Enhancing rice yields, water productivity, and profitability through alternate wetting and drying technology in farmers’ fields in the dry climatic zones of West Africa

Abstract

Irrigated rice farming is crucial for meeting the growing rice demand and ensuring global food security. Yet, its substantial water demand poses a significant challenge in light of increasing water scarcity. Alternate wetting and drying irrigation (AWD), one of the most widely advocated water-saving technologies, was recently introduced as a prospective solution in the semi-arid zones of West Africa. However, it remains debatable whether AWD can achieve the multiple goals of saving water while increasing yield and farmer income in diverse edaphic and climatic growing environments. We carried out participatory on-farm trials in four major irrigation schemes of Burkina Faso, (i) to assess the effects of AWD on yield, water productivity, and profitability in comparison to farmers’ irrigation practices, and (ii) to identify the environmental conditions and cropping practices determining yield gain of AWD over farmers’ irrigation practices. During the 2018 and 2019 wet and dry seasons, we conducted 154 pairwise comparisons of AWD at the threshold of 15 cm below the ground surface, and farmers’ irrigation practices (fields being submerged as frequently as water availability allowed according to the scheme-dependent water provision schedule). The drivers of yield gains associated with AWD were identified using brute force and random forest machine learning algorithms. Across irrigation schemes and seasons, AWD reduced irrigation water input by 30 %, while increasing grain yield by 6 % (p < 0.05). Consequently, AWD increased the irrigation water productivity by 64 % and profit by 5 % over farmers’ irrigation practices. The AWD-associated yield gains were higher in fields with poor access to irrigation water, and higher for indica than for tropical japonica varieties. Overall, AWD appears to be an effective strategy to improve yields, water productivity, and profitability in rice irrigation schemes in dry climatic zones in West Africa. This study suggests a need for reshaping rice irrigation practices, involving a systematic monitoring of field water levels in the region.