Mobilization of different phosphate fractions in the rhizosphere |
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Authors: | Jungk A Seeling B Gerke J |
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Institution: | (1) Institute of Agricultural Chemistry, Georg August University, von Siebold-Str. 6, D-37075 Göttingen, Germany |
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Abstract: | Availability of soil P fractions and mechanisms of acquisition by plants were studied. Plants mobilize soil P by desorption via depletion of P solution concentration around roots. In an oxisol, the process was enhanced by nitrate N nutrition of ryegrass, which increased soil pH, and by carboxylate release by white lupin. Ligand exchange and Fe/Al solubilization are assumed to be the mechanisms. Ammonium N nutrition of ryegrass decreased pH and allowed P mobilization in a luvisol but had no such effect in an oxisol, due to acid solubility of P in these soils. Organic P dissolved in soil solution contributed one third to the P uptake of field-grown barley on a luvisol. Laboratory experiments suggest that organic P is hydrolyzed by phosphatases at the root surface and replenished by micro-organisms. |
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Keywords: | barley Ca-P organic P P depletion P fractions P mobilization rhizosphere ryegrass sorbed P white lupin |
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