference between humic acid and humic substances?
There is no difference between humic acid and humic substances. Both names refer to the same thing. Humic acid generally refers to humic substances, so there is no difference between them; they mean the same thing.

Humic acid is a large-molecule organic substance widely found in nature and is widely used in agriculture, forestry, animal husbandry, petroleum, chemical industry, building materials, medicine and health, environmental protection, and other fields. Especially with the current advocacy of ecological agriculture, pollution-free agricultural production, green food, and pollution-free environmental protection, "humic acid" has become even more popular. Facts have proven that human life and survival are inseparable from humic acid.
Humic acid can also be called black humic acid, humic acid, humic acid, nitrohumic acid, and humic acid-like substances.
II. What is the difference between potassium humate and humic acid?
Potassium humate and humic acid differ in their chemical properties, sources, and functions:
1. Source: Potassium humate: Potassium humate is mainly extracted from humic acid and produced through microbial fermentation and chemical synthesis. Humic acid: Humic acid is widely found in nature, mainly originating from soil, aquatic sediments, and plant and animal remains.
2. Chemical properties: Potassium humate: Potassium humate is a water-soluble organic acid salt, the main component of which is potassium humate. Potassium humate has a relatively low molecular weight and exhibits good water solubility and biological activity. Humic acid (HA, humic acid): Humic acid is a natural, large-molecule organic compound mainly found in soil, aquatic sediments, and plant and animal remains. Humic acid has a relatively high molecular weight, usually with long carbon chains and multiple functional groups, giving it high biological activity and multifunctionality.
3. Function: Potassium humate: Potassium humate has the functions of regulating soil structure, improving nutrient utilization, and promoting plant growth. Humic acid: Humic acid has strong adsorption, exchange, complexation, and chelation chemical properties, which can improve soil structure, increase soil fertility, protect plant roots, and promote plant growth. In addition, humic acid also has antioxidant, pest and disease resistance, and crop quality improvement functions.
In short, potassium humate and humic acid are both beneficial soil amendments and fertilizer additives, but they differ in their sources, chemical properties, and functions.