Integrated assessment of the determinants of the maize yield gap in Sub-Saharan Africa: towards farm innovation and enabling policies

产量差距估计和解释提供了关于通过更好的耕作系统、农场管理和扶持政策在现有农田上增加产量的范围的重要信息。该项目的目的是制定和实施一个框架，以确定影响SSA玉米产量差距的关键生物物理和管理因素，以及这些因素与现有的体制、基础设施、社会经济和政策制约因素之间的关系。研究的重点是SSA的主要粮食作物玉米，主要由小农生产。玉米是几乎所有撒哈拉以南非洲国家的重要粮食作物。因此，从粮食安全和贫困的角度来看，解决玉米的产量表现都是有价值的。该项目将侧重于加纳和埃塞俄比亚作为玉米种植案例研究国家，在这些国家建立现有数据和当地伙伴关系。人们认为，增进对这两个来自西非和东非的国家的了解将具有更广泛的意义。该项目的创新之处在于采用了一个综合了农学和经济学方法的框架，以评估产量差距并分析农场和地块一级的农业绩效。分析分为三个阶段。在第一阶段，使用作物生长和经济生产模型来计算国家和区域一级的潜在产量、技术效率(“最佳实践”)和经济上限产量，然后将这些产量与调查的实际产量数据结合起来，计算各种产量差距。在第二阶段，利用计量经济学技术分析观测到的产量差距在空间上的变化，并将它们与地块水平、农场水平和环境决定因素联系起来。在第三阶段，在村一级组织了少量当地案例研究，以深化分析并彻底了解产量差距的决定因素，从而能够确定农场和管理创新以及政策干预措施。有关产量潜力和实际产量的信息将来自全球产量差距地图集(GYGA)，该地图集目前由内布拉斯加州大学、瓦赫宁根大学和SSA的许多合作伙伴开发。埃塞俄比亚和加纳的农场/家庭数据和地块水平信息将来自世界银行的生活水平衡量研究--农业综合调查(LSMS-ISA)和加纳EGC-ISSER(预计将于2013年底提供)。此外，将在每个个案研究地区组织一次调查，以收集关于地块层面作物生产和管理的额外和详细的信息，如土壤特性、耕作历史和农艺管理。这些结果将被用来得出有针对性的政策和耕作建议，说明南沙地区男女农民经营的复杂环境，并纳入将农场业绩与更广泛的有利环境联系起来的基本机制。这一进程将得到支持，一方面将启动参与性农场示范试验，另一方面将与利益攸关方进行政策对话。

Yield gaps estimations and explanations provide important information on the scope for production increases on existing agricultural land through better farming systems, farm management and enabling policies. The aim of this project is to develop and implement a framework that identifies the key bio-physical and management factors that influence the maize yield gap in SSA and how these are related to existing institutional, infrastructural, socio-economic and policy constraints. The research focuses on the major food crop in SSA, maize, mainly produced by small scale farmers. Maize is an important food crop in almost all Sub-Saharan African countries. Addressing yield performance in maize is therefore valuable from both a food security and poverty perspective. The project will focus on Ghana and Ethiopia as maize-growing case study countries where it builds on existing data and local partnerships. It is assumed that enhanced understanding for these two countries from West and East Africa will have wider meaning. The innovative part of this project is the use of a framework that integrates agronomic and economic approaches to assess the yield gap and analyse agricultural performance at the farm and plot level. The analysis consists of three stages. In the first stage crop growth and economic production models are used to calculate potential, technical efficient ('best practice') and economic ceiling yields at the national and regional level, which are subsequently combined with actual yield data from surveys to compute the various yield gaps. In the second stage, econometric techniques are used to analyse variations in the observed yield gaps in space and relate them to plot-level, farm-level and context determining factors. In the third stage, a small number of local case studies are organised at the village level to deepen the analyses and to thoroughly understand the determinants of yield gaps to allow identification of farm and management innovations and policy interventions. Information on yield potentials and actual yields will be taken from the Global Yield Gap Atlas (GYGA) that is currently being developed by University of Nebraska, Wageningen University and many partners from SSA. Farm/household level data and plot level information for Ethiopia and Ghana will be taken from the World Bank's Living Standards Measurement Study-Integrated Surveys on Agriculture (LSMS-ISA) and EGC-ISSER Ghana (expected to become available end of 2013). In addition, a survey in each of the case-study regions will be organised to collect additional and detailed information on plot-level crop production and management such as soil characteristics, cultivation history and agronomic management. The results will be used to derive targeted policy and farming recommendations that account for the complex environments in which male and female farmers in the SSA-region operate and incorporate the basic mechanisms that link farm performance to the broader enabling environment. This process will be supported by initiating participatory on-farm demonstration trials on the one hand and a policy dialogue with stakeholders on the other hand.