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International audience; In context of global challenges facing agriculture, our article addresses the extent to which the synergistic nature of agroecological innovations may reconcile environmental and technical efficiency of farms. We develop an empirical model, namely conditional efficiency framework, which explicitly accounts for context-dependent drivers like synergy and complementarity of innovations. Using a sample of 567 banana farms in the French West Indies, our estimates confirm the complementarity effect since the joint adoption of agroecological innovations increases the technical efficiency scores much more than other drivers and each of the innovations taken in isolation. We also show that advice and extension services as well as human capital variables are key adoption levers for public policy since they reduce the variability of production and thus the risk associated with the joint adoption of the agroecological innovations.

International audience; Soil organic carbon stocks have been declining for more than a century, mostly in the tropics. Maintaining soil organic matter is critical to tackling climate change and controlling soil health. One way to address this problem is to encourage farmers to improve soil carbon on their farms. We provide an ex-ante assessment of the cost-effectiveness of innovative Agri-Environmental Measures (AEM) that subsidize the use of compost. To do so, we ran a choice experiment in Guadeloupe, in the northeastern Caribbean, where there is an urgent need to preserve soil organic matter levels. The 305 farmers who participated were asked to choose one of several AEM that offer financial support in exchange for using compost in their farming activities, as well as free technical assistance, a collective financial bonus, and the possibility of combining chemical fertilisers with composts. We found that offering free technical assistance increases the participation rate by 30 percentage points and offering a collective bonus increases it by 14 percentage points. In contrast, including a requirement on the reduction of chemical fertilization would decrease the probability of participation by only two percentage points. We then estimated the amount of carbon that would be sequestered in the soil using compost as prescribed under each of the AEM proposed. We found that the most effective AEM would sequester up to 25,000 teqCO2 per year at the territory level and that the most cost-effective scheme would reach this target at a cost of about 500 euros per teqCO2. Finally, we find that the so-called 4 per 1000 target could be reached through AEM under a variety of scenarios..

International audience; Biomass is a potential source of renewable energy that can be produced in agricultural fields. However, its introduction at regional scale should not only provide energy, but also economic, social and environmental benefits. In order to study the potential benefit of introducing energy cane cropping systems for electricity production, we developed 62 scenarios for energy cane-based biomass power plants, for which impacts were modeled with a regional bioeconomic model. Impacts were calculated and aggregated with weights on 14 issues obtained from 51 stakeholders using an analytic hierarchy process. Regression models were applied to explain the determinant of sustainability. The results showed that stakeholder preferences for local development priorities fell into four different types, while the impacts of the scenarios also differed greatly according to their attributes. The main issues appeared to be "Disruption of existing agricultural sectors", "Potential loss of biodiversity" and "Change in farmers' revenue". The factor "Output of power plant" was positively correlated with the level of contribution to local development and to "Quantity of bagasse" and "Sustainable management of energy cane". Developing energy cane biomass appears therefore to be potentially beneficial for local development, with options favoring power plants relying on different forms of biomass produced in the vicinity and managed in a sustainable way. The novel approach devised here helped to address the complex multi-dimensional development issues regarding production of biomass and to provide satisfactory compromise solutions for different stakeholders. It can also provide guidance on exploration of options to obtain the most sustainable scenario.

International audience; Bioeconomic models make it possible to assess ex-ante the consequences of public interventions in the agriculture sector. Yet since policymakers rarely participate in their design or use, these models are often too complex or do not address their questions. This article describes the implementation of a nine-step participatory modelling process involving regional policymakers, and analyses the contribution of this process to the cross-brainstorming between policymakers and researchers. In the preliminary stage, researchers develop a prototype bioeconomic model which links the farm level, where trade-offs between productions are considered, with the regional level, where the balance between production and consumption per product is considered. Public actors are then mobilised to identify issues and characterise the scenarios that can be used to explore the questions selected. The scenarios are simulated with the bioeconomic model, which evolves depending on the needs, and the outputs are discussed with the public actors. The method was applied in La Réunion (France) on the design and assessment of aid mechanisms related to the development of organic farming. The results showed (i) which farms convert to organic farming according to aid amounts, (ii) how local demand per product is satisfied and (iii) what are the amounts of the ensuing budgets for subsidies. The approach proved to be relevant for exchanging knowledge between public actors and researchers, regarding in particular innovative farming systems, farm diversity and multi-criteria evaluation of policy choices. The simulated scenarios offered powerful support for discussions about market evolutions and environmental challenges. These results indicate that transparent modelling tools and long-term partnerships with policymakers are required to implement such an approach at the regional scale.

Context In a region already plagued by food insecurity and challenges to the sustainability of the agricultural sector, the COVID-19 pandemic was a brutal shock in the Caribbean with immediate and significant socio-economic consequences. Objective In this paper, we assessed what are the immediate impacts of the COVID-19 crisis on the agricultural and food systems of the Caribbean. Methods To this end, we conducted online surveys among farmers, households and experts of the region. We assessed the nature, strength and reversibility of the impacts but also the factors of resilience in the face of the crisis. Results and conclusions Our study shows that the COVID-19 crisis has had strong impacts on Caribbean farmers and has weakened agricultural systems. The main impacts identified were a drop in income, production losses due to difficulties in marketing through conventional channels, but also difficulties in managing the farming systems due to reduced access to inputs and labor. In order to cope, farmers have adapted to be more self-sufficient: reduction in the size of cultivated areas, search for short marketing channels, diversification of production and reorientation towards the needs of the local market, recourse to mutual aid between farmers. If these effects appear to be non-irreversible in an island like Guadeloupe, the situation is different in other islands of the region where farmers have had to sell livestock, seek new off-farm income and sometimes sell land to cope. In terms of impacts on food systems, the crisis has led to strong constraints such as a reduction in food intake and diversity and increased reliance on family and social mutual aid. Our study also shows that the crisis has had an impact on consumer behavior and their perception of the importance of the agricultural sector: reduction of food waste, return to fresh and local products, adaptation of the diet, consumption of new products, and cultivation of food gardens. Finally, our study shows that the crisis has had an effect of strengthening the links between farmers and the rest of the population. Significance Thus if the crisis has had seriously damaging consequences, it can also be the trigger and catalyst for an agro-ecological transition and the development of a circular and territorialized bio-economy to strengthen the resilience of Caribbean agricultural and food systems and facilitate the achievement of sustainability and food security objectives.

In this article, we provide an ex-ante assessment of the cost-effectiveness of a series of innovative Agri-EnvironmentalMeasures (AEM) that subsidize the use of compost. To do so, we ran a choice experiment in the western islands of French Polynesia where the soil organic carbon content is extremely low. The 305 farmers who participated were asked to choose one of several AEM that offer financial support in exchange for using compost in their farming activities, aswell as free technical assistance, a collective financial bonus, and the possibility of combining chemical fertilizers with composts. We found that offering free technical assistance increases the participation rate by 30 percentage points and offering a collective bonus increases it by 14 percentage points. In contrast, including a requirement on the reduction of chemical fertilization would decrease the probability of participation by only two percentage points. We then estimated the amount of carbon that would be sequestered in the soil using compost as prescribed under each of the AEM proposed. We found that the most effective AES would sequester up to 25,000 teqCO2 per ha and per year and that the most cost-effective scheme would reach this target at a cost of about 500 euros per teqCO2. Finally, we find that the so-called 4 per 1000 target could be easily reached through most cost-effective measures even if only half of the farms were enrolled in the program.

International audience; The assessment of agriculture at a regional scale is necessary to better guide regional agricultural planning. To improve the contribution of agriculture to sustainable regional development, assessments must take account of the locations and diversity of cropping systems. We have therefore developed a method based on a set of multi-scale indicators to assess the contribution of agriculture to the sustainable development of regions, and its evolution over time. This method can identify: i) sustainability issues, ii) relevant indicators that will provide information on impacts at the field scale, iii) a method to aggregate indicators, iv) data on cropping systems, and v) a database containing spatial units to analyse the whole region. Application of this method to Guadeloupe (2004-2010) enabled the definition of ten issues and 16 indicators, with three procedures to aggregate information from 36 cropping systems allocated to 11,908 fields between 2004 and 2010. Economic, social and environmental sustainability was poor in 2004, with high dependency on subsidies (47.3 M€.yr-1), low agricultural added value (48.5 M€.yr-1), low employment (only 1799 2 workers), significant risks of crop contamination and pressure on water quality. The total value of subsidies and the risks of river pollution tended to decrease between 2004 and 2010 because of a reduction in intensive banana cropping systems. In parallel, we were able to see that sugar cane, the most widespread crop in Guadeloupe, made only a small contribution to employment and food self-sufficiency during the studied period. The spatial representation revealed that improvements have been seen in southern Guadeloupe due to reductions in banana cultivation. This method was therefore helpful in identifying the most critical agricultural development issues and helping to highlight areas where relevant agricultural land use policies could be formulated.

International audience; Disease perception and adequate management practices are two essential issues faced by farmers, especially in the current context of climate change which may potentially increase disease risk. We investigated the diversity of water yam cropping systems in Guadeloupe through interviews, how producers and international yam research scientists perceived anthracnose, and how this perception correlated with farmers’ risk management strategies. We found that disease perception by farmers is very close to perception by international yam experts, as both have the same perception of the hierarchy of factors translating into disease. Three different yam production strategies coexist at a local scale, where agronomic practices and socio-economic profiles are distinct and consistent with attitude toward anthracnose risk management. Six factors were perceived as decreasing the disease: associated crop species; crop rotation; staking; weeding; crop monitoring and varietal admixture. Yam producers raising crops more intensively were risk prone, while others usually sought practices to manage disease appearance and spread. Both cumulative risk and past anthracnose epidemic experiences translated into heavier reliance on chemicals. These results have practical implications for designing best yam crop management systems and control of yam anthracnose.

online en avril 2016; International audience; In West and Central Africa and in the Caribbean, yam is one of the most important sources of carbohydrates and has a great potential to improve food security. The yam production sector is, however, now challenged by the satisfaction of evolving consumers' preferences. Since little is known about consumers' preferences regarding yams' characteristics, product quality, and the drivers of yam purchase, six focus group discussions were conducted (for a total of 31 participants). Among the purchasing criteria, price was considered more important than the others. It was followed by the external damage, the origin, and the size of the tuber. The most frequently cited consumption criteria were the taste, the texture, and color of flesh after cooking. Taste was considered more important than the other criteria. Three consumers' profiles were established reflecting heterogeneity in preferences, especially as concerns the willingness to pay for yam and consumption habits. They were designated as the Hedonistic, the Thrifty and the Flexible. Our results suggest that innovations can be implemented to sustain and stimulate the development of the yam sector in Guadeloupe. Two main development paths were identified. The first path is the valorization of the great existing diversity of yam varieties and the increase in the level of information for consumers about product attributes such as the cooking mode, the origin, and the mode of production. Building a marketing strategy based on the valorization of this diversity can help maintain and preserve yam's agro-biodiversity and the satisfaction of rapidly evolving consumption habits. The second path is the definition of yam ideotypes that suit consumers' needs. We expect that tailoring the production to consumers' needs will have a positive impact on global food security in the Caribbean region.

International audience; Biomass is a promising renewable alternative to decarbonize and to secure energy production on small islands, as most insular power generation systems rely heavily on imported fossil fuels. Feedstock procurement is a key aspect of bioenergy chain sustainability, and local resources as well as imported biomass can be considered if the electricity generated presents environmental benefits. We used Life Cycle Assessment (LCA) to evaluate the environmental impacts of 1 kWh of electricity produced in Guadeloupe from the combustion of locally grown energy cane and imported wood pellets. The energy cane agricultural supply was simulated using a bio-economic model to elaborate and analyze five scenarios involving different biomass mixes and geographical areas of production. Our results show that electricity produced from energy cane reduced the impacts of ABIOTIC DEPLETION, ACIDIFICATION and PHOTOCHEMICAL OXIDATION by 29% compared with pellet-based electricity. The environmental impacts of the energy cane cultivation stage varied by a factor of 1.5-3.7 among regional areas of cultivation because of differences in yields, soil emissions and land conversion for energy crop farming. The substitution of 5% of fossil energy by biomass in the island electricity mix can reduce GLOBAL WARMING and ABIOTIC DEPLETION impact by 4.5%. However, this change requires 3.5 to 5.2 times higher LAND OCCUPATION per unit of energy produced. Given the limited land availability on small islands, this latter point confirms that the combination of locally grown energy crops with imported biomass will be a suitable strategy to develop sustainable bioenergy for small islands.

Although the use of composts is considered as an option for recycling organic wastes and replacing chemical fertilizers in Caribbean agriculture, little is known about the factors that might encourage farmers to adopt this practice. The aim of this study was to identify the determinants of compost adoption in French West Indies, considering both commercial and on-farm produced composts. A survey including 520 farmers covering a broad range of agro-ecological regions and cropping systems was performed to characterize current uses of compost and the perception of constraints by farmers. Fourteen biophysical and socio-economic variables were included in a logit regression model to explain compost adoption. The adoption rate was 18%, which is relatively low because it was not limited by compost availability. Most adopters declared that they apply composts as an organic amendment and to replace chemical fertilizers to reduce pollution risks. Nearly 60% of adopters apply composts manually and 80% use commercial products. The labour intensity of manual application, the cost of the practice and the lack of information about compost quality were the principal constraints highlighted by no adopter farmers. Compost adoption varied with the cropping system and farmer characteristics. The adoption rate was 40% for banana planters (used as organic fertilizer) and only 3% for sugarcane planters. The experience of farmers and their level of education had a positive effect on adoption, whereas farmer age and a lack of professional organisation affected it negatively. Several levers need to be combined to increase both the adoption rate and the specific rate in sugarcane, which represents one third of the agriculture land. This includes subsidies so that peasant associations can purchase spreaders adapted to different cropping systems, and the development of efficient knowledge dissemination channels.

UMR SYSTEM : équipe AMPLUS; To improve agriculture faced with regional sustainability issues, agricultural landscapes providing a diversity and high level of ecosystem services are necessary. We have developed and tested the MOSAICA-f framework to build innovative multi-functional agricultural landscapes that can consider explicitly: 1) the performance of cropping systems at the field scale, 2) farmers' decision processes on the adoption of cropping systems, and 3) possible scenarios for innovations and policy changes at the regional scale. This framework is based on a scenario approach that encompasses normative, exploratory and optimized scenarios to assess the relevance of combinations of new agricultural policies, changes to the external context (market and regulations) and innovations in cropping systems. The impacts of these changes on sustainability issues are simulated using the regional bioeconomic model MOSAICA for farmers' decision processes regarding the adoption of cropping systems at the field scale throughout a region. Applied in Guadeloupe (French West Indies), the MOSAICA-f framework enabled the design of a scenario increasing agricultural added value, food and energy self-sufficiency, employment and the quality of water bodies and reducing greenhouse gas emissions. This sustainable scenario combines new cropping systems tuned to farm types with a reorientation of subsidies, an increased workforce and banning food crop production on polluted soils. It can be used to understand the potential contribution of agriculture to sustainability issues and to help local decision makers define policies that will account for the spatial diversities of farms and fields in a landscape. Beyond the design of such a win-win scenario, MOSAICA-f has revealed trade-offs in the provision of services by agriculture.

Loss of varietal diversity is a worldwide challenge to crop species at risk for genetic erosion, while the loss of biological resources may hinder future breeding objectives. Loss of varieties has been mostly investigated in traditional agricultural systems where variety numbers are dramatically high, or for most economically important crop species for which comparison between pre-intensive and modern agriculture was possible. Varietal dynamics, i.e., turnover, or gains and losses of varieties by farmers, is nevertheless more rarely studied and while we currently have good estimates of genetic or varietal diversity for most crop species, we have less information as to how on farm agro-diversity changes and what cause its dynamics. We therefore investigated varietal dynamics in the agricultural yam system in the Caribbean island of Guadeloupe. We interviewed producers about varieties they cultivated in the past compared to their current varieties, in addition to characterizing yam cropping characteristics and both farm level and producers socio-economic features. We then used regression tree analyses to investigate the components of yam agro-diversity, varietal dynamics and impact of anthracnose on varieties. Our data demonstrated that no dramatic loss of varieties occurred within the last decades. Cultivation changes mostly affected widespread cultivars while frequency of uncommon varieties stayed relatively stable. Varietal dynamics nevertheless followed sub-regional patterns, and socio-economic influences such as producer age or farm crop diversity. Recurrent anthracnose epidemics since the 1970s did not alter varietal dynamics strongly, but sometimes translated into transition from Dioscorea alata to less susceptible species or into a decrease of yam cultivation. Factors affecting changes in agro-diversity were not relating to agronomy in our study, and surprisingly there were different processes delineating short term from long term varietal dynamics, independently of disease risk. Our results highlighted the importance of understanding varietal dynamics, an often overlooked component of agriculture sustainability, in addition to evolutionary forces shaping agro-diversity and genetic diversity distribution within crops. It is also crucial to understand how processes involved do scale up worldwide and for different crop species, so as not to mislead on-farm conservation efforts and efficacy of agro-diversity preservation.

International audience; In French West Indies, the high dependency of the electricity mix on imported fossil fuels has led local authorities to propose the conversion of some land to the production of energy cane. This conversion mainly concerns land polluted by the pesticide chlordecone, where most crops for human consumption have been banned. This molecule has a strong affinity for soil organic matter (SOM). The aims of this study were to assess the impact of crop residue management and compost application on the stocks of SOM and chlordecone in soils cultivated with energy cane and to determine the minimum SOM input required to maintain SOM stocks. A field experiment was conducted to determine the yield and biomass partitioning of energy cane, and laboratory incubations were performed to estimate humification from crop residues. Changes in SOM and chlordecone stocks over a 30-year period were investigated using models already calibrated for the land under study. Non-harvestable biomass left on the field (tops, litterfall and roots) covered >60 % of SOM mineralization. A full offset of mineralization required the return of 10 % of harvestable biomass or the application of compost at a rate of 40 Mg ha−1 every 5 years. With the total removal of harvestable biomass and without compost applications, SOM and chlordecone losses increased by 23 and 13 %, respectively, which was associated with high SOM mineralization and chlordecone leaching under tropical climate. The estimated break-even price for cane biomass indicated that compost application would be more profitable for farmers than the return of a part of the harvestable biomass.

As one of the largest users of pesticides in the world, banana production is responsible for numerous types of pollution affecting water, soil and air and causing a variety of health issues. Agroecological innovations can help to reduce pesticide use and achieve cleaner and more sustainable banana production systems. Innovations must be well suited to the diversity of banana farms and acceptable to the stakeholders involved in production. We tested the impact of 18 agroecological innovations in Guadeloupe on the sustainability of three contrasted production systems, using the multi-criteria assessment model MASC. These innovations included different types of fallow (A), bans on pesticides (B), conditional applications of pesticides (C), intercropping (D), resistant cultivars (E), and integrated systems (F). In the assessment, we introduced the views of 29 stakeholders involved in sustainability issues relative to banana grouped through three sets of weightings, obtained by direct weighting of the indicators used in a multi-criteria assessment tool. We analysed the effects of each set of weightings on the sustainability level for these different banana production systems. Our results showed that the adoption of innovations can have negative, positive or no effects on the overall sustainability of banana production systems. Although none of the innovations had a positive effect on all cropping systems, some innovations were relevant to several farm types. However, this depended on the sets of weightings considered, because we found several types of stakeholder with opposing views on the importance of sustainability components. Integrated and organic systems produced the best results in terms of increasing sustainability and were relevant to current farming systems. However, in order to obtain cleaner banana production at the landscape scale, a combination of these innovations, tailored to the diversity of farmers' situations and stakeholder preferences, still needs to be proposed.

Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699; This paper proposes an ex ante evaluation of the willingness to adopt agro-ecological innovations aimed at reducing pesticide use for banana production in the French West Indies. Four innovative systems, including intercropping, improved fallow and new pest-tolerant varieties, are proposed to a sample of 607 planters, with innovation and policy attributes calibrated from a bio-economic farm model. The model interacts technological and economic innovation attributes with farmer individual factors, and allows for a dual source of unobserved heterogeneity. We estimate a system of random coefficient Logit models, to obtain marginal values of innovation traits that can be useful for targeting farm types with appropriate innovations and designing policies for securing agricultural revenue.

International audience; Farmers are inundated with advertisements about many innovations that are supposed to increase their yields or reduce environmental impact. However, the benefit of these innovations depends on the farming context. Here we present the ad hoc adaptation of the crop model SIMBA and a method to evaluate 16 innovations in six types of farms previously selected through a typology of the banana farming systems in Guadeloupe. The innovations include regulation of pesticide use, rotations and fallows, intercropping, conditional application of pesticides, resistant cultivars, and integrated systems. Our results show that, for a given innovation, the yield and pesticide reduction vary widely with different farm types. We show that environmentally friendly innovations often cause a greater decrease in yield in more productive farm types. Nevertheless, despite an apparent trade-off between yield and pesticide use, some innovations address both production and environmental issues, e.g., rotation with fallows improved with cover crops, regular fallows, and rotations with pineapples for the most intensive farm types. Our modelling study confirms the importance of innovation-farm type interactions and the usefulness of models for assessing large numbers of technological innovations among a wide range of biophysical and technical contexts.

International audience; AbstractAgroecosystems represent 38 % of global land use. Agroecosystems are located close to human settlements and are managed to produce food and fibers, traded in markets. Agroecosystems also produce other goods and services essential to human beings, such as climate regulation, flood mitigation, and landscape amenity. Economists and ecologists have developed the ecosystem services framework to foster the provision of these non-commercial services. Scientists can therefore help decision makers to develop sustainable ecosystems by studying ecosystem services. Here, we analyze the trade-offs of ecosystem services of farming systems. We discuss case studies of mixed perennial crops. The set of ecosystem services provided by these agroecosystems depends on their composition, structure, and management. Complex rule-based management will be required if winegrowers are to maintain an adequate set of ecosystem services across contrasting climatic years. Innovations including cover crops in banana systems can fulfill most of the objective set but will rely on increased farm labor. We then discuss the advantages, challenges, and opportunities to include the description of relations between ecosystem services in cropping system design. We propose to extend the yield gap analysis to ecosystem services, as a service gap analysis. This extension faces methodological questions about the potential provision of a service in a region. We conclude on the challenges that need to be faced if we want to use ecosystem services trade-offs to improve the contribution of agricultural systems to human well-being.

International audience; To understand the effects of policy changes on organisations and compositions of cropping systems at regional scale and their contribution to the sustainable development of regions, we built a regional, spatially explicit, multi-scale, bioeconomic model called MOSAICA. This model explicitly incorporates information at field, farm, sub-regional and regional scale to provide cropping system mosaics by way of regional optimisation of the sum of individual farmer's utilities under field, farm and territory biophysical and socio-economic constraints. Its generic structure means it can be used in different regions with geographic information on the location of the field and farm, data on cropping system performance, on location factors and on policy schemes. We used the model in Guadeloupe to test the impact of three scenarios of change on the agricultural subsidy regimes. The model produced three cropping system mosaics which reduced the area under banana and sugarcane, turned specialized banana and sugarcane farming systems into breeding systems while improving the overall contribution of agriculture to sustainable development. The spatially explicit results of changes in ecosystem services, and in farming systems with MOSAICA make it an appropriate decision-aid tool for regional planning.

International audience; Ensuring the success of agriculture is at the heart of food security, and it is necessary to examine strategies that tackle agricultural development through the production and consumption of sustainable food products. One way to increase food security in small island states is to develop local food sectors by increasing consumers’ awareness about local products with sustainable characteristics. We designed an economic experiment to assess consumers’ willingness-to-pay (WTP) for yams with sustainable characteristics: the origin, the intrinsic quality of an alternative variety and the mode of production. The results showed that labelling significantly changes consumers’ valuation of the different yam profiles. Consumers’ WTP for local yams (2.85 € kg-1) was significantly higher than for imported yams (1.80 € kg-1), while the organic mode of production derives a significant premium if information on production methods has been disseminated. The results also suggested that organoleptic characteristics of new varieties should not be overlooked. We conclude on how the labelling strategy could be facilitated through a policy targeting the development of the local food sector.

Agri-environmental schemes (AESs) are the main public policy instrument used in Europe to encourage farmers to adopt environmentally-friendly farming practises. Some AESs designed in French West Indies to replace N fertilizers with composts to reduce nitrate pollution and enhance C sequestration have been unsuccessful because few farmers adopted them despite the subsidies offered for the provision of environmental benefits. To explain this low adoption rate, we assessed the agri-environmental and economic impacts of two AESs and compare them with the most widely-applied strategy based on inorganic N fertilizer (NFER), and with an organic strategy based on sewage sludge (SLUD), a free organic amendment. The first AES was proposed in 2007 (AESold) and only concerned with the use of composts. The second was proposed in 2014 (AESnew) and combines the use of composts and inorganic N fertilizer at a rate 25% lower than NFER. The study was applied to water yam using a crop model to obtain agri-environmental indicators over a period of ten years, which were then used to calculate economic outputs for small and large farms. Although AESold increased C sequestration by 300% and reduced nitrate leaching by 80% compared to NFER, it also reduced yields (13%) and net income for farmers (30%). The subsidy offered by AESold did not compensate the loss of productivity, which explains its low rate of adoption. AESnew and SLUD increased C sequestration (350% and 400%) and reduced nitrate leaching (45% and 34%), and maintained yields and net income after five years of implementation. Yields and net income during the first five years were 5–10% lower than under NFER. Although the land area concerned by SLUD is limited because of regulatory constraints, AESnew could be a satisfactory policy instrument in French West Indies because it promotes environmental benefits and maintains economic income in the medium term for smallholder using family labour. The economic performance of AESs was lower for large farms; the adoption rate could be improved for these farmers through the implementation of mechanization to reduce labour costs. For both farm types, it may be necessary to increase subsidies during the first five years to offset yield losses during this period and the fixed and transition costs attached to adoption.

International audience; Agriculture provides many ecosystem services such as food, fiber, clean water, and sequestration of carbon. The efficiency of such ecosystem services depends on crop composition and farmer decisions. Current knowledge on landscape changes is focused on crop allocation process at farm scale and rotations at field scale, whereas the impact of farmer decisions on the choice of crop acreages is poorly known. Therefore, we have built a method to assess the evolution of farm crop acreages in time and space and to identify factors ruling agricultural landscape changes. We use a dynamic typology, which is a multi-year classification of farmers. The seven steps of the method include three steps on farm typology, three steps on landscape changes, and then one step on change factors. We applied the method on 3,591 farms in Guadeloupe. Eight farm types were distinguished according to crop acreages. Our results show evidence of a diversification of 111 sugarcane growers toward production of vegetables and fruits. Spatial analysis revealed a relationship between diversification and water availability. Our method could be used to measure ecosystem services or disservices associated with changes in agricultural landscapes.

Nowadays, consumers are more and more concerned about the traceability of the food they purchase. As a response to this phenomenon, labels have flourished highlighting the environmental impact of products for some, their nutritive characteristics or their origin for others. In this context, we wonder about how food production sectors can meet the consumers’ demand and about the role of labeling as a tool to foster the sustainable development of food sectors. We base our analysis on the case of the yam sector in Guadeloupe. Food sectors in the tropics face heavy constraints (Scott, Rosegrant et al. 2000; Charlery de la Masselière 2002). Yam is the first food crop in Guadeloupe both in area (450 ha) and production (6 300 t). It covers 78% of the needs of the territory (Agreste 2009; Chambre Agriculture 2010). Nevertheless, the decrease by half of its cultivated area during the last decade reveals that it is on the decline (Agreste 2009). During this period of time, the production and consumption of yam has been highly impacted by the discovery of a long-lasting pollution of soils by chlordecone, a pesticide that was previously used in banana fields. Today, by decree, farmers who want to grow yam in the contaminated perimeter have to get their production analyzed before selling it on the marketplace. Guadeloupian consumers are quite suspicious regarding the presence of pesticides in local food but still yam is still part of the diet of the population (Merlo, 2007). Given the above we wondered about consumers’ perception of local yam if they could be reassured regarding the absence of pesticides in yam tubers. We also investigate the interest and implication of certification for yam farmers. Our work aims to shed light on how farmers and consumers can interact to design a sustainable food production sector. We look at both the supply and demand side and discuss about the ways to connect both views in a labeling scheme. According to the existing literature about farmers’ decision making (Cerf and Sébillotte 1988; Duru, Papy et al. 1988; Sébillotte and Soler 1988; Bonneval 1993; Marshall, Bonneviale et al. 1994), we studied farmers’ productive and commercial strategies regarding yam and accordingly built a typology of the different farming systems that exist in Guadeloupe. We then looked for each type at the costs and returns of growing yam – using the economic results simulation tool of yam crop: Ignamarge© - and examined the economic implications of certification. Our analysis revealed the existence of six types of yam producing farms for commercial purposes. For some types, yam appears to be the most important crop and is mostly sold in direct sale therefore procuring the highest returns to the farmers. For some others, it is only part a diversification crop among others and is traded via a farmers’ cooperative or thanks to intermediaries. In those last schemes, the value is shared among the different actors along the food chain. Getting certified could match with some of the strategies developed by farmers but would imply them to change some of their production and commercial practices. Additionally certification would require the yam sector to increase its organizational capacity since farmers’ strategies are rather individual at present. On the other hand we set up a laboratory experiment to investigate whether consumers were willing to pay a premium for two different types of labels since Levitt and List (2007) showed that laboratory behavior is a good indicator of behavior in the field. We based our experiment on the protocol developed by Lange et al. (2002) and adopted by Bougherara and Combris (2009). The experimental method makes it feasible to estimate consumers’ valuation of specific characteristics by controlling precisely the information on products. Therefore it is possible to compare consumers’ willingness-to-pay for a little variation in characteristics of otherwise identical products. This comparison allows appraising the substitution relation among two characteristics. To achieve this goal, we used the BDM procedure (Beker, De Groot, Marshak, 1964) to elicit the willingness-to-pay for locally produced yams (outside of the contaminated perimeter) and organically grown yams. Consumers were recruited according to a set of criteria such as their yam consumption habits, getting involved in food purchasing at home and not being regular participants of marketing studies. Then we estimated tobit models of the participants’ willingness to pay, one for each profile. Results showed a significant change of the participants’ WTP when yams were labeled (figure 1) and that they were ready to pay a premium for locally produced yam and organically grown yam. Considering the above we discuss the consequences of labeling for farmers and consumers and how the strategies of those different actors can coincide. Our work raises the question of the type of policy instruments that need to be implemented to ensure that certification schemes help food sectors to guaranty quality and achieve sustainability.

International audience; Agricultural research can support farmers and policy makers’decisions by identifying the causes of spatial variability in crop yield at a regional level. In this paper, we propose a method that combines spatial autocorrelation measures and a farm network survey. This method is intended to describe the causes of spatial variability in crop yields, along with key crop management practices for reaching the best yields and the physical and socio-economic constraints of adopting these practices. This causal and hierarchical analysis of cropping system performance has the advantage of (1) preventing bias in the correlation between variables from the yield gap analysis and (2) formulating spatially targeted policies that are aimed at relaxing adoption constraints at the territorial level. After introducing the method and its different steps, we present the results of the assessment of the spatial variability in banana yields in Martinique (Caribbean). Our study has clearly shown that the planting stage is one of the most important aspects of banana production: allowing a long fallow period, plowing for soil preparation and using seedlings that are produced by tissue culture were associated with the best yields. However, several constraints limit their adoption by farmers at the regional level. The limiting factors were steep slopes, small farm size and low cash flow. We observed no relationship between pesticide use and yields. These study results finally permit the elaboration of spatially targeted policy recommendations to improve crop yields in a sustainable manner. It mainly consists in promoting and facilitating the adoption of good plantation practices for smallholders.

International audience

National audience; Agro-ecological innovations are needed to reduce the impacts of current intensive agricultural practices on biodiversity and ecosystems. Whereas many published studies focus on the biophysical impacts of such innovations at field level, few attention has been given to the analysis of the potential of adoption of these innovations at farm and regional levels. In order to reduce the gap between on station and in silico innovation and farmer’s adoption process, we developped an interdisciplinary method based on the combination of simulations models and on farm surveys to assess ex ante the potential of adoption of agro-ecological innovations by farmers.

Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699; International audience; The ex ante assessment of innovative agro-ecological innovations is a key step in the development of more sustainable crop management systems. To this end, models are useful tools because they make it possible to rapidly assess numerous innovations in different contexts. Whereas many farm optimisation models focusing on the farmer’s strategic decision to adopt new crop management systems have been published, little attention has been given to the ex ante modelling of the dynamic operational impacts of innovation adoption at the farm level. BANAD, a mechanistic model for such applications,is proposed. It allows the ex ante assessment of innovative management systems including new agroecological techniques, while taking into account different farming contexts and policy and market conditions. It includes three components: (i) a crop management system model, (ii) a crop model (SIMBA) and (iii) a farming system model. Our results applied to the ex ante assessment of six innovative banana management systems for three contrasted farm types in Guadeloupe showed that the impacts of agroecological innovations, which include rotations, improved fallow, intercropping, pest-resistant cultivar, and an integrated organic system, can vary considerably according to (i) the farm type in which the innovation is integrated, (ii) the nature of the agro-ecological innovations, and (iii) the criteria considered and the temporal horizon of the assessment. Innovative intercropping systems that were effective at the field level in terms of the yield improvement and decreased pesticide use could be problematic at the farm level because they increased the workload and decreased income. The adoption of rotations or improved fallow seemed to be relevant for smallholders but could induce a critical period of 1.5–2.5 years during which income decreased drastically. Under certain conditions of markets and subsidies, very environmentally friendly innovations that are less productive can however be economically effective.

International audience

Chantier qualité GA Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699; International audience; Banana is the second most important agricultural commodity in Guadeloupe (French West Indies—FWI) and, to compensate the decline in international prices during the last 15 years, banana growers have intensified their production systems by increasing the use of technological inputs. Such intensification strategies, that require both material and investment increases, may impose economic as well as environmental risks, given the fragile island ecosystems. In order to assess the environmental performance of banana production in Guadeloupe, emergy synthesis methods were applied to six different types of banana cropping systems previously identified in the island. Additionally, aiming at improving managerial capacity and investment decision making, environmental performance results were contrasted with economic analysis for the six cropping systems. As a general outcome, these analyses showed that the better the environmental performance of the cropping system, the worse its economic performance. This result was corroborated by an increased contrast among cropping systems as related to their dependence on purchased inputs, although all cropping systems followed the same intensive and arguably wasteful agricultural model. Therefore, the analyses point out that sustainable banana production in Guadeloupe depends on a shift from the high fossil input model to a natural resources intensive one. In this sense, emergy flow analysis shows that innovation towards environmentally sound practices that would enhance nutrient cycling; integrate weeds, pests and diseases control; and improve the banana packing process might result in most positive impacts on overall sustainability. Economic analysis showed that the high labour costs contribute largely to the dependency of banana production on agricultural subsidies. However, reorienting the current European agricultural income policy to an environmental performance-based subvention might be a policy opportunity to achieve the present social goals while promoting sustainability in banana production. Furthermore, the EC regulation on quality standards for commercial bananas, by imposing strict aesthetic benchmarks, has a negative effect on the sustainability of banana production because substantial non-renewable and purchased emergy inflows into banana production systems aim to improve aesthetic standards over sound ecological management.

Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699; Prototyping methods are useful for designing alternative crop management systems (CMS), but they are usually considered mainly at the field level and are poorly equipped to take into account farm diversity in terms of economic, social and natural constraints. This may limit the likelihood of adoption of alternative CMS. This paper proposes a two-step methodological framework that takes into account the diversity of farms in the prototyping of new CMS. The first step of the framework is to design a farm typology that is able to characterise the diversity of current CMS in terms of their technical nature, farming context, and performance. We define a farming context as a set of characteristics at the farm level that are likely to influence the structure and the biophysical and economic performances of CMS at the field level. The typology is designed from a statistical analysis of a set of descriptive variables collected for a sample of farms. The second step of the framework uses this farm typology in a specific work agenda with a panel of experts in order to design a set of alternative CMS prototypes. Prototypes, and the objectives they are meant to reach, are designed by analysing current CMS performances and by mobilising agro-ecological knowledge to identify technical ways to improve them. The typological characterisation of farm diversity then makes it possible to define a set of constraints (SOC) for each farm type. Once the prototypes are designed, the experts use a compatibility indicator (CI) ranging from zero to one to measure the level of compatibility between each prototype and the SOC of each farm type. We define a prototype as compatible with a farm type if the prototype is not likely to increase the constraints of a farm of that type (CI = 1). Using this indicator in a process of iterative improvement of prototype design makes it possible to define a set of a priori compatible prototypes for each farm type. The aim of this paper is to present our methodological framework and its application for prototyping new banana crop management systems in Guadeloupe. The six-class typology we developed corresponded to a great diversity of CMS with contrasting performances and farming contexts. The method led to the prototyping of 16 innovative CMS, involving different modalities of intercropping, patterns of pesticide use, choices of hybrid cultivars, and rotations with cover or cash crops. Finally, we discuss the limits of our methodological framework and its utility for improving prototyping approaches.

Food sectors have to face lots of hurdles today and their sustainability is called into question. We present here an original method that we developed to analyze the yam (Dioscorea sp.) food sector in Guadeloupe (FWI) and devise recommendations for its sustainable development. This three-step method aims at giving an overview of the sector by describing and analyzing the strategies and expectations of farmers, retailers and consumers. This overview makes it possible then to draw conclusions for improving the sustainability of the sector. In the first step we enquired yam farmers in order to characterize their productive strategies. We identified six different types of farms according to the importance placed on yam for income generation. In the second step we focused on marketing chains. We found that local yam is mostly traded informally via five main distribution chains that reflect farmers and retailers’ strategies. In the third step, we focused on yam consumers in order to identify ways to boost yam consumption. Focus group discussions helped us to identify the determinants of yam consumption and to devise hypotheses about ways to increase it. We then tested those hypotheses through a laboratory experiment in which we elicited consumers’ willingness to pay for different types of market signals: i) the intrinsic quality of a variety resistant to pathogens and of high testing quality, ii) a label about the local origin, iii) a label about the organic production. Our results showed that consumers were ready to pay a premium for the local and organically grown yam. We then discussed the interest of moving onto a certification scheme for the different types of farms and agents identified in the first and second stage. This study suggests that a way to improve the sustainability of the yam sector in Guadeloupe would be to mobilize farmers around a collective product qualification strategy.

National audience; Cultiver de la canne dédiée à la production électrique a-t-il un intérêt? Dans certains contextes spécifiques, comme en Guadeloupe sur les sols pollués à la chlordécone, une filière canne dédiée à la production électrique pourrait être une solution alternative à la production alimentaire rendue délicate sur ces sols. Elle constituerait aussi un atout pour améliorer l’autonomie énergétique de l’île. Toutefois, une telle filière doit également présenter un intérêt environnemental pour la collectivité ainsi qu’un intérêt économique pour ses futures parties prenantes (agriculteurs, industriels et usagers). Une démarche est proposée pour évaluer la rentabilité économique de cette filière et son intérêt environnemental. Elle comprend trois volets interdépendants : l’analyse de l’acceptabilité par les agriculteurs de cette nouvelle filière, l’analyse des conditions de sa rentabilité économique et son évaluation environnementale via la méthodologie de l’Analyse de Cycle de Vie. L’article se focalise sur les méthodes et les outils développés spécifiquement pour évaluer différents scénarios d’organisation de filières. A titre illustratif, les outils ont été utilisés pour tester deux scénarios hypothétiques, portant sur un cas d’étude en Guadeloupe. L’évaluation de ces scénarios se fait à la lumière des performances agronomiques, économiques et environnementales depuis la production du matériel végétal jusqu’à sa combustion. Elle permet de mettre en évidence quelques paramètres déterminants de la faisabilité de cette filière en cours d’étude. Cette étude a été réalisée dans le cadre du programme de recherche REBECCA (REcherche Biomasse Energie Canne dans la région de CApesterre) mené par le Cirad en partenariat avec un industriel (Cann’elec Développement) et l’INRA.

International audience; Farm modelling has been widely used over the past ten years for the assessment of agricultural systems in face of policy changes, technological innovation, economic and climate changes. Beyond the various modelling methods (optimisation, rule-based, agent-based...), these models are framed by their objectives -defining input data and users- which can be: policy assessment, technological innovation assessment, farming systems resilience studies, optimisation of water management at regional level, agricultural landscape design, a « boundary object » for strategic thinking in a stakeholder arena. Indeed these farm modelling tools are still poorly used for the design of innovative cropping systems which remains mostly based on field level experiments and modelling.Nevertheless driving forces and assessment criteria for the design of sustainable cropping systems are increasingly expressed at larger scales than field or even farm. For exemple most environmental services are provisionned at landscape (e.g. biodiversity) or whatershed levels (e.g. water quality), at regional level (e.g. climate mitigation) and in more global socio-systems (e.g. food security, rural development). On the other hand, a large part of the functions supporting these services are operating at field level where the interactions between farmer’s decisions (crop selection, combination and management) and biophysical processes (soil, plants, pests, weeds and diseases) are occuring. A large part of these biophysical processes also occur at landscape level (biodiversity, water flows...) but they require information at field level to be upscaled in a landscape mosaïc. In-between these two levels (field and region) the farm level plays a key role in agricultural systems imulation: (i) it is the decision level of farm activities (crops, livestock, trees...) further applied to field level ; (ii) it is the first level of expression of socio-economical services (labour, income, food production...) and (iii) farm diversity is a major driver of assessment indicators value and evolution at regional scale. In order to combine these up and downscalling processes between farm, field and regional levels for a multi-criteria design of agricultural systems, we propose a «farm-centered» integrated modelling of agricultural systems framework. In this approach farm models and typologies are the central node of scenario based analysis of technological innovation in a biophysical and socio-economic context. We will illustrate how it has been used in a wide range of assessment studies and how we plan to further develop it for the design of a « plant-diversity based » agro- ecological transition of agricultural systems.

Current agricultural systems are responsible for many different environmental, social and economic issues at both local and global scales. Agricultural sciences have contributed to the design of several methods at the farm and field scale in order to prototype cropping systems and farming systems to address these issues. However, few methods have been designed at the regional scale, while this scale seems to be indispensable in order to address these issues. In order to fill this gap, we here propose a new methodological framework for i) simulating the consequences of policy changes on farmer's cropping plan, described individually, by modeling the evolution of farming systems and to ii) assess the impacts of cropping system changes at the regional scale, with a set of indicators that generate spatially explicit information on the contribution of agriculture to sustainable development. The methodological framework starts with the design of a farm typology over the territory based on the similarity of farmer's crop acreages. In parallel, a set of indicators is adapted to the landscape scale in order to assess the impacts of cropping system externalities by integrating a set of scale change procedures. A generic, multi-scale, spatially explicit bioeconomic model called MOSAICA, which uses the farm typology and the indicators, is created for generating cropping system mosaics and assessing their contribution to sustainable development. This model coupled to a scenario approach composed of exploratory and normative scenarios can simulate the impact of several type of agronomic, socio-economic, environmental, organizational and technical levers of change on the farmer's choice in term of cropping systems and in fine the impacts of new cropping system mosaics on the contribution to sustainable development of territories. We applied this methodological framework for building scenarios of sustainable agricultural development in Guadeloupe. We first developed a typology of farming systems encompassing eight types of farming systems that revealed several farmer's decision processes. Then, we developed 19 indicators to assess cropping system mosaics. The assessment of the current cropping system mosaic showed low levels of response of the current mosaic to economic and social issues especially the food and energy self-sufficiency. Different normative and exploratory scenarios integrating levers of change have been simulated with MOSAICA. The assessment of cropping system mosaics from these scenarios highlighted the positive effect of agronomic levers of change such as organic crop-gardening and social levers such as the vocational training of supplementary workforce for improving the contribution of agriculture to sustainable development of the guadeloupean territory. The mechanistic modeling of the agricultural territory allows us to integrate a wide range of knowledge on the location of cropping systems, their levels of performance , their impacts and the decision process of farmer's that drive the farming system characteristics and the farm functioning. This methodological framework helps visualize the cropping system changes at the regional scale and their associated impacts at the landscape scale which is helpful in order to produce knowledge on the levers of change that can improve the response of local agriculture to local and global issues. The framework and tools designed are particularly useful for decision-aid on the future levels of contribution of agriculture to sustainable development., L'agriculture actuelle est impliquée dans de multiples problématiques environnementales, sociales et économiques, aux échelles locales et globales. En agronomie, de nombreux travaux à l'échelle du champ et de l'exploitation visent aujourd'hui à concevoir des systèmes de culture et des systèmes de production en lien avec ces problématiques. En revanche, peu de travaux portent sur la conception et l'évaluation de systèmes agricoles à l'échelle du territoire, alors que cette échelle apparaît pourtant incontournable pour faire face à des enjeux de développement durable. Pour combler ce manque, nous proposons un ensemble méthodologique permettant i) de simuler les conséquences de scénarios de politiques agricoles sur les choix d'assolement des agriculteurs, décrits individuellement, en modélisant l'évolution de leurs système de production et ii) d'évaluer l'impact de ces changements d'assolements à l'échelle du territoire, à l'aide d'indicateurs qui apportent de l'information spatiale sur la contribution de l'agriculture au développement durable. L'ensemble méthodologique proposé débute par la construction d'une typologie des exploitations agricoles du territoire sur la base de la similarité de leur assolement. Parallèlement, l'adaptation d'indicateurs à l'échelle du territoire permet d'évaluer les impacts des externalités des systèmes de culture en mobilisant des procédures de changements d'échelles. Un modèle bioéconomique générique, multi-échelle, spatialement explicite, appelé MOSAICA, qui utilise la typologie et les indicateurs d'impact de l'agriculture à l'échelle régionale, est créé pour produire des mosaïques de systèmes de culture et évalue leur contribution au développement durable du territoire. Ce modèle, couplé à un itinéraire de définition de scénarios exploratoires et normatifs permet de tester l'impact de différents types de leviers agronomiques, socio-économiques, environnementaux, organisationnels et techniques sur les choix des exploitants et in fine sur la contribution de la mosaïque de systèmes de culture au développement durable du territoire. Nous avons appliqué cet ensemble méthodologique à la conception de scénarios de développement agricoles durables en Guadeloupe. Nous avons dans un premier temps développé une typologie des systèmes de production comprenant huit types distincts et relevant de processus décisionnel différents. Puis nous avons adapté à l'échelle du territoire 19 indicateurs pour l'évaluation des mosaïques de systèmes de culture. L’évaluation de la mosaïque actuelle nous a permis de repérer de faibles niveaux de contribution aux enjeux d’autonomie alimentaire et énergétique. Différents scénarios normatifs et exploratoires intégrant des leviers de changement de la mosaïque ont été testés avec MOSAICA. Les évaluations réalisées nous ont permis d'identifier que des leviers agronomiques comme le développement du maraîchage sans intrants chimiques et des leviers sociaux comme la formation de main-d'œuvre supplémentaire permettraient d'améliorer la contribution de l’agriculture au développement durable du territoire Guadeloupéen. La modélisation mécaniste de l’évolution du territoire agricole permet d'intégrer des connaissances sur la localisation, les performances, les impacts des systèmes de culture et sur les processus décisionnels des exploitants régissant l’orientation productive et le fonctionnement des exploitations. Cette démarche permet de visualiser les changements de système de culture et leurs impacts de manière spatialement explicite, ce qui permet de générer des connaissances sur les leviers susceptibles de faire évoluer positivement l'agriculture du territoire. La démarche et les outils mis en œuvre sont donc particulièrement utiles pour l'aide à la décision publique pour améliorer la durabilité de l'agriculture dans son ensemble.

In a constantly changing environment, characterized by global change, agricultural sectors face new challenges (weather conditions, changes in the regulatory environment, health standards, consumers’ lifestyles, etc.). This finding implies the need to develop other food sector organizations that allow them to adapt to these new challenges. The objective of this thesis is to contribute to scientific progress on new ways of organizing food sectors. We suggest a diagnosis and design approach for sustainable agricultural sectors, focuses on the issue of the conditions of emergence of product quality. From a literature review, we build an original approach which is then applied to the yam sector in Guadeloupe. Our method consists of two steps. In a first step, we identify development strategies to improve the sustainability of the sector and the levers to operate to implement these strategies. In a second step, we analyze the consistency of these levers to three segments in the chain: consumption, production and marketing. The overall approach implements investigative tools at each segment in the chain and their joint use as well as a cross-sectional analysis of the results, to answer the issue of a sustainable management of the sector by product quality. The yam value chain analysis in Guadeloupe, showed that action on the demand side, by stimulating it, was one of the possible strategies to improve the sustainability of the sector. One of the relevant levers of action identified to implement this strategy is to improve the quality of yam. We then evaluated the consistency of this lever to the different segments in the chain by: i/ measuring consumer willingness to pay for different yam profiles (a local yam, organic yam, and a yam variety qualified as of superior sensory quality) ii / evaluating strategic and operational compatibility of the identified lever with farm structures, in particular via the issue of transition to organic production of yams and technical and economic performances of these crop management systems; iii / leading a cross approach to the perception of the quality of yam by producers and intermediaries and reviewing their business strategies. In order to do so, we have mobilized many and varied methods and tools, such as the field diagnosis, interviews, focus groups, experimental economics, farm typologies and simulation. In addition to the results produced, the work carried raises new questions, suggesting ways for interdisciplinary research. It also paves the way to a global approach for the future of the yam sector in a strong interaction with the various stakeholders. The method we offer and the results might be useful for this reflection. The final chapter of this thesis discusses the requirements for the implementation of the proposed methodology and its overall strengths and weaknesses. It appears that, although the method can be further improved, it could easily be applied to other sectors in other contexts., Dans un contexte en constante évolution et caractérisé par des changements globaux, les filières agricoles doivent faire face à de nouveaux enjeux (aléas climatiques, évolutions du contexte réglementaire, des normes sanitaires, des modes de vie des consommateurs, etc.). Ce constat implique la nécessité de concevoir d’autres organisations de filière qui leur permettent de s’adapter à ces nouveaux enjeux. L’objectif de cette thèse est de contribuer à l’avancée des travaux sur les nouveaux modes d’organisation des filières et de proposer une démarche de diagnostic-conception de filières agricoles durables centrée sur la question des conditions d’émergence de la qualité dans les filières. A partir d’une analyse de la littérature, nous construisons une démarche originale qui est ensuite appliquée à la filière igname en Guadeloupe. Notre méthode se décompose en deux étapes. Dans un premier temps, nous identifions des stratégies de développement pour améliorer la durabilité de la filière ainsi que les leviers à actionner pour mettre en œuvre ces stratégies. Dans un deuxième temps, nous analysons la cohérence de ces leviers aux trois maillons de la filière : la consommation, la production et la commercialisation. La démarche globale met en œuvre des outils d’investigation à chaque maillon de la filière et envisage leur articulation afin de répondre, par une analyse transversale des résultats, à l’enjeu d’une structuration durable de la filière par la qualité. L’analyse de la filière igname en Guadeloupe a montré qu’une action au niveau de la demande, en la stimulant, était une des stratégies envisageables pour améliorer la durabilité de la filière. Un des leviers d’action pertinent identifié pour mettre en œuvre cette stratégie est l’amélioration de la qualité de l’igname. Nous avons alors évalué la cohérence de ce levier aux différents maillons de la filière en : i/mesurant le consentement à payer des consommateurs pour différents profils d’igname (une igname locale, une igname biologique, une variété d’igname qualifiée comme de qualités organoleptiques supérieures); ii/évaluant la compatibilité stratégique et opérationnelle du levier identifié avec les structures d’exploitations, en particuliers via la question du passage à la production d’igname biologique et des performances technico-économiques de ces itinéraires techniques dans les différents types d’exploitations ; iii/menant une approche croisée de la perception de la qualité de l’igname selon les producteurs et les intermédiaires et en examinant leurs stratégies commerciales. Nous avons pour cela mobilisé des méthodes et outils nombreux et variés, tels que le diagnostic de terrain, les entretiens d’enquête, les focus groups, l’économie expérimentale, les typologies d’exploitations agricoles et la simulation. Outre les résultats produits, les travaux réalisés soulèvent de nouvelles questions, suggérant des pistes de recherches interdisciplinaires et ouvrant ainsi le champ à une réflexion globale pour l’avenir de la filière igname en interaction forte avec les différents acteurs de la filière. La méthode que nous proposons et les résultats obtenus pourraient utilement servir à cette réflexion. Le dernier chapitre de cette thèse revient sur les conditions de mise en œuvre de l’ensemble méthodologique proposé et ses forces et faiblesses. Il apparaît que, bien que la méthode puisse être encore améliorée, celle-ci pourrait aisément être appliquée à d’autres filières dans d’autres contextes.

2 ann. 7 p.