Water-soluble fertilizers (WSF) are a type of fast-acting fertilizer with high-purity raw materials that dissolve completely in water. Their core characteristics are no residue and easy absorption. They can be applied through drip irrigation, sprinkler irrigation, and fertigation to achieve integrated water and fertilizer management, precisely matching the nutrient needs of crops at different growth stages. They are a mainstream high-efficiency fertilizer variety for facility agriculture and cash crop cultivation.
I. Core Characteristics and Raw Material Requirements
Completely Water-Soluble: The raw materials for water-soluble fertilizers must be high-purity chemical salts or chelated compounds. After dissolving, they leave no solid residue and will not clog irrigation equipment such as drip tapes and sprinklers.
Macronutrient Raw Materials: Industrial-grade urea, potassium dihydrogen phosphate, potassium nitrate, potassium magnesium sulfate, etc., with a purity typically ≥98%.
Micronutrient Raw Materials: Chelated zinc (EDTA-Zn), chelated iron (EDTA-Fe), boric acid, etc., avoiding binding with ions in the soil and loss of efficacy.
Micronutrient Raw Materials: Flexible Nutrient Ratios
Formulas can be customized according to crop nutrient requirements, for example:
Seedling Stage Fertilizer: High-phosphorus formula to promote root development;
Fruit Expansion Stage Fertilizer: High-potassium formula to enhance fruit sweetness and color;
All-Purpose Fertilizer for the Entire Growth Stage: Balanced nitrogen, phosphorus, and potassium formula to meet the basic growth needs of crops.
II. Main Product Types
Water-soluble fertilizers can be divided into two main categories based on nutrient type and form, suitable for different fertilization scenarios:
Macronutrient Water-soluble Fertilizers:
Powder Type: Low water content, convenient for transportation and storage, dissolves quickly, and is the most common type on the market, suitable for fertigation and drip irrigation of various crops;
Liquid Type: No dissolution required, can be directly diluted for more uniform mixing and faster fertilizer effect, suitable for automated irrigation systems, commonly found in high-end facility agriculture.
Micronutrient Water-soluble Fertilizers: Primarily composed of micronutrients such as calcium, magnesium, sulfur, iron, zinc, and boron, mostly produced using chelation technology, maintaining activity in soils with different pH values and avoiding soil fixation. Primarily used to correct nutrient deficiency symptoms in crops, such as blossom-end rot in tomatoes (calcium deficiency) and yellow leaf disease in fruit trees (iron deficiency).
III. Core Application Method: Fertilizer and Water Integration The core advantage of water-soluble fertilizers lies in their integration with irrigation systems, achieving simultaneous water and fertilizer supply. There are three common application methods:
Drip Irrigation Fertilization: Diluted fertilizer solution is injected into drip irrigation pipes, slowly dripping into the soil near the crop roots through emitters, precisely supplying nutrients. This method offers the best water and fertilizer savings, with water utilization rates exceeding 90%, and nutrient utilization rates 30%-50% higher than traditional fertilization.
Sprinkler Irrigation Fertilization: Fertilizer solution is added to the sprinkler irrigation system and sprayed evenly into the field with irrigation water. Suitable for field crops (such as wheat and corn) and orchards, this method is convenient, labor-saving, and time-saving.
Fertigation/Leaching: Fertilizer is dissolved and applied between crop rows with irrigation water. Suitable for open-field vegetables, melons, and other crops, this method is lower in cost, but the nutrient utilization rate is slightly lower than drip irrigation.
IV. Core Advantages
Extremely High Nutrient Absorption Efficiency: Water-soluble fertilizers exist directly in ionic form after dissolving, allowing for rapid absorption and utilization by crop roots. This avoids the lengthy “dissolution-conversion-absorption” process of traditional compound fertilizers, resulting in rapid onset of action and timely relief of crop nutrient deficiency symptoms.
Water, Fertilizer, and Labor Savings, Reducing Planting Costs: Integrated water and fertilizer technology can reduce irrigation water consumption by over 50% and fertilizer waste by over 30%. Simultaneously, it eliminates the need for manual trenching and topdressing, significantly reducing labor costs, making it particularly suitable for large-scale, mechanized planting.
Precise Nutrient Regulation, Enhancing Crop Quality: Fertilizer formulas and application concentrations can be flexibly adjusted according to the nutrient requirements of crops at different growth stages. For example, increasing potassium fertilizer during the fruit expansion stage of melons and fruits can significantly improve fruit sugar content and storage and transport resistance; increasing nitrogen fertilizer in leafy vegetables can promote tender and thick leaves.
Precise Nutrient Regulation, Enhancing Crop Quality: Fertilizer formulas and application concentrations can be flexibly adjusted according to the nutrient requirements of crops at different growth stages. Suitable for facility agriculture, with a wide range of applications. Not only suitable for greenhouse vegetables, greenhouse flowers, fruit trees, and other cash crops, but also for topdressing field crops, especially suitable for fertile soils such as saline-alkali soil and sandy soil.
V. Precautions for Use
Strictly control the concentration to avoid fertilizer damage. Water-soluble fertilizers have high nutrient concentrations; insufficient dilution can easily lead to root and leaf burn in crops. Generally, the application concentration for field crops is 0.2%-0.5%, and for facility crops, it is 0.1%-0.3%, with adjustments made according to the crop variety.
Avoid indiscriminate mixing. Different types of water-soluble fertilizers should be tested for compatibility before mixing. For example, phosphate fertilizers should not be mixed with calcium-containing fertilizers, otherwise calcium phosphate precipitates will form, clogging irrigation equipment.
Prepare and use immediately; do not store for extended periods. Fertilizer solutions should be applied as soon as possible after preparation, especially chelated fertilizers containing trace elements. Prolonged storage will cause the chelation structure to break down, resulting in nutrient loss.
Combine soil fertilization with long-lasting effects. Water-soluble fertilizers have a fast effect but a short duration of effect. It is recommended to use them in combination with organic fertilizers and slow-release fertilizers to meet the nutrient needs of crops for long-term growth.
Conclusion: Integrating Precision Application with Efficient Production
In summary, water-soluble fertilizers (WSF) represent the pinnacle of precision nutrient delivery, enabling targeted, efficient crop nutrition through fertigation systems. Their rapid uptake and flexibility perfectly align with the demands of modern, high-value agriculture.
For producers, the efficient manufacturing of the raw nutrient salts used in WSF is equally critical. This is where advanced npk granulation machine technology plays a foundational role. A complete npk fertilizer manufacturing process typically involves precise formulation via an npk blending machine or npk bulk blending machine, followed by shaping the mixture into uniform granules using an npk fertilizer granulator or a complete npk granulation machine line. The choice of npk fertilizer granulator machine equipment directly influences product quality and the overall NPK fertilizer production price, making it a key investment for manufacturers supplying the growing WSF market.
Ultimately, the synergy between high-purity granulated nutrient sources and precise water-soluble application methods creates a powerful toolkit for sustainable intensification, helping farmers achieve higher yields and better quality with optimal resource use.