Water Soluble Fertilizer

1.Classification and Chemical Properties

1.1 Primary Categories of Water-Soluble Fertilizers

1.1.1 Straight Water-Soluble Fertilizers

• Nitrogen Sources:
  • Urea (46-0-0): CO(NH₂)₂ - 2200 g/L solubility at 20°C
  • Ammonium Nitrate (34-0-0): NH₄NO₃ - 1900 g/L solubility at 20°C
  • Calcium Ammonium Nitrate (27-0-0): CAN - 1500 g/L solubility at 20°C
  • Ammonium Sulfate (21-0-0): (NH₄)₂SO₄ - 700 g/L solubility at 20°C
• Phosphorus Sources:
  • Monopotassium Phosphate (0-52-34): KH₂PO₄ - 225 g/L solubility at 20°C
  • Monoammonium Phosphate (12-61-0): NH₄H₂PO₄ - 365 g/L solubility at 20°C
  • Diammonium Phosphate (18-46-0): (NH₄)₂HPO₄ - 575 g/L solubility at 20°C
  • Phosphoric Acid (0-85-0): H₃PO₄ - Completely miscible with water
• Potassium Sources:
  • Potassium Nitrate (13-0-46): KNO₃ - 316 g/L solubility at 20°C
  • Potassium Sulfate (0-0-50): K₂SO₄ - 120 g/L solubility at 20°C
  • Potassium Chloride (0-0-60): KCl - 344 g/L solubility at 20°C
  • Monopotassium Phosphate (0-52-34): KH₂PO₄ - dual nutrient source

1.1.2 Complex Water-Soluble Fertilizers

• NPK Water-Soluble Blends:
  • High Nitrogen: 20-20-20, 30-10-10, 25-5-5
  • Balanced: 20-20-20, 15-15-15, 19-19-19
  • High Phosphorus: 10-52-10, 13-40-13 (starter formulations)
  • High Potassium: 15-5-30, 12-12-36 (fruit/flower development)
• Specialty Complex Fertilizers:
  • Calcium Nitrate Based: 15.5-0-0 + 19% Ca
  • Magnesium Enhanced: NPK + Mg formulations
  • Micronutrient Enriched: NPK + chelated micronutrients
  • pH Adjusted: Buffered formulations for specific pH ranges

1.1.3 Micronutrient Water-Soluble Fertilizers

• Chelated Micronutrients:
  • EDTA Chelates: Iron, manganese, zinc, copper chelates
  • DTPA Chelates: More stable in alkaline conditions
  • EDDHA Chelates: Iron-specific, highly stable
  • Amino Acid Chelates: Organic chelation for enhanced uptake
• Sulfate Forms:
  • Iron Sulfate: FeSO₄·7H₂O - 200 g/L solubility
  • Manganese Sulfate: MnSO₄·H₂O - 700 g/L solubility
  • Zinc Sulfate: ZnSO₄·7H₂O - 965 g/L solubility
  • Copper Sulfate: CuSO₄·5H₂O - 203 g/L solubility

1.2 Physical and Chemical Properties

1.2.1 Solubility Characteristics

• Complete Solubility: 100% dissolution in water within specified time
• Clear Solutions: No residue or precipitate formation
• Dissolution Rate: Fast dissolution (typically
• Temperature Dependency: Solubility increases with water temperature
• Concentration Limits: Maximum solution concentration without precipitation

1.2.2 Solution Properties

• Electrical Conductivity (EC):
  • Ranges from 0.5-3.0 mS/cm depending on concentration
  • Critical parameter for fertigation system management
  • Plant tolerance varies by species and growth stage
• pH Characteristics:
  • Acidic: Ammonium-based fertilizers (pH 4.0-5.5)
  • Near Neutral: Nitrate-based fertilizers (pH 6.0-7.5)
  • Alkaline: Some potassium sources (pH 7.5-8.5)
• Osmotic Pressure:
  • Higher concentrations increase osmotic pressure
  • Can affect plant water uptake if excessive
  • Requires careful concentration management

1.2.3 Physical Forms and Characteristics

• Crystalline Powder: Fine crystals, rapid dissolution, dusty
• Granular: 1-4 mm particles, reduced dust, easier handling
• Prilled: Spherical particles, uniform size, good flow properties
• Liquid Concentrates: Pre-dissolved solutions, ready-to-use or dilutable
• Soluble Tablets: Compressed forms for small-scale applications

1.3 Quality Standards and Specifications

• Solubility Requirements:
  • Complete dissolution within specified time frame
  • No visible residue in standard test solutions
  • Stability of solution over storage period
• Purity Standards:
  • Minimum nutrient content guarantees
  • Maximum impurity levels (heavy metals, chlorides)
  • Micronutrient specifications and chelation stability
• Physical Properties:
  • Particle size distribution
  • Bulk density and flowability
  • Moisture content and storage stability
  • Caking resistance and dust content