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A Computer Simulation of Fe(III) and Fe(II) Complexation in Limited Nutrient Solution: I. Program Development and Testing
Author(s) -
Schwab A. P.,
Lindsay W. L.
Publication year - 1989
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1989.03615995005300010006x
Subject(s) - redox , ferric , chelation , chemistry , nutrient , pascal (unit) , ferric iron , function (biology) , inorganic chemistry , thermodynamics , physics , organic chemistry , ferrous , evolutionary biology , biology
The mechanism by which Fe‐stressed roots increase Fe availability was determined with the assistance of a computer model (written in PASCAL) that predicted the effects of redox and pH on the stability of Fe chelates. The program solves a series of simultaneous equilibrium equations to calculate the concentrations of all species in a nutrient solution containing Fe, Ca, and two competing chelating agents as a function of pH and redox potential. Experimental data were used to test the model. Model calculations based on results published by other investigators supported the theory that Fe‐deficient soybean [ Glycine max (L.) Merr.] plants have the ability to lower the redox potential near their roots. It also showed that this phenomenon is the primary means by which iron‐stressed plants are able to increase the availability of Fe. The redox potential of a nutrient solution at pH 5 must be below pe + pH 7 to account for observed trends in the stability of ferric chelates and the availability of Fe to soybean.