Meynard Jean-marc - Profile on Academia.edu (original) (raw)

Papers by Meynard Jean-marc

OCL, 2013

-Le processus d'intensification des élevages, entamé dans les années 1970, s'est accompagné d'un ... more -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.

Alors que l’'INRA affiche comme une priorite, dans son document d’'orientation 2010-2020,... more Alors que l’'INRA affiche comme une priorite, dans son document d’'orientation 2010-2020, la « conception, l’'experimentation et l’'evaluation de nouveaux systemes agricoles s’'inscrivant dans le cadre exigeant du developpement durable », le dispositif experimental de l''Institut est appele a renouveler ses thematiques et son mode de fonctionnement : investissement sur des pratiques inspirees de l'agroecologie (une trentaine de sites concernes, d’'apres le rapport Soussana, 2012), ouverture a un partenariat scientifique et socio-economique elargi, contribution accrue a la mise au point et a la demonstration de prototypes de systemes de production innovants… Cette evolution du dispositif impose des changements profonds dans les pratiques, les competences et l’'organisation des equipes d'’experimentateurs. C’est a ces changements que l'’on s’interesse dans cet article.

Sustainable Agriculture, 2009

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific r... more HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Agronomie, 2001

Although it is well known that environmental conditions in greenhouse crops are often not uniform... more 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 overirrigation 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. Résumé -L'hétérogénéité du milieu en production de laitue sous abri accroît le risque de pollution nitrique et affecte la qualité du produit. Bien que l'hétérogénéité des conditions du milieu soit un phénomène bien connu pour les cultures abritées, elle est rarement prise en compte dans les études portant sur les déterminants de la qualité des produits et de la pollution. Or les hétérogénéités d'irrigation, de rayonnement ou dues à l'effet de la compaction ont sans doute un rôle fondamental dans les problèmes de qualité (homogénéité des calibres) et de pollution nitrique auxquels sont confrontés les producteurs de laitues sous abri plastique. Un suivi réalisé sur quatre cultures de laitues montre qu'il existe une forte hétérogénéité du milieu, structurée par les techniques culturales utilisées, et en partie responsable de la variabilité des calibres des laitues. L'utilisation d'un modèle de fonctionnement du système solplante montre que cette hétérogénéité induit une forte pollution nitrique : la satisfaction des besoins des laitues les plus défavorisées entraîne une sur-irrigation et une sur-fertilisation azotée sur certaines zones de l'abri. Nier cette hétérogénéité pourrait donc amener à proposer des solutions ne répondant pas aux objectifs fixés, en terme de qualité du produit et de respect de l'environnement.

Agronomie, 2003

We assessed new crop management systems for winter oilseed rape based on very early sowing dates,... more 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•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. cropping systems / winter oilseed rape / sowing dates / nitrate leaching / nitrogen management / integrated pest management Résumé-Évaluation en France d'itinéraires techniques du colza d'hiver favorables à l'environnement, basés sur des semis très précoces. Notre objectif est l'évaluation de nouveaux itinéraires techniques du colza basés sur des semis très précoces, afin d'améliorer le bilan environnemental de cette culture sans affecter son bilan économique. Sur un réseau de 36 essais pendant 3 années en France, les nouveaux itinéraires techniques se sont avérés plus efficaces que les itinéraires techniques actuellement recommandés au niveau des performances environnementales : absorption, au cours de l'automne, de la quasi totalité de l'azote minéral du sol même après épandage d'effluent organique ; teneur en nitrate de l'eau percolée inférieure à 50 mg•l-1 ; réduction de l'emploi de molluscicides, même en année de forte infestation de limaces. En terme de marge brute, les résultats moyens furent favorables aux semis très précoces qui permirent, sur la majorité des essais, un rendement supérieur ou égal à celui des semis à date normale. Une typologie des essais reliant la différence de rendement entre les deux itinéraires techniques à différents facteurs limitants (implantation de la culture, phoma, nutrition azotée), est utilisée afin de définir le domaine de validité des nouveaux itinéraires techniques. itinéraires techniques / colza d'hiver / dates de semis / lixiviation du nitrate / gestion de l'azote / protection intégrée

Agriculture, Ecosystems & Environment, 2001

The aim of model GeneSys is to rank cropping systems according to their risk of gene escape from ... more The aim of model GeneSys is to rank cropping systems according to their risk of gene escape from genetically modified, herbicide tolerant winter oilseed rape cultivars to rapeseed volunteers. The model integrates the effects of crop succession and crop management at the level of a region. The first part of the model presented in this paper describes the temporal evolution of rapeseed volunteers in a field, using an annual life-cycle comprising stages such as seed bank, seedlings, adult plants, flowers or freshly produced seeds. The relationships between the various stages depend on the crops grown each year and the cultivation techniques (stubble breaking, soil tillage, sowing date and density, herbicides, cutting and harvesting). Parameter values were either deduced from existing models and literature, or estimated from experimental studies and field surveys. The extension of the temporal sub-model to include the genetic evolution of rapeseed volunteers and the spatial dimension is presented in a second paper [

Agricultural Systems, 1997

The diagnosis of agronomic problems in cropping systems is often limited to surveys among farmers... more The diagnosis of agronomic problems in cropping systems is often limited to surveys among farmers, in which they are asked the problems they encounter. This paper describes an alternative method of diagnosis to understand the variations in crop yield on a regional scale. It is based on multiannual on-farm surveys, where data are collected on the cropping system, environment and crop yield build-up. The different steps of the method -choice of study area and of farmers' fields, choice of methods, design of further experiments, and diagnosis itself, plus the way they are linked to each other, are developed and discussed.

Agronomie, 2003

Variability of the efficiency of N, P, K and Mg fertilisation on a low-input bean/maize intercrop... more Variability of the efficiency of N, P, K and Mg fertilisation on a low-input bean/maize intercrop (BMI) was analysed in an upland of Haïti using the combination of a simple equation predicting the fertiliser requirements and an agronomic diagnosis in farmers' fields. The study results in a classification of cropping systems according to factors limiting the fertiliser response of the intercrop species (mainly bean root necrosis and high soil K supply) and in fertilisation rules specifically adapted to the diversity of agronomic conditions. Bean root necrosis due to a parasitic complex with Fusarium solani f. sp. phaseoli decreased the fertiliser efficiency and was higher wherever the topography of a field was concave and where beans were frequent in the rotation. High soil exchangeable K content was generally found where the preceding crop was cabbage, a cash crop that is given large amounts of N-P-K fertiliser. Additional fertiliser applied to the BMI decreased nodulation of the bean, N and Mg uptake and bean yield. Because of the competition from the associated bean crop, the maize did not respond to fertiliser. low-input system / bean-maize intercropping / fertiliser rules / ferralsols / tropical highland Résumé -Élaboration de règles de fertilisation pour la diversité des systèmes de culture d'une région : le cas d'une association haricot/ maïs à bas intrants dans une région d'altitude d'Haiti. La variabilité de l'efficience d'un engrais complet (N, P, K, Mg) sur une association culturale haricot/maïs à bas niveau d'intrants cultivée dans une petite région d'altitude en Haïti, est analysée en combinant l'utilisation d'une équation simple de calcul de dose d'engrais et un diagnostic en parcelles d'agriculteurs. Une classification des systèmes de culture en fonction des facteurs limitants de la réponse à l'engrais de l'association (principalement les nécroses racinaires du haricot et la richesse du sol en K) permet d'adapter la fertilisation à la diversité des conditions agronomiques de la région. Les nécroses des racines du haricot, dues à un complexe parasitaire dominé par Fusarium solani f. sp. phaseoli, sont à l'origine d'une faible efficience de l'engrais sur cette espèce ; elles sont importantes sur les sols à topographie concave, et dans les rotations où le haricot revient fréquemment. Une teneur élevée du sol en K échangeable est observée sur les parcelles antérieurement cultivées en chou, culture de vente fortement fertilisée. Sur ces parcelles, l'apport d'engrais à l'association haricot/maïs entraîne une diminution de la nodulation et du rendement du haricot, ainsi que du prélèvement de N et de K par cette culture. À cause de la structure de l'association, la concurrence du haricot empêche toute réponse du maïs aux apports d'engrais. système à bas intrants / association haricot-maïs / fertilisation / sols ferralitiques / zone tropicale d'altitude

A Conceptual Model to Design Prototypes of Crop Management: A Way to Improve Organic Winter Oilseed Rape Performance in Farmers' Fields

intechopen.com

Characterization of multiple disease systems and cultivar susceptibilities for the analysis of yield losses in winter wheat

ABSTRACT The relationship between winter wheat (Triticum aestivum L.) cultivar susceptibility to ... more ABSTRACT The relationship between winter wheat (Triticum aestivum L.) cultivar susceptibility to four main fungal diseases, multiple disease systems, and yield loss (YL) levels was studied. Data from 276 wheat cultivar trials carried out in major wheat-growing areas in France over 12 years (1991–2002) were analyzed. Two variables were defined for each disease: actual disease intensity, referring to individual cultivar and potential disease intensity for each trial, calculated from the disease intensities measured on susceptible cultivars. Cultivar was represented by its level of susceptibility to each disease, previously given by GEVES and based on a semi-quantitative scale. YL was estimated for a given cultivar as the difference between the mean yield of fungicide-protected and of untreated plots. Nonparametric multivariate analysis provided a characterization of relationships among variables. Eight cultivar susceptibility profiles (CP), five potential disease profiles (PDP), and six actual disease profiles (ADP) were determined by cluster analysis. Correspondence analyses led to a good description of variation in YL when potential or ADP were considered. General linear models were developed for each of the five PDP, which involved a significant interaction between CP and PDP on YL. These empirical models provided a means of quantifying the effects of CP on YL. These models represent a practical tool to support choices for multiple-disease resistances in a given area, depending on the prevailing disease profile. Results from this study can also be used to improve the disease module of an agronomic model for wheat aimed at designing “cultivar×crop management” combinations for a given environment and cost/price ratio.

Agriculture, Ecosystems & Environment, 2005

An impact assessment of current upland cropping systems in Haiti was carried out using a combined... more An impact assessment of current upland cropping systems in Haiti was carried out using a combined experimental and agronomic survey approach on fields that were chosen as being representative of the diversity of land use practices and intensities. These cropping systems were mostly developed on ferralsols with differing degrees of weathering owing to the varying depths to the limestone bedrock. Three soil types for which the CEC of the mineral fraction was less than 3, 4-7, or 11-18 cmol (+) kg −1 were distinguished. The study shows that apart from phosphorus, soil cation availability (K, Mg) is the most limiting factor for a successful bean crop. With the insertion of a fertilized cabbage crop into the rotation, the soil bioavailable P at the sowing of the bean-maize intercrop (BMI) did not significantly increase, whereas the exchangeable K content of the soils increased from 0.22 to 0.38 and led to a significant increase in the bean yield from 654 to 1079 kg ha −1. It is clear that the trend of the cropping systems towards a shorter fallow period, increasing frequency of the BMI and introduction of N-P-K fertilizers, may all increase crop production in the short term. However, these changes are unlikely to lead to sustained benefits. One of the potential risks is the soil Mg depletion due to K fertilization as revealed by a microlysimeter experiment. Another risk is the increased proportion of plants with bean root diseases, due to the shortening of the BMI rotation interval. The proportion of plants with bean root diseases increased from 7 to 22% in 1989 and from 10 to 39% in 1990, when the bean rotation interval was reduced from 3 to 1 years. Another risk is the spatial spread of fall armyworm (Spodoptera frugiperda) from the plots covered with residues of a preceding maize crop, to the neighboring plots recently sown with maize. Future research should therefore focus on optimizing the K:Mg ratio of fertilizer, breeding bean varieties resistant to Fusarium disease, diversifying the range of crops cultivated, and management of the maize residues. The evolution of the cropping systems in the last 10 years is somewhat consistent with the diagnosis made about 15 years earlier.

Spatialisation de scénarios d'évolution du ruissellement érosif et implications pour les politiques publiques locales

Espace géographique

ABSTRACT

Activites, 2007

New cultivars have always been a key element in the development of cropping systems. The assessme... more New cultivars have always been a key element in the development of cropping systems. The assessment of new cultivar performance in a diverse range of environments (soil, climate, production methods) is a key issue for the actors along the chain which links breeders to growers and food suppliers. As agronomists and ergonomists, we worked together to design a tool aimed at supporting these actors in assessing cultivar performance in order to link three aspects of the design process: (i) the crystallisation in the tool of an activity model, (ii) the flexibility of the tool, (iii) the joint development of the tool and the activity. To produce specifications based on these aspects, we analysed respectively (i) the invariants of the activity system of cultivar assessment, (ii) the diversity of actions performed by actors involved in cultivar assessment, (iii) the contradictions which arise within the activity system. Our analysis calls on existing historical studies but is based mainly on interviews with 21 people involved in cultivar assessment and gave us an insight into the actions of assessment activity. This analysis enables us to point out that the network of field trials is a key tool for the activity of cultivar assessment and to study how actors take advantage of the vagueness of the various tools to transform them into instruments. It also shows that, historically, the object of the activity has been built around assessing the stability of cultivar performance and that stability still gives direction to the actions undertaken by actors today. Eleven different actions for evaluating cultivars were identified. Our analysis highlights the contradictions which emerge today within the object of the activity system due to the new issues that actors have to face. It led us to define specifications for a prototype tool which is flexible enough to adapt to the diversity of actions and which could be used to enable actors to overcome some of the contradictions identified.

Methodology for designing sustainable farming systems: prototyping and model-based explorations in a participatory research setting

Yield variation of organic winter wheat; a crop diagnosis on a field network in South-East of France

Agronomy for Sustainable Development

The assessment of a decision making tool for managing the nitrogen fertilization of organic winter wheat

European Journal of Agronomy

En prolongement du texte d'Amédée Mollard, l'objectif de cet article est de proposer quelques réf... more En prolongement du texte d'Amédée Mollard, l'objectif de cet article est de proposer quelques réflexions d'agronome sur la désintensification. Nous nous appuierons pour cela sur une analyse des travaux réalisés à l'INRA sur cette question, et tenterons de dégager quelques pistes quant aux priorités de recherche pour les années à venir.

Les enjeux de la production de blé tendre en agriculture biologique

Le Courrier de l'Unesco

Analysis of necessary adjustements of farming practices

OCL, 2013

-Le processus d'intensification des élevages, entamé dans les années 1970, s'est accompagné d'un ... more -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.

Alors que l’'INRA affiche comme une priorite, dans son document d’'orientation 2010-2020,... more Alors que l’'INRA affiche comme une priorite, dans son document d’'orientation 2010-2020, la « conception, l’'experimentation et l’'evaluation de nouveaux systemes agricoles s’'inscrivant dans le cadre exigeant du developpement durable », le dispositif experimental de l''Institut est appele a renouveler ses thematiques et son mode de fonctionnement : investissement sur des pratiques inspirees de l'agroecologie (une trentaine de sites concernes, d’'apres le rapport Soussana, 2012), ouverture a un partenariat scientifique et socio-economique elargi, contribution accrue a la mise au point et a la demonstration de prototypes de systemes de production innovants… Cette evolution du dispositif impose des changements profonds dans les pratiques, les competences et l’'organisation des equipes d'’experimentateurs. C’est a ces changements que l'’on s’interesse dans cet article.

Sustainable Agriculture, 2009

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific r... more HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Agronomie, 2001

Although it is well known that environmental conditions in greenhouse crops are often not uniform... more 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 overirrigation 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. Résumé -L'hétérogénéité du milieu en production de laitue sous abri accroît le risque de pollution nitrique et affecte la qualité du produit. Bien que l'hétérogénéité des conditions du milieu soit un phénomène bien connu pour les cultures abritées, elle est rarement prise en compte dans les études portant sur les déterminants de la qualité des produits et de la pollution. Or les hétérogénéités d'irrigation, de rayonnement ou dues à l'effet de la compaction ont sans doute un rôle fondamental dans les problèmes de qualité (homogénéité des calibres) et de pollution nitrique auxquels sont confrontés les producteurs de laitues sous abri plastique. Un suivi réalisé sur quatre cultures de laitues montre qu'il existe une forte hétérogénéité du milieu, structurée par les techniques culturales utilisées, et en partie responsable de la variabilité des calibres des laitues. L'utilisation d'un modèle de fonctionnement du système solplante montre que cette hétérogénéité induit une forte pollution nitrique : la satisfaction des besoins des laitues les plus défavorisées entraîne une sur-irrigation et une sur-fertilisation azotée sur certaines zones de l'abri. Nier cette hétérogénéité pourrait donc amener à proposer des solutions ne répondant pas aux objectifs fixés, en terme de qualité du produit et de respect de l'environnement.

Agronomie, 2003

We assessed new crop management systems for winter oilseed rape based on very early sowing dates,... more 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•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. cropping systems / winter oilseed rape / sowing dates / nitrate leaching / nitrogen management / integrated pest management Résumé-Évaluation en France d'itinéraires techniques du colza d'hiver favorables à l'environnement, basés sur des semis très précoces. Notre objectif est l'évaluation de nouveaux itinéraires techniques du colza basés sur des semis très précoces, afin d'améliorer le bilan environnemental de cette culture sans affecter son bilan économique. Sur un réseau de 36 essais pendant 3 années en France, les nouveaux itinéraires techniques se sont avérés plus efficaces que les itinéraires techniques actuellement recommandés au niveau des performances environnementales : absorption, au cours de l'automne, de la quasi totalité de l'azote minéral du sol même après épandage d'effluent organique ; teneur en nitrate de l'eau percolée inférieure à 50 mg•l-1 ; réduction de l'emploi de molluscicides, même en année de forte infestation de limaces. En terme de marge brute, les résultats moyens furent favorables aux semis très précoces qui permirent, sur la majorité des essais, un rendement supérieur ou égal à celui des semis à date normale. Une typologie des essais reliant la différence de rendement entre les deux itinéraires techniques à différents facteurs limitants (implantation de la culture, phoma, nutrition azotée), est utilisée afin de définir le domaine de validité des nouveaux itinéraires techniques. itinéraires techniques / colza d'hiver / dates de semis / lixiviation du nitrate / gestion de l'azote / protection intégrée

Agriculture, Ecosystems & Environment, 2001

The aim of model GeneSys is to rank cropping systems according to their risk of gene escape from ... more The aim of model GeneSys is to rank cropping systems according to their risk of gene escape from genetically modified, herbicide tolerant winter oilseed rape cultivars to rapeseed volunteers. The model integrates the effects of crop succession and crop management at the level of a region. The first part of the model presented in this paper describes the temporal evolution of rapeseed volunteers in a field, using an annual life-cycle comprising stages such as seed bank, seedlings, adult plants, flowers or freshly produced seeds. The relationships between the various stages depend on the crops grown each year and the cultivation techniques (stubble breaking, soil tillage, sowing date and density, herbicides, cutting and harvesting). Parameter values were either deduced from existing models and literature, or estimated from experimental studies and field surveys. The extension of the temporal sub-model to include the genetic evolution of rapeseed volunteers and the spatial dimension is presented in a second paper [

Agricultural Systems, 1997

The diagnosis of agronomic problems in cropping systems is often limited to surveys among farmers... more The diagnosis of agronomic problems in cropping systems is often limited to surveys among farmers, in which they are asked the problems they encounter. This paper describes an alternative method of diagnosis to understand the variations in crop yield on a regional scale. It is based on multiannual on-farm surveys, where data are collected on the cropping system, environment and crop yield build-up. The different steps of the method -choice of study area and of farmers' fields, choice of methods, design of further experiments, and diagnosis itself, plus the way they are linked to each other, are developed and discussed.

Agronomie, 2003

Variability of the efficiency of N, P, K and Mg fertilisation on a low-input bean/maize intercrop... more Variability of the efficiency of N, P, K and Mg fertilisation on a low-input bean/maize intercrop (BMI) was analysed in an upland of Haïti using the combination of a simple equation predicting the fertiliser requirements and an agronomic diagnosis in farmers' fields. The study results in a classification of cropping systems according to factors limiting the fertiliser response of the intercrop species (mainly bean root necrosis and high soil K supply) and in fertilisation rules specifically adapted to the diversity of agronomic conditions. Bean root necrosis due to a parasitic complex with Fusarium solani f. sp. phaseoli decreased the fertiliser efficiency and was higher wherever the topography of a field was concave and where beans were frequent in the rotation. High soil exchangeable K content was generally found where the preceding crop was cabbage, a cash crop that is given large amounts of N-P-K fertiliser. Additional fertiliser applied to the BMI decreased nodulation of the bean, N and Mg uptake and bean yield. Because of the competition from the associated bean crop, the maize did not respond to fertiliser. low-input system / bean-maize intercropping / fertiliser rules / ferralsols / tropical highland Résumé -Élaboration de règles de fertilisation pour la diversité des systèmes de culture d'une région : le cas d'une association haricot/ maïs à bas intrants dans une région d'altitude d'Haiti. La variabilité de l'efficience d'un engrais complet (N, P, K, Mg) sur une association culturale haricot/maïs à bas niveau d'intrants cultivée dans une petite région d'altitude en Haïti, est analysée en combinant l'utilisation d'une équation simple de calcul de dose d'engrais et un diagnostic en parcelles d'agriculteurs. Une classification des systèmes de culture en fonction des facteurs limitants de la réponse à l'engrais de l'association (principalement les nécroses racinaires du haricot et la richesse du sol en K) permet d'adapter la fertilisation à la diversité des conditions agronomiques de la région. Les nécroses des racines du haricot, dues à un complexe parasitaire dominé par Fusarium solani f. sp. phaseoli, sont à l'origine d'une faible efficience de l'engrais sur cette espèce ; elles sont importantes sur les sols à topographie concave, et dans les rotations où le haricot revient fréquemment. Une teneur élevée du sol en K échangeable est observée sur les parcelles antérieurement cultivées en chou, culture de vente fortement fertilisée. Sur ces parcelles, l'apport d'engrais à l'association haricot/maïs entraîne une diminution de la nodulation et du rendement du haricot, ainsi que du prélèvement de N et de K par cette culture. À cause de la structure de l'association, la concurrence du haricot empêche toute réponse du maïs aux apports d'engrais. système à bas intrants / association haricot-maïs / fertilisation / sols ferralitiques / zone tropicale d'altitude

A Conceptual Model to Design Prototypes of Crop Management: A Way to Improve Organic Winter Oilseed Rape Performance in Farmers' Fields

intechopen.com

Characterization of multiple disease systems and cultivar susceptibilities for the analysis of yield losses in winter wheat

ABSTRACT The relationship between winter wheat (Triticum aestivum L.) cultivar susceptibility to ... more ABSTRACT The relationship between winter wheat (Triticum aestivum L.) cultivar susceptibility to four main fungal diseases, multiple disease systems, and yield loss (YL) levels was studied. Data from 276 wheat cultivar trials carried out in major wheat-growing areas in France over 12 years (1991–2002) were analyzed. Two variables were defined for each disease: actual disease intensity, referring to individual cultivar and potential disease intensity for each trial, calculated from the disease intensities measured on susceptible cultivars. Cultivar was represented by its level of susceptibility to each disease, previously given by GEVES and based on a semi-quantitative scale. YL was estimated for a given cultivar as the difference between the mean yield of fungicide-protected and of untreated plots. Nonparametric multivariate analysis provided a characterization of relationships among variables. Eight cultivar susceptibility profiles (CP), five potential disease profiles (PDP), and six actual disease profiles (ADP) were determined by cluster analysis. Correspondence analyses led to a good description of variation in YL when potential or ADP were considered. General linear models were developed for each of the five PDP, which involved a significant interaction between CP and PDP on YL. These empirical models provided a means of quantifying the effects of CP on YL. These models represent a practical tool to support choices for multiple-disease resistances in a given area, depending on the prevailing disease profile. Results from this study can also be used to improve the disease module of an agronomic model for wheat aimed at designing “cultivar×crop management” combinations for a given environment and cost/price ratio.

Agriculture, Ecosystems & Environment, 2005

An impact assessment of current upland cropping systems in Haiti was carried out using a combined... more An impact assessment of current upland cropping systems in Haiti was carried out using a combined experimental and agronomic survey approach on fields that were chosen as being representative of the diversity of land use practices and intensities. These cropping systems were mostly developed on ferralsols with differing degrees of weathering owing to the varying depths to the limestone bedrock. Three soil types for which the CEC of the mineral fraction was less than 3, 4-7, or 11-18 cmol (+) kg −1 were distinguished. The study shows that apart from phosphorus, soil cation availability (K, Mg) is the most limiting factor for a successful bean crop. With the insertion of a fertilized cabbage crop into the rotation, the soil bioavailable P at the sowing of the bean-maize intercrop (BMI) did not significantly increase, whereas the exchangeable K content of the soils increased from 0.22 to 0.38 and led to a significant increase in the bean yield from 654 to 1079 kg ha −1. It is clear that the trend of the cropping systems towards a shorter fallow period, increasing frequency of the BMI and introduction of N-P-K fertilizers, may all increase crop production in the short term. However, these changes are unlikely to lead to sustained benefits. One of the potential risks is the soil Mg depletion due to K fertilization as revealed by a microlysimeter experiment. Another risk is the increased proportion of plants with bean root diseases, due to the shortening of the BMI rotation interval. The proportion of plants with bean root diseases increased from 7 to 22% in 1989 and from 10 to 39% in 1990, when the bean rotation interval was reduced from 3 to 1 years. Another risk is the spatial spread of fall armyworm (Spodoptera frugiperda) from the plots covered with residues of a preceding maize crop, to the neighboring plots recently sown with maize. Future research should therefore focus on optimizing the K:Mg ratio of fertilizer, breeding bean varieties resistant to Fusarium disease, diversifying the range of crops cultivated, and management of the maize residues. The evolution of the cropping systems in the last 10 years is somewhat consistent with the diagnosis made about 15 years earlier.

Spatialisation de scénarios d'évolution du ruissellement érosif et implications pour les politiques publiques locales

Espace géographique

ABSTRACT

Activites, 2007

New cultivars have always been a key element in the development of cropping systems. The assessme... more New cultivars have always been a key element in the development of cropping systems. The assessment of new cultivar performance in a diverse range of environments (soil, climate, production methods) is a key issue for the actors along the chain which links breeders to growers and food suppliers. As agronomists and ergonomists, we worked together to design a tool aimed at supporting these actors in assessing cultivar performance in order to link three aspects of the design process: (i) the crystallisation in the tool of an activity model, (ii) the flexibility of the tool, (iii) the joint development of the tool and the activity. To produce specifications based on these aspects, we analysed respectively (i) the invariants of the activity system of cultivar assessment, (ii) the diversity of actions performed by actors involved in cultivar assessment, (iii) the contradictions which arise within the activity system. Our analysis calls on existing historical studies but is based mainly on interviews with 21 people involved in cultivar assessment and gave us an insight into the actions of assessment activity. This analysis enables us to point out that the network of field trials is a key tool for the activity of cultivar assessment and to study how actors take advantage of the vagueness of the various tools to transform them into instruments. It also shows that, historically, the object of the activity has been built around assessing the stability of cultivar performance and that stability still gives direction to the actions undertaken by actors today. Eleven different actions for evaluating cultivars were identified. Our analysis highlights the contradictions which emerge today within the object of the activity system due to the new issues that actors have to face. It led us to define specifications for a prototype tool which is flexible enough to adapt to the diversity of actions and which could be used to enable actors to overcome some of the contradictions identified.

Methodology for designing sustainable farming systems: prototyping and model-based explorations in a participatory research setting

Yield variation of organic winter wheat; a crop diagnosis on a field network in South-East of France

Agronomy for Sustainable Development

The assessment of a decision making tool for managing the nitrogen fertilization of organic winter wheat

European Journal of Agronomy

En prolongement du texte d'Amédée Mollard, l'objectif de cet article est de proposer quelques réf... more En prolongement du texte d'Amédée Mollard, l'objectif de cet article est de proposer quelques réflexions d'agronome sur la désintensification. Nous nous appuierons pour cela sur une analyse des travaux réalisés à l'INRA sur cette question, et tenterons de dégager quelques pistes quant aux priorités de recherche pour les années à venir.

Les enjeux de la production de blé tendre en agriculture biologique

Le Courrier de l'Unesco

Analysis of necessary adjustements of farming practices