Deficit irrigation as a sustainable option for improving water productivity in Sub-Saharan Africa: the case of Ethiopia. A critical review

Desale Kidane Asmamaw,Seifu Tilahun,Wim Cornelis,Kristine Walraevens,Enyew Adgo,Mekete Dessie,Pieter Janssens,Jan Nyssen

doi:10.1088/2515-7620/ac2a74

Desale Kidane Asmamaw, Seifu Tilahun + Show 6 more

Open Access

https://doi.org/10.1088/2515-7620/ac2a74

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Abstract

Improving irrigation water management and enhancing water productivity (WP) is required to address future water scarcity in the sub-Saharan region. Maximizing WP by exposing the crop to a certain level of water stress using deficit irrigation (DI) is considered a promising strategy. To adopt DI strategies, a shred of comprehensive evidence concerning DI for different crops is required. This review aims to provide adequate information about the effect of DI on WP. The result showed that DI considerably increased WP compared to full irrigation. Despite higher WP, the reduced yield was obtained in some of the studied DI practices compared to full irrigation. It was also found that yield reduction may be low compared to the benefits gained by diverting the saved water to irrigate extra arable land. Maize revealed the highest (2.7 kg m−3) and lowest (0.5 kg m−3) WP when irrigated at only the initial stage compared with being fully irrigated in all growth stages. Also, onion showed a decreasing WP with increased irrigation water from 60% crop water requirement (ETc) (1.8 kg m−3) to 100% ETc (1.3 kg m−3). Increasing water deficit from 100 to 30% ETc led to an increase of wheat WP by 72%. For tomato, the highest WP (7.0 kg m−3) was found at 70% ETc followed by 50% ETc (7.0 kg m−3) and 85% ETc (6.9 kg m−3), while 100% ETc showed the least WP (6.8 kg m−3). Teff showed the lowest WP (1.7 kg m−3) under optimal irrigation, while it was highest (3.0 kg m−3) under 75% ETc throughout the growing season. The regression analysis for WP increment and yield reduction versus saved water showed higher values, indicating that DI could be an option for WP increment and increasing overall yield by expanding irrigated area and applying the saved water in water-scarce regions.

Highlights

Food production requires to increase to feed the growing world population (Bouman 2007)
Abiyu and Alamirew (2015) found the highest maize yield (5.9 t ha−1) when full irrigation was applied during all growth stages under Nitisol in northwest Ethiopia
A higher water productivity (WP) (1.6 kg m−3) was obtained when 50% deficit irrigation (DI) was applied during development and mid-season growth stages, compared to 75% ETc treated plots at all growth stages (1.3 kg m−3)

Summary

Introduction

Food production requires to increase to feed the growing world population (Bouman 2007). This increase needs to be accomplished under a changing climate, so water shortages might increasingly materialize (Scheierling and Treguer 2016). With the growing water shortage in developing countries, enhancing agricultural water management strategies is of paramount importance to reduce food insecurity (Giordano et al 2016). Increasing water productivity (WP) is mainly suitable where water is limited compared with other resources involved in crop production (Molden et al 2010). It is hardly possible to address the food demands of the world population that is expected to surpass 7 billion in the 2020 s (FAO 2011)

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