The formula for water-soluble fertilizers should be determined based on crop types, soil conditions, and fertilization methods (drip irrigation/sprinkler irrigation/flushing). Here I have compiled several common water-soluble fertilizer formula ideas (universal+special functional) for you to refer to:
1、 Common universal formula
Universal balanced type (suitable for most crop growth periods)
Calcium ammonium nitrate (Ca (NO3) ₂ · 4H ₂ O): 20%
Potassium dihydrogen phosphate (KH ₂ PO ₄): 10%
Magnesium sulfate (MgSO ₄· 7H ₂ O): 10%
Urea: 15%
Potassium nitrate (KNO3): 20%
Trace elements (EDTA Fe, Zn, Mn, Cu, B, etc.): 0.5-1%
The remaining amount is filler or adjusting agent
The NPK ratio is approximately 20-20-20, suitable for general irrigation or drip irrigation of most vegetables and fruits.
2、 Example of functional formula
High nitrogen type (promotes seedling stage and leaf growth)
Urea: 30%
Calcium ammonium nitrate: 20%
Magnesium sulfate: 10%
Potassium dihydrogen phosphate: 8%
Potassium nitrate: 15%
Trace elements: appropriate amount
The NPK ratio is around 30-10-10.
High phosphorus type (promotes root system, flowering and fruiting)
Potassium dihydrogen phosphate: 30%
Urea: 15%
Potassium nitrate: 20%
Magnesium sulfate: 10%
Trace elements: appropriate amount
NPK ratio is 10-30-10.
High potassium type (swelling fruit, improving quality)
Potassium nitrate: 30%
Potassium dihydrogen phosphate: 20%
Urea: 10%
Calcium ammonium nitrate: 15%
Magnesium sulfate: 10%
Trace elements: appropriate amount
NPK ratio is 10-10-30.
3、 Trace element addition
Common trace elements use chelated states to prevent precipitation and improve solubility:
Fe：EDTA-Fe / DTPA-Fe(0.2–0.5%)
Zn：EDTA-Zn(0.1–0.3%)
Mn：EDTA-Mn(0.1–0.3%)
B: Borax/Boric Acid (0.1-0.3%)
Cu：EDTA-Cu(0.05–0.1%)
Mo: ammonium molybdate (trace amount is sufficient)
4、 Precautions
Formula solubility: Avoid excessive combination of Ca ² ⁺ with SO ² ⁻ and PO ³ ⁻ to form precipitates.
Different salts should be dissolved in separate tanks (such as calcium fertilizer and sulfate/phosphate dissolved separately).
EC and pH control: The conductivity (EC) of the solution should not be too high, and the pH should be maintained between 5.5-6.5.
Tailored to local conditions: nitrate nitrogen should be used for saline alkali land, and calcium and magnesium should be supplemented for acidic soil.
