The key difference between humic acid and fulvic acid is that humic acid is not absorbed by plants whereas fulvic acid is absorbed.
Humic acids and Fulvic acids are frequently used as plant nutrient supplements. Normally, a humic substance contains many molecules. Some molecules contain aromatic nuclei with attached phenolic and carboxylic groups. These contribute to the surface charge of the molecule. Humic acids behave like dibasic acids. However, humic acid is not absorbed by plants whereas fulvic acid is absorbed. Therefore, Fulvic acids are more plant active forms than humic acids.
CONTENTS
1. Overview and Key Difference
2. What is Humic Acid
3. What is Fulvic Acid
4. Side by Side Comparison – Humic Acid vs Fulvic Acid in Tabular Form
5. Summary
What is Humic Acid?
Humic acid is a component of humic substances. In other words, humic acid is the collective name of the acid radical present in a humic matter. These are soluble in water at greater pH value, but not under acidic conditions. Liquid humic acid is a suspension. We can apply it in plant production as a plant growth stimulant and soil conditioner.
Moreover, we can isolate potassium humates from leonardite and then dissolve them in water. The outcome is an aqueous suspension that has a high content of humic acids, iron, and potassium as well as a large number of trace elements. Now, this is ready for uptake by plants. These are very important in horticulture.
Figure 1: Structure of Humic Acid
Plant growth depends on inorganic compounds. Organic matter is useful for plants only if it breaks down into inorganic forms. Humus increases the water-holding capacity of the soil and influences soil fertility. Humic acid helps plant tissues to acquire the required amount of oxygen for aerobic respiration. It also can combine with sunlight and photosynthesis. When we spray humic acid on to the leaves, the amount of oxygen the plant takes up changes significantly; this enhances plant growth. Humic acid also can increase the productivity of microorganisms. They can also act as hydrogen acceptors in plant root storage tissues. Humic acid, if we spray it on to the leaves, can also increase the chlorophyll content in the leaves. Moreover, it can also directly influence enzyme synthesis.
What is Fulvic Acid?
Fulvic Acid is a type of humic acid compounds. It is the most plant active humic acid compound. Fulvic acid gives many physical, chemical and biological benefits. This compound helps to dissolve minerals and metals. They dissolve into ionic forms. Fulvic acid turns these metals and minerals into a readily absorbable, bioavailable form. Moreover, it can weather and dissolve silica.
Figure 2: Structure of Fulvic Acid
Fulvic acid increases the availability of nutrients and makes them more readily absorbable by plants. Furthermore, it can readily complex with minerals and metals. Then, they become available to plant roots and are easily absorbed through cell walls. Fulvic acid can help the immobile elements to be easily transported. Moreover, it can also dissolve vitamins, coenzymes, auxins, hormones, and natural antibiotics and make them easily available. Fulvic acids have the capability to react with each other and with cells and synthesize new mineral compounds. One of the best examples is the transmutation of vegetal silica and magnesium to form calcium in animal and human. In addition, fulvic acid can store complex vitamins.
What is the Difference Between Humic Acid and Fulvic Acid?
Humic acid is a component of humic substances, and fulvic acid is a type of humic acid compounds. The key difference between humic acid and fulvic acid is that humic acid is not absorbed by plants whereas fulvic acid is absorbed. Furthermore, all fulvic acids are humic acids, but not all humic acids are fulvic acids.
Moreover, fulvic acids have a lower molecular weight than humic acids. It is because the size of the humic acid molecule is larger than the size of the fulvic acid molecule. Besides, a visible difference between humic acid and fulvic acid is that the humic acid has a black or dark brown color while substances containing fulvic acid have a yellowish brown color.
Summary – Humic Acid vs Fulvic Acid
Fulvic acids are more plant active forms than humic acids. Therefore, the key difference between humic acid and fulvic acid is that humic acid is not absorbed by plants whereas fulvic acid is absorbed. Moreover, humic acid is important to retain the moisture content in the soil while fulvic acid is important in carrying nutrients to the plant.
Reference:
1. “Humic Acid and How It Benefits Soil.” EcoFarming Daily, 11 Mar. 2019, Available here.
Image Courtesy:
1. “Humic acid” By Ronhjones – Own work (CC BY-SA 3.0) via Commons Wikimedia
2. “Fulvic acid” By Michał Sobkowski – Own work (Public Domain) via Commons Wikimedia