Characteristics and Functions of Water-Soluble Humic Acid Fertilizers

　　The extraction (or isolation) of humic acid and fulvic acid refers to the process by which these substances are separated from raw materials using solvents such as strong alkaline solutions, neutral salts, organic acid salts, organic solvents, and organic chelating agents. Through specific technical treatments—such as acidification, sulfonation, nitration, degradation, and oxidation—the chemical and biological activities of humic acid (and fulvic acid) can be enhanced and improved. Water-soluble humic substances generally refer to fulvic acid, or to the portions of humic acid, nitro‑humic acid, and fulvic acid that exist as monovalent salts soluble in water.

　　 Characteristics of Water-Soluble Humic Acid Fertilizers

　　Water-soluble fertilizer (WSF) refers to a multi‑element compound fertilizer that can completely dissolve in water, offering notable advantages such as rapid solubility, high nutrient uptake, quick effectiveness, no residue, and ease of application. Water‑soluble humic acid fertilizer is a liquid or solid water‑soluble fertilizer formulated by incorporating humic acid at proportions suitable for plant growth, along with appropriate amounts of macronutrients—nitrogen, phosphorus, and potassium—or micronutrients such as zinc, boron, iron, molybdenum, manganese, and copper. After being dissolved or diluted in water, it can be used for fertigation, foliar application, soilless cultivation, seed soaking, root dipping, and other purposes. Its key characteristics include:

　　First, the use of modern technologies to purify water-soluble humic acids and formulate a novel fertilizer enriched with macro-, meso-, micro-, and special‑element nutrients has demonstrated remarkable efficacy, thereby providing robust support for producing green, health‑promoting food, mitigating environmental pollution, and reducing farmers’ production costs.

　　Second, water-soluble humic acid fertilizers can significantly enhance nitrogen availability, solubilize phosphorus, and promote potassium uptake in the soil, thereby improving soil fertility and stimulating root development in crops.

　　Third, water-soluble humic acid fertilizers are widely applicable to food crops, cash crops, oilseed crops, and ornamental flowers, with a broad spectrum of suitable crops and a wide range of recommended application concentrations.

　　Fourth, water-soluble humic acid fertilizers feature a well-balanced nutrient formulation and exhibit synergistic nutritional effects, enabling a substantial reduction in the application rates of chemical fertilizers and pesticides.

　　Fifth, water-soluble humic acid fertilizers are economical, safe, convenient, and highly efficient.

　　Water-soluble humic acid fertilizers can be formulated as multi‑nutrient complexes. Among these, macronutrient formulations are available in either solid or liquid forms, while micronutrient formulations are offered exclusively as solid products.

　　 The integration of humic acid with bulk fertilizers

　　Humic acid, as a versatile fertilizer enhancer, can integrate nitrogen (N), phosphorus (P), and potassium (K) into single‑component, binary, or ternary formulations—such as humic‑acid‑based nitrogen fertilizers, phosphorus fertilizers, potassium fertilizers, and compound fertilizers. By combining N, P, and K, humic acid offers flexible and diversified applications, outstanding functionality, significant yield‑boosting effects, and high nutrient utilization, achieving an integrated synergy that exceeds the sum of its parts.

　　The organic integration of humic acid with nitrogen fertilizers yields a humic‑acid‑based nitrogen fertilizer that combines both rapid and slow release, thereby reducing nitrogen losses and the resulting ammonia pollution. Humic acid enhances nitrogen use efficiency by 10% and can increase crop yields by more than 15%.

　　When combined with phosphate fertilizers, humic acid can reduce phosphorus fixation and enhance phosphorus use efficiency. Moreover, the incorporation of humic acid into the soil can mobilize previously fixed phosphorus, thereby increasing the soil’s available phosphorus supply. The combined effect typically boosts available phosphorus by 6.7 to 8.3 mg/kg, and humic‑acid‑based compound phosphate fertilizers can increase crop yields by more than 10%.

　　The organic combination of humic acid and potassium fertilizer yields a humic‑potassium fertilizer that delivers both rapid and sustained nutrient release. Moreover, when humic acid binds with potassium ions (K+), the resulting complex is more stable than the one formed with ammonium ions (NH4+). Humic‑potassium exhibits excellent water solubility, which does not hinder plant uptake but instead prolongs fertilizer efficacy. Studies have shown that humic acid can increase potassium absorption by crops by more than 30% and boost yields by over 12%.

　　 The integration of humic acid with specialized fertilizers

　　Leveraging the intrinsic properties of humic acid, it is possible to develop specialized fertilizers for field crops, cash crops, and floriculture, as well as substrates for seedling cultivation. The development of functional fertilizers has become an urgent need in agricultural production. Water-soluble fertilizers formulated with humic acid chelating selenium, zinc, magnesium, and other nutrients can be used to cultivate and produce products—such as shiitake mushrooms, apples, and rice—that are rich in these elements; these products not only offer superior taste but are also easily absorbed and play a crucial role in boosting immunity.