Micronutri Fe

Prayon Micronutri FE
+ 2.8% Fe

Iron (Fe) is an essential element for plants. Since the 1960s, the only way to guarantee iron uptake in soilless cultures was through organic binding, i.e. chelates. But Prayon has now developed micronutri Fe, an alternative, innovative fertilizer that guarantees iron uptake in soilless cultures. Micronutri Fe is a patented combination of multiple polyphosphates and iron.


  • Less chlorosis
  • Efficient and proven iron uptake
  • Good harvests 

Efficient iron fertilizer


  • Guaranteed iron uptake, even in the presence of fluctuating pH levels
  • A pure water-soluble iron fertilizer containing only nutrients: iron, phosphate and potassium
  • Less chlorosis, as proven in multiple trials

Additional benefits

  • Greater efficiency in the presence of UV disinfection due to enhanced transmission and less deterioration
  • Iron availability is reversible when the pH level fluctuates and/or is corrected
  • Easy to use via a separate C tank
  • Polyphosphates mean less precipitation in the irrigation system and better phosphate uptake

Proven in tests in 2012 and 2013

Prayon Micronutri FE tomatoesResearch carried out previously by Prayon’s R&D department showed that micronutri Fe can retain the iron within a nutrient solution. The next step was to test iron uptake.

The first trials on cucumbers - conducted in early 2012 in collaboration with Wageningen UR (led by researcher Wim Voogt) - immediately confirmed the potential of micronutri Fe. Iron uptake was tested in various pH ranges in a pure hydroponic system (no substrate). Cucumbers are quick to reveal iron deficiency. The results showed that micronutri Fe, tested alongside a conventional chelate, efficiently makes iron available to plants in a hydroponic system. Moreover, less tipburn was observed when using micronutri Fe.

In August 2012 a soilless trial on cucumbers was launched at Wageningen UR. Less chlorosis was observed with micronutri Fe; the plants were greener. The harvest proceeded normally and good harvest results were achieved.

In 2013 we ran a full soilless trial on tomatoes in the Hoogstraten Research Center. No chlorosis was observed throughout the entire year. Further confirmation that micronutri Fe is the perfect iron fertilizer.

In 2013 a soilless trial on strawberries in Hoogstraten proved that micronutri Fe could easily be used as an iron fertilizer. Once again good results were achieved. There was no chlorosis and the harvest proceeded perfectly!

Enhanced UV stability

Multiple trials have proven that micronutri Fe breaks down much less in the presence of UV disinfection while ensuring better transmission than organic chelates. That means more effective UV disinfection and less iron is lost.

pH range and reversibility

Just like a DTPA, micronutri Fe can make iron available up to pH 7. At higher pH values, corrections must be made to prevent difficulties with the other nutrients.

When the pH is corrected (e.g. by adding ammonium, NH4) to bring it back to 5.8, then the iron provided by micronutri Fe will once again be available to the plant. This is not true with organic chelates, where the iron is lost.

Easy to use in a separate C tank

Using a separate dosing tank, micronutri Fe can be easily and correctly dosed in the mixing tank. In other words, no pH correction is needed in the fertilizer tanks and mistakes can be avoided. In addition, there will be no precipitation or contamination in the tanks. Currently, only micronutri Fe may go in the separate tank; in the future, other elements may be added.

Pure fertilizer

Micronutri Fe is a pure fertilizer; all elements are taken up by the plant. It is a fully biodegradable, 100% water-soluble fertilizer and, like the entire Hortipray® range, contains virtually no sodium.

In addition to iron, micronutri Fe also contains phosphate and potassium, 2 of the 3 main elements. Its NPK formula is 0-42-47+2.8% Fe.

Prayon Micronutri FE How to


  mol w/w %
Fe 500 mmol/kg 2,8
P 5,87 mol/kg  
K 10,15 mol/kg  
OH- 4,28 mol/kg  
P2O5   42
K2O   47
Solubility 400 g/L water (20° C)
pH solution 1% 9,9
EC 1g/L 1,03 mS/cm

Phosphate and potassium 

Naturally, all elements must be taken into account when calculating the full nutrient solution: i.e. phosphate and potassium, in addition to iron.

Online calculation tool

Prayon has developed an easy-to-use online calculation tool, available at www.prayon.com/micronutriFe

Simply choose the iron used and fill in the quantities in your standard composition. The application will then automatically calculate how much micronutri Fe you need to use and which fertilizers require modification. With these modifications you produce a new composition and give the same quantity of nutrients as in your first composition.

Nutrients Table in different units

… KG micronutri Fe IN 100.000L WATER
micronutri Fe (kg) 1 kg 2 kg 3 kg 4 kg 5 kg 10 kg 20 kg
Fe (µmol/L) 5 10 15 20 25 50 100
input H2PO4 (mmol/L) 0,06 0,12 0,18 0,23 0,29 0,59 1,17
input K+ (mmol/L) 0,10 0,20 0,30 0,41 0,51 1,02 2,03
Fe3+ (µeq/L) 15 30 45 60 75 150 300
input H2PO4 - (meq/L) 0,06 0,12 0,18 0,23 0,29 0,59 1,17
input K+ (meq/L) 0,10 0,20 0,30 0,41 0,51 1,02 2,03
Fe (ppm) 0,28 0,56 0,84 1,12 1,40 2,79 5,59
input P (ppm) 1,8 3,6 5,5 7,3 9,1 18,2 36,4
input K (ppm) 4 8 12 16 20 40 79