Modelling farmer's choice to evaluate GM and non-GM coexistence strategies
Résumé
European regulations (EC, 2003) define a product as GM when GM adventitious presence is over than 0.9%. During collection, crops from many fields are combined to fill a silo. In the case of maize, to avoid the risk of mixing GM and non-GM harvests, it is possible to dedicate silos to a specific production or to define a time period for GM and non-GM delivery at silos. To evaluate these strategies, we propose an economic model of variety choice by farmer based on the gain at field level for the considered production, taking into account delivery cost and differences in prices and costs between GM and non-GM products. The model gives maize crop distributions, whether GM or non-GM, that were used as input data for a spatially-explicit gene flow model (MAPOD). It was thus possible to calculate the level of GM adventitious presence in the non-GM silos, and therefore to evaluate the possibility to access non-GM and food markets