Phosphorus uptake byZea maysL. is quantitatively predicted by infinite sink extraction of soil P.
OBJECTIVE
Sink extraction of phosphorus from soils has been utilised to study soil P desorption kinetics and as index of plant availability, but not for quantitative prediction of P uptake by plants. Here we investigate the potential of a modified sink extraction method for determining P desorption kinetics and for quantifying plant available soil P.


METHODS
Modified diffusive gradients in thin films samplers were immersed in shaken soil suspensions for long-term extraction of soil P. Results were evaluated in terms of P desorption kinetics and compared to the P uptake ofZea maysL. and standard soil extracts.


RESULTS
In contrast to literature reports, four of the six studied soils only showed a rapid, but not a slowly desorbing P fraction. The quantity of P desorbed by long-term sink extraction not only showed the highest correlation to plant P uptake, but also matched plant P uptake quantitatively.


CONCLUSIONS
Our data indicates that soils with only a fast desorbing P fraction might exist. Sink extraction methods have the potential to quantitatively predict plant P uptake. Furthermore, they could become valuable research tools for understanding P acquisition and might serve as a benchmark for calibrating soil P tests.
Vienna, Department of Forest and Soil Sciences, Institute of Soil Research, University of Natural Resources and Life Sciences, Konrad-Lorenz-Strasse 24, 3430 Tulln, Austria. jakob.santner@boku.ac.at.
Jakob
J
Santner
Vienna, Department of Forest and Soil Sciences, Institute of Soil Research, University of Natural Resources and Life Sciences, Konrad-Lorenz-Strasse 24, 3430 Tulln, Austria. martina_mannel@hotmail.com.
Martina
M
Mannel
Vienna, Department of Forest and Soil Sciences, Institute of Soil Research, University of Natural Resources and Life Sciences, Konrad-Lorenz-Strasse 24, 3430 Tulln, Austria. burrell07@hotmail.com.
Leigh D
LD
Burrell
Vienna, Department of Forest and Soil Sciences, Institute of Soil Research, University of Natural Resources and Life Sciences, Konrad-Lorenz-Strasse 24, 3430 Tulln, Austria. christoph.hoefer@boku.ac.at.
Christoph
C
Hoefer
Vienna, Department of Forest and Soil Sciences, Institute of Soil Research, University of Natural Resources and Life Sciences, Konrad-Lorenz-Strasse 24, 3430 Tulln, Austria. andreas.kreuzeder@boku.ac.at.
Andreas
A
Kreuzeder
Vienna, Department of Forest and Soil Sciences, Institute of Soil Research, University of Natural Resources and Life Sciences, Konrad-Lorenz-Strasse 24, 3430 Tulln, Austria. walter.wenzel@boku.ac.at.
Walter W
WW
Wenzel
Diffusive gradients in thin films; Infinite sink extraction; Phosphorus; Plant uptake