How lysimetric monitoring of Technosols can contribute to understand the temporal dynamics of the soil porosity M. Tifafi a,b , R. Bouzouidja a , S. Leguédois a , S. Ouvrard a , G. Séré a, ⁎ a Laboratoire Sols et Environnement, UMR 1120 Université de Lorraine-INRA, 2, avenue de la forêt de Haye - BP 20163, 54505 Vandoeuvre-lès-Nancy Cedex, France b Laboratoire des Sciences du Climat et de l'Environnement, LSCE/IPSL, CEA-CNR-UVSQ, Université Paris-Saclay, F-91191 Gif-sur-Yvette, France abstract article info Article history: Received 6 November 2016 Accepted 19 February 2017 Available online 2 March 2017 Soil poral architecture controls soil functioning and is submitted to temporal changes. The monitoring of soil structure dynamics is complicated by inherent technical constraints in its measurement that are either punctual or complex. In this study, four soils, from a natural one to incrementally anthropized (including three Technosols: Spolic Toxic, Terric Transportic, Spolic Garbic Hydric), have been studied. Seven 2-m 3 lysimetric columns have been setup to compare planted and non-planted treatments over 3 to 6 years. Data on the water balance and the hydrodynamics were continuously acquired. Differences were observed between the various soils as a func- tion of their texture. The presence of vegetation also led to significant differences, especially in hot periods, be- tween the vegetated and the bare soils treatments: the amount of water stored into the soil was up to 210 L m -2 higher for bare soil. Furthermore, the analysis of the “critical water storage capacity” highlighted dif- ferences in the hydrodynamics at two time scales. For vegetated soils, similar seasonal variations depending on the climatic conditions were observed for all soils, with higher S CRIT values in cold periods compared to hot pe- riods (differences were up to 190 L m -2 ). These results were attributed to roots development over the climatic year that decreases water storage capacity and increases preferential flows. Besides, significant trend evolution was also observed but only for the youngest i.e. the most anthropized soils. Their total water storage capacity de- creased down to 52%. It is possibly due to soil compaction, the increase of pore connectivity related to root devel- opment and the formation of organo-mineral associations. Our work promotes the association of monitored lysimeters as tool and the study of soils within a gradient of anthropization in order to describe a pedogenetic process like the dynamics of soil porosity. © 2017 Elsevier B.V. All rights reserved. Keywords: Level of anthropization Porosity Technosol Pedogenesis Lysimeter Water balance 1. Introduction Soil structure and porosity, as defined by Oades (1984), are key com- ponents of soil health and functioning. Actually water and gas flows, sol- ute transport, and biological activity are directly affected by the geometry of the available pore space (Angers and Caron, 1998; Vogel and Roth, 2001; Strudley et al., 2008; Alaoui et al., 2011). Soils pore size distribution and their connectivity influence many aspects of the soil functioning. Macroporosity contributes to water flows in wet pe- riods, whereas microporosity is involved in water and solutes ex- changes, even during dry periods (Jarvis, 2007; Lipiec et al., 2012). Natural factors such as climate and biological activity or human actions through tillage, fertilization, drainage or compaction induce significant temporal changes of the soil pore system (Alaoui and Helbling, 2006; Jarvis, 2007; Montagne et al., 2009; Schwen et al., 2011a, 2011b; Jangorzo et al., 2013; Dal Ferro et al., 2013; Mora and Lazaro, 2014). Soil pore architecture is not a static property. Actually, the whole soil system is governed by external and internal forces that contribute to its evolution (Cocos, 1997). A two-tier evolution has been recently pro- posed: i) fast and cyclic — smartly entitled as “soil beats” by Mora and Lazaro (2014) — due to seasons and growing cycles; ii) slow and steady — due to pedogenesis (Séré et al., 2012). The changes of pore ar- chitecture over short term have been shown under the influence of wetting-drying cycles as well as during vegetative and seasonal cycles (Farkas et al., 2006; Mora and Lazaro, 2014). A decrease of the macroporosity at the soil surface due to rainfall has been explicitly assessed by Sandin et al. (2017). It has also been demonstrated that soil compaction leads to a global decrease of total porosity even if its im- pact on the different sizes of pores is notably related in a complex way with soil depth (Lipiec et al., 2012). The seasonal variability of hydraulic properties, and consequently of the soil porosity, is large. For example, in a tilled soil, the values of the saturated water content measured at the beginning and the end of the vegetation period can differ signifi- cantly from 0.37 to 0.49 m 3 m -3 (Farkas et al., 2006; Schwen et al., 2011a, 2011b). In the same context, Das Gupta et al. (2006) found that, while the relationships between soil hydraulic conductivity and Geoderma 296 (2017) 60–68 ⁎ Corresponding author. E-mail address: geoffroy.sere@univ-lorraine.fr (G. Séré). http://dx.doi.org/10.1016/j.geoderma.2017.02.027 0016-7061/© 2017 Elsevier B.V. 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