Role of root derived organic acids in the mobilization of nutrients from the rhizosphere |
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Authors: | David L Jones Peter R Darrah |
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Institution: | (1) U.S. Plant, Soil and Nutrition Lab., Cornell University, 14853-2901 Ithaca, NY, USA;(2) University of Oxford, Department of Plant Sciences, OX1 3RB Oxford, UK |
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Abstract: | The role of organic acids in the mobilization of plant nutrients from the rhizosphere was assessed in seven contrasting soil types. The results indicated that malate was poor at mobilizing micronutrients from all the test soils, whilst citrate was capable of mobilizing significant quantities. Citrate was also capable of mobilizing P from one soil which possessed a large Ca-P fraction. This mobilization of P was due to both the complexing action of the citrate anion and due to the dissolution properties of the protons released from citric acid upon equilibrium with the soil solution. The reaction of citrate with cations was found to be near instantaneous with significant absorption to the solid phase in some soils at low concentrations. Soil decomposition studies indicated that citrate was rapidly broken down in organic soils but was more resistant to degradation in subsoil horizons. It was concluded that organic acids can be expected to be of little consequence in nutrient mobilization from high pH soils, whilst in acid soils they may be involved both in a more general mechanism for micronutrient uptake or as a potential Al detoxification mechanism.Abbreviations C6H8O7
Citric acid and H-citrate indicates
- C6H5O7Na3
whilst Na-citrate indicates |
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Keywords: | nutrient mobilization organic acids rhizosphere root exudates |
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