Can a superabsorbent polymer synthesised a CaCO₃ based biofiller improve soil and plant available water and crop growth under salt stress?

The use of superabsorbent polymers (SAPs) in dryland agricultural areas utilizing brackish irrigation water is a strategy to increase plant available water (AW). However, water retention by SAPs may be adversely affected under salinity. SAP containing calcium carbonate (Ca-SAP) is considered to be more resistant and provide more plant AW under saline conditions compared to conventional SAP (C-SAP) and to control. This research investigated two replicated lettuce trials to evaluate three treatments (Ca-SAP, C-SAP and control) subjected to irrigation water with electrical conductivities of 0.0, 0.5, 1.0, 2.0 and 4.0 dS m(-1). Both SAP treatments increased AW by an average of 0.16 m(3) m(-3) as compared to the control. Decrease in AW with salinity was lower in Ca-SAP (0.07 m(3) m(-3)) as compared with C-SAP (0.13 m(3) m(-3)). Lettuce fresh weight (g plant(-1)) was higher for Ca-SAP (22.9) as compared to C-SAP (16.4), however, did not differ from control (20.6). As water salinity increased, lettuce fresh biomass was higher in Ca-SAP as compared to C-SAP up to 2 dS m(-1) with no significant differences from control. The Ca-SAP is less affected by salts than the C-SAP, although its use did not benefit lettuce growth under saline conditions as expected.