1、Humic acids: Structural properties and multiple functionalities for

Humic acids (HAs) are macromolecules that comprise humic substances (HS), which are organic matter distributed in terrestrial soil, natural water, and sediment.

2、Molecular Characterization of Size

Understanding the relationship between the structure and function of HA is the key to efficient utilization of HA in the field of activating soil legacy phosphorus (P) and promoting crop growth. In this work, HA was prepared using lignite as raw materials by the ball milling method.

3、Development and characterization of phosphate tailings

The purpose of this study was to use ball milling technology and sludge acid to activate phosphate tailings and humic acid, and successfully synthesize activated phosphate tailings-based humic acid slow-release fertilizer (APHF) under normal temperature and pressure.

4、Molecular Signatures of Humic Acids from Different Sources as Revealed

JFHA, SRHA, and LEHA from soil, river, and leonardite, respectively, are arranged in order from the lowest to highest degree of humification, according to molecular unsaturation and aromaticity of HAs. Soil HA is more labile and contains many large molecular weight compounds with low unsaturation.

5、Adsorption of Humic Acid by Acid

Adsorption capacities for humic acid were appraised for each type. Nitric acid and sulfuric acid modification increased humic acid adsorption capacity, as compared with untreated and base–modified activated carbon.

2e.xps

Humic acid (normal and activated) was sprayed at two concentrations of 2 and 3 ml per liter of water. Spraying activated humic acid gives relatively better results than spraying conventional extracted humic acid.

Content of Total humic acid, free humic acid and water

The total humic acid content refers to the sum of free humic acid and humic acid combined with high-valent metal ions such as Ca2+, Mg2+, Fe3+, Al3+ (the latter is commonly referred to as “bound humic acid”).

Editorial: Molecular characterization of humic substances and

In the study by Olk et al., the authors described the presence of 11 phenol and five carbohydrate monomers in the whole plant stover, over four growing seasons, and roots, over two growing seasons, of maize. These determinations were made at physiological maturity in two rainfed fields in Iowa (USA) after HS application.

Acid–base properties of humic acid from soils amended with different

This current study investigates the acid–base properties of humic acid (HA) extracted from the soils and its implication for plant nutrient availability.

Advances and challenges in humic acid production technologies from

NCM-based HAs have a high molecular weight, low —COOH content, and high Ar—OH content, while soil-based HAs contain more acidic groups, lower molecular weight, lower aromatic content, lower C/N ratio, and higher —COOH content [18].

Activated humic acid is an organic matter primarily derived from the decomposition of animal and plant residues under microbial action. It is rich in essential nutrients such as nitrogen, phosphorus, and potassium, as well as various trace elements and vitamins, significantly promoting plant growth. Determining the normal range of activated humic acid content is complex, as it is influenced by multiple factors including soil type, climatic conditions, crop species, and growth stages. The following are recommendations for the normal range of activated humic acid content:

1. Soil Type: Different soil types have varying requirements for activated humic acid. Generally, sandy and loamy soils tend to have higher activated humic acid content, while clay soils have lower levels. when selecting fertilizers, appropriate products should be chosen based on soil type.

2. Climatic Conditions: Climate also affects activated humic acid content. In arid regions, where soil moisture is limited, higher amounts of activated humic acid are needed to maintain soil fertility; whereas in humid areas, where soil moisture is abundant, the usage can be appropriately reduced.

3. Crop Species and Growth Stages: Different crops have distinct demands for activated humic acid. For example, legumes and corn require higher levels, while cotton and wheat need less. Additionally, crop growth stages influence the demand. During the growth phase, when nutrient absorption is strong, activated humic acid application can be increased; during flowering and fruiting stages, when absorption weakens, the dosage should be reduced.

4. Soil pH: Soil acidity or alkalinity impacts activated humic acid content. Acidic soils typically have lower levels, while alkaline soils have higher concentrations. Thus, fertilizer selection should consider soil pH.

5. Fertilizer Quality: Activated humic acid products from different brands may vary in concentration. Reliable brands should be chosen to ensure effectiveness and safety.

6. Fertilization Methods: Proper application techniques are crucial for maintaining optimal activated humic acid levels. Fertilization rates and timing should align with crop growth stages and soil conditions. For instance, increase application during growth phases and reduce during flowering and fruiting. Avoid over-application to prevent resource waste and environmental pollution.

the normal range of activated humic acid content depends on various factors. comprehensive consideration of these elements is essential during fertilization to achieve suitable levels. Additionally, selecting reliable brands and employing correct application methods ensures both efficacy and safety of the fertilizer.