Fertilizer Solubility Table

Fertilizer Solubility Table for Fertigation Solutions

The solubility of a fertilizer is the maximum amount that can be completely dissolved into a given volume of water. Exceeding this maximum results in precipitation — tying up nutrients and potentially clogging small orifices in your fertigation system.

Solubility is expressed in weight per volume of water (e.g., grams/liter or lb/gallon). The table below lists values in grams per 100 mL.

Important: Solubility increases with water temperature. You cannot dissolve a fertilizer at high temperature and then cool the solution without risking precipitation. For example, ammonium sulfate dissolves at 78 g/100 mL at 80°F, but only 73 g/100 mL at 60°F — cooling a hot concentrated solution will cause 5 g/100 mL to precipitate out.

Theoretical Maximum Solubility of Fertilizer Compounds (g/100 mL)
Fertilizer Compound 60°F 70°F 80°F
Ammonium Sulfate (Solugreen) 73 77 78
Ammonium Phosphate Monobasic (NovaMAP) 30 37 46.4
Boric Acid (Optibor) 3.49 4.72 6.23
Borate, Disodium Octa (Solubor) 4.79 10.78 27.5
Calcium Chloride Anhydrous (Vitro) 64.7 74.5 100
Calcium Sulfate Solution Grade (Valufil) 0.244 0.255 0.264
Calcium Nitrate (YaraLiva) 95 120 150
Calcium Nitrate (Haifa Cal Prime) 114 121.3 164
Copper EDTA 15% — 40 —
Copper Sulfate 27.5 32 37.8
Iron EDDHA 6% 5 6 7
Iron DTPA 10% 10 11 12
Iron Sulfate 20% 20 30 40
Magnesium Nitrate (Magnific) 220 240 270
Magnesium Sulfate Epsom (Magriculture) 61 71 91
MagPhos — 40 —
Manganese EDTA 13% — 80 —
Manganese Sulfate 59.7 62.9 62.9
Potassium Hydroxide 103 112 126
Potassium Nitrate (Krista K) 21 31 45
Potassium Phosphate Monobasic (MKP) 18 23 29
Potassium bisPhosphate (PeKacid) — 67 —
Potassium Silicate (AgSil 16H) 13 15 16
Potassium Sulfate (Ultrasol SOP52) 8 10 11
Sodium Molybdate 64.7 65.3 66.9
Zinc EDTA 14% — 100 —
Zinc Sulfate 47.2 53.8 61.3

Data sourced from product tech sheets and SDS documents. Values are theoretical maximums and serve as a guide. Growers should seek further assistance when dealing with specific fertilizer mixes and blends.

The Common Ion Effect

The common ion effect is a decrease in the solubility of an ionic compound as a result of the addition of a common ion. For example, adding calcium ion to a saturated solution of calcium sulfate causes additional CaSO₄ to precipitate. Similarly, adding potassium sulfate introduces sulfate ions — the same common ion — which lowers the solubility of calcium sulfate further. Even if two fertilizers are technically compatible in the same tank, shared ions reduce each compound’s maximum solubility when combined.

Download the Fertilizer Solubility Table (PDF)

Questions about mixing stock solutions? Contact us or see our Fertilizer Compatibility Guide.