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The soil ecosystem
Published in Stephen R. Gliessman, V. Ernesto Méndez, Victor M. Izzo, Eric W. Engles, Andrew Gerlicz, Agroecology, 2023
Stephen R. Gliessman, V. Ernesto Méndez, Victor M. Izzo, Eric W. Engles, Andrew Gerlicz
In the form of hydraulic redistribution with greatest relevance for agriculture, upward hydraulic redistribution, water is drawn from the deep layers of the soil penetrated by the plant’s long tap roots and redistributed to the soil near the surface occupied by the lateral roots. Upward hydraulic redistribution has been investigated in a number of annual crops including corn (Wan et al. 2000), tomato (Yan et al. 2020), and the deep-rooted pigeon-pea (Cajanus cajan) (Sekiya & Yano 2004). Hydraulic redistribution also has relevance for agroecosystems in semi-arid regions when those systems include non-crop plants that exhibit hydraulic redistribution (Liste & White 2008). In the African Sahel, for example, crops of pearl millet show significant yield increases, especially during drought years, when intercropped with the hydraulic-redistributing native woody shrub Guiera senegalensis (Bogie et al. 2018).
Soil salinity and moisture content under non-native Tamarix species
Published in International Journal of Phytoremediation, 2020
Solomon W. Newete, Mohamed A. Abd Elbasit, Tesfay Araya
The highest soil moisture (60%) was found at a soil depth of 30 cm close to the water point with the lowest Tamarix density, a depth at which the soil EC seems to correlate well, although it was the lowest (28 mS/m) reported. This suggests a dilution effect of the high soil moisture closer to the water point where the Tamarix salt uptake and transpiration effect is minimal due to their low density mainly at juvenile stage. The maximum temperature was 40 °C at the time of the data collection and the water channels and flood plains were completely dry but a soil moisture of 25–40% were reported at the top 30–40 cm of the soil depth further away from the river water course at the banks of the river under the Tamarix species, suggesting a hydraulic lift from the deeper groundwater close to the surface soil (top 30 cm or so) where most of the fine roots used for water uptake from soil to the plant are located. This finding also agrees with those reported by Yu et al. (2013) which showed a greater soil moisture between 30 cm and 50 cm under T. ramosissima than those in the top 10 and 80 cm during the dry season. Several studies showed that one of the typical adaptations of desert plants in response to hyperarid conditions or extreme water stress among others is a hydraulic redistribution of water extracted from deeper groundwaters by long tap roots upward to the fine root zone where water absorption occurs (Burgess et al.1998; Nadezhdina et al.2010; Hultine et al.2003; Warren et al.2007). Tamarix are a facultative phreatophyte with deep root system that often grows 5 m deep (Brotherson and Winkel 1986; Brotherson and Field 1987), but sometimes up to 50 m (Baum 1978; DiTomaso 1998) depending on water availability in the environment they grow. The fact that most of the soil moisture in this study occurred in the first 30–40 cm under the Tamarix canopies and the water channels or floodplains were dry and the moisture in the deeper soils (60–100 cm) showed a steep reduction (Figure 4B and C) conforms the ideas of the hydraulic lift from the deep groundwaters (140 cm deep) as indicated by Yu et al. (2013).