Water-Soluble Fertilizer Knowledge

Water-soluble fertilizer is a type of fertilizer that dissolves quickly in water without residue, with nutrients present in ionic form. It enables integrated water and fertilizer management, with an absorption and utilization rate as high as 70%–90%. It is suitable for drip irrigation, foliar spray, and other scenarios, making it a core choice for efficient fertilization in modern agriculture. Below is a comprehensive introduction covering definition, classification, advantages, application, selection, and precautions.

I. Core Definition and Standards

Water-soluble fertilizer (WSF) refers to solid or liquid fertilizers that can be dissolved or diluted in water for fertigation, foliar application, soilless culture, etc. Its water-insoluble content is ≤5%, and nutrients are mainly in ionic form for direct crop uptake. Applicable agricultural industry standards include:

• Macroelements: NY 1107

• Secondary and trace elements: NY 1428

• Amino acid-containing: NY 1429

• Humic acid-containing: NY 1106

II. Main Types and Characteristics

It is divided into solid (granular, powder) and liquid (clear solution, suspension). Solid forms are easy to store and transport; liquid forms dissolve faster and are more convenient to apply.

III. Core Advantages (vs. Traditional Compound Fertilizer)

1. High absorption efficiency: Ionic nutrients are directly absorbed, with 70%–90% utilization (2–3 times that of traditional fertilizers), showing effects in 3–5 days.

2. Precise and controllable: Formulas can be adjusted according to crop growth stages.

3. Integrated water and fertilizer: Suitable for drip and sprinkler irrigation, saving 30%–50% water and 20%–40% fertilizer.

4. Environmentally friendly: Low impurities and residue, reducing soil compaction and groundwater pollution.

5. Flexible application: Drip irrigation, sprinkler irrigation, foliar spray, seed soaking, root dipping.

IV. Scientific Application Methods

1. Drip / Micro-sprinkler irrigation

• Dilution ratio: Macroelements 1000–2000× to avoid root burn.

• Frequency: Vegetables every 7–10 days, fruit trees every 10–15 days.

2. Foliar application

• Concentration: Macroelements 0.2%–0.5%, trace elements 0.1%–0.2%, amino/humic acid 0.3%–0.5%.

• Timing: Before 10 AM or after 4 PM on sunny days; re-spray if rain within 4 hours.

3. Flood / Drench application

• Used in open fields without drip systems, applied with irrigation water.

4. Formula matching

• Seedling stage: High P + amino/humic acid (rooting & strong seedlings)

• Flowering stage: High P-K + boron (flower and fruit retention)

• Fruit swelling stage: High K + Ca/Mg (fruit expansion & cracking prevention)

V. Selection and Precautions

1. Selection tips

• Check labels: nutrient content, standards, water-insoluble content.

• Raw materials: Industrial-grade raw materials (potassium nitrate, potassium dihydrogen phosphate); chelated trace elements (EDTA/EDDHA).

• Solubility: Clear and residue-free in water to avoid clogging drip lines.

2. Application taboos

• Two-step dilution: Dissolve in a small bucket first, then mix into the main tank.

• Avoid antagonism: Separate Ca from P/K to prevent precipitation; do not mix with alkaline pesticides.

• Prepare fresh solution, especially in hard water areas.

• Reduce concentration for young seedlings and high temperatures.

• Sealed storage: Keep solids dry, liquids away from light.

VI. Common Misunderstandings

• Water-soluble fertilizer ≠ flood-applied fertilizer: WSF is a fertilizer type; flood application is a method.

• Higher price ≠ better quality: Choose formulas based on crop needs.

• Cannot replace basal fertilizer: WSF is mainly for topdressing; use with organic or slow-release fertilizer as base.