Abstract
Much of the Ganges’ coastal region remains fallow during the dry (Rabi) season due to the unavailability of freshwater, soil and water salinity, and inadequately tested irrigation strategies. Therefore, the aims of this research were: (i) to assess the effectiveness of irrigation with brackish water for crop yield, water use, and water productivity (WP), (ii) to analyze how irrigation affects soil solute potential (SP) during the growing season and its implications for crop growth. Two field experiments tested four irrigation treatments (T1-one irrigation at crown root initiation (CRI) stage, T2-two irrigations at CRI and booting, T3-two irrigations at CRI and grain development, T4-three irrigations at CRI, booting, and grain development) with three replications on wheat and barley in 2018–2019 and 2019–2020 in two locations (Dacope and Amtali) in the coastal region of the Ganges delta. The brackish water (≤ 4 dSm-1) irrigation had a significant effect on wheat and barley yields. When irrigation water was provided at later growth phases of wheat, treatment T4 produced highest yield of 2.5 tha− 1 at Amtali and 1.7 tha− 1 at Dacope. In both locations, barley grain yield significantly increased with each additional irrigation. WP of wheat and barley under different irrigation regimes varied with an average of 0.9 and 1.5 kgm− 3 at Dacope and 1.5 and 1 kgm− 3 at Amtali, and 1.1 and 1.6 kgm− 3 at Dacope and 1.6 and 1 kgm− 3 at Amtali in 2019 and 2020, respectively. Irrigation had significant effect on WP, and increased SP as well as yield in both locations and years. SP rose as soil dryness decreased and vice versa. In February-March SP was significantly lower in the upper soil depths. Two or three irrigations with brackish water may be useful for increasing cropping intensity and WP of wheat and barley with a little yield reduction in the Ganges delta.