THE AVAILABILITY OF IRON IN NUTRIENT SOLUTIONS 
FOR WHEAT 1 
W. E. Tottingham and E. J. Rankin 
(Received for publication August 3, 1922) 
The efficiency of the usual trace of iron when employed in culture so¬ 
lutions may be expected to vary with the nature of the compound in which 
it is supplied, with the composition and reaction of the solution in which 
it is employed, and with the species of plant. Gile and Carrero have shown 
that the reaction of the nutrient solution (whether acid, neutral, or alkaline) 
(6), as well as soil conditions (7), have a marked influence upon the availa¬ 
bility of iron to the rice plant. Corsan and Bakke (4) count ferrous iron 
less efficient than ferric iron, when used in the forms of phosphates. Jones 
and Shive (9) have pointed out that, in the nutrient solution which they 
employed, iron in the form of ferrous sulphate was very readily available to 
the wheat plant, but was evidently somewhat toxic in the highest concen¬ 
trations used. Ferric phosphate, on the contrary, was very slowly and 
difficultly available to these plants, even when supplied in relatively large 
quantities. In later work (10) they found that ferrous sulphate was su¬ 
perior to ferric phosphate as a source of iron for plants grown in a nutrient 
solution containing calcium nitrate. When ammonium sulphate was em¬ 
ployed as the source of nitrogen, however, the solution increased in acidity 
and ferric phosphate supported growth of the plants better than did ferrous 
sulphate. Hoagland (8) has suggested that the presence of sufficient 
dissolved iron in the culture solution will depend upon the form and quan¬ 
tity of the iron salt used, and considers iron citrate and tartrate the most 
effective forms. Duggar (5) has recommended a special form of “ soluble” 
iron prepared from ferric citrate and sodium phosphate. 
Experimentation 
Solubility 
In the present investigation an attempt was made to determine which 
of the following salts of iron, namely: ferric citrate, FeP 0 4 , Fe2(S04)3, 
and FeSCL, would remain in solution in the greatest amounts at the two 
hydrogen-ion concentrations of pH 4.2 and pH 6.0, using the Livingston- 
Tottingham nutrient solution; and also to determine which of these forms 
of iron would be most available to the wheat plant when supplied in varying 
amounts, at the latter pH value of the nutrient solution. 
1 Published with the permission of the Director of the Wisconsin Agricultural Experi¬ 
ment Station. This investigation was supported by a grant from the research funds of 
the University of Wisconsin. 
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