Ecological practices such as intercropping maize (Zea mays) with cowpea (Vigna unguiculata L.) have been promoted to combat parasitic weeds like Striga (Striga asiatica). Intercropping has been promoted across Africa as a Striga control practice (SCP) and food security measure. Despite past efforts, millions of smallholder farmers (cultivating < 2 ha of maize) still struggle to implement SCPs. Social and ecological factors that prevent SCP implementation are well documented in the literature, but their underlying interactions have remained elusive. System dynamics modeling can uncover these interactions and assess their effect on intercropping rates as well as Striga emergence. This study presents a participatory mixed methods approach to build a system dynamics model based on two theories: diffusion of innovations and resource pool dynamics. The model estimates the population of fields where Striga emerged in response to intercropped fields when various interventions were implemented. According to model simulations, if new policies are not enacted to support intercropping, Striga is likely to spread to 2,625,000 maize fields, parasitizing almost 75% of smallholder farms across Central Malawi by 2036. The participatory approach allowed us to evaluate several policies, one of which sustained enough adopters to limit Striga emergence to < 500,000 fields, reducing the weed’s threat to food security. This policy considers how input costs and erratic rainfall can lead to disadoption, therefore, supporting the implementation of five to six consecutive years of intercropping by providing both fertilizer subsidies and demonstration plots. In this study, our participatory approach has shown to develop a model that can highlight interactions in social ecological systems, their leverage points, and how they can be exploited to develop effective food security policies.

The post Technology adoption and weed emergence dynamics: social ecological modeling for maize-legume systems across Africa first appeared on Ecology & Society.

玉米（ Zea mays）与豇豆（Vigna unguiculata L.）间作等生态实践已得到推广，以防治独脚金（Striga asiatica）等寄生杂草。间作已作为 Striga 控制实践 (SCP) 和粮食安全措施在非洲得到推广。尽管过去付出了努力，数百万小农（种植玉米面积<2公顷）仍然在努力实施SCP。阻碍 SCP 实施的社会和生态因素在文献中有详细记录，但它们潜在的相互作用仍然难以捉摸。系统动力学建模可以揭示这些相互作用并评估它们对间作率以及独脚金出苗的影响。本研究提出了一种参与式混合方法来构建基于两种理论的系统动力学模型：创新扩散和资源池动态。该模型估计了在实施各种干预措施时，Striga 因间作田地而出现的田地数量。根据模型模拟，如果不制定支持间作的新政策，到 2036 年，Striga 可能会蔓延到 2,625,000 块玉米田，寄生在马拉维中部近 75% 的小农农场。参与式方法使我们能够评估多项政策，其中之一是它维持了足够多的采用者，将独脚金的出现面积限制在 50 万块以下，从而减少了这种杂草对粮食安全的威胁。该政策考虑了投入成本和不稳定的降雨量如何导致不采用，因此，通过提供化肥补贴和示范地来支持连续五到六年间作的实施。在这项研究中，我们的参与方法表明开发了一个模型，可以突出社会生态系统的相互作用、它们的杠杆点，以及如何利用它们来制定有效的粮食安全政策。

后技术采用和杂草出现动态：非洲玉米豆类系统的社会生态模型首次出现在《生态与社会》上。