What is the Difference Between Humic Acid Fulvic Acid and Humin?

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Humic acid, fulvic acid, and humin are all humic substances found in soil, but they have differences in their solubility, molecular structure, and functional properties. Here are the main differences between humic acid, fulvic acid, and humin:

  • Solubility: Fulvic acids are soluble in water at all pH values, while humic acids are soluble at higher pH values (pH>2) but insoluble at lower pH values. Humin is insoluble in water at all pH values.
  • Molecular Size and Structure: Humic acids have larger and more complex molecular structures than fulvic acids. Fulvic acids have smaller molecular sizes and can be easily absorbed by plant roots, stems, and leaves.
  • Oxygen and Carbon Content: Fulvic acids have a higher oxygen content compared to humic acids.
  • Functional Properties: Humic acids and fulvic acids work together synergistically to support plant growth. Humic acids improve soil structure, stimulate root and shoot growth, and improve the soil's ability to retain water and nutrients. Fulvic acids, due to their smaller size and electrical charge, are effective chelating agents that can bind and transport nutrients into plants. They also stimulate root growth, allowing plants to increase both water and nutrient uptake.

Both humic and fulvic acids are essential for healthy plant growth, and using one without the other may not provide the most effective benefits. It is recommended to use both humic and fulvic acids together, as they work in harmony to support plant growth and overall soil health.

Comparative Table: Humic Acid Fulvic Acid vs Humin

Here is a table comparing the differences between humic acid, fulvic acid, and humin:

Property Humic Acid Fulvic Acid Humin
Solubility in Water Insoluble at acidic pH, soluble at alkaline pH Soluble in water at all pH values Insoluble in water at any pH
Molecular Size Large molecules Smaller than humic acids, but larger than simple organic molecules Not defined in the search results
Molecular Weight Higher molecular weight Lower molecular weight than humic acids Not defined in the search results
Carbon and Oxygen Content Higher carbon content and lower oxygen content than fulvic acids Lower carbon content and higher oxygen content than humic acids Not defined in the search results
Acidity Alkaline solutions Acidic solutions Not defined in the search results
Color Dark brown to black Golden yellow Not defined in the search results
Biological Activity Less biologically active than fulvic acids More biologically active than humic acids Not applicable
Function in Soil Helps provide an optimal growing environment Enhances plant growth and nutrient uptake Not applicable

Humic acid and fulvic acid are both humic substances, along with humin. They are different in chemical structure and appearance, mainly due to their solubility in water and their carbon, oxygen, and acidity content. Humic acids are large molecules that function best in soil to provide an optimal growing environment, while fulvic acids are smaller molecules that enhance plant growth and nutrient uptake. Humin is insoluble in water at any pH and does not play a direct role in plant growth.