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More Strategic Use of Fresh Water Can Produce a Four to Eight-Fold Increase in Fresh Water Productivity in Irrigated Sunflower on Saline Soils in the Ganges Delta
Journal article   Open access

More Strategic Use of Fresh Water Can Produce a Four to Eight-Fold Increase in Fresh Water Productivity in Irrigated Sunflower on Saline Soils in the Ganges Delta

Afrin Jahan Mila, Richard W. Bell, Edward G. Barrett-Lennard and Enamul Kabir
SSRN Electronic Journal, Preprint
2022
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Abstract

Industrial and Manufacturing Engineering Business and International Management History Polymers and Plastics
Fresh water is becoming increasingly scarce in coastal areas due to competition for use, climate change and global sea-level rise. Our aim was to maximise crop output per unit of fresh water (i.e. fresh water productivity – FWP, defined as the ratio of yield to fresh irrigation water supply) using sunflower as a test crop. Two field experiments were conducted in southern Bangladesh during the Rabi seasons to increase FWP. Irrigation water of electrical conductivity (EC w ) 2–3 (fresh), 5–6 and 10 dS m -1 was applied to sunflower at up to 3–4 growth stages. Seed was sown on two dates: 30 November (SD 1 ) and 15 December (SD 2 ). Irrigation treatments are named using a sequence of suffixes indicating the EC w of the irrigation water applied at the vegetative, pre-flowering and grain filling growth stages (2018) and the vegetative, pre-flowering, flowering and grain filling growth stages (2019), respectively. In 2018, seven irrigation treatments (T 2/2/- , T 2/-/10 , T 2/10/-, T 2/2/5 , T 2/2/10 , T 2/10/10 and T 6/10/10 ) were examined for SD 2 . In 2019, eight irrigation treatments (T -/-/-/-_SD1 , T -/-/-/-_SD2, T -/2/2/3_SD1 , T -/2/2/10_SD1 , T 2/2/2/3_SD1 , T 2/2/3/-_SD2 T 2/10/10/10_SD2 and T 2/2/3/2_SD2 ) were trialled. One fresh irrigation at the vegetative stage and two to three highly saline irrigations from flowering to grain filling stage (T 2/10/10_SD2 and T 2/10/10/10_SD2 ) increased FWP by 4–8 fold compared to control treatments with all fresh irrigation applications (i.e. T 2/2/5_SD2 and T 2/2/3/2_SD2 ). The saline water treatments sacrificed 0.16–0.33 t ha -1 of yield but saved a substantial amount of fresh water (89–93% of the total irrigation). The risk of accumulated salt in the root zone through the long-term use of saline water may be mitigated in this landscape because it receives more than 1200 mm of annual monsoonal rainfall.

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