1、Soil Organic Matter Revisited: Why Humic Substances Still Matter

We propose that HS indeed differ from non-humic substances, with HS consisting of both residual and synthetic quasi-macromolecular substances components, which collectively form unique compounds or compound groups with independent characteristics.

2、Soil Organic Matter, Humus, and Humic Acid: Unlocking the Secrets to

Humus can be divided into different components based on its structure and chemical properties, including humin, humic acid, fulvic acid, and ulmic acid. Here are the main distinctions among them:

3、ORGANIC MATTER, HUMUS, HUMATE, HUMIC ACID, FULVIC

Humus is the major soil organic matter component, making up 65% to 75% of the total. Humus assumes an important role as a fertility component of all soils, far in excess of the percentage contribution it makes to the total soil mass.

4、Microsoft Word

As organic matter breaks down in soil, humic acids (Humic acid & Fulvic acid) are formed. To some extent they are the biological heart of natural organic matter.

5、Humic Acid Fertilizer vs Organic Fertilizer: Key Differences

Organic fertilizer supplies nutrients directly, while humic acid fertilizer improves the soil’s ability to retain, transport, and make those nutrients available to plant roots.

Understanding the Role of Humic Acids on Crop Performance and Soil Health

Humic acids (HA) are organic molecules that play essential roles in improving soil properties, plant growth, and agronomic parameters. The sources of HA include coal, lignite, soils, and organic materials.

The essential role of humified organic matter in preserving soil health

This review first describes the contemporary understanding of the supramolecular structure of soil humus and the derived modern method to identify the totality of humic components to an unprecedented extent in soils under different soil management and cropping systems.

HUMIC ACID: THE SCIENCE OF HUMUS AND HOW IT BENEFITS SOIL

We must begin by understanding that there is a difference between soil organic matter and humus. “Humus” is a general term that describes a group of separate but distinct humic substances.

Microsoft Word

Humic substances are recognized by most soil scientists and agronomists as the most important component of a healthy fertile soil. To illustrate how humic substances function, the following summary, based on published scientific data, has been prepared as a guide for an educational program.

Humic substances: Structure, function and benefits for

This review advocates switching to use of organic matter (manure and compost) that contains vital nutrients for plant growth and helps restore soil health. Humic substances (HSs), derived from degraded plant remains and found ubiquitously in nature, are an important source of organic matter.

Humic acid and soil organic matter (SOM) are two critical components in soil, playing key roles in soil formation, structure, and functionality. Although both exist in organic forms, their sources, properties, and functions differ significantly. Below is a detailed comparison:

1. Different Sources

Humic acid primarily originates from the decomposition of organic materials (e.g., plant and animal residues, manure) driven by microbial activity. In contrast, SOM encompasses a broader range of organic materials found in soil, including plant residues, animal excreta, fallen leaves, and other biomass.

2. Different Properties

Humic acid is a high-molecular-weight organic compound with a complex structure composed of aromatic hydrocarbons, aliphatics, heterocyclics, and oxygen-containing functional groups (e.g., carboxyl, phenolic hydroxyl, and ketone groups). These functional groups enable strong adsorption and chelation capabilities.

SOM, meanwhile, has a simpler molecular structure, mainly consisting of carbon-based chains or branched structures. It contains elements like carbon, hydrogen, nitrogen, phosphorus, sulfur, and trace minerals.

3. Different Functions

Humic acid acts as a soil amendment, enhancing fertility, water retention, and physical properties (e.g., reducing soil bulk density and increasing porosity). It also regulates soil pH and improves stress resistance.

SOM serves broader functions, including nutrient provision for plants, stimulating microbial activity, and improving soil structure. It enhances water/nutrient retention, aeration, and overall soil health.

4. Different Formation Processes

Humic acid forms through prolonged microbial decomposition of organic matter, a slow process. SOM formation involves diverse biological and chemical processes, such as the breakdown of plant litter, animal waste, and other organic inputs.

5. Different Application Areas

Humic acid is widely used in agriculture as an organic fertilizer or soil conditioner. SOM, has broader applications, extending to environmental protection (e.g., carbon sequestration) and energy development (e.g., biofuel production).

While both humic acid and SOM are organic, they differ in origin, composition, function, and formation. Understanding these distinctions helps optimize their use in agriculture and ecology.

Key Terms:

• Humic Acid: A complex organic molecule formed via microbial decomposition.
• Soil Organic Matter (SOM): A diverse mix of organic materials in soil, crucial for ecosystem health.