Abstract
The uptake of phosphorus (P) by roots results in a depletion of phosphate ions (PO4) in the rhizosphere. The corresponding decrease in PO4 concentration in the soil solution (CP) gives rise to a replenishment of P from the solid phase which is time- and CP-dependent. This PO4 exchange which reflects the buffer power of the soil for PO4 also varies with the composition and the physico-chemical conditions of the soil. As root activity can modify these physico-chemical conditions in the rhizosphere, the question arises whether these modifications affect the ability of PO4 bound to the soil solid phase to exchange with PO4 in soil solution. The aim of the present work was to measure and compare the parameters which describe the amount of PO4 bound to soil solid phase that is capable to replenish solution P for both rhizosphere and bulk soils. The soil sample was a P-enriched, calcareous topsoil collected from a long-term fertiliser trial. Rhizosphere soil samples were obtained by growing dense mats of roots at the surface of 3 mm thick soil layer for one week. Three plant species were compared: oilseed rape (Brassica napus L., cv Goeland) pea (Pisum sativum L., cv. Solara) and maize ( Zea mays L., cv. Volga). The time- and CP-dependence of the PO4 exchange from soil to solution were described using an isotopic dilution method. The measured CP values were 0.165 mg P L−1 for bulk soil and 0.111, 0.101 and 0.081 mg P L−1 for rhizosphere soils of maize, pea and rape, respectively. The kinetics of the PO4 exchange between liquid and solid phases of soil were significantly different between rhizosphere and bulk soils. However, when changes in CP were accounted for, the parameters describing the PO4 exchange with time and CP between soil solution and soil solid phase were found to be very close for bulk and rhizosphere soils. For this calcareous and P-enriched soil, plant species differed in their ability to deplete PO4 in solution. The resulting changes in the ability of the soil solid phase to replenish solution PO4 were almost fully explained by the depletion of soil solution P.
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References
Barber S A 1984Soil nutrient bioavailability: a mechanistic approach. John Wiley, New York.
Barrow N J 1983On the reversibility of phosphate sorption by soils. J. Soil Sci. 34, 751–758.
Bhat K K S, Nye P H and Baldwin J P 1976Diffusion of phosphate to plant roots in soil. IV. The concentration distance profile in the rhizosphere of roots with root hairs in a low-P soil. Plant Soil 44, 63–72.
Darrah P R 1993The rhizosphere and plant nutrition: a quantitative approach. Plant Soil 155/156, 1–20.
Fardeau J C 1981Cinétiques de dilution isotopique et phosphore assimilable des sols. Ph.D. Thesis, Université Paris VI, France.
Fardeau J C 1993Le phosphore assimilable des sols: sa représentation par un modèle fonctionnel à plusieurs compartiments. Agronomie 13, 317–331.
Fardeau J C, Morel C and Boniface R 1991Cinétiques de transfert des ions phosphate du sol vers la solution du sol: paramètres caractéristiques. Agronomie 1, 787–797.
Gahoonia T S, Claassen N and Jungk A 1992Mobilisation of phosphate in different soils by ryegrass supplied with ammonium or nitrate. Plant Soil 140, 241–248.
Hinsinger P 1998How do plant roots acquire mineral nutrients? Chemical processes involved in the rhizosphere. Adv. Agron. 64, 225–266.
Hinsinger P and Gilkes R J 1996Mobilization of phosphate from phosphate rock and alumina-sorbed phosphate by the roots of ryegrass and clover as related to rhizosphere pH. Eur. J. Soil Sci. 47, 533–544.
Hübel F and Beck E 1993In-situ determination of the P-relations around the primary root of maize with respect to inorganic and phytate-P. Plant Soil 157, 1–9.
Huet S, Jolivet E and Messean A 1992La régression non-linéaire. Méthodes et applications en biologie. Ed. INRA, Collection «mieux comprendre» Paris. 236 p.
Iyamuremye F, Dick R P 1996Organic amendments and phosphorus sorption by soils. Adv. Agron. 56, 139–185.
Jones D L, and Darrah P R 1995Influx and efflux of organic acids across the soil-root interface of Zea mays L. and its implications in rhizosphere C flow. Plant Soil 173, 103–109.
John M K 1970Colorimetric determination of phosphate in soil and plant material with ascorbic acid. Soil Sci. 109, 214–220.
Kraus M, Fusseder A and Beck E 1987In situ-determination of the phosphate-gradient around a root by radioautography of frozen soil sections. Plant Soil 97, 407–418.
Lajtha K and Harrisson A F 1995Strategies of phosphorus acquisition and conservation by plant species and communities. In Phosphorus in the Global Environment. Ed. H Tiessen. pp 140–146. Scope 54. Wiley, Chichester.
Lewis D G and Quirk J P 1967Phosphate diffusion in soil and uptake by plants. III. 31P-movement and uptake by plants as indicated by 32P-autoradiography. Plant Soil 27, 445–453.
Morel C, Tiessen H, Moir J and Stewart J W B 1994Phosphorus transformations and availability due to crop rotations and mineral fertilization assessed by an isotopic exchange method. Soil Sci. Soc. Amer. J. 58, 1439–1445.
Morel C, Tiessen H and Stewart J W B 1996Sensitivity to equilibration periods of phosphate sorption and isotopic exchange methods assessing Q/I relationships in soils. Soil Sci. 161, 459–467.
Morel C and Torrent J 1997Sensitivity of isotopically exchangeable phosphate in soil suspensions to the supporting solution. Soil Sci. Soc. Amer. J. 61, 1044–1052.
Niebes J F, Dufey J E, Jaillard B and Hinsinger P 1993Release of nonexchangeable potassium from different size fractions of two highly K-fertilised soils in the rhizosphere of rape (Brassica napus cv Drakkar). Plant Soil 155/156, 403–406.
Nye P H 1981Changes of pH across the rhizosphere induced by roots. Plant Soil 61, 7–26.
Riley D and Barber S A 1971Effect of ammonium and nitrate fertilisation on phosphorus uptake as related to root-induced pH changes at the root–soil interface. Soil Sci. Soc. Amer. Proc. 35, 301–306.
SAS Institute 1995SAS/STAT Version 6.11 Ed. SAS Institute, Cary, NC.
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Morel, C., Hinsinger, P. Root-induced modifications of the exchange of phosphate ion between soil solution and soil solid phase. Plant and Soil 211, 103–110 (1999). https://doi.org/10.1023/A:1004485432261
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DOI: https://doi.org/10.1023/A:1004485432261