Hello,
I want to use CaCO3 in Hoagland nutrient solution until simulate conditions usually found in the field lead to iron deficiency. Do you think using CaCO3 in Hoagland nutrient sloution lead to EDTA precipitation?
In your idea in this condition, which kind of Fe fertilizers can I use without precipitation problem?
Thanks,
The most important point is chelate compounds like Fe-EDTA not participate in chemical reactions ,and its Fe absorb by plant roots, on the other hand the solubility of CaCO3 is very low 0.013 g/l .
Yes I agree with professor Akram. Chelate compounds will not precipitate in chemical reactions
The pH of the sistem is significant in the Hoagland solution. A pH araound 5.5 vill increase the solubility more than pH difference x100. Therefore the Ca concentration in the solution will increase too much. In this case some of EDTA-Fe will probably replaced by Ca and the rest of Ca may react with phosphate or sulphate depending on the concentration of these ions. Possible reaction between Fe with phophate may be observed. In thıs case just run the solution composition in the MINTEQ, whether any solid phase can precipitate.
I had prepared nutritional solutions with CaCO3 at pH=7,09 but its low solubility does it poor usefull for that purpose. And doesn't interferes with Fe-chelates.
In my opinion depending upon the quantity of calcium carbonate used an equilibrium with solution concs. of Ca and HCO3 ions will be established which would shift the pH of the system. The addition of calcium carbonate would also affect the concs. of Mn, P and Zn besides the interference in Fe uptake by bicarbonate and carbonate ions. The ppt. of EDTA is not likely.
CaCO3 in Hoagland sloution is not precipitation if Fe-EDTA is add in the solution.
The answer of Dr. Veli Uygur is correct when prescribed pH of Hoagland solution is maintained as rules of chemistry. At pH 7.09 (Dr. Victoria Morales) observation also seems useful. But I think the precipitation of Ca with EDTA-Fe and P can not be ruled but needs quantification since Ca will be available in solution at equilibrium with solid phase CaCO3. Again the success of the experimenter will depend upon the required accuracy and precision of results.
I would abandon Hoaglands solution as it is unrealistically concentrated. Have you thought about whether you want the many complications associated with high pH or simply want some limiting Fe concentrations.
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