Estimating Mexican Farmers’ Valuation of Milpa Diversity and Genetically Modified Maize: A Choice Experiment Approach

The milpa is a traditional intercropping system of maize, bean, and squash. Milpas are repositories of agrobiodiversity in México, not only rich in inter- and infra-crop species diversity, but also in landraces of maize, which are building blocks for future improvements in this globally important staple crop. Even though they are still widely cultivated across México, sustainability of milpa cultivation is threatened by farmers’ integration into labour and output markets and recently, by the flow of transgenic constructs from genetically modified (GM) maize varieties to landraces in milpas. In this paper a choice experiment is employed to investigate farmer valuation of the agrobiodiversity found in traditional milpa systems and the option to cultivate GM maize varieties in milpas. Data are collected from 414 farm households across three states of México, and analysed using the random parameter logit model with interactions, which can detect for unobserved and observed sources of heterogeneity in the sample. The results reveal that there is considerable heterogeneity in farmers’ preferences for milpa diversity and GM maize across and within the three states. The location and characteristics of farmers who value milpa diversity the most, as well as those of farmers who value the option to cultivate GM maize the most are identified. These findings have policy implications in terms of designing least cost on farm conservation programmes for traditional milpas, as well as for understanding the potential in adoption of GM maize in México.