Exploring climate-resilient and risk-efficient cropping strategies using a new pond irrigation system: An experimental study in northern Ghana

Abstract CONTEXT The planned interventions to enhance adaptation and build resilience of predominantly rainfed and vulnerable smallholder production systems to climate change in African drylands include small-scale irrigation using rainwater harvesting reservoirs. However, the required technological improvement, participatory breakthroughs, institutional settings, farm risk management, and investment justification are rarely established comprehensively and integrated into adaptive planning. OBJECTIVES To develop and assess new reservoir-based climate-resilient and risk-efficient irrigation cropping strategies synthesizing technological, participatory, institutional, managerial, and investment capabilities. METHODS We crafted an innovative rice and vegetable pond irrigation system together with governance arrangements and cropping schedule adjustments tailored to the system. The system was validated through a five-year participatory on-farm experiment in northern Ghana. Using agronomic, hydrological, and socioeconomic data obtained from the experiments and surveys, we constructed and extended empirical bioeconomic models through simple risk programming to identify irrigation cropping strategies that are the most efficient in securing smallholders' food and income and resilient to interannual climate fluctuations. The net present values were computed to determine the financial effects of the identified strategies on the investment payback of the pond system. RESULTS AND CONCLUSIONS Shifting sowing dates allowed smallholders to irrigate timely, albeit sparingly, without compromising their autonomous adaptations in rainfed systems. Supplementary irrigation and improved weed control increased the average rice yield by 23%, more than doubled the profitability, and lowered the coefficients of its variation compared to that of rainfed rice (from 48% to 38%). Vegetable irrigation in the dry season was even more profitable. The risk-efficient cropping strategies identified by empirical models mostly combined multiple rainfed crop choices with balanced irrigation allocation between rice and vegetables, enabling food self-sufficiency and increased income level and stability. A 5000 m3 pond storage capacity was sufficient to secure these benefits under the observed climate fluctuations. The cropping strategy found to produce sufficient financial increments to achieve mid-term (8-to-12-years) payback of pond investment under the same level of risk that smallholders accepted under rainfed systems is among the most advisable. SIGNIFICANCE We addressed multidimensional challenges underlying planned adaptation through reservoir irrigation. The innovative pond system established can offer promising alternatives and complement smallholder autonomous adaptations to secure food and income under a changing climate. The identified strategic compromise between farm risk management and investment payback can reconcile local intention and policy guidance to develop concerted adaptation actions.