Ecological intensification through pesticide reduction: weed control, weed biodiversity and sustainability in arable farming

Summary

Amongst the biodiversity components of agriculture,weeds are an interesting model for exploring managementoptions relying on the principle of ecologicalintensification in arable farming. Weeds can cause severecrop yield losses, contribute to farmland functional biodiversityand are strongly associated with the generic issue ofpesticide use. In this paper, we address the impacts of herbicidereduction following a causal framework starting withherbicide reduction and triggering changes in (i) the managementoptions required to control weeds, (ii) the weedcommunities and functions they provide and (iii) the overallperformance and sustainability of the implemented landmanagement options. The three components of this frameworkwere analysed in a multidisciplinary project that wasconducted on 55 experimental and farmer’s fields thatincluded conventional, integrated and organic croppingsystems. Our results indicate that the reduction of herbicideuse is not antagonistic with crop production, provided thatalternative practices are put into place. Herbicide reductionand associated land management modified the compositionof in-field weed communities and thus the functions of weedsrelated to biodiversity and production. Through a long-term simulation of weed communities based on alternative (?)cropping systems, some specific management pathwayswere identified that delivered high biodiversity gains andlimited the negative impacts of weeds on crop production.Finally, the multi-criteria assessment of the environmental,economic and societal sustainability of the 55 systems suggeststhat integrated weed management systems fared betterthan their conventional and organic counterparts. Theseoutcomes suggest that sustainable management could possiblybe achieved through changes in weed management,along a pathway starting with herbicide reduction.