Environmental impacts of agricultural robots and possible improvements: example of weeding robots used in vineyards

International audience

anglais. In France, the Ecophyto II+ program aims to reduce pesticide use in agriculture by 50% at the horizon 2025 and to phase out glyphosate by the end of 2020 for the main uses and by 2022 at the latest for all uses. Viticulture, as well as other crops, is facing obligation to reduce the use of herbicides and to develop alternative solutions to chemical weed control. These alternatives can be achieved by mechanical weeding either using tractors or weeding robots. France is the country with the most agricultural and field robots sold and in use with at least hundreds robots for weed management and about fifty robots being used by viticulture entrepreneurs. However, it is not possible to argue if robots are a better or worse solution to achieve environmental impact reduction in agriculture compared to the traditional use of tractors, as no studies were available up to date.This paper aims to fulfill this urgent need for accurate impact assessment by providing a quantitative life cycle environmental impact assessment of intra-row and inter-row weeding practices using autonomous electrical robot systems in three French vineyards. Twenty-seven scenarios were built to assess chemical, mechanical or a combination of the two for intra row weeding management combined with mechanical weeding or mowing as inter row management.LCA results show that scenarios using weeding robots for the intra row management have greater impacts than conventional ones on mineral resources, human toxicity, freshwater ecotoxicity and marine eutrophication due to: (1) the manufacture of the robot, in particular related to the manufacture of motors and electric cables, and active and passive electronic components, (2) the lifetime of robots, especially when this lifetime is assuming short, (3) the functionality of robots.The use of full electric robots has fewer impacts than tractors on climate change, fossil resources, ozone depletion, acidification and particle formation, especially when robots are used on plots closed to the winery. However, this reduced impact compared to conventional solutions is partly counterbalanced by the transport of the robot to the field.This study had shed some light on the relative impacts of a robotic machine intended to replace tractors and vine straddles tractors in certain tillage operations. Improvements can therefore be achieved by increasing the robot lifetime and use intensity, by optimizing transport logistics flows for robots and operators, by increasing the robot functionality either by providing additional services or making possible the use on different crops. We also highlight that there is a need to consolidate inventory data for (i) agricultural tractors in order to achieve equivalent comparison between the two technologies, (ii) the use of robots in the field (i.e. work performance, electrical consumption) for each of weeding tools available for robots (inter vine hoe, disks…).