Keywords: phosphorus, phosphate fertiliser, inter-laboratory comparisons, calibration, recommendation, soil-P tests.
The procedure for applying phosphorus (P) fertiliser to soil can be divided into three consecutive steps: (1) Measurement of soil-P availability, (2) calibration of the soil-P fertility level and (3) estimation of the recommended P dose. Information on each of these steps was obtained for eighteen European countries and regions with the aim of comparing P fertiliser recommendation systems at the European scale. We collected information on P fertiliser recommendations through conventional or grey literature, and personal contacts with researchers, laboratories and advisory services. We found much variation between countries for each of the three steps. There are more than 10 soil-P tests currently in use, apparent contradictions in the interpretation of soil-P test values and more than 3-fold differences in the P fertiliser recommendations for similar soil-crop situations. Moreover, soil properties (pH, clay content) and crop species characteristics (P responsiveness) are used in some countries in the calibration and recommendation steps, but in different ways. However, there are also common characteristics: soil-P availability is determined in all countries by extraction with chemical reagents and the calibration of the soil-P test values and the fertiliser recommendations are based on the results from empirical field trials. Moreover, the fertiliser recommendations are nearly all based on the amount of P exported in the crops. As long as rational scientific and theoretical backgrounds are lacking, there is no point in trying to synchronise the different chemical methods used. We therefore call for a mechanistic approach in which the processes involved in plant P nutrition are truly reproduced by a single standard method or simulated by sorption-desorption models.
L. Jordan-Meille, Université de Bordeaux, UMR1220 TCEM, F-33883 Villenave d’Ornon, France; INRA, UMR1220 TCEM, F-33883 Villenave d’Ornon, France.
G.H. RubÃƒÂ¦k, Aarhus University Dept. of Agroecology, Blichers Allé 20, P.O. BOX 50 DK-8830 Tjele, Denmark.
P.A.I. Ehlert, Wageningen University and Research Centre PO Box 47 6700 AA Wageningen, Netherlands.
V. Genot, University of Liege, Gembloux Agro-Bio Tech, Soil Science Unit, Passage des Déportés, 2 5030 Gembloux, Belgium.
G. Hofman, Ghent University, Faculty of Bioscience Engineering Dept. Soil Management Universiteit Gent, Coupure Links 653 B-9000 Gent, Belgium.
K.W.T Goulding, Department of Sustainable Soils and Grassland Science, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, UK.
J. Recknagel, Landwirtschaftliches Technologiezentrum, Augustenberg AuÃƒÅ¸enstelle MÃƒÂ¼llheim, Auf der Breite 7, D-79379 MÃƒÂ¼llheim/Baden, Germany.
G. Provolo, Dipartimento di Ingegneria Agraria Università degli Studi di Milano Via G. Celoria 2, 20133 Milano, Italy.
P.B. Barraclough, Department of Plant Science, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, UK.
28 pages, 4 figures, 4 tables, 80 references.