Journal of Experimental Agriculture International

Agriculture accounts for approximately 70% of global freshwater withdrawals, and this proportion rises to over 90% in many arid and semi-arid regions. As the global population approaches 10 billion and climate change intensifies hydrological variability, the imperative to produce more food with substantially less water has never been more urgent. Deficit irrigation (DI) and precision water management (PWM) have emerged as central pillars of climate-smart agriculture (CSA), offering the twin capacity to sustain crop productivity while dramatically reducing water consumption. This review synthesises scientific evidence on the conceptual foundations, technological advancements, agronomic outcomes, and policy implications of DI and PWM within a CSA framework. Strategies encompassing regulated deficit irrigation (RDI), partial root zone drying (PRD), sensor-based scheduling, remote sensing, Internet of Things (IoT)-enabled smart irrigation, and decision support systems are critically evaluated. Evidence from diverse agroecological contexts indicates that well-implemented DI regimes can reduce irrigation water use by 20–50% with minimal yield penalties, particularly when stress is confined to drought-tolerant growth stages. Integration of precision technologies enhances temporal and spatial resolution of irrigation decisions, further improving water productivity. The review also highlights the alignment of DI and PWM with the three pillars of CSA—increased productivity, enhanced adaptation, and mitigation of greenhouse gas emissions. Notwithstanding documented agronomic and environmental co-benefits, several barriers persist, including knowledge asymmetries among smallholder farmers, high initial investment costs for precision technology, and inadequate institutional and policy support. The review identifies critical research gaps, including a need for more long-term field trials, economic analyses in smallholder contexts, and improved crop-model integration with real-time sensing. The article concludes that a convergence of precision technology, adaptive management, and enabling governance can position DI and PWM as transformative climate-smart strategies for sustainable agriculture globally.