Fjölrit RALA - 15.06.2004, Síða 68

ones (Fig. 1), from Cryic-Frigid/Udic to Mesic/Udic temperature/moisture regime,
respectively.
Many changes in physical properties are associated with this change of void volume; for
example, proportion of water-stable aggregates was negatively related to their porosities for of
the 40°C dried soils whereas this relationship was only a tendency for their wet soil
counterparts (Fig. 2a). Furthermore, an increase of water-stable aggregates occurred when the
wet soils were 40°C dried. This was related to total volumetric shrinkage (Fig. 2b).
Total porosity (cm !.cm “) Total shrinkage (%)
of wet (field) or 40 °C dried soiis
Figure 2 Relationships between proportion of > 200 pm water-stable aggregates and total
porosity for both the wet soils and their 40°C dried soil counterparts (a) and between the
increase of water-stable aggregates occurring during drying and total volumetric shrinkage
(see Fig. 1 for symbols legend). Large and small symbols of figure 2a correspond to the wet
soils and to their 40°C dried soil counterparts, respectively.
Finally, the drainage and shrinkage kinetics, and the shrinkage curves will be also discussed
as well as complementary results obtained on wet aggregates (bulk wet soil sampled in plastic
bags and stored at 4°C thereafter) using the new approach, recently designed by Poulenard et
al. (2002), combining mercury porosimetry and vacuum drying kinetics.
We thank Jorge Pinheiro and Manuel Madeira (Azores), Olafur Amalds and Hlynur
Oskarsson (Iceland), Marisa Tejedor and Jose Hemandez-Moreno (Tenerife) for the selection
of the COST 622 reference profiles, Toine Jongmans (The Netherlands) and Folkert van Oort
(France) for the soil and site description, Paul Quantin (France) for the WRB soil
classification, Elisabeth Schouller and Gérard Burtin (France) for technical assistance.
References
Bartoli, F., Burtin, G. and Herbillon, A. J. 1991. Disaggregation and clay dispersion of
Oxisols: Na resin, a recommended methodology. Geoderma 49: 301-317.
Poulenard, J., Bartoli, F. and Burtin, G. 2002. Shrinkage and drainage in aggregates of
volcanic soils: a new approach combining mercury porosimetry and vacuum drying kinetics.
European Joumal of Soil Science 53: 563-574.
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