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Humic Acid vs. Fulvic Acid: What's the Difference?

Edited by Harlon Moss || By Janet White || Published on December 7, 2023
Humic acid is a large, complex molecule in soil organic matter, improving soil structure; fulvic acid is smaller, aiding nutrient absorption in plants.

Key Differences

Humic acid is a major component of humic substances, which are key elements of soil organic matter and contribute to soil health and fertility. Fulvic acid, while also a component of humic substances, is smaller in molecular size and plays a crucial role in the transport and absorption of nutrients in plants.
In terms of composition, humic acid is characterized by its large, complex molecules. These molecules are known for improving soil structure, water retention, and nutrient content. Fulvic acid has a lower molecular weight and is more biologically active, enhancing plant growth by facilitating the uptake of minerals.
Humic acid is known for its dark color, which can vary from dark brown to black, and is insoluble in water under acidic conditions. Fulvic acid is typically yellow to light brown and remains soluble across a wide range of pH levels, making it more available to plants in various soil types.
The benefits of humic acid in agriculture include improved soil aeration, increased water retention, and enhanced nutrient preservation. Fulvic acid is highly valued for its ability to chelate minerals, making them more bioavailable to plants, and for stimulating plant metabolism and root development.
When it comes to environmental remediation, humic acid is used to improve soil structure and reclaim contaminated soils. Fulvic acid, due to its smaller size and chemical properties, is effective in detoxifying pollutants and improving the overall health of plants in stressed environments.

Comparison Chart

Molecular Size

Larger, complex molecules
Smaller, simpler molecules


Insoluble in water under acidic conditions
Soluble across a wide pH range


Dark brown to black
Yellow to light brown

Role in Soil

Improves soil structure, water retention
Enhances nutrient uptake, plant growth

Environmental Applications

Soil conditioning, remediation
Plant health improvement, pollutant detoxification

Humic Acid and Fulvic Acid Definitions

Humic Acid

Humic acid is a key component in organic fertilizers.
Organic fertilizers rich in humic acid are preferred for sustainable farming.

Fulvic Acid

It stimulates plant growth and metabolism.
Using fulvic acid led to increased growth rates in the greenhouse plants.

Humic Acid

It enhances soil structure and nutrient retention.
The farmer used humic acid to enrich the nutrient content of his fields.

Fulvic Acid

Fulvic acid helps in detoxifying pollutants in the soil.
Fulvic acid was used to improve the health of plants in the polluted urban garden.

Humic Acid

Humic acid is used in environmental soil remediation.
Humic acid was key in reclaiming the contaminated industrial site.

Fulvic Acid

It facilitates the transport and absorption of minerals in plants.
The addition of fulvic acid to the soil enhanced the uptake of essential minerals by crops.

Humic Acid

Humic acid is a complex molecule part of soil organic matter.
Humic acid application improved the water-holding capacity of the sandy soil.

Fulvic Acid

Fulvic acid remains soluble across various pH levels.
Fulvic acid's solubility makes it effective in both acidic and alkaline soils.

Humic Acid

It is dark-colored and improves soil water retention.
The dark color of the soil is indicative of its high humic acid content.

Fulvic Acid

Fulvic acid is a small, bioactive component of humic substances in soil.
Fulvic acid's presence in the soil significantly boosts plant nutrient absorption.


Are humic and fulvic acids found together in nature?

Yes, they are both components of humic substances in soil.

Is fulvic acid useful in all types of soil?

Due to its solubility across various pH levels, fulvic acid is effective in many soil types.

What is humic acid?

Humic acid is a large, complex molecule found in soil that improves soil structure and fertility.

How do humic and fulvic acids differ in molecular size?

Humic acid molecules are larger and more complex than fulvic acid molecules.

Can both humic and fulvic acids improve soil health?

Yes, both contribute to soil health, but in different ways: humic acid improves soil structure, while fulvic acid enhances nutrient uptake.

Does fulvic acid aid in plant metabolism?

Yes, fulvic acid stimulates plant growth and metabolism.

What role does humic acid play in environmental remediation?

Humic acid is used to improve soil structure and reclaim contaminated soils.

What is fulvic acid?

Fulvic acid is a smaller component of humic substances, aiding in nutrient absorption and transport in plants.

How does humic acid affect soil water retention?

Humic acid improves soil's ability to retain water, benefiting plant growth.

Can humic acid be used in organic farming?

Yes, humic acid is commonly used in organic farming practices.

How does fulvic acid affect plant nutrient uptake?

Fulvic acid increases the bioavailability of nutrients, making them easier for plants to absorb.

Is fulvic acid soluble in water?

Yes, fulvic acid remains soluble across a wide range of pH levels.

Are there any commercial uses for humic acid?

Humic acid is used in agriculture, horticulture, and environmental remediation.

Can humic acid improve plant growth?

Indirectly, by enhancing soil quality, humic acid can foster better plant growth.

How do humic and fulvic acids benefit plants?

Humic acid improves soil health, while fulvic acid enhances nutrient absorption and plant growth.

How do farmers apply humic acid to crops?

Humic acid is often applied to crops as a component of organic fertilizers or soil conditioners.

What is the color of humic acid?

Humic acid is typically dark brown to black in color.

Can fulvic acid be used in hydroponic systems?

Yes, fulvic acid is beneficial in hydroponic systems for its nutrient chelating and plant growth-stimulating properties.

Can fulvic acid detoxify soil pollutants?

Yes, fulvic acid helps in detoxifying pollutants in the soil.

Does fulvic acid have any role in sustainable agriculture?

Yes, fulvic acid is valued in sustainable agriculture for its role in enhancing nutrient efficiency and plant health.
About Author
Written by
Janet White
Janet White has been an esteemed writer and blogger for Difference Wiki. Holding a Master's degree in Science and Medical Journalism from the prestigious Boston University, she has consistently demonstrated her expertise and passion for her field. When she's not immersed in her work, Janet relishes her time exercising, delving into a good book, and cherishing moments with friends and family.
Edited by
Harlon Moss
Harlon is a seasoned quality moderator and accomplished content writer for Difference Wiki. An alumnus of the prestigious University of California, he earned his degree in Computer Science. Leveraging his academic background, Harlon brings a meticulous and informed perspective to his work, ensuring content accuracy and excellence.

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