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3220527 
Journal Article 
Review on iron availability in soil: interaction of Fe minerals, plants, and microbes 
Colombo, C; Palumbo, G; He, JiZ; Pinton, R; Cesco, S 
2014 
Yes 
Journal of Soils and Sediments
ISSN: 1439-0108
EISSN: 1614-7480 
14 
3 
538-548 
WOS:000331642000009 
The rationale of this paper is to review the state of the
art regarding the biotic and abiotic reactions that can influence Fe availability in soils. In
soil, the management-induced change from oxic to anoxic environment results in temporal and
spatial variations of redox reactions, which, in turn, affect the Fe dynamics and Fe mineral
constituents. Measuring the Fe forms in organic complexes and the interaction between bacteria
and Fe is a major challenge in getting a better quantitative understanding of the dynamics of Fe
in complex soil ecosystems. We review the existing literature on chemical and biochemical
processes in soils related with the availability of Fe that influences plant nutrition. We
describe Fe acquisition by plant and bacteria, and the different Fe-organic complexes in order to
understand their relationships and the role of Fe in the soil carbon cycle. Although total Fe is
generally high in soil, the magnitude of its available fraction is generally very low and is
governed by very low solubility of Fe oxides. Plants and microorganisms can have different
strategies in order to improve Fe uptake including the release of organic molecules and
metabolites able to form complexes with Fe-III. Microorganisms appear to be highly competitive
for Fe compared with plant roots. Crystalline Fe and poorly crystalline (hydro)oxides are also
able to influence the carbon storage in soil. The solubility of crystalline Fe minerals in soil
is usually very low; however, the interaction with plant, microbes, and organic substance can
improve the formation of soluble Fe-III complexes and increase the availability of Fe for plant
growth. Microbes release siderophores and plant exudates (e.g., phytosiderophores, organic acids,
and flavonoids), which can bind and solubilize the Fe present in minerals. The improved
understanding of this topic can enable the identification of effective solutions for remedying Fe
deficiency or, alternatively, restricting the onset of its symptoms and yield's limitations in
crops. Therefore, development and testing of new analytical techniques and an integrated approach
between soil biology and soil chemistry are important prerequisites. 
Fe soil availability; Weathering of Fe-containing minerals; Microbial siderophores; Plant exudates