In areas where the water table is within or slightly below the root zone, crops uptake water from both a thin unsaturated vadose zone and saturated ground water (Shah et al. 2007). Groundwater contribution to crop water use by groundwater evaporation (ETgw) is one important term of soil water balance in the presence of shallow water tables (Liu et al. 2006; Bourgault et al. 2014). Therefore, groundwater should be used efficiently (Boyraz & Kazezyilmaz-Alhan 2014). The volume of drainage and irrigation water can be reduced by using shallow groundwater to meet a portion of the crop water requirement (Ayars et al. 1999). However, the groundwater contribution is influenced by many factors, and among them, groundwater depth and the soil water storage in root zone are two important influencing factors of ETgw (Raes & Deproost 2003; Doble et al. 2006; Luo & He 2008).

Table 1

Bulk density and soil texture of the silt soil in the lysimeters

Soil texture
Soil depth (m)Bulk density (g cm−3)Sand (%)Silt (%)Clay (%)
0–0.2 1.25 15.0 80.3 4.7
0.2–1.5 1.42 13.4 81.7 4.9
Soil texture
Soil depth (m)Bulk density (g cm−3)Sand (%)Silt (%)Clay (%)
0–0.2 1.25 15.0 80.3 4.7
0.2–1.5 1.42 13.4 81.7 4.9

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