Reconciling pesticide reduction with economic and environmental sustainability in arable farming.

International audienceReducing pesticide use is one of the high-priority targets in the quest for a sustainable agriculture. Until now, most studies dealing with pesticide use reduction have compared a limited number of experimental prototypes. Here we assessed the sustainability of 48 arable cropping systems from two major agricultural regions of France, including conventional, integrated and organic systems, with a wide range of pesticide use intensities and management (crop rotation, soil tillage, cultivars, fertilization, etc.). We assessed cropping system sustainability using a set of economic, environmental and social indicators. We failed to detect any positive correlation between pesticide use intensity and both productivity (when organic farms were excluded) and profitability. In addition, there was no relationship between pesticide use and workload. We found that crop rotation diversity was higher in cropping systems with low pesticide use, which would support the important role of crop rotation diversity in integrated and organic strategies. In comparison to conventional systems, integrated strategies showed a decrease in the use of both pesticides and nitrogen fertilizers, they consumed less energy and were frequently more energy efficient. Integrated systems therefore appeared as the best compromise in sustainability trade-offs. Our results could be used to re-design current cropping systems, by promoting diversified crop rotations and the combination of a wide range of available techniques contributing to pest management

Weed dynamic in Conservation Agriculture: experiences from the Isite-BFC regional network of farmers and cropping system experiments on agroecology in France.

ISBN: 978-84-09-37744-2International audienceConservation Agriculture (CA) relies on three fundamental pillars: diversified crop rotation, permanent soil coverand no soil disturbance. Weed control relies on few tools because pre-sowing tillage, pre-emergence herbicidespraying and in-crop mechanical weeding are not possible. This could lead to drastic changes in weed communitiesand quickly after the transition to CA, with fewer annual species (weed seeds remain on the soil surface, a conditiondeemed to be unfavourable to weed germination) and higher perennial species. However, the implementation ofCA principles could be transcribed into a wide array of cropping systems because the objectives of farmers differ,and/or because systems are implemented in different production situations (e.g., associated or not to livestock, soiltype, irrigation). Therefore, the Isite-BFC regional network gathers CA farmers and experimenters from cooperatives and research institute (INRAE) to share their experiences, detailed practices and weed surveys initiated since2007 in some sites. Weed diversity was high in all systems compared to what is known from tillage-based agriculture. Weed community changes over time depending on the diversity of crop rotation tested and initial weedingpressure. Since CA is challenged by potential glyphosate ban in Europe, the application of glyphosate was stoppedin 2018 in some sites and thus, cropping systems were redesigned accordingly to ensure weed management overthe long run, economic profitability and multiperformance

Relationship between sustainability indicators and relative TFI.

<p>Cropping system performances according to their relative TFI. Conventional, integrated and organic cropping systems are represented by blue, green and red symbols respectively. Filled symbols correspond to the cropping systems with grain crops only and empty symbols refer to the cropping systems including crops for which the whole above-ground biomass is harvested. Each sustainability indicators is expressed as the natural logarithm of the ratio between the cropping system and the local reference indicators. Linear regressions are represented with their standard error for cumulated I-Pest (Pearson correlation test: r_p = 0.74, P = 5*10⁻⁸), nitrogen fertilization (Pearson correlation test: r_p = 0.48, P = 0.002), and energy efficiency (Pearson correlation test: r_p = −0.38, P = 0.02). Performance metric included: a) productivity, b) energy efficiency, c) cumulated I-Pest, d) fuel consumption, e) nitrogen fertilization, f) semi-net margin, g) sensitivity to price volatility, h) workload.</p

Significantly different groups for a given performance indicator.

<p>Mann-Whitney tests (α = 0.05). All P-values are below 0.05, indicating that the differences between means of the sub-samples are significant for the corresponding indicators.</p

Rank correlation between Crop Sequence Indicator Isc and sustainability indicators.

<p>Spearman correlation tests (α = 0.05). r_s is the Spearman correlation coefficient. Values of r_s followed by (NS) are not significant.</p