Potential of crop mixtures to reduce pesticide use in France. A data analysis

Over the last 50 years, agricultural intensification has led to simplified agricultural systemshighly dependent on fertilisers and pesticides, causing biodiversity loss, changes in the balanceof nutrients, water and soil contamination. The total amount of pesticides applied each yearin France makes it the main consumer of plant protection products in Europe, and arable cropsare currently the most pesticide-consuming production systems. Reducing pesticide use inarable crops is thus a major challenge. There is now evidence that crop diversification in time,with more diversified rotations, and in space, through crop mixtures, can help restoreecosystem services and represent a potential key lever to reduce pesticide use (Lechenet etal., 2016). However, research has often analysed the effects of crop mixtures on pesticide useover small areas (e.g., single plots or fields), whereas these effects need to be evaluated overlarger and more realistic spatial extents to fully assess their potential to reduce pesticide use.By focusing on species mixtures, we aim to (i) quantify the potential of crop mixtures forpesticide use reduction in France and (ii) identify the drivers of mixture use leading to itstemporal and spatial dynamics observed at a national scale.We combined data from a network of over 3000 farmers (DEPHY Farms) who voluntarilycommitted to reducing their use of pesticides, and the French Land Parcel IdentificationSystem (FLPIS). Data from the DEPHY network have been collected annually since 2010 andprovide information on farm location, cultivated crops and yield, farming management, andthe levels of pesticide use through the Treatment Frequency Index (TFI). The FLPIS is a Frenchwide database reporting information on the geographical coordinates of the fields, their area,cultivated crops, the type of management (organic or not) at field-scale. It is based on farmers’declaration for the Common Agriculture Policy subsidies. In the FLPIS, each field is attached toits farm through a unique identification number. More than 80% of the French farms arerepresented in the database, and since 2015, farmers have reported the species mixtures. Forthis reason, we only used data starting from 2015 until 2020.These databases provide information on the distribution of species mixtures cultivated inFrance and the related TFI levels. We compared the TFI levels of different species mixtureswith those of corresponding pure crops. For example, grain species mixtures (e.g., wheat,barley, or triticale mixed with pea or faba bean) and annual fodder mixtures (e.g., triticale,oat, and pea) were compared with pure wheat, and rapeseed undersown with companioncrops were compared with pure rapeseed. We assigned each farm of the FLPIS to a farmingSystem (e.g., arable or livestock farming) based on the type of crops cultivated.338We found significantly lower TFI for crop mixtures when compared with those of pure crops,confirming that crop mixtures are an effective lever to reduce the use of pesticides. Resultsindicated that from 2015 to 2020, the French arable land area cultivated with crop mixturesincreased, diffusing from hotspots. Organic agriculture is a strong driver for crop mixtures butis not the only one; in fact, livestock systems turn out to be strategic to foster cropdiversification. Indeed, grassland and fodder mixtures, directly used to feed animals, arecurrently the most widespread species mixtures in France, thus explaining that in some Frenchdistricts, more than 90% of crop mixture areas are cultivated in livestock systems. On thecontrary, cereals and oilseeds, primarily used in transformation processes, appear harder tovalue as mixtures.Lechenet et al. 2016. Profiling farming management strategies with contrasting pesticide usein France. Agricultural Systems.