Remediation of Cocoa Soils in Ghana as a Route to more Sustainable Cocoa Production

可可在西非广泛种植，产量占世界总产量的75%。加纳是第二大可可生产国，可可生产为大约80万小农提供了生计。西非可可行业面临的主要挑战之一是可可农场的土壤长期恶化，原因是不良的耕作方式导致土壤养分枯竭。这导致了种植模式的转变，可可种植者迁移到原始森林地区，这显然是不可持续的。改善土壤健康的措施将提高农场产量，从而提高可可小农的生计。雷丁大学和加纳可可研究所（CRIG）之前的合作研究表明，许多可可农场缺乏关键的土壤养分，而且许多农民负担不起无机肥料。在此背景下，本项目旨在探索通过利用农场废弃物来改善可可农场土壤的途径，从而促进更可持续的作物生产，从而维持可可小农的生计。该项目将探索使用堆肥和热解（在无氧条件下燃烧有机材料以产生“生物炭”）农场废物作为土壤改良剂，以提高可可小农场的土壤肥力和健康。实验将在之前一个项目中建立的可可农场网络上进行，以确定堆肥农场废物和生物炭对现有可可树性能的影响。这将通过产量的变化和通过测量病虫害的存在来评估植物健康来进行评价。在CRIG进行的遮荫试验也将用于确定维持在头顶的遮荫树对土壤微观和宏观动物的影响。补充试验还将在CRIG温室进行盆栽育苗试验，以确定不同土壤改良剂对幼可可生产性能的影响。这些试验还将评估在用不同堆肥改良的土壤上耕作是否能改善植物在干旱条件下的表现。此外，温室试验将考虑在用不同堆肥改良的土壤中生长的植物是否不易受到虫害和疾病的侵袭。另外的盆栽实验将在雷丁大学进行，在不同的土壤改良剂中种植的可可幼苗将在生长柜中接受不同的温度制度。将对堆肥改良后的土壤特性进行分析。这些将评估通过堆肥和生物炭生产改善阳离子交换能力和养分可得性的程度。将堆肥改良土壤的微生物和大型动物作为影响作物养分有效性的关键因素与对照进行比较。在项目后期，将通过农民田间学校探索使用堆肥和生物炭的成本效益比并传达给农民。这些活动将在进行试验的农场进行，并向农民展示堆肥方法/热解方法。我们的研究结果总结将在加纳举行的项目结束研讨会上发表，可可生产链上的主要利益相关者将参加该研讨会。此外，我们将制作一份手册和视频，作为推广人员的工具，将开发的技术推广给更多的农民

SummaryCocoa is grown extensively in West Africa, producing 75% of world production. Ghana is the second most important cocoa producing country, where cocoa production provides a livelihood for an estimated 800,000 smallholder farmers. One of the main challenges facing the cocoa sector in West Africa is long-term soil deterioration on cocoa farms because of the depletion of soil nutrients caused by poor farming practices. This has resulted in a shifting cultivation pattern, and migration of cocoa farmers into virgin forest areas which is clearly unsustainable. Measures to improve soil health would improve both on-farm yields and thus the livelihoods of smallholder cocoa farmers. Previous collaborative research between the University of Reading and the Cocoa Research Institute of Ghana (CRIG) has demonstrated that many cocoa farms are deficient in key soil nutrients but also that inorganic fertilisers are unaffordable for many farmers. Against this background, this project seeks to explore routes for soil improvement on cocoa farms through utilisation of on-farm waste products, thereby contributing to more sustainable crop production and thus maintenance of livelihoods of smallholder cocoa farmers.The project will explore the use of composted and pyrolysed (burning organic materials in the absence of oxygen to produce "biochar") farm waste as soil amendments to improve soil fertility and health on cocoa smallholdings. Experiments will be conducted on a network of cocoa farms, established in a previous project, to ascertain the impact of composted farm waste and biochar on the performance of established cocoa trees. This will be evaluated through changes in yield and assessments of plant health by measuring the presence of pests and diseases. Shade trials at CRIG will also be utilised to ascertain the impact of maintained overhead shade trees on soil micro and macro fauna. Complementary experiments will also be conducted in the greenhouses of CRIG on seedlings in pots to ascertain the impacts of different soil amendments on the performance of juvenile cocoa. These experiments will also assess whether the performance of plants subjected to drought is improved by cultivation on soils ameliorated with different composts. Furthermore, the greenhouse experiments will consider whether plants grown in soils ameliorated with different composts are less susceptible to attack by insect pests and by diseases. Additional pot experiments will be conducted at the University of Reading in which cocoa seedlings grown in different soil amendments will be subjected to different temperature regimes within growth cabinets.Analyses will be conducted on the properties of soils amended with composts. These will assess the extent to which cation exchange capacity and availability of nutrients are improved through composting and biochar production. The microbiology and macrofauna of compost amended soils will be compared with controls as a critical factor that impacts on nutrient availability to the crop.The cost: benefit ratio of using composts and biochar will be explored and communicated to farmers through farmer field schools in the latter stages of the project. These events will be conducted on farms on which the trials were conducted and composting methods/ pyrolysis methods will be demonstrated to farmers.A summary of our findings will be presented at an end of project workshop which will be held in Ghana and attended by key stakeholders in the cocoa production chain. Furthermore, we will produce a manual and video that will be used as tools by extension agents to take the technologies developed out to larger numbers of farmers