Are crop sequence evolutions influenced by farm territory dynamics?

Crop sequence can be defined as the temporal arrangement of crops and is influenced by four major types of constraint: the timing of agricultural operations, the minimum area of each crop, the minimum return period between the same crop, and the benefits or risks associated to preceding-following crop pairs (Castellazzi et al., 2008). Crop sequence is a key factor for assessing the environmental impact of farming systems (Leteinturier et al., 2006). Thus, analyzing the evolution of crop sequences and its drivers (e.g. European regulations or changes in farm size) is essential to understand farming system dynamics. The aim of this work was to analyze the link between farm territory dynamics and crop sequence evolutions. We specifically analyzed the evolutions of crops preceding winter wheat on cereal farms with contrasted dynamics of their territory (growth or stability of their Used Agricultural Area (UAA))

Characterization of crop rotations variability by combining modelling and local farm interviews

The characterization of actual crop rotations on a large territory is a major challenge for local stakeholders in order to understand agricultural impacts on natural resources, e.g., nitrate leaching (Beaudouin et al., 2005). Although various mathematical descriptions and simulations of crop rotations have been proposed (e.g., Castellazi et al., 2010), few models propose to reconstruct actual crop sequences and to simplify their diversity in a reasonable number of crop rotations. The aim of this work was thus to combine modelling and farm interviews to characterize crop rotations which were representative of different soil characteristics and farming systems over a whole agricultural area of 70,000 ha

Diversité des agricultures – le cas des filières céréales, oléagineux et légumineuses à graines

L’objectif de cet article est de décrire, sans être exhaustif, la diversité des agricultures en mobilisant des exemples au niveau du système technique et des pratiques culturales, pour la France métropolitaine et pour trois filières : les céréales, les oléagineux et les légumineuses à graines. L’analyse de la diversité des agricultures montre que des voies de diversification des systèmes techniques et des pratiques culturales existent, mais que celles-ci sont fortement dépendantes de la diversité des voies de valorisation dans les filières. Au sein de ces dispositifs de valorisation, hormis quelques dispositifs spécifiques, les recommandations sur les pratiques sont suffisamment vastes pour permettre une diversité de systèmes de culture et de production, dès lors que les critères technologiques d’accès à la filière sont atteints. Il convient alors de s’interroger sur le poids de ces critères technologiques sur les choix techniques des agriculteurs. Il apparait également nécessaire de questionner la valeur donnée à la diversité par les différents acteurs des filières, de l’agriculteur au consommateur, en évaluant notamment la performance économique des systèmes agricoles les plus diversifiés ainsi que les leviers pour augmenter les performances d’une agriculture diversifiée. Il s’agit d’élargir le socle de connaissances sur lequel les acteurs pourront concevoir eux-mêmes de nouvelles formes de diversité et d’ouvrir le débat avec les acteurs des filières sur la préservation des formes de diversité des agricultures comme potentiel de résilience

Utilisation d'un modèle de culture pour évaluer le comportement des génotypes: Pertinence de l'utilisation d'Azodyn pour analyser la variabilité du rendement et de la teneur en protéines du blé tendre

The change of crop management to less intensive systems requires to rapidly forecast the ability of each variety to valorise theses systems for various pedo-climatic conditions. The experiments, generally conducted in this aim, often give a partial response because, the range covered are limited comparatively to the agricultural conditions in wich these genotypes are able to be used, and too long in regard of the rapid change of varieties used by farmers. To accelerate this step of cultivar evaluation, it is possible to use new forecasting tools. The work presented here aims at studying the possibilities offered by the use of crop models to analyse and predict the production of different cultivars, in a large range of crop conditions, for existing or future genotypes. The questions raised focused on the necessary adaptation of these tools to give a good account of the genotype behaviour and we have proposed new tracks to evaluate the ability of such tools to choose the best variety adapted to particular conditions. The concepts and formalisms included in the crop models make them a priori relevant to evaluate and predict the variability of genotype behaviour, as the interactions between crop functioning and environment status are simulated. However, few studies aimed at developing methods for estimating genotypic parameters. And few of these studies evaluated the ability of various crop models adapted to cultivars to give a good account to their various production among environments. Based on the example of one crop model, Azodyn, simulating yield elaboration and grain protein content through the different processes of nitrogen absorption and remobilisation in the crop-soil system, we have proposed a method to identify and estimate the genotypic parameters of the model, and several criteria for the evaluation of this adapted model to give an account of the cultivar behaviour. In a first step, we identified, among all parameters of the model (around 80), those which varied among cultivars, from specific experiments, from the literature or the expertise. Thus we have identified that only three parameters and three inputs of the model which variations among genotypes were necessary to be taken into account to improve the predictive quality of the model. These genotypic characteristics act as behaviour markers and can be easily measured by the different variety users. These parameters have been estimated for fourteen genotypes, through a direct measurement on specific experiments. The influence of the parameters and input, identified as genotypic, on yield and grain protein content were quantified by a sensitivity analysis of the model. This study enabled us to propose a hierarchy between those six characteristics, which appeared variable among environments. This was then a good means to identify the adaptation factors of the varieties to the environments, which were mainly: the maximum grain weight, the precocity at the beginning of stem elongation and at flowering, and the ability to produce a high grain number. No parameters specific to nitrogen nutrition appeared as determinant in the model outputs. Then, we have evaluated the ability of the model to give a good account of the genotype production on 21 environments, varying through the nature and the intensity of limiting factors. We showed that, taking into account only the low number of genotypic parameters, it was possible to give a good account of the mean yield and grain protein content of each genotype, for a large range of environments. We also showed that the crop model used was a relevant tool to predict the genotype variability and the classification of the various genotypes for several crop conditions.L'évolution des pratiques agricoles vers des systèmes moins intensifs nécessite d'évaluer rapidement la capacité des nouvelles variétés à valoriser ces systèmes pour des conditions pédoclimatiques variées. Les expérimentations traditionnellement réalisées dans cet objectif offrent une réponse souvent partielle, car les gammes explorées sont limitées par rapport à celles rencontrées dans la pratique agricole, et trop lente par rapport au renouvellement rapide des variétés en blé tendre. Pour accélérer cette étape d'évaluation des variétés, il est possible de s'appuyer sur de nouveaux types d'outils prévisionnels. Le travail présenté ici a pour objectif d'étudier la possibilité d'utiliser un modèle de culture pour analyser et prévoir le comportement variétal, dans une gamme d'environnements variés, pour des variétés existantes ou à créer. Nous nous sommes interrogés sur les adaptations nécessaires de ces outils pour prendre en compte le comportement variétal et nous avons proposé des pistes d'évaluation de la capacité de tels outils à choisir la variété la mieux adaptée aux conditions du milieu considéré. Les concepts et formalismes développés dans les modèles de culture en font des outils a priori pertinents pour l'évaluation et la prédiction du comportement variétal, les interactions entre la culture et le milieu étant simulées. Cependant, peu d'études se sont attachées à proposer des méthodologies d'estimation des paramètres génotypiques et d'évaluation de la capacité des modèles ajustés à rendre compte du comportement variétal. A partir d'un exemple de modèle de culture, Azodyn, intégrant dans son formalisme l'élaboration du rendement et de la teneur en protéines des grains, ainsi que les différents processus d'absorption et de transfert d'azote dans le système Sol-Plante, nous avons proposé une méthodologie d'identification et d'ajustement des paramètres génotypiques des modèles de culture, ainsi que différents critères d'évaluation de la capacité de ces modèles à rendre compte du comportement variétal. Nous avons dans un premier temps identifié, parmi tous les paramètres du modèle, ceux qui variaient en fonction du génotype, à partir d'expérimentations spécifiques, des acquis de la littérature et des connaissances d'experts. Nous avons identifié trois paramètres et trois variables d'entrée du modèle, variables entre génotypes, et susceptibles de représenter des marqueurs du comportement facilement accessibles aux différents utilisateurs de variétés. Les paramètres du modèle ont été ajustés pour un ensemble de quatorze génotypes par mesure directe de la valeur du paramètre dans des expérimentations spécifiques. Les effets des différents paramètres et variables d'entrée génotypiques sur les variations de la teneur en protéines des grains et du rendement ont été estimés par une analyse de sensibilité du modèle. Cette approche nous a permis d'identifier les principaux facteurs d'adaptation des variétés aux environnements, à savoir le poids de mille grains, les précocités à montaison et à floraison, et la capacité à fabriquer un nombre de grains élevé. Aucun paramètre spécifique à la nutrition azotée n'est apparu comme déterminant des sorties. Nous avons ensuite évalué la capacité du modèle à rendre compte du comportement des différents génotypes expérimentés sur 21 environnements, variant par la nature et l'intensité de facteurs limitants du rendement. Nous avons montré que, sur la base de ce faible nombre de paramètres variétaux, il était possible de rendre compte des niveaux moyens de rendements et de teneurs en protéines des grains des différents génotypes, pour des environnements variés. Nous avons également montré que le modèle de culture était un outil pertinent de prédiction du comportement des génotypes, que l'on s'intéresse à la stabilité des différents génotypes ou à leur classement pour différentes conditions de culture

Comparisons of temporal changes in carabid communities inhabiting five different crops

Agricultural areas are currently expanding in the world. It resulted in the decline of biodiversity, affectingecosystem functioning and the provision of ecosystem services associated. To decrease the pressure ofagricultural activities, we should better manage the ecosystem services delivered by natural enemies, suchas carabids. Carabids are usually considered as providers of ecosystem functions, such as pest regulation.The objective of this study was to investigate the effect of five different crops (Wheat, Sugar beet, Oilseedrape, Pea and Barley) under non-inversion tillage on carabid communities’ dynamics during spring. Wequantified three diversity indices (abundance-activity, number of species and equitability index) and usedfunctional-trait based approach, the communities’ diet profiles, as an evaluation of the ecosystem servicesdelivered by carabid’s community. The study was conducted every year from 2009 to 2012 in 5 sites locatedin the Seine et Marne region. The carabid communities were recorded from 67 fields cropped with: oilseedrape (9 fields), winter wheat (27 fields), sugar beet (12 fields), spring barley (11 fields) and spring pea (8fields). Carabids were sampled using three replicate pitfall traps per field, each fulfilled with a saturated saltsolution containing a small amount of strong detergent as a preservative. The carabids were sampled oncetime every month during four months, from March to June. 33 621 individuals have been trapped in 4 yearsand 11 carabid species represented each at least 2% of the total abundance-activity. In all crop, totalabundance-activities significantly increased during the year as the number of species. Contrary to the indicesrelated to taxonomic diversity, the equitability indices did not significantly change during the year in allsampled crops. Crops were characterised by significantly different composition of carabid species in April,May and June but not in March. Concerning the diet profile, the expression of phytophagous significantlyincreased while the expression of zoophagous significantly decreased with time, whatever the cropconsidered. Despite great differences between crops, ecosystem services delivered by carabid’s communitychanged similarly during spring. According to the crop studied, agricultural practices were probably notexplaining changes in carabid communities and demonstrated strong influences of resources availability. Thelatter seemed to be the main cause of changes in diet characteristics of carabid communities. To maximiseecosystem services related to pest regulation, it seems necessary to better understand the influences ofresources used by carabid in order to control their diet expression

Estimation des paramètres génotypiques des modèles

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Genotypic variability of nitrogen remobilisation in wheat

*UMR d'Agronomie, Bibliothèque, 78850 Thiverval-Grignon Diffusion du document : UMR d'Agronomie, Bibliothèque, 78850 Thiverval-GrignonInternational audienc

Using the French LPIS database to highlight farm area dynamics: The case study of the Niort Plain

Decreases in the number of farms over the last decade have led to an increase in mean farm size and a fragmentation of the land on the remaining farms. These changes can influence the management of cropping systems by farmers, generally leading to a decrease in crop diversity at the landscape scale and a homogenization of agricultural practices between fields, to reduce logistic costs. At the landscape scale, these changes can modify agricultural pressure on natural resources (e.g. water, soil, biodiversity), by creating hotspots of fields subject to intensive management. Consequently, natural resource management, mostly at the local scale, requires new monitoring tools dedicated to local farm dynamics. This work aimed to characterize farm area dynamics between 2007 and 2013 on the Niort Plain, a sensitive area located in the South-West of France that is subject to water and biodiversity issues. Changes in farm area were characterized, taking into account not only farm size, but also the spatial distribution of the islets included in the land pattern. The LPIS database, which provides quasi-continuous broad coverage of the French agricultural areas, was used to analyze changes in farm area, through characterization of the annual changes in farm area and their effects in terms of land fragmentation and farm size distribution. Six types of farm area dynamics were characterized: the enlargement of farms with and without a reconfiguration of the land use pattern, a decrease in the utilized agricultural area (UAA) of farms with and without a reconfiguration of the land use pattern, and a stable UAA with and without reconfiguration of the land use pattern. We found that 5.5% of the farms were either split into smaller units or stopped seeking CAP subsidies during the period considered. Two patterns predominated: a stable farm area and enlargement of the farm area. Farms of many different initial sizes displayed enlargement, generally through the acquisition of islets from another farm that was split up. Farm dynamics had a limited impact on the fragmentation of farm land. Farm enlargement led to a slight increase in the dispersion of islets from the farm center.The procedure developed here for the characterization of farm area dynamics is particularly suitable for application at the temporal scales used by planners working on environmental programs. By monitoring farm area dynamics, planners could also set specific devices to enable them to focus either on the total number of farms or exclusively on a subset of farms of strategic importance for the management of natural resources due to their area dynamics, location or aggregation in the environment

Caractérisation spatialement explicite des systèmes de culture sur les zones de captage à partir d’informations hétérogènes: Rapport de synthèse projet PACS-AAC

Rapport confidentielCaractérisation spatialement explicite des systèmes de culture sur les zones de captage à partir d’informations hétérogènes. Rapport de synthèse projet PACS-AA

Analysis of differences in N absorption due to wheat genotypes to adapt N fertilisation

*UMR Agronomie, Bibliothèque, 78850 Thiverval-Grignon Diffusion du document : UMR Agronomie, Bibliothèque, 78850 Thiverval-GrignonNational audienc