Abstract
Low-molecular-weight organic acids are considered to be effective in the release of inorganic phosphorus (P) but their effectiveness to mobilize organic P is not well understood. The aim of this study was to examine the role of three common organic acids (maleic, oxalic, and citric acids) in mobilizing organic P in forest soils. Soil samples tested in this study were collected from either native or plantation forests in subtropical and tropical Australia with 16–87% of soil total P being in organic form. At a concentration of 10 mM organic acid kg−1 soil, all three organic acids did not enhance the release of inorganic P as compared with water, whereas the three organic acids displayed different capacities in mobilizing organic P. Citric acid significantly enhanced the solubilization of organic P by 34.7% as compared with water; whereas no significant differences were observed in the mobilization of organic P among maleic acid, oxalic acids, and water. The amount of organic P solubilized by citric acid was not correlated with soil pH but increased with increasing soil organic P as the values were below 200 mg kg.−1 The possible mechanisms of the effective mobilization of organic P by citric acid were discussed. Our results implied that organic P might play an important role in P nutrition of plants in subtropical and tropical forests due to its substantial proportion in soil P and the effective mobilization by organic acids.
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Acknowledgment
Authors would like to thank Marijke Heenan for her assistance in some analyses. This project is funded in part by the ARC Future Fellowship grant (FT0990547).
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Wei, L., Chen, C. & Xu, Z. Citric acid enhances the mobilization of organic phosphorus in subtropical and tropical forest soils. Biol Fertil Soils 46, 765–769 (2010). https://doi.org/10.1007/s00374-010-0464-x
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DOI: https://doi.org/10.1007/s00374-010-0464-x