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Gene flow in rapeseed is a process taking place both in space and over the years and cannot be studied exclusively by field trials. Consequently, the GENESYS model was developed to quantify the effects of cropping systems on transgene escape from rapeseed crops to rapeseed volunteers in neighbour plots and in the subsequent crops. In the present work, this model was used to evaluate the risk of rape harvest contamination by extraneous genes in various farming systems in case of co-existing GM, conventional and organic crops. When 50 % of the rape varieties in the region were transgenic, the rate of GM seeds in non-GM crop harvests on farms with large fields was lower than the 0.9 % purity threshold proposed by the EC for rape crop production (food and feed) harvests, but on farms with smaller fields, the threshold was exceeded. Harvest impurity increased in organic farms, mainly because of their small field size. The model was then used to evaluate the consequences of changes in farming practices and to identify those changes reducing harvest contamination. The effects of these changes depended on the field pattern and farming system. The most efficient practices in limiting harvest impurity comprised improved set-aside management by sowing a cover crop in spring on all set-aside fields in the region, permanently banning rape crops and set-aside around seed production fields and (for non-GM farmers) clustering farm fields to reduce gene inflow from neighbour fields.

Dans le cadre d’une réflexion générale sur les alternatives durables à la suppression des farines carnées dans l’alimentation animale, l’introduction et le renforcement des oléoprotéagineux dans les systèmes de production apparaissent comme les solutions les plus crédibles. Néanmoins, le caractère durable des solutions envisagées doit être évalué sur des bases techniques, environnementales et économiques qui permettront, en outre, d’estimer l’acceptabilité par les agriculteurs des scénarios proposés.

On a beaucoup parlé, lors de l’examen des demandes d’autorisation de mise en culture de variétés transgéniques de colza, des risques d’hybridation interspécifique du colza avec les crucifères sauvages, et d’introgression de transgènes dans les espèces adventices [1, 2]. Les flux de gènes intraspécifiques ont moins attiré l’attention du grand public; ils sont pourtant bien plus probables. Les transgènes peuvent être disséminés dans le temps, par l’intermédiaire de repousses de colza apparaissant dans les cultures suivant les variétés transgéniques, à cause de la perte d’une partie des graines produites par les cultures de colza avant ou pendant la récolte [3, 4], et dans l’espace, par l’intermédiaire de semences et de pollen disséminés par le vent ou d’autres vecteurs tels que les oiseaux ou les insectes [5-8]. Les semences dispersées peuvent produire directement des repousses de colza dans des champs voisins, tandis que le pollen peut transmettre le transgène en fécondant des plantes de colza présentes dans ces autres champs. Ce flux de gènes peut être à l’origine de différents problèmes tels que l’apparition de repousses de colza résistantes aux herbicides, difficiles à éliminer lorsqu’il s’agit d’un transgène de résistance à un herbicide, ou la pollution de récoltes de colza classique par le transgène, quelle que soit sa nature, et l’impossibilité d’écouler ces récoltes dans une filière « non-OGM ». Il est donc apparu nécessaire et urgent de mieux évaluer ce risque et d’identifier les moyens de le maîtriser. Les premiers éléments de réponse ont été donnés par les plates-formes « plantes transgéniques » des instituts techniques [9, 10]; cependant, ces plates-formes sont limitées dans le temps et l’espace et il n’est pas possible d’y rendre compte de la variabilité régionale des systèmes de culture et de leurs effets sur le devenir des repousses de colza; il n’est pas non plus possible d’attendre les résultats des plates-formes pour estimer des risques à long terme. Pour ces raisons, nous avons entrepris de construire un modèle rendant compte de la répartition spatiale des systèmes de culture ainsi que de leurs effets sur la dissémination, dans le temps et l’espace, d’un transgène (par exemple un gène de résistance aux herbicides ou un gène codant pour un acide gras) et sur sa persistance dans les populations de repousses de colza, sur des parcelles ayant ou non été cultivées avec la variété de colza transgénique. Les autres risques liés aux cultures transgéniques (résistance aux antibiotiques, allergies alimentaires, etc.) ne sont pas considérés dans cette étude. Dans cet article, nous allons présenter les grands principes du modèle d’évolution démographique et génétique des repousses de colza fonctionnant au niveau d’un champ cultivé, puis l’intégration et le fonctionnement de ce modèle au niveau régional. Les exemples décrits lors de la présentation du modèle et des simulations se rapportent généralement à un colza transgénique résistant à un herbicide. Mais le modèle peut également être utilisé pour évaluer le flux de gènes à partir de nouvelles variétés obtenues par sélection classique et/ou pour des gènes codant pour d’autres caractéristiques telles qu’une teneur en acide gras.

All innovation in agriculture constitutes a significant and complex ecological disturbance, even if limited to a single and simple action. Indeed, whatever the nature and objective of the action, a large number of ecological processes are affected and numerous discontinuities may occur within the agro-ecosystem, in both time and space. As the GMO example illustrates, it is not sufficient to focus on direct effect of innovation, it is necessary to forecast mid- and long-term impacts of innovation with respect to the environment. Modelling phenomena appear then to be a key element to achieve this goal.

We assessed new crop management systems for winter oilseed rape based on very early sowing dates, with a view to improving environmental performance without decreasing economic benefits. In a network of 36 trials conducted over 3 years in France, the new systems turned out to be more effective than current systems in terms of environmental variables: absorption of almost all the mineral N present in the soil in autumn, even after organic manure spreading; nitrate concentration of the percolated water below 50 mg $\cdot$ l$^{-1}$, and lower levels of molluscicide use, even in years of heavy slug infestation. The gross margin was optimised by very early sowing, which in most trials resulted in yields equal to or greater than those for crops sown at the usual date. We typed the trials, linking the difference in yield between the two crop management systems to various limiting factors (crop establishment, stem canker and nitrogen nutrition), to identify situations appropriate for the new crop management systems.

Which decision support tools should be developed to help agricultural stakeholders manage nitrogen in an environmentally friendly way? This paper presents the limitations of current decision support tools with respect to the implementation of a four-step quality spiral. PLAN: planning technical actions that satisfy both economic and environmental constraints. The priorities are to develop decision tools at the farm and the regional levels, and to estimate the indirect effects of nitrogen on the environment due to its interaction with pesticides. DO: implementation of technical actions. The design of decision support tools must integrate more information about the way in which farmers and their advisors will use the tools. CHECK: efficiency of the ”PLAN/DO” steps must be evaluated on different scales. The priority is to propose and validate environmental indicators. ACT: definition of new priorities for the next loop. Research is required on diagnosis tools for tracing back the causes of environmental problems.

Models of response to applied N can be useful for deriving improved N dose recommendations. Here we show how response model parameters can be estimated and how model predictions and model N dose recommendations can be evaluated. For parameter estimation, we use a statistical approach based on random parameter models. Two methods for evaluating models are applied. The first method is to calculate mean squared error of prediction (MSEP) by cross validation, and the second is to perform nonparametric regressions to evaluate the profitability of calculated optimal N rates. The proposed methods are used with a data set consisting of 37 winter wheat (Triticum aestivumL.) experiments. Different functions taking into account end‐of‐winter mineral soil N are evaluated. The results show that the different functions all have similar MSEP values for predictions of yield and grain protein content and lead to N recommendations of similar profitability. However, there are substantial differences in MSEP for residual mineral N at harvest. One of these models is then compared with a model that does not include any site‐year characteristic and with a model that does not have random parameters. We find that using the model without a site‐year characteristic leads to predictions that are less accurate and optimal N rates that are less profitable by F 17 to F 105 ha−1. Another result is that the gross margin obtained with the optimal N rates calculated using the model without random parameters is lower by F 438 to F 550 ha−1.

Although it is well known that environmental conditions in greenhouse crops are often not uniform, this is rarely taken into account in research into the factors determining product quality and pollution. Yet non-uniformity of irrigation, radiation and effect of compaction doubtless plays a fundamental part in the problems of quality (uniform size) and N pollution faced in lettuce production under plastic. A monitoring study of four lettuce crops showed a high degree of environmental non-uniformity, structured by the cropping methods used, and partly responsible for the variability in lettuce size. A model of the behaviour of the soil-plant system showed that this non-uniformity leads to serious N pollution: meeting the needs of the most disadvantaged plants leads to over-irrigation and over-fertilisation in nitrogen in some zones of the tunnel. If this non-uniformity is ignored, solutions may be proposed that do not match the objectives set in terms of product quality and environmental protection.

Genotype × environment interaction is fully analyzed when genotypes and environments are well characterized. Probe genotypes were studied in a simplified crop diagnosis to show how variates of yield components can strengthen characterization of environments by usual indicators of yield‐limiting factors. The objective of this study was to determine the main limiting factors of yield and to analyze their effects in wheat (Triticum aestivumL.) trials. Fixed genotypes (Talent, Soissons, Camp‐Rémy, and Arminda) were studied as probe genotypes at five experimental stations of the Institut National de la Recherche Agronomique (I.N.R.A.) (Rennes, Mons, La Miniére, Dijon, and Ondes) during 1991 and 1992. Two important variates, the reduction of kernel number and the reduction of thousand kernel weight, were analyzed to characterize the environments during the formation of yield. The former described the time‐period until flowering and the latter the grain‐filling period. In addition, factors that limit yield were determined through indicators such as water deficits, the ratio between nitrogen absorbed and kernel number, radiation, temperature, development of diseases (powdery mildew, strike rust, leaf rust, leaf and glume blotch), and lodging. Our study resulted in providing critical values for grain yield, kernel number, and thousand kernel weight for the four probe genotypes. Then reductions of yield components could be determined and analyzed. They provide useful information for characterizing environments subjected to numerous yield‐limiting factors. Our study also revealed that the biological variates (essentially susceptibility to powdery mildew and to lodging) affected yield more than the climatic variates.

The proper use of N fertilizer is fundamental for farm profitability and environmental protection. In France, fertilizer recommendations are generally based on the balance‐sheet method, which is not sensitive to the economic or regulatory context. A way to generalize the balance‐sheet method is to use models that describe crop response to applied N. The goal of this paper is to propose, in the case of winter wheat (Triticum aestivumL.), functional forms for the response of yield, grain protein content, and residual mineral N left in the soil at harvest to applied N. The originality of our models is that all three responses (yield, protein, and residual mineral N) are modeled, using N uptake as an intermediate variable. Furthermore, these models have two clear links with the balance‐sheet method. First, the parameters of the balance‐sheet method appear explicitly in the models. Second, the N dose recommended by the balance‐sheet method appears in our models as the smallest N dose that maximizes yield. Within this general modeling framework, three variants of the yield model, three variants of the grain protein content model, and two variants of the residual mineral N model are considered. The different models are adjusted, site‐year by site‐year, to 28 site‐years of data. All models give satisfactory fits to the data. For example, the root mean square error varies between 0.21 and 0.23 Mg ha−1for the yield models. Almost all the adjusted parameter values vary widely from site‐year to site‐year. This must be taken into account when calculating optimal N doses for new site‐years.

Two deep-working soil tillage tools, one which inverts soil (plough) and one which does not (chisel), were used before sowing wheat after various crop successions combining eyespot host and non-host crops. Soil structure was nearly the same and crop residues were located in the different soil layers. Eyespot sporulation was estimated by visually assessing pot plants which had been on the trial plots for a fixed length of time. Field plants were also assessed for disease at several wheat growth stages. A kinetic equation expressing disease level as a function of degree-days was fitted to the disease levels observed on the field plants. This equation is based on eyespot epidemiology and depends on two parameters reflecting the importance of the primary and the secondary infection cycles respectively. Pot plant and early field plant disease levels and primary infection were closely correlated to the presence of crop residues in the top layer. The amount of residues depended on both crop succession and soil tillage. Where the previous crop was a host crop preceded by a non-host crop, soil inversion buried host residues, thus decreasing the primary infection risk. Where however the previous crop was a non-host crop preceded by a host crop, soil inversion carried the host residues back to soil surface, thus increasing the primary infection risk. Secondary infection was not correlated to either crop succession or soil tillage.

Le plan national Ecophyto, lancé en 2008 par le gouvernement français, qui visait une réduction de l’usage des pesticides de 50 % en dix ans, « si possible », est un échec : en effet, au cours des cinq premières années de son application, la consommation de ces produits a augmenté. Ce constat a conduit les pouvoirs publics à annoncer un plan Ecophyto 2, en cours de mise en place. Pour les auteurs de cet article (agronomes et sociologues), l’échec était prévisible, au vu des caractéristiques des actions mises en place. Ils le montrent par l’analyse de deux actions phares du plan (le Bulletin de santé du végétal, base de l’information diffusée pour évaluer en temps réel les risques de bioagresseurs, et le réseau DEPHY de fermes de démonstration, conçu pour expérimenter et déployer des techniques économes en produits phytosanitaires), et l’analyse de l’usage fait des indicateurs de suivi du plan. Mais l’échec est imputable, plus encore peut-être, au fait que les actions n’ont ciblé que les agriculteurs et leurs conseillers, sans tenir compte des effets de « verrouillage sociotechnique », c’est-à-dire des interdépendances qui relient l’ensemble des acteurs économiques engagés dans la logique de systèmes agricoles pour lesquels les pesticides jouent un rôle de pivot. Le plan Ecophyto a cependant envoyé un signal symbolique fort, qui peut être déterminant à moyen et long termes : les pouvoirs publics annoncent clairement la fin de l’usage massif des pesticides en agriculture.

Bien loin d'une simple fusion entre agronomie et écologie, l'agroécologie apparaît comme un projet innovant, qui se positionne à la fois dans le champ des sciences de la nature, des sciences économiques et sociales, de la politique et de l'action. L'agroécologie nous conduit à explorer de nouveaux champs de savoir, aux interfaces entre disciplines, sur les impacts agronomiques des régulations biologiques autant que sur les systèmes socioécologiques. Mais, plus encore, elle nous engage à faire évoluer nos manières de travailler : développer les approches systémiques, en renonçant aux séduisantes simplifications du type « un problème, un intrant » ; revaloriser les savoirs locaux et les mettre en synergie avec les savoirs scientifiques ; décloisonner l'innovation, en repositionnant l'agriculture au sein des territoires et des systèmes alimentaires ; enfin, favoriser les dynamiques d'apprentissage individuel et collectif, source d'innovation et d'adaptation aux situations locales.

La spécialisation, à l’œuvre dans les exploitations françaises depuis plusieurs décennies, a remodelé le paysage agricole de l’Hexagone : la céréaliculture est aujourd’hui largement dominante dans le centre du Bassin Parisien, en Alsace ou en Aquitaine, tandis que l’Ouest de la France, qui se consacre à l’élevage intensif, donne une large place dans ses assolements, au maïs ensilage et aux prairies monospécifiques de courte durée. Cette spécialisation régionale s’accompagne d’une réduction du nombre d’espèces cultivées, et d’un raccourcissement des rotations, qui engendre des difficultés à maîtriser les populations d’adventices ou les parasites et de nombreux problèmes écologiques (perte de biodiversité; faible recyclage des éléments minéraux N, P, K...).

Le processus d’intensification des élevages, entamé dans les années 1970, s’est accompagné d’un développement croissant du recours aux aliments dits « composés », fabriqués à partir de différentes matières premières pour la plupart d’origine végétale. Les pratiques de la formulation des fabricants d’aliments composés, fondées sur une très forte substituabilité des matières premières, génèrent une concurrence très forte entre ces commodités. Dans un tel contexte de marché, la valorisation de certaines espèces repose sur des mécanismes permettant de contourner ou de s’affranchir de cette concurrence, mais dont l’efficacité reste fortement dépendante de l’organisation des acteurs au sein des filières. À partir de la comparaison des filières pois et lin, nous montrons ainsi qu’au-delà de la reconnaissance de propriétés nutritionnelles spécifiques pouvant valoriser différemment certaines espèces, la coordination des acteurs le long d’une filière est déterminante dans la diffusion des incitations économiques et informationnelles nécessaires à une orientation des agriculteurs en faveur d’espèces de diversification d’intérêt agro-écologique.

La diversification des cultures est souvent présentée comme un levier d’action pour accroître la durabilité des systèmes de production agricoles. Bien raisonnée, elle favorise en effet une réduction de l’usage d’intrants extérieurs à l’exploitation – pesticides, engrais, eau – et des nuisances environnementales associées à leur utilisation excessive. À l’inverse, la simplification des systèmes de culture engagée depuis plus de 40 ans s’est accompagnée d’un recours croissant aux intrants. Cependant, malgré son intérêt pour les systèmes de production en termes de durabilité écologique mais aussi économique (répartition des risques), et son inscription dans divers plans et dispositifs incitatifs, la diversification des cultures progresse peu. Les ministères en charge de l’agriculture et de l’environnement ont donc commandé à l’INRA une étude visant à identifier les freins à la diversification des cultures en France et les leviers mobilisables, par les pouvoirs publics notamment, pour la favoriser. L’hypothèse de travail est que ces freins relèvent du fonctionnement global du système agro-industriel, et de la capacité de développement de filières valorisant les cultures de diversification. L’étude a examiné un certain nombre de cas représentatifs de la diversité des filières et notamment de leurs modes d’organisation, qui déterminent la coordination et l’engagement des acteurs économiques impliqués dans le développement d’une culture de diversification.

Agronomy for Sustainable Development When the journal Agronomie was created 24 years ago, agronomy was still mainly the science of crop production and soil fertility. Scientific investigation has since progressively taken into account the study of the environmental impact of agriculture, as well as the setting up of advanced cropping systems that reconcile both production and environment. Since 1990, the framework of the journal Agronomie has been adapted to integrate new environmental topics, leading to the addition of the sub-title Agriculture & Environment to the current journal name. Nowadays the scientific sub-disciplines of Agronomy are broadening to answer issues regarding sustainable development, which require knowledge about the relationships between technical, ecological, economical and social processes. The investigations should, for instance, try to connect studies on various scales from the single plot to the farm, the production basin and the landscape. They should also bridge the short-term effects of day-to-day agricultural practices and the long-term evolution of natural resources. Moreover, there is a growing need for new methods that allow the evaluation of the sustainability of current practices. There is also a need for innovative cropping systems, farming systems and landscape organisations. Furthermore, the forecast of the future impact of global warming on production and cropping systems is a major concern. Such changes along scientific lines in agronomy will foster the development of multidisciplinary studies that associate agronomy with ecology, economics, sociology and geography. Therefore, the title, the topics and the format of the journal Agronomie, Agriculture & Environment are currently being adapted to novel, cutting-edge research fields located at the frontiers of agriculture and sustainable development. The new journal title will be Agronomy for Sustainable Development. Accordingly, a new ”Aims and Scope” section is shown below. The selection of articles will also be slightly increased to focus the manuscripts better on innovative points. The number of journal issues will thus be reduced to four per year. Short articles demonstrating outstanding findings and review articles will be particularly welcome. The journal will also publish solely articles written fully in English to gain a wider audience and to allow more submissions from non-French-speaking scientists. Those changes are planned to take place definitively in January 2005. Aims and scope Agronomy for Sustainable Development is an international journal for scientific research on the interactions between cropping systems and other activities in the context of sustainable development. The Editors welcome monodisciplinary contributions in agronomy that will constitute the grounds of sustainability from environmental, economical or social viewpoints. The Editors also welcome multidisciplinary articles that bridge agronomy with ecology, environmental and social sciences. Manuscripts should focus on novel findings underlining those relationships. The journal publishes original research articles that demonstrate a clear scientific breakthrough versus current knowledge. The material should not have been previously published elsewhere. Review articles on a particularly hot subject may be suggested to the Editor-in-Chief. Contributions may be on either methodological approaches, or approaches addressing major issues in the scope of the journal. The journal covers application fields such as sustainable agriculture, sustainable land use, agriculture and global changes, agriculture and preservation of natural resources and health, agriculture and biodiversity, ecological, economical and social impacts of genetic engineering applications, agricultural production of renewable energies, environmental management in agriculture, food quality and security management, geographical indicators for agricultural products, decision support systems, and social and economical issues of agricultural changes. Selected examples of topics covered by the journal are given below. Environmental impact - Impact of agriculture on ecosystems - Soil, water, air, plant and food quality - Biodiversity changes - Agroclimatology and modelling - Biogeochemistry of agrosystems - Ecotoxicology, risk assessment, food safety - Use of genetically modified organisms (GMOs) in cropping systems - Any other topic relative to the environmental impact of agriculture Ecological production - Ecological production methods - Ecological farming systems - Ecological pest control, biopesticides - Methods for production of organic food - Methods for preservation of natural resources - Methods for production of renewable energies - Agrochemistry and soil fertility - Any other topic relative to ecological production