Steiner Universal Nutrient Solution is one of the most well-known hydroponic formulations and was developed by Dr. Arthur Steiner . It features a balanced ratio of macro- and micronutrients and is particularly suitable for universal applications (e.g., vegetables, herbs, fruit-bearing plants). Here is the typical composition:
Steiner Universal Nutrient Solution (standard recipe)
(Figures in grams per 1000 liters of water, converted to grams per liter )
| nutrient salt | Quantity (g/L) | Nutrients supplied |
|---|---|---|
| Potassium nitrate (KNO₃) | 0.6–0.8 g/L | K (potassium), N (nitrate nitrogen) |
| Calcium nitrate (Ca(NO₃)₂) | 0.6–0.8 g/L | Ca (calcium), N (nitrate nitrogen) |
| Magnesium sulfate (MgSO₄) | 0.4–0.5 g/L | Mg (magnesium), S (sulfur) |
| Monopotassium phosphate (KH₂PO₄) | 0.2–0.3 g/L | K (potassium), P (phosphorus) |
| Iron chelate (Fe-EDTA) | 0.02–0.03 g/L | Fe (iron) |
| Trace element mix | 0.01–0.02 g/L | Mn, Zn, Cu, B, Mo (as sulfates/borates) |
Macronutrient Ratio (NPK):
- Nitrogen (N) : ~100–150 mg/L (from KNO₃ and Ca(NO₃)₂)
- Phosphorus (P) : ~30–50 mg/L (from KH₂PO₄)
- Potassium (K) : ~200–250 mg/L (from KNO₃ and KH₂PO₄)
- Calcium (Ca) : ~80–100 mg/L
- Magnesium (Mg) : ~40-50 mg/L
Micronutrients
- Iron (Fe) : 2–3 mg/L (as chelated Fe-EDTA for better availability)
- Manganese (Mn) : 0.5–1 mg/L
- Zinc (Zn) : 0.05–0.1 mg/L
- Copper (Cu) : 0.02-0.05 mg/L
- Boron (B) : 0.1–0.3 mg/L
- Molybdenum (Mo) : 0.01–0.02 mg/L
Properties of the solution
- pH value : Ideally between 5.5–6.5 (adjust with HNO₃ or KOH if necessary).
- Conductivity (EC) : ~1.5–2.5 mS/cm, depending on the plant stage.
- Advantages :
- Stabilizes nutrient absorption through high potassium and calcium levels.
- Suitable for NFT systems, Deep Water Culture (DWC) and Dutch Buckets.
Customization tips
- For fruit plants (tomatoes, cucumbers): Increase potassium (K) to 300–350 mg/L.
- For leafy vegetables (lettuce, spinach): reduce potassium and increase nitrogen.
- In case of iron deficiency : increase Fe-EDTA to 0.05 g/L.
Note on practice
Steiner's solution is often offered commercially pre-mixed (e.g., from manufacturers like Hydroponic Systems ), but many growers also mix it themselves from individual salts. Make sure the salts are of high purity (≥99%, technical grade) and always dissolve them in the correct order (calcium and magnesium salts first, then phosphates, and finally iron and trace elements).
Source: https://de.wikipedia.org/wiki/Hydrokulturd%C3%BCnger#N%C3%A4hrl%C3%B6sung_nach_Abram_Steiner
Image: https://www.pexels.com/de-de/@sasha-kim/
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