1/25/2020
SOLUBILITY OF FERTILIZERS FOR FERTIGATION SOLUTIONS
The solubility of a fertilizer is determined as the maximum amount that can be completely dissolved into a determined volume of water. Exceeding this maximum amount will result in precipitation of the fertilizers in the irrigation system and can be a very serious problem with clogging of small orifices with in the fertigation system.
The solubility is expressed in units of weight per volume of water. For example: grams/liter or lb/gallon. Our table lists grams per 100 milliliters.
The solubility of each fertilizer is dependent on the temperature of the water in which it is being dissolved. The solubility of most fertilizers increases with the temperature. Therefore, at lower temperatures, the fertilizer stock solutions must be more diluted. At higher temperatures, more concentrated stock solutions can be prepared, but when the solution cools the maximum solubility falls in conjunction. So for example, you can not dissolve 78 grams of ammonium sulfate in 100 milliLiters of 80 degree water and then cool it to 60 degreees with out 5 grams of amonium sulfate precipitating out of solution, because the max solubility of ammonium sulfate at 60 degrees is only 73 grams per 100 milliLiter.
| Fertilizer Compound- Common Name | 60° farenheit | 70° f | 80° f |
|---|---|---|---|
| Ammonium Sulfate- Solugreen | 73 g/100ml | 77 g/100ml | 78 g /100ml |
| 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 for this table was taken from product tech sheets and msds. The information offered in this table is a guide and it is recommended growers seek further assistance when dealing with specific fertilizer mixes and blends. | |||
The common ion effect is a decrease in the solubility of an ionic compound as a result of the addition of a common ion.
Adding calcium ion to a saturated solution of calcium sulfate causes additional CaSO4 to precipitate from the solution, lowering its solubility. The addition of a solution containing sulfate ion, such as potassium sulfate, would result in the same common ion effect. So although two fertilizer materials may be compatible in the same tank, if they contain a common ion, each of their respective maximum solubilities is lowered when combined in the same tank.