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.

中文翻译：

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使用新型池塘灌溉系统探索具有气候适应力和风险高效的种植策略：加纳北部的一项实验研究

语境

计划采取的旨在加强适应和增强主要是雨养和脆弱的小农生产系统对非洲干旱地区气候变化的适应性干预措施，包括使用雨水收集水库的小规模灌溉。但是，所需的技术改进，参与性突破，机构设置，农场风险管理和投资合理性很少得到全面确立，并不能纳入适应性计划。

目标

开发和评估基于水库的，具有气候适应力和风险效率的新灌溉作物种植策略，以综合技术，参与，机构，管理和投资能力。

方法

我们精心设计了一种创新的水稻和蔬菜池塘灌溉系统，以及针对该系统的治理安排和作物种植计划调整。该系统通过在加纳北部进行的一项为期五年的农场试验进行了验证。我们使用从实验和调查中获得的农业，水文和社会经济数据，通过简单的风险规划来构建和扩展经验生物经济模型，以识别最有效地确保小农的粮食和收入并能抵御年际气候波动的灌溉作物策略。计算净现值以确定确定的策略对池塘系统投资回报的财务影响。

结果与结论

播种时间的变化使小农尽管适度地进行了适时的灌溉，却不影响他们在雨养系统中的自主适应能力。与雨养水稻相比，补充灌溉和改进的杂草控制使水稻平均单产提高了23％，利润翻了一番还多，并且变异系数降低了（从48％降至38％）。干旱季节的蔬菜灌溉更有利可图。通过经验模型确定的高风险农作策略大多将多种雨养作物选择与稻米和蔬菜之间的均衡灌溉分配相结合，从而实现了粮食自给自足并提高了收入水平和稳定性。5000 m ³在观察到的气候波动下，池塘的储存能力足以确保这些益处。最可取的是，这种种植策略可产生足够的财务收益，以期在中期（8至12年）投资回报的前提下，实现池塘投资的中期（8至12年）投资回报。

意义

我们解决了通过水库灌溉进行的计划适应所面临的多维挑战。建立的创新性池塘系统可以提供有前途的替代方案，并补充小农户的自主适应能力，以在气候变化的情况下确保粮食和收入。在农场风险管理和投资回报之间确定的战略妥协可以调和地方意图和政策指导，以制定一致的适应行动。