Using a farming system model to evaluate cropping system prototypes: Are labour constraints and economic performances hampering the adoption of Integrated Weed Management?

International audienceThis study extends into the economic domain the analysis of a trial comparing cropping system prototypes based on the principles of Integrated Weed Management (IWM), which demonstrated their potential for managing weed infestations. A farm simulation model was used to analyse the consequences of implementing such IWM-based cropping systems at the farm scale. The labour requirement for field operations and their distribution over the year were compared to the amount of time when field conditions were suitable for the corresponding equipments. In the simulated IWM-based virtual farms, repeated shallow soil cultivations for promoting pre-sowing weed emergence and mechanical weeding could both be accommodated during suitable periods, but the rule of late cereal sowings for escaping periods of peak weed emergence generated possible labour bottlenecks. Machinery costs were calculated from the farm simulations so that the economic profitability of the virtual farms could be compared. In the economic context of 2006, the saving of input costs did not offset low yields of spring crops introduced in the crop sequence for diversifying sowing dates as required by IWM principles. The method of farm simulations could be used with other data sets from cropping system experiments to provide the required knowledge for supporting future policy development in Europe