14 research outputs found
Indicators of weed competition on Organic Winter Wheat
Organic winter wheat production is limited by climatic and agronomic factors, including weed competition. The incidence of weeds on yield limitation can be characterized through various early indicators to predict weed occurrence and competition. A network of 10 fields of organic winter wheat was implemented in the South East of France in 2005-2006. Results showed that weed density, dynamics and diversity are good indicators for weed occurrence and competition
Improvement of the soil-crop model AZODYN under conventional, low-input and organic conditions
The use of mechanistic crop modelling, simulating the dynamics of crop N requirements and nitrogen supply from the soil and fertilizers, can provide sound advice to users. This paper describes a methodological way to improve soil-crop modeling used for N management of conventional and organic wheat
Can legume companion plants control weeds without decreasing crop yield? A meta-analysis
Companion plant intercropping involves growing a cash crop with another plant that is not harvested, to confer a set of benefits on the crop and the environment. Weed control and herbicide use reduction are one of the principal reasons for adopting this approach. Companion plants should compete with weeds for light, nutrients and water, but they may also compete with the crop. The species grown must therefore be carefully chosen and managed so as to outcompete weeds but limit competition with the crop and yield loss. In this meta-analysis, we aimed to quantify the effects of companion plants on weed regulation and cash crop yields, and to analyze their sources of variability. We reviewed different intercropping systems involving an annual cash crop and a legume companion plant from around the world. We report data from 34 scientific articles, corresponding to 476 experimental units (i.e. combinations of site Ă year Ă cash crop Ă legume companion plant species Ă agricultural practices), and we explore whether intercropping with legume companion plants can control weeds while maintaining crop yield. Yield and weed biomass ratios were analyzed as response variables. We used the type of cash crop (straw cereals, maize or other crops), the methods used to establish the companion plants (living mulch, synchronized sowing or relay intercropping) and the overlap between the growth periods of the companion plants and the cash crop as explanatory variables.Intercropping with a companion plant resulted in a lower weed biomass and a higher yield (win-win situation) than non-weeded or weeded control treatments, in 52% and 36%, respectively, of the experimental units considered. A higher weed biomass associated with a lower yield (lose-lose) was observed in only 13% and 26% of the experimental units, in comparisons with non-weeded and weeded control treatments, respectively. Considering all the experimental units together, the companion plants had no significant effect on cash crop yield, but significantly decreased weed biomass, by 56% relatively to a non-weeded control treatment, and 42% relative to a weeded control treatment. The greatest benefits from companion plant intercropping were reported for maize, with yields 37% higher than those for non-weeded control treatments. The other explanatory variables tested had no significant effect on yield or weed control. Thus, the use of legume companion plants generally seems to enhance weed control without reducing crop yield, but the conditions giving rise to win-win situations should be explored further, to encourage the spread of this technique among farmers
Assessment of the benefits of frost-sensitive companion plants in winter rapeseed
International audienceThe intercropping of rapeseed with frost-sensitive companion plants (CP) has recently been proposed as a way to mitigate the negative environmental impact of rapeseed crops. Using mixed-effect linear models, we compared the yield and weed amounts of rapeseed intercropped with different CP species with that of rapeseed as a sole crop in an unique dataset of 79 field experiments covering a wide range of climate, soil and practices conditions in the northwestern part of France, from 2009 to 2015. Bayesian model averaging procedure was used to determine the relative contributions of sites characteristics to the effects of intercropping.& para;& para;Before winter, field pea and faba bean had accumulated the largest amounts of dry mass, with more than 100 g m(-2). Rapeseed biomass was reduced by 56% by non-legume CPs and by only 18% by legume CPs, the largest decrease being caused by pea. Non-legumes decreased the nitrogen nutrition index of rapeseed by 7%, whereas pea and faba bean increased this index by 6% and 3%, respectively. Intercropping with non-legume and legume CPs reduced weed amounts by 52% and 38% respectively, with no difference between CP species. Non legume CPs decreased rapeseed yield at harvest by 0.581 ha(-1), whereas faba bean and faba bean + lentil in creased yield by 0.16 and 0.12 t ha(-1) respectively, when fertilized at the recommended rate. Intercropping with faba bean, lentil or a mixture of both made it possible to reduce nitrogen applications by 30-40 kg ha(-1) with no significant decrease in rapeseed yield. Faba bean and faba bean + lentil mixtures had the best overall performance. This work suggests that intercropping rapeseed is promising, particularly in soils with low nitrogen content with an early sowing date in the late summer
ALLIANCE: Amélioration des performances écologiques et économiques par association de plantes de services légumineuses dans des systÚmes de grandes cultures.
Lâobjectif de ce projet Ă©tait de (1) quantifier les services Ă©cosystĂ©miques rendus par les associations « cultures de rente â Plantes de services » pour le colza dâhiver et le blĂ© tendre dâhiver, et leurs effets sur les cultures suivantes dans des systĂšmes de grandes cultures stricts (plus ou moins diversifiĂ©s) et de polycultures Ă©levages, en agriculture conventionnelle et biologique (2) tester diffĂ©rentes conduites culturales et des outils pour accompagner cette innovation Ce travail a dĂ©marrĂ© par une mĂ©ta-analyse de rĂ©sultats expĂ©rimentaux extraits de 34 articles scientifiques couvrant 17 pays, et a montrĂ© que les plantes compagnes associĂ©es Ă diffĂ©rentes cultures annuelles conduisent Ă une rĂ©duction de 56% de la biomasse dâadventices par rapport Ă une culture seule non-dĂ©sherbĂ©e, et 42% par rapport Ă une culture seule dĂ©sherbĂ©e. Puis des expĂ©rimentations en parcelles agricoles et en conditions semis controlĂ©es ont Ă©tĂ© mises en place. Concernant le colza, des plantes de services gĂ©lives, le plus souvent choisies dans la famille des lĂ©gumineuses ont Ă©tĂ© semĂ©es en mĂȘme temps que le colza pour concurrencer les adventices et perturber les insectes pendant lâautomne (Lorin et al., 2015). La plante de services ne survivant pas Ă lâhiver, le colza termine son cycle sans concurrence et bĂ©nĂ©ficie dâazote restituĂ© par les rĂ©sidus de plantes. Les rĂ©sultats de 79 essais menĂ©s en France entre 2009 et 2016 ont permis de valider cette technique et dâĂ©valuer les intĂ©rĂȘts multi-critĂšres de plusieurs conduites. Les plantes lĂ©gumineuses gĂ©lives associĂ©es au colza permettent Ă la fois de rĂ©duire la fertilisation de 30 kg N/ha sans perdre de rendement. En agriculture biologique, en comparaison Ă un semis aprĂšs la rĂ©colte du blĂ©, le semis sous couvert au printemps permet aux lĂ©gumineuses de se dĂ©velopper plus rapidement une fois le blĂ© rĂ©coltĂ©. Les effets sur le blĂ© sont nĂ©gligeables, alors que le contrĂŽle des adventices est directement liĂ© Ă la biomasse produite avant la fin de lâĂ©tĂ© et ne sera effectif quâaprĂšs la rĂ©colte du blĂ©, pendant lâinterculture. Un outil, permettant dâaider au choix de lâespĂšce Ă associer en fonction dâobjectifs agronomiques, a Ă©tĂ© conçu selon une dĂ©marche participative afin dâintĂ©grer et partager les connaissances existantes sur les associations colza â plantes de services. Le modĂšle dĂ©veloppĂ© sâappuye sur une dĂ©marche fonctionnelle reliant les traits des espĂšces candidates, aux processus et aux services potentiel
Regards croisés sur l'effet des espaces semi-naturels et de l'assolement sur les bio-agresseurs de grandes cultures
Alors qu'un objectif de rĂ©duction d'usage des produits phytosanitaires est posĂ©, le potentiel de leviers paysagers est explorĂ©. Ici nous Ă©valuons sur neuf des principaux bioagresseurs du blĂ©, du colza et du maĂŻs si lâaugmentation de la surface cultivĂ©e augmente la pression de bioagresseurs et si les espaces semi-naturels (bois, haies, prairies) tendent Ă protĂ©ger les cultures. Pour cela nous avons compilĂ© de maniĂšre structurĂ©e la littĂ©rature scientifique, rassemblĂ© les connaissances dâexperts nationaux et analysĂ© des donnĂ©es nationales dâabondance de bioagresseurs (VigiculturesÂź) en lien avec les donnĂ©es du registre parcellaire graphique et de la BD TOPOÂź de lâInstitut national de lâinformation gĂ©ographique et forestiĂšre (IGN). A ce stade nos rĂ©sultats suggĂšrent que, suivant les bioagresseurs, les Ă©lĂ©ments semi-naturels (bois, haies, prairies) peuvent avoir un effet protecteur, dĂ©favorable ou neutre. Par contre, lâaugmentation de la prĂ©sence dâune culture semble augmenter la pression de ses bioagresseurs.As an objective of reducing the use of plant protection products is laid, the potential for landscape levers is explored. Here, we evaluate for nine of the main bio-aggressors of wheat, rapeseed and maize if the increase in cultivated area increases the pressure of bio-aggressors and if the seminatural areas (wood, hedges, grasslands) tend to protect cultures. For this purpose, we compiled in a structured way the scientific literature, gathered the knowledge of national experts and analysed national data of abundance of bio-aggressors (VigiculturesÂź) in connection with data from the Common Agricultural Policy and the BDTOPOÂź of the Institut GĂ©ographique National. At this stage our results suggest that, depending on the bio-aggressors, semi-natural elements (wood, hedges and meadows) may have a protective, unfavourable or neutral effect. On the other hand, increasing the presence of a crop seems to increase the pressure from its bio-aggressors
Intercropping frost-sensitive legume crops with winter oilseed rape reduces weed competition, insect damage, and improves nitrogen use efficiency
Mixing plant species in agroecosystems is highlighted as an agroecological solution to reduce pesticides and fertilizers while maintaining profitability. In the French context, intercropping frost-sensitive legume crops with winter oilseed rape is potentially interesting and began to be implemented by farmers. In this study we aimed at measuring the services and disservices of this intercrop with three different legume mixtures, in terms of growth and yield for rapeseed, ground cover of weeds in autumn and damage caused by rape winter stem weevil. The experiment was carried out at four sites from 2011 to 2014. We showed higher total aerial dry weights and total aerial nitrogen contents in the intercrops compared to sole winter oilseed rape in November. The companion plants contributed to the control of weeds and the mitigation of rape winter stem weevil damage, notably through the increase in the total aerial weight. In spring, after destruction of the companion plants, the intercrops had partially compensated a reduction in the N fertilization rate (-30 kg per hectare) in terms of aerial nitrogen content in rapeseed, with no consequences on the yield which was maintained or even increased. There were probably other interactions such as an improvement in rapeseed root exploration. The consequences were an increase in the nitrogen use efficiency in intercrops. The intercrop with faba bean and lentil showed the best results in terms of autumn growth, weed control, reduction in rape winter stem weevil damage, and rapeseed N content in spring and yield. Intercropping frost-sensitive legume crops with winter oilseed rape is thus a promising way to reconcile yield and reduction in pesticides and fertilizer use and perhaps to benefit more widely to the cropping system
Multi-scale studies of the relationships between cropping structure and pest and disease regulation services
National audienc
Influence des pratiques agricoles individuelles, des systÚmes de culture sur les abondances des ravageurs, leurs auxiliaires et la régulation biologique
International audiencePour modifier la rĂ©gulation naturelle des bioagresseurs dans les cultures, les deux leviers majeurs qui peuvent ĂȘtre mobilisĂ©s Ă lâĂ©chelle parcellaire sont, dâune part, lâaugmentation de la biodiversitĂ© cultivĂ©e et, dâautre part, la rĂ©duction des perturbations chimiques et mĂ©caniques gĂ©nĂ©rĂ©es par le travail du sol et le recours aux produits phytosanitaires dans le champ cultivĂ©. Alors que la littĂ©rature apporte beaucoup dâinformations sur lâimpact des habitats semi-naturels sur les auxiliaires des cultures (Tcharntke et al. 2007 ; ChaplinâKramer et al. 2011; Pywell et al. 2016), le rĂŽle des pratiques sur les liens bioagresseursâauxiliaires des cultures est moins regardĂ© (Rusch el al. 2013). Lâobjectif de cette prĂ©sentation est dâillustrer au travers des sorties des projets Peerless et Sebiopag-Phyto comment lâhabitat cultivĂ© au travers des effets de certaines pratiques individuelles, voire des systĂšmes de culture, influence les bioagresseurs et leurs ennemis naturels. Nous montrons comment certaines pratiques perturbent la recherche de la plante hĂŽte ; comment lâhabitat cultivĂ© peut fournir des ressources alimentaires alternatives pour les auxiliaires ; comment certaines pratiques accentuent la mortalitĂ© des organismes et enfin, comment lâitinĂ©raire technique de la parcelle ne peut se raisonner indĂ©pendamment de son environnement immĂ©diat. Dans le cadre de ces deux projets, des parcelles agricoles, essentiellement de blĂ© et de colza, prĂ©sentant un gradient de recours aux pesticides (dâabsence de pesticides Ă des IFT proche des rĂ©fĂ©rences conventionnelles) et pour certaines un gradient de travail du sol (semis direct dâanciennetĂ© variable Ă labour frĂ©quent) ont Ă©tĂ© mobilisĂ©es. Par ailleurs, des dispositifs expĂ©rimentaux en station de recherche sur des systĂšmes de culture sans pesticides ont Ă©galement Ă©tĂ© Ă©tudiĂ©s. De ces expĂ©rimentations quatre rĂ©sultats majeurs sont Ă retenir : (i) les mĂ©langes dâespĂšces dans la parcelle ou lâutilisation de plantes piĂšges peuvent rĂ©duire les attaques de certains insectes ravageurs du colza, probablement en perturbant la recherche des ravageurs de leur plante hĂŽte. (ii) les espĂšces cultivĂ©es nâont pas le mĂȘme rĂŽle vis-Ă -vis des auxiliaires du fait de leur « attractivitĂ© » diffĂ©rentielle : le colza semble systĂ©matiquement associĂ© Ă un meilleur statut nutritionnel des carabes prĂ©dateurs gĂ©nĂ©ralistes (par exemple Amara similata et Poecilus cupreus, LabruyĂšre et al. 2016). La prĂ©dation des graines dâadventices et dâautres proies sentinelles semble aussi varier selon les cultures indĂ©pendamment des pratiques culturales (projet Casimir). (iii) les pratiques agronomique telles que le travail du sol et les insecticides induisent des modifications de communautĂ©s dâinsectes auxiliaires et impacte Ă©galement la prĂ©dation des graines dâadventices par les carabes (Petit et al. 2017). (iv) enfin, ces effets de lâhabitat cultivĂ© sur les liens ravageurs-auxiliaires ne peuvent ĂȘtre pensĂ©s indĂ©pendamment des Ă©lĂ©ments non cultivĂ©s, cultures et des pratiques dans lâenvironnement immĂ©diat de la parcelle (Puech et al 2015)
MĂ©langes variĂ©taux et mĂ©langes plurispĂ©cifiques â atouts et contraintes
article issus du colloque « BiodiversitĂ© et durabilitĂ© des agricultures » qui sâest tenu Ă Paris le 11 avril 2019https://www6.inra.fr/ciag/CIAg-Environnement/Biodiversite-et-agriculturesPour rĂ©duire les impacts nĂ©gatifs des systĂšmes agricoles, la transition agroĂ©cologique appelle en premier lieu Ă lâutilisation dâune plus grande biodiversitĂ© cultivĂ©e. Une telle diversification peut ĂȘtre conduite Ă l'Ă©chelle de la parcelle, en associant diffĂ©rentes espĂšces, ou diffĂ©rentes variĂ©tĂ©s d'une mĂȘme espĂšce. Nous abordons les avantages de cette diversification intra-parcellaire, en dĂ©veloppant 5 exemples : (1) les mĂ©langes variĂ©taux de blĂ© en France, (2) les populations de riz au YuanYang, (3) le colza associĂ© Ă des plantes de services, (4) les mĂ©langes dâespĂšces fourragĂšres et (5) les associations cĂ©rĂ©ales-lĂ©gumineuses Ă graines. Nous discutons des avantages confĂ©rĂ©s par cette diversification sur : (i) lâoptimisation et la stabilisation des productions, (ii) les interactions avec les pratiques culturales, (iii) la sĂ©lection variĂ©tale, et (iv) lâimpact de ces peuplements et pratiques sur la biodiversitĂ© sauvage associĂ©e