Fulvic Acid & Humic Acid: Concepts, Characteristics and Applications

1. What is Humic Acid?

Humic Acid is a class of complex organic macromolecular substances widely found in nature. It mainly comes from the products formed by the long-term interaction of plant residues (such as fallen leaves and straw) with soil minerals after microbial decomposition, and is also abundant in natural minerals such as lignite, peat, and weathered coal.

Based on chemical properties and solubility, Humic Acid is usually divided into three major components:

• Humic Acid (narrow sense): Insoluble in water and acid, only soluble in alkaline solutions. It is the part of Humic Acid with large molecular weight and the most complex structure;

Humic Acid is a class of complex organic macromolecular substances widely found in nature. It mainly comes from the products formed by the long-term interaction of plant residues (such as fallen leaves and straw) with soil minerals after microbial decomposition, and is also abundant in natural minerals such as lignite, peat, and weathered coal.

• Huminic Acid: Soluble in dilute alkaline solutions, insoluble in water and dilute acid. Its molecular size and activity are between Humic Acid (narrow sense) and Fulvic Acid;

• Fulvic Acid: Fully soluble in water, acid and alkali. It is the component of Humic Acid with the smallest molecular weight and strongest activity, and also the most concerned part in agricultural applications.

2. Core Characteristics and Functions of Humic Acid

1. Improve Soil and Optimize Growth Environment

Humic Acid can combine with clay particles in the soil to form a stable "aggregate structure", reducing soil compaction, improving soil air permeability and water/fertilizer retention capacity; at the same time, it can adjust soil pH (neutralize acidity in acidic soil and alleviate salinization in alkaline soil), creating suitable conditions for crop root growth.

2. Adsorb Harmful Substances and Purify Soil

The macromolecular structure of Humic Acid has strong adsorption capacity, which can combine with heavy metal ions (such as lead, cadmium, mercury) in the soil to form stable chelates, preventing heavy metals from being absorbed by crops; at the same time, it can adsorb pesticide residues, reduce their activity in the soil, and reduce environmental pollution.

3. Activate Nutrients and Improve Fertilizer Utilization Rate

Humic Acid can promote the reproduction of microorganisms such as nitrogen-fixing bacteria, phosphorus-solubilizing bacteria and potassium-solubilizing bacteria in the soil, converting "invalid phosphorus and invalid potassium" (difficult to absorb by crops) in the soil into "available nutrients" (usable by crops); at the same time, it can reduce nitrogen fertilizer volatilization and leaching loss, extend the effective period of fertilizers, and reduce the amount of chemical fertilizers used.

3. What is Fulvic Acid? Its Relationship with Humic Acid

Fulvic Acid is the component of Humic Acid with the smallest molecular weight (1000-5000 Daltons), highest oxidation degree and strongest activity. It is named because it appears yellow in acidic solutions (the meaning of "Fulvic" is "yellow and soluble").

Its relationship with Humic Acid can be summarized as: "Fulvic Acid is the 'essence part' of Humic Acid, and Humic Acid is the 'matrix' of Fulvic Acid" — Fulvic Acid does not exist independently, but is the most functionally prominent component among the three major components of Humic Acid, with more "extreme" characteristics than Humic Acid:

1. Full Water Solubility, Wider Application Scenarios

Different from Humic Acid (narrow sense) and Huminic Acid (only soluble in alkali), Fulvic Acid can be completely dissolved in solutions of any pH value, with no precipitation or flocculation. It can be used in various fertilization methods such as foliar spraying, drip irrigation and drenching, especially suitable for the water-fertilizer integration system in modern agriculture.

2. Small Molecules for Easy Absorption, Faster Action Speed

Fulvic Acid has a small molecular weight and can be directly absorbed and utilized by crop roots and leaves without microbial decomposition and transformation; 1-3 days after use, the effect of crop leaves turning green and root germination can be observed, which is faster than Humic Acid (requiring 7-10 days).

3. Stronger Stress Resistance, Significant Effect in Alleviating Stress

Fulvic Acid can promote the synthesis of "stress-resistant substances" such as proline and soluble sugar in crops, enhancing the ability of crops to resist adverse environments such as drought, low temperature and salinity; at the same time, it has a significant alleviating and repairing effect on physiological diseases such as "small leaf disease" and "yellowing disease" caused by trace element deficiency.

4. Main Application Fields of Fulvic Acid and Humic Acid

1. Agricultural Field (Core Application)

• As a fertilizer additive: Mixed with NPK compound fertilizers to make "Humic Acid compound fertilizers" and "Potassium Fulvate fertilizers", improving fertilizer efficiency and reducing loss;

• Direct application: Humic Acid is mostly used as base fertilizer (to improve soil), and Fulvic Acid is mostly used as topdressing (to promote growth and resist stress), suitable for food crops, fruits, vegetables and cash crops;

• Seedling raising and transplanting: Fulvic Acid can be used for seed soaking and root dipping to improve seed germination rate and transplant survival rate.

2. Environmental Governance Field

• Soil remediation: Used for the improvement of heavy metal-contaminated soil and saline-alkali land, reducing the activity of pollutants;

• Water purification: Added to sewage to adsorb organic matter and heavy metals, improving the water environment.

3. Other Fields

• Feed industry: As a feed additive, it improves the intestinal environment of livestock and poultry and enhances immunity;

• Pharmaceutical and daily chemical industry: Due to its antioxidant and anti-inflammatory properties, Fulvic Acid can be used as a raw material for skin care products and pharmaceutical excipients (such as oral ulcer ointment).

5. Precautions for Selection and Use

1. Pay Attention to Source and Purity

• Humic Acid/Fulvic Acid from mineral sources (lignite, peat) has higher activity than products from plant sources (straw, manure);

• Choose products with third-party test reports to ensure that the Fulvic Acid content (≥50% is recommended for agricultural use) and heavy metal content (lead ≤5mg/kg, cadmium ≤0.5mg/kg) meet the standards.

2. Reasonable Matching to Avoid Conflict

• Avoid mixing with strongly alkaline pesticides (such as Bordeaux mixture) and high-concentration chemical fertilizers to prevent the failure of active ingredients;

• The combination of Fulvic Acid and trace elements (iron, zinc, boron) can enhance the chelating effect and improve absorption and utilization rate.

3. Control Dosage to Avoid Waste

• The general dosage of Humic Acid is 50-100kg per mu (base fertilizer), and the dosage of Fulvic Acid is 100-200g per mu (foliar spraying) or 1-2kg per mu (drenching);

• Excessive use will not improve the effect, but may lead to soil salt accumulation or excessive crop growth.