The quantitative effect of chemical phosphate mobilization by carboxylate anions on P uptake by a single root. I. The basic concept and determination of soil parameters

Autor/in: Gerke J., L. Beißner, W. Römer
Jahr: 2000
Zeitschrift: J. Plant Nutr. Soil Sci. 163
Seite/n: 207-212

Published in Projekt Veröffentlichungen, die keinem Projekt und keiner Abteilung zugeordnet sind / Abteilung Additional projects and publications

Abstract

Model calculations on the uptake of inorganic nutrients by single roots and root systems do not include chemical nutrient mobilization by root exudates. In this paper, a model description of Nye (1984) was applied to the case of a single root (cylindrical case) and chemical mobilization of phosphate (P) by carboxylates. Experimental results are reported which allow the quantification of soil parameters required for the model calculation. These include the solubilizing effect of carboxylates on P. The experiments showed a strong positive correlation between carboxylate adsorption to the soil solid phase and chemical P mobilization by the carboxylate. Below a concentration of adsorbed citrate and oxalate of 10 mmol g-1 soil no mobilization occurred in the 3 soils which were investigated. Differences in pH did not affect P solubility, but did, however, affect the quantity of adsorbed carboxylate and thereby the mobilization of P. Citrate and oxalate have a greater ability to mobilize soil P as compared with oxaloacetate and malate. Model calculations which are based on these experimental results are presented in a second paper.

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