Cocoa; future yields across West Africa

世界上70%的可可产量是由西非的小农户生产的。然而，可可产量低，面临气候变化、虫害和疾病的风险，许多种植可可的家庭生活在国际贫困线附近或以下。为了发展可持续的供应链，需要进行重大变革。能够准确预测可可产量和产量将是这样的变化之一。目前，只有少数几家大型跨国可可公司和经纪商才能获得准确的产量预测，他们基于对数百个可可农场的实物监测，运行自己的专有预测程序。可可行业的所有其他参与者都缺乏关于预期收成的可靠信息来源。然而，这样的预测对于支持整个供应链的规划和适应至关重要。它们对价格形成也是至关重要的，价格形成是由期货市场决定的，期货市场取决于参与者对未来收成的预期。目前，市场上的信息是不对称的，这对少数几家大公司有利。在这里，我们建议使用一种已演示的技术来生成准确的预测模型，而成本仅为专有系统的一小部分，使可可行业的广大受众能够负担得起这些模型，从而促进可可行业的民主化。我们将长时间(20-40年)可用的一系列数据源与机器学习和模型相结合，以生成一个强大的预测工具。我们现在有了产量关键决定因素的时间序列图，包括降雨量、叶面积指数、表层土壤水分、土壤物理性质。我们也有地区和国家的产量数据。有强有力的证据表明气候(土壤湿度)对产量有影响，但关于干旱胁迫影响的临界阈值的信息很少。在这里，我们使用过程建模，通过根区将植物产量与土壤湿度联系起来。我们在现场尺度上校准我们的模型以耦合植物-土壤过程，然后在区域和国家尺度上校准模型以耦合产量与植物-土壤指标。该结果是一个强大的工具，用于生成全年产量预测，具有明确的置信度区间。这些信息为可可价值链提供了新的投入。这项研究的成果将形成商业供应商向可可行业最终用户提供产品和服务的科学基础，两个项目合作伙伴证明了这一点。一旦可可被证实，这种方法可以在一系列其他作物上复制，从谷物到热带商品再到植物油。

Seventy percent of the world cocoa production is produced by small holders in West Africa. However, yields are low and at risk from climate change, pests and diseases and many cocoa farming families live around or below the international poverty line. Major changes are needed to develop a sustainable supply chain. Being able to accurately predict cocoa yields and production will be one such change. Currently, accurate production forecasts are only available to a handful of large multinational cocoa companies and brokers, who run their proprietary forecasting programmes, based on physical monitoring of hundreds of cocoa farms. All other actors in the cocoa industry lack a reliable source of information about the expected harvest. However, such forecasts are essential to support planning and adaptation across the supply chain. They are also essential to price formation, which is determined in futures markets, which rely on participants' expectations of future harvests. Currently, information is asymmetrical in the market, favouring the few big players. Here we propose to use a demonstrated technology to generate accurate forecasting models at a fraction of the cost of the proprietary systems, making them affordable for a broad audience in the cocoa industry and hence contributing to the democratisation of the cocoa sector. We combine a range of data sources now available over long periods (20-40 years) with machine learning and models to generate a robust forecast tool. We now have time series mapping of critical determinants of yield, including rainfall, leaf area index, surface soil moisture, soil physical properties. We also have regional and national yield data. There is strong evidence of climate (soil moisture) impacts on yield, but little information on the critical thresholds in drought stress effects. Here we use process modelling to link plant production to soil moisture through the rooting zone. We calibrate our model at site scale to couple plant-soil processes, and then calibrate the model at regional and national scale to couple yield to plant-soil indicators. The outcome is a robust tool for generating forecasts of yield through the year, with clear confidence intervals. This information provides the novel input for the cocoa value chain.The output from this research will form the scientific basis on which commercial providers can offer products and services to end-users in the cocoa industry, as demonstrated by two project partners. Once proven for cocoa, the approach can be replicated in a range of other crops, from grains to tropical commodities to vegetable oils.