Abstract We examined a procedure to elicit the tacit models underlying expert opinions on environmental factors that affect the absolute yield benefits expected from the adoption of conservation agriculture (CA) practices in southern Africa. The procedure is based on expert evaluation of the expected improvement in crop yield on adoption of CA in a particular scenario or ‘state’, a state being a specified set of soil conditions captured by a standard soil profile description from a specified agroecological zone (AEZ) of Zambia. Mixed groups of scientists including soil scientists, agronomists, agricultural economists and other environmental scientists, facilitated by experienced senior researchers, were presented with multiple subsets each of three states, and asked to rank the states in each subset with respect to expected yield improvement under CA. The groups of scientists could be divided into two sets. Each set comprised two groups, and the agreement on ranking between groups within each set was larger than would be expected if the ranking were done at random. For both sets of groups the ranking could be modelled with respect to properties of the soil, and the contrast between AEZ. The models revealed two contrasting groups of conceptual assumptions. One group broadly expected larger absolute yield improvements from conservation agriculture in settings where water is most likely to be limiting and the carbon status of the soil is poor. By contrast, the other group expected larger improvements where water was less likely to be limiting. These contrasting views are relevant to current discussions as to whether conservation agriculture, which is promoted as a ‘climate smart’ strategy for cropping, is sufficiently attractive for smallholder producers in conditions where crop production is already challenging, and whether the potential benefits in areas where water availability is not of itself a common limitation should be considered. The elicited models could be translated directly into competing hypotheses to be tested, perhaps in on-farm trials of conservation agriculture practices over contrasting soils in the different AEZ. The method, based on modelling the ranking process, could be of more general interest for the elicitation of expert opinion about complex soil, crop and environmental systems.

中文翻译：

---

引出专家解释土壤信息的默认模型，保护性农业潜在效益评估的一个例子

摘要 我们研究了一个程序，以引出作为专家意见的隐性模型，这些环境因素影响了南部非洲采用保护性农业 (CA) 实践所预期的绝对产量收益。该程序基于专家对在特定场景或“状态”中采用 CA 后作物产量预期提高的评估，状态是一组特定土壤条件，由来自特定农业生态区 (AEZ) 的标准土壤剖面描述捕获) 赞比亚。在经验丰富的高级研究人员的协助下，包括土壤科学家、农学家、农业经济学家和其他环境科学家在内的混合科学家群体被展示了三个州的多个子集，并要求根据 CA 下的预期产量改进对每个子集中的状态进行排名。科学家小组可以分为两组。每组包括两组，每组内各组之间的排名一致性大于随机排名时的预期。对于两组组，可以根据土壤特性和 AEZ 之间的对比对排名进行建模。这些模型揭示了两组截然不同的概念假设。一组普遍预计，在水资源最有可能受到限制且土壤碳状况较差的环境中，保护性农业的绝对产量提高幅度更大。相比之下，另一组预计在水不太可能受到限制的情况下会有更大的改进。这些截然不同的观点与当前的讨论有关，即保护性农业作为一种“气候智能”种植战略，在作物生产已经面临挑战的条件下对小农生产者是否具有足够的吸引力，以及在这些地区的潜在利益是否水供应本身并不是一个应考虑的普遍限制。引出的模型可以直接转化为竞争性假设进行测试，或许可以在不同 AEZ 中对比土壤的保护性农业实践的农场试验中进行测试。该方法基于对排序过程进行建模，对于获取有关复杂土壤、作物和环境系统的专家意见可能具有更广泛的意义。作为一种“气候智能”种植战略，在作物生产已经面临挑战的条件下，对小农生产者具有足够的吸引力，以及是否应考虑在水资源供应本身不是普遍限制的地区的潜在利益。引出的模型可以直接转化为竞争性假设进行测试，或许可以在不同 AEZ 中对比土壤的保护性农业实践的农场试验中进行测试。该方法基于对排序过程进行建模，对于获取有关复杂土壤、作物和环境系统的专家意见可能具有更广泛的意义。作为一种“气候智能”种植战略，在作物生产已经面临挑战的条件下，对小农生产者具有足够的吸引力，以及是否应考虑在水资源供应本身不是普遍限制的地区的潜在利益。引出的模型可以直接转化为竞争性假设进行测试，或许可以在不同 AEZ 中对比土壤的保护性农业实践的农场试验中进行测试。该方法基于对排序过程进行建模，对于获取有关复杂土壤、作物和环境系统的专家意见可能具有更广泛的意义。以及是否应该考虑在水资源可用性本身不是一个普遍限制的地区的潜在利益。引出的模型可以直接转化为竞争性假设进行测试，或许可以在不同 AEZ 中对比土壤的保护性农业实践的农场试验中进行测试。该方法基于对排序过程进行建模，对于获取有关复杂土壤、作物和环境系统的专家意见可能具有更广泛的意义。以及是否应该考虑在水资源可用性本身不是一个普遍限制的地区的潜在利益。引出的模型可以直接转化为竞争性假设进行测试，或许可以在不同 AEZ 中对比土壤的保护性农业实践的农场试验中进行测试。该方法基于对排序过程进行建模，对于获取有关复杂土壤、作物和环境系统的专家意见可能具有更广泛的意义。