As a pass-time, I like to grow food crops hydroponically. Soybeans in particular are sensitive to iron deficiency, they don't grow well when they grow
in an iron poor environment.
Iron exists as an aqueous ion at low pH's, but low pH's can also adversely affect plant growth.
Is there a way to keep iron in solution at close to neutral pH's?
No matter how hard I try, iron always comes out of solution as iron hydroxide when the pH is raised above a certain point.
Has anyone tried to purposely get iron to come out of solution by raising the pH and failed?Hexavalent - 8-1-2012 at 09:01
What form is the iron in . . . .which salt?Arthur Dent - 8-1-2012 at 09:21
Yes, blood meal should do it. Remember that plants really only need quite small amounts of iron, so low solubility isn't really much of an issue I
should think...Hexavalent - 8-1-2012 at 09:57
Most iron (II) salts are neutral in solution, so you should consider looking into why the water goes above pH7.White Yeti - 8-1-2012 at 10:07
I tried iron acetate, iron citrate and iron sulphate, none of these salts could keep iron in solution at higher pH's.
I didn't think of blood meal, but that works as well. I'm not sure how it would work for a hydroponics set up, but I can figure it out.
I was looking for an iron ligand that could remain stable though a wide range of pH's. Iron thiocyanate perhaps? Iron complexed with cyanate?Mr. Wizard - 8-1-2012 at 10:59
I live in the SW USA and the soil and water here are saturated with lime (Calcium Carbonate). This causes almost every plant not native to the area to
be deficient in iron and suffer from chlorosis. The yellow leaves can be mistaken for a lack of nitrogen, and I tried to correct the problem with
nitrogen rich fertilizers, without any effect. Any soluble iron compounds here tend to end up as a red stain in the soil, unusable by most plants.
I have found that an iron chelate fertilizer called K-Rex ( contains Sequestrene ) if very effective in supplying iron to my fruit trees. It is a
blood red powder with some other pellets ( Ferrous Sulfate?) mixed in. It smells like fresh blood, which I suppose is the iron. It will even green up
leaves when sprayed as a dilute solution on the foliage. Care must be used as too much will burn the leaves, leaving bright green leaves, with burned
brown edges. To spray it, I have to mix it with water, and filter it to remove the pellets and powder that doesn't dissolve. It has to property of
dissolving paper coffee filters that I used for this purpose. I now just let the big chunks settle out before decanting into my sprayer. Spraying is
always the last resort as the solution will badly stain concrete, paint, brick, and stucco. I now try to stay ahead of the problem by putting it
around the base of the trees on rainy days.
Iron availability doesn't seem to be a problem where the natural rain keeps the soil acidic, but the calcium carbonate rich soil of my area is a
problem.
Mr. Wizard - 11-1-2012 at 08:09
The chelated Iron fertilizer was named KeRex. I am unable to edit my last post to correct the spelling.UnintentionalChaos - 11-1-2012 at 11:08
I think sodium Iron (III) EDTA is usually specifiedAirCowPeaCock - 11-1-2012 at 12:15
Well if you don't want to have some chemistry fun, I strongly suggest blood meal in the water. If you want to have it absorb through the leaves,
spray Iron citrate on the undersides of the leaves daily. I've never gone hydro, but Ive done plenty of indoor growing.
