Reproducibility of the wet part of the soil water retention curve: a European interlaboratory comparison
B. Guillaume,
H. Aroui Boukbida,
G. Bakker,
A. Bieganowski,
Y. Brostaux,
W. Cornelis,
W. Durner,
C. Hartmann,
B. V. Iversen,
M. Javaux,
J. Ingwersen,
K. Lamorski,
A. Lamparter,
A. Makó,
A. M. Mingot Soriano,
I. Messing,
A. Nemes,
A. Pomes-Bordedebat,
M. van der Ploeg,
T. K. D. Weber,
L. Weihermüller,
J. Wellens,
A. Degré
Affiliations
B. Guillaume
Uliège – Gembloux Agro-Bio Tech, TERRA Teaching and Research Centre, Passage des Déportés 2, 5030 Gembloux, Belgium
H. Aroui Boukbida
Instrumentation, Moyens Analytiques, observatoire en Géophysique et
Océanographie (UAR IMAGO), Institut de Recherche pour le Développement (IRD), 13002 Marseille, France
G. Bakker
Wageningen University and Research, Wageningen, Netherlands
A. Bieganowski
Institute of Agrophysics, Polish Academy of Sciences, Lublin, Poland
Y. Brostaux
Uliège – Gembloux Agro-Bio Tech, TERRA Teaching and Research Centre, Passage des Déportés 2, 5030 Gembloux, Belgium
W. Cornelis
Ghent University, Gent, Belgium
W. Durner
Technische Universität Braunschweig, Braunschweig, Germany
C. Hartmann
Instrumentation, Moyens Analytiques, observatoire en Géophysique et
Océanographie (UAR IMAGO), Institut de Recherche pour le Développement (IRD), 13002 Marseille, France
B. V. Iversen
Department of Agroecology, Aarhus University, Aarhus, Denmark
M. Javaux
UCLouvain, Earth and Life Institute, Louvain-la-Neuve, Belgium
J. Ingwersen
Institute of Soil Science and Land Evaluation, University of Hohenheim, Hohenheim, Germany
K. Lamorski
Institute of Agrophysics, Polish Academy of Sciences, Lublin, Poland
A. Lamparter
Federal Institute for Geosciences and Natural Resources, Hanover, Germany
A. Makó
Department of Soil Physics and Water Management, Institute for Soil Sciences, Centre for Agricultural Research, Herman Ottó Street 15,
1022 Budapest, Hungary
A. M. Mingot Soriano
Swedish University of Agricultural Sciences, Uppsala, Sweden
I. Messing
Swedish University of Agricultural Sciences, Uppsala, Sweden
A. Nemes
Norwegian Institute of Bioeconomy Research, Ås, Norway
A. Pomes-Bordedebat
Uliège – Gembloux Agro-Bio Tech, TERRA Teaching and Research Centre, Passage des Déportés 2, 5030 Gembloux, Belgium
M. van der Ploeg
Wageningen University and Research, Wageningen, Netherlands
T. K. D. Weber
Institute of Soil Science and Land Evaluation, University of Hohenheim, Hohenheim, Germany
L. Weihermüller
Agrosphere Institute IBG-3, Forschungszentrum Jülich GmbH, Jülich, Germany
J. Wellens
Uliège – Gembloux Agro-Bio Tech, TERRA Teaching and Research Centre, Passage des Déportés 2, 5030 Gembloux, Belgium
A. Degré
Uliège – Gembloux Agro-Bio Tech, TERRA Teaching and Research Centre, Passage des Déportés 2, 5030 Gembloux, Belgium
The soil water retention curve (SWRC) is a key soil property required for predicting basic hydrological processes. The SWRC is often obtained in the laboratory with non-harmonized methods. Moreover, procedures associated with each method are not standardized. This can induce a lack of reproducibility between laboratories using different methods and procedures or using the same methods with different procedures. The goal of this study was to estimate the inter- and intralaboratory variability of the measurement of the wet part (from 10 to 300 hPa) of the SWRC. An interlaboratory comparison was carried out between 14 laboratories, using artificially constructed, porous reference samples that were transferred between laboratories according to a statistical design. The retention measurements were modelled by a series of linear mixed models using a Bayesian approach. This allowed the detection of sample-to-sample variability, interlaboratory variability, intralaboratory variability and the effects of sample changes between measurements. The greatest portion of the differences in the measurement of SWRCs was due to interlaboratory variability. The intralaboratory variability was highly variable depending on the laboratory. Some laboratories successfully reproduced the same SWRC on the same sample, while others did not. The mean intralaboratory variability over all laboratories was smaller than the mean interlaboratory variability. A possible explanation for these results is that all laboratories used slightly different methods and procedures. We believe that this result may be of great importance regarding the quality of SWRC databases built by pooling SWRCs obtained in different laboratories. The quality of pedotransfer functions or maps that might be derived is probably hampered by this inter- and intralaboratory variability. The way forward is that measurement procedures of the SWRC need to be harmonized and standardized.
