On the influence of coarse fragments on soil water retention

Abstract

[1] The classical determination of the soil water retention curve (SWRC) by measuring soil water content q at different matric potentials y using undisturbed soil samples is time consuming and expensive. Furthermore, undisturbed soil sampling can be an intricate task when coarse soil fragments (>2 mm) are present. The objective of this study was to test whether tension infiltrometry could be used to estimate the SWRC of stony soils and to investigate to what extent the coarse fragments affected the SWRC. Tension infiltrometer measurements were conducted at 44 sites with stony soils in arid Chile. Soil water retention curves obtained through inverse modeling were compared with laboratory-determined water retention (q, y) data pairs. Differences were found to be small, confirming the applicability of the inverse modeling method. Rock fragments had a significant indirect influence on water retention for matric potentials higher than À0.30 kPa, which could be attributed to their direct influence on pore size distribution.

The contribution of rock fragments to the available water content of stony soils: Proposition of new pedotransfer functions

“…The latter was confirmed by laboratory experiments on remoulded samples (Ma et al, 2010;Urbanek and Shakesby, 2009;Zhou et al, 2009). Baetens et al (2009) have demonstrated the decrease of water content at a given water potential by in situ infiltrometer experiments and laboratory measurements of the water retention curve on large undisturbed samples. Nevertheless, as far as the water retention curve is concerned, the determination of the water content at a given potential on a heterogeneous soil can be calculated by independent measurements on each phase, i.e., for stony soils, by independent measurements of the water content of the fine earth and of the rock fragments.…”

“…According to Baetens et al (2009), the water content of a soil horizon usually decreases when the rock fragments content increases (Baetens et al, 2009;Cousin et al, 2003;Poesen and Bunte, 1996), but the horizon water content depends on i) the nature of the rock fragments, ii) their position in the soil (Childs and Flint, 1990) and their degree of weathering: Poesen and Lavee (1994) demonstrated that the water content in rock fragments may vary according to their weathering, the smallest rock fragments -supposed to be the most altered -being able to absorb a higher quantity of water. In some cases, rock fragments can contribute to a proportion of a quarter of the total available water content (Fies et al, 2002).…”

Relating Cone Penetration and Rutting Resistance to Variations in Forest Soil Properties and Daily Moisture Fluctuations

“…For example, the space available for water retention would decrease with increasing CF content. Consequently, there would be less PS to fill between the coarse fragments during wet weather conditions, and there would also be less water available for root uptake during warm summer weather [46]. This being so, The ForHyM-generated projections in Figure 6 by location and soil layer show greater MC v and MC ps variations for the stony UNB location, followed by the less stony SM and the more sandy OP locations.…”

Effect of rock fragments content on water consumption, biomass and water-use efficiency of plants under different water conditions

“…Li et al, 2008;Zhou et al, 2009;Baetens et al, 2009;Ma et al, 2010;Novák et al, 2011;Tetegan et al, 2011). Water movement in, and the hydraulic properties of, soils are strongly dependent on the availability of water for plants.…”