Search

Rice farming systems in the irrigated areas of central Thailand, unlike other parts of the country, have undergone limited changes over the past two decades. These systems are based on two rice crops per year. Generally, they are characterized by the intensive use of chemical fertilizers and pesticides. Most of these rice farming systems provide full-time employment to farmers. However, the sustainability of these rice farming systems has been undermined by two factors: the decision to end policies to support rice prices on the domestic market and the aging farming population. The study analyzes the experience of farmers located in Prachinburi Province, who began changing their farming systems in order to move away from conventional rice production. Thirty-eight of these farmers were interviewed, about their objectives, the process of change, and the impacts of these changes. One group of farmers started growing non-rice crops and another group began to produce organic rice collectively. Profitability has increased, but many farmers see also these changes as an opportunity to increase home consumption. In addition, the changes have made the farming systems more flexible. These developments help rice farmers in central Thailand build their capacities for change to be able to adaptto ongoing evolutions of the agricultural sector. However, upscaling these changes in farming systems and in farmers' capacities will require wide-ranging support.

This paper seeks to explain the emergence of South African inclusive agricultural business models in relation to the land reform policy. We demonstrate that in South Africa such policy instruments linking small-scale and large-scale farmers respond to endogenous dynamics linked to the failure of its land reform policy. We study the land reform policy change induced by its policy instruments. Indeed, introducing the market as the preferred means to implement land reform caused unanticipated side effects, creating constant pressure for change that such inadequate instrument exerted on the set policy objectives during the first phase of policy implementation. After cohabitating uneasily with rather antagonistic policy goals, policy instruments ultimately led to a change in policy objectives, shifting from supporting small-scale black subsistence agriculture to targeting a class of emerging farmers committed to commercial agriculture. Inclusive Business Model's policy instruments were subsequently identified as the best fit to achieve the re-adjusted policy goal.

Unravelling the dynamics of land-use change is key to assess the environmental and socioeconomic impacts of land-based strategies regarding climate or energy. In this prospect, this paper proposes an analytical decomposition of land-use change resulting from a shock in agricultural demand which takes into account indirect effects from price signals. This analytical equation is numerically estimated using a global model of land-use combining biophysics and economics. While being relatively simple, this model captures the main processes of land-use change: change in the intensive and extensive margins, international trade, change in intermediary demand and possible by-products. At the global scale, our results show that yield losses due to the conversion of marginal land amount approximately to half of yield gains due to fertiliser use. At the regional scale, patterns of yield and area responses are depicted by assessing the potentials for intensification (yield gaps) and extensification (areas of extensive pastures) given the future pathways of agricultural demand.

This research aim to study changes in rubber production and farmers' practices at Subsomboon village, Doonsard sub-district, Kranuan district, Khon Kaen province since the promotion of rubber plantation. Data were collected by using literature review, semi-structured interview (SSI) with Key-informants (KIs) using sub-topics and interviewing with a sample of 30 accessible rubber farmers using a closed ended questionnaire. It was found that rubber production in the area could be divided into 3 periods including the first period: Beginning of rubber cultivation (1992-2003) farmers started rubber plantation with government support for the production inputs and knowledge, the second period: Rubber booming (2004-2011) where the area of rubber dramatically increased mostly by farmer' s own investment and partly supported by the government and the third period: Declining of rubber (2012-present), when limited expansion of new rubber area was farmers own investment and no rubber replanting in some farms. Moreover, the study found that there are different practices among farmers at each period showing the adaptation of farmers in their plots according to the situation of family condition and rubber production in each period.

International audience; Intensive agriculture is a major disturbing factor for water quality in Brittany, France. Observations of chemical data from 350 catchments over a 15 year period show that the high variability of hydrochemical dynamics between catchments in relation to geographic characteristics and farming practices, decreases with an increase in the catchment size. A stable signature of nitrate and DOC dynamics does emerge for bigger catchments, and was evidenced statistically.

International audience; Rice is cultivated as staple for over half of the World's population. In Camargue (South of France) rice fields have been established on very young soils developed from historic fluvial deposits of the Rhône River. The comparison of clay mineralogy in a paddy field cultivated for 60 years and in a control shows a significant increase of the clay crystallinity in the paddy field soil, which implies a decrease of their solubility. In the paddy soils, phytoliths, poorly crystallized clays, such as smectite and to a lesser extent kaolinite, are progressively dissolved to supply Si for rice requirements. The sustainability of the crop system requires the clearing of silica exportations.

International audience; Mechanisms to standardize sustainable agricultural practices first emerged in the early 2000s with the goal of establishing responsible rules of corporate behaviour. Based on voluntary commitments by firms, these mechanisms are usually structured around a particular agricultural product and bring together the global value chain’s various actors (producers, buyers, processors, retailers), as well as NGOs, banks, and sometimes governments, to define and monitor sustainable production practices. They aim to regulate the environmental and social impacts of agriculture, especially large-scale industrial agriculture. And yet, some authors have noted the difficulty of ‘internalizing’ the negative effects and costs that international trade makes invisible, due to a ‘distance’ effect. By basing itself on the work of Thomas Princen (1997), this chapter explores the ability of standardization mechanisms to make visible again the effects that are ‘obscured’ by distance and the strategic action of firms and governments. Distance is understood here in terms of different dimensions: geographical, but also (and particularly) pertaining to contractual asymmetries; a limited cognitive ability of interpretation in an exchange between ‘foreign’ people and places; or a large number of intermediaries. From an empirical analysis of standardization mechanisms and a literature review, we show that sustainability standards have brushed aside part of the social and environmental criticism raised in a wider public debate, much like they exclude certain concerns raised by the affected people themselves. Characterized as a form of ‘government by the stakeholders’, such mechanisms in fact lead to the depoliticization of the debate and therefore to the exclusion of certain political perspectives and expressions of the common good. Moreover, they deliberately ignore some relationships that people have with their environment, thus making invisible part of the damage. Thus, these sustainability standards simply do not take some of negative impacts of the exports of biomass by industrial agriculture into account. These mechanisms have so far excluded or dismissed the constructions of sustainability whose aim was precisely to reduce the various dimensions of distance.

Recent developments in the global agriculture have been char¬acterized by the emergence of the concept of ecological inten¬sification, as a means to decrease the use of inputs and their impacts on the environment, while increasing and/or stabiliz¬ing crops and livestock yields. In the meantime, research stud¬ies have emphasized the ability of crops integration with live¬stock farming systems to adapt themselves to numerous stresses (economic, climate, etc.) in comparison to specialized systems with only crops or livestock. In the oasis, such integration has been traditionally achieved, as it has allowed for centuries the resilience of the cropping activities, in an environment charac¬terized by numerous constraints, particularly frequent water shortages. However, this resilience has nowadays become chal¬lenged by increased stresses, above all climate change and its consequences and also social changes, with growing demands of the local population for better livelihoods. Therefore, in this study, the focus was on the ability of livestock to contribute to the ecological intensification of the farming systems adopted in the oasis. A sample of twelve (12) farms located in the oasis of the Drâa valley was selected and it was representing four types of livestock systems (i.e. 3 farms per system). A follow-up of farms was adopted to characterize inputs uses, water vol¬umes and their origins (rainfall, surface irrigation and ground¬water) and incomes from crops. The same methods were used for livestock production. In addition, work needs for crops and livestock were also measured, by determining the contribution of off-farm work uses. The results showed the importance of crop/livestock association in all the systems, in order to implement a sustainable farming activity. The intensification of livestock sys¬tems (retrieved in farms with prominent off-farm feed uses, i.e. D'man breed flocks and dairy cattle) showed the best incomes from crops, and that was mostly remarkable for date palms, which benefitted from the surplus irrigation of the underlying alfalfa, as well as manure from the herds. In the contexts where agriculture intensification was not feasible (due to water, land or capital scarcity), livestock remained the main source of incomes, adding value to vast pastoral areas (as in the area of M'hamid EL Ghizlane) and to crop by-products (mainly date wastes). Al¬together, the results imply the need of further research devoted to the performances of the farming systems in the oasis, and the use efficiency of scarce inputs, such as water, land and work.

In Vietnam, the dairy sector has emerged since the 2000s, in response to the rapid growth of the demand for dairy products. After having supported small-scale dairy production farms, the national policies since 2008 (the “2020 Livestock Development Strategy” in 2008, and the “Livestock sector Restructuring Action Plan towards greater Added Value and Sustainable Development” in 2014) highlighted the government's priorities for large-scale and industrial farms. Those recent programs focused on reducing the import dependency to meet the increasing domestic demand and improving price competitiveness vis-à-vis imported dairy products. However, in the context of a rapid transition of the economy and of the ecosystems, smallholder and family farms are still the mainstay of the agricultural sector and continue to play an important role in sustainable development. The present study raises the question of the viability, sustainability and inclusiveness of different dairy farming models, taking into account the land constraint (farmland availability: 0.8 ha per farm, 0.12 ha per capita), labor abundance, especially in agriculture (50% of the total active population) as well as the environmental challenges related to animal products value chains. This thesis aims to contribute to the current policy debates in Vietnam in order to know whether the future dairy sector should be based on family farming or on large-scale production. The first section is dedicated to the analysis of the structural and agrarian transformation in relation to the ongoing dynamics of the livestock and dairy sector more weighted on the larger commercial farms. To better understand the market dynamics, the second section characterizes the governance of the dairy value chain in the largest milk-shed in the Red River Delta (Ba Vi district, Ha Noi). Based on interviews with 70 actors involved in local dairy value chain, the thesis underlines factors shaping a mixed relational-captive governance and the close connection between the local authorities and firms that might threaten the inclusion of smallholder dairy farmers in the chain. In the third section, we report on a participatory scenario planning exercise conducted with stakeholders of the dairy sector (one scenario planning seminar at district level, two seminars at the national level) to discuss about future policy orientations. In support to this participatory scenario planning, a quantitative simulation was done. 4 potential plausible scenarios for the Vietnamese dairy sector until 2030 were drawn up. In all scenarios, Vietnam still has to import large quantities of milk products and animal feed raw materials from abroad, but the 4 proposed scenarios differ on policy implications upon labor absorption, land availability and efficiency, and environmental impact. In particular, a “Dual System” scenario is discussed to accommodate different farm models (private mega-farms, specialized family farms and mixed crops-livestock farms) in view of balancing supply and demand as well as adapting to the puzzles of local land, labor and environment. Taking into account the co-existence and cohabitation of the different farms, appropriate policy actions are needed to ensure the sustainable and inclusive development of the dairy sector.

International audience; Leaf area index and Fraction of Absorbed Photosynthetically Active Radiation are important land biophysical parameters that enable monitoring and quantitative assessment of vegetation state. Remote sensing data from space can be used to estimate these parameters at regional and national scale. High temporal satellite imagery is usually required to capture main parameters of crop growth. In this paper, we assess efficiency of using satellite images at high spatial and temporal resolution acquired within the SPOT-5 Take 5 initiative for mapping biophysical parameters.

Metadata only record Two agricultural intensification policies currently have a foothold in Southern Africa: intensification by plough-based, animal integrated practices and intensification by conservation agricultural practices including natural resource management. The former ideology originated from colonialism while the latter is currently promoted by nongovernmental organizations and development agencies. However, analysis on farmer knowledge relating to both of these practices reveals a predisposition towards extensification, or the farming on more land and using more resources to increase yields, instead of intensification. Other factors include limited cash, elevated risks, fluctuations in labor availability, and high input prices. Interestingly, the authors cite reliance on purely technical fixes, the disregarding of local or placed-based knowledge, and ultimately the lack of innovation on the side of researchers, development agencies, and policy-makers as the true reasons why Africa farmers are "failing to yield."

Morocco began an ambitious agricultural policy called the Green Morocco Plan (GMP) in 2008. This paper analyses the rationale behind the plan, that is, the overall consistency between: (i) the initial assessment of the agricultural sector; (ii) the goals defined for the plan; and (iii) the instruments used to achieve these goals. The analysis is based on a review of policy documents and instruments implemented in the framework of the Plan. The original assessment, which was conducted to frame the Plan, highlighted a dual agricultural sector with traditional and modern farms. The key goals of the GMP are to increase agricultural production and farm income, and to ensure the sustainable development of rural territories. The rationale of the Plan is that, to achieve these goals, public actions should break away from the dual structure of the sector, support investments, and improve the organisation of agricultural value chains. However, this paper shows that the farm typology outlined in the original assessment was in fact inaccurate, and that, in practice, the Plan does not take the diversity of farms into account. Moreover, most of the instruments designed to improve the organisation of agricultural value chains do not give importance to the share of the value added that benefits farmers, and most of the instruments of the plan do not take the territorial level into account. As a result, the aim of the GMP is to transform rural areas through improved economic performance but, due to inaccuracies in its rationale, its focus is generally limited to enhancing agricultural production.

Identifying the environmental hot spots of agriculture is crucial in a context where humanity has to produce more food and pollute less. Life Cycle Assessment (LCA) is a powerful tool to evaluate the environmental impacts of agricultural systems, but is still fraught with shortcomings, notably for the evaluation of impacts of freshwater use and of salinisation of water and soil. The core complexity lies in the double status of water and soil resources in LCA which are both a resource and a compartment. The three questions answered by the thesis were: How to better assess the impacts associated with water and salts fluxes? What model should be developed for a relevant inventory of field water and salts fluxes? Is the developed model operational for an LCA study on a perennial crop? The first question was answered through a literature review on salinisation impacts in LCA. It revealed the main environmental mechanisms of salinisation, the factors involved, and discussed the soil and water status, notably through a consistent definition of the technosphere and ecosphere boundary. To answer the second question, a critical analysis of water inventory and agri-food LCA databases showed their inadequacy for the LCA-based ecodesign of cropping systems: they provide estimates of theoretical water consumed, rely on data and methods presenting limitations, and do not support the calculation of both consumptive and degradative water use impacts. For the LCA-based ecodesign of cropping systems, the inventory of water flows should be based on a model simulating evapotranspiration, deep percolation and runoff accounting for crop specificities, pedo-climatic conditions and agricultural managements. For herbaceous crops, the FAO Aquacrop model constitutes a relevant and operational model, but no dedicated model is available to-date for perennials. To fill this gap, a tailored and simple model, so called E.T., was elaborated for the inventory of field water and salt flows for annual and perennial crops. The model combines daily water and salts balances, accounting for soil, climate, agricultural practices and possible crop water and salinity stresses. A first testing of the E.T. model demonstrated its discriminating power for agricultural practices and its robustness. Its validity domain can be extended and its accuracy increased thanks to the recommendations provided. E.T. was also tested in the LCA of a Mandarin grown in Morocco. For most impact categories, electricity use for irrigation was the main contributor revealing a water-energy nexus. Water use had a major contribution to damages for all areas of protection. Overall, to further improve the assessment of impacts due to water use (including salinization impacts) we recommend using a more mechanistic and hydrological approach.

Extensive livestock farming was the driver of agricultural colonization and territorial structuring in the Amazon. Since 2008, Amazonian agriculture has been faced with radical changes in Brazilian policies concerning agricultural land use and the preservation of forest areas. The very viability of livestock systems is threatened and there is thus an urgent need for feasible alternatives to enable the development of sustainable agriculture. Some alternatives are currently being tested by public extension services and private operators. The question is, can these alternatives really be considered as ecological intensification? Defined as ecologically friendly agricultural development, this new trend of intensification aims to reconcile cattle ranching and the protection of Amazon forest ecosystems. Our analysis, based on three contrasted municipalities in Para State, focuses on the points of view of different stakeholders in the livestock sector. Results show the dominance of classical intensification among the alternatives envisaged, but it is an option that small family farmers cannot easily afford. Alternatives based on land sharing, which promotes agricultural production and environmental preservation on the same areas, are less well known and will require more coordination among local actors.; L'elevage extensif a ete un moteur dans l'avancee des fronts agricoles et la construction des territoires en Amazonie bresilienne. Depuis 2008, l'agriculture amazonienne est confrontee a des changements radicaux de la politique bresilienne concernant l'usage des terres agricoles et la preservation des zones forestieres. La viabilite des systemes d'elevage est aujourd'hui menacee ; il est urgent de trouver et de mettre en oeuvre des solutions viables, techniques et sociales, pour permettre le developpement durable de l'agriculture en Amazonie. Une serie d'alternatives sont testees par les services publics, prives et des organisations non gouvernementales (bresiliennes et internationales) afin d'amorcer une trajectoire d'intensification tout en preservant la foret. Notre question est : les alternatives envisagees contribuent-elles a un mouvement d'intensification ecologique ? Defini comme developpement agricole respectueux de l'environnement, ce mouvement est considere comme un des facteurs d'une coexistence entre elevage et foret. Sur la base d'une etude realisee dans trois communes contrastees de l'Etat du Para, l'analyse porte sur la connaissance qu'ont les acteurs impliques dans le secteur de l'elevage sur ces alternatives. Nous analysons egalement en quoi les alternatives citees par les acteurs sont liees a l'intensification ecologique. Les resultats montrent qu'il s'agit la plupart du temps de methodes conventionnelles d'intensification, difficiles a atteindre pour les petits producteurs familiaux, et qui separent les zones de production intensive des zones a proteger. Les alternatives basees sur l'integration de la production agricole et de la protection de l'environnement sur les memes espaces sont moins connues et demandent une coordination plus grande entre les acteurs locaux.

Conversion of tropical forests to agriculture contributes significantly to global warming, causing an estimated 12-18% of global greenhouse gas (GHG) emissions. However, estimates of ecosystem carbon fluxes are not accurate mainly because of the limited understanding of their belowground components. Root dynamics, i.e. root production, mortality and decomposition, are crucial elements of ecosystem functioning; an understanding of root dynamics is required to estimate the carbon cycle accurately. This systematic review will assess the current evidence for how tropical and subtropical forest degradation and land-use changes to agriculture affects fine root dynamics. Several stages of forest degradation will be examined during the review process, including current agricultural conversion systems, such as oil palm plantations in Southeast Asia and soybean plantations and pastures in Latin America. The search strategy will follow a specific a priori review protocol. Searches will be conducted in English across six different scientific databases and Google Scholar will be used to ensure comprehensiveness of the evidence base. The retrieved articles will undergo a three-stage screening by title, abstract and full text using predefined inclusion/exclusion criteria. Screening consistency will be evaluated using kappa tests. From the final list of included studies, relevant information on fine root dynamics (i.e. rates and methods used), summary statistics (i.e. mean and variance), ecosystem (i.e. forest type or agricultural system), geographical location and climate and soil variables will be extracted and entered into a database. A meta-analysis will be conducted on subgroups such as root production, root mortality and root decomposition, to show how land-use change affects different components of fine root dynamics. The review will also synthesize the current methods used to assess fine root dynamics and discuss their methodological limitations and variances. (Resume d'auteur)

Etudes & documents; In the context of the rapid development of the cultivation of genetically modified soybeans in Argentina, we conduct a hedonic analysis of agricultural land values. The main objective is to evaluate the impact of land tenure systems and agricultural practices on these values. Data on 338 parcels, located in the Pampas region, are analyzed. The tenure appears to be a particularly important variable. We find that plots rented either by physical persons or by companies are negatively valued in relation to plots owned. Results also highlight the importance, though not to a large degree, of a diversified cropping pattern compared to soybean monoculture. Soil quality, location of the plots, distance to markets, as well as to the nearest city, were also found to affect land values.

Crop pests are a major constraint to the intensification of agricultural production in the tropics, with novel issues related to global change (climate, land use, biological invasions, etc.), food security and preservation of natural resources and biodiversity. A research, extension and education network called DIVECOSYS (Diversity of cropping systems and ecologically-based pest management in West Africa) was launched in 2010 to synergize applied research actions in response to growing concerns on the vulnerability of agricultural systems to pest management in West Africa. This scientific network brings together research and academic institutions, with expertise spanning a multidisciplinary perspective from biology and ecology to remote sensing, agronomy and integrated pest management. Its main scientific objective is to explore the potential of biodiversity and ecological processes such as pest regulation, enabling novel ecologically-based models for productive systems, reduction of pesticide use, and adaptation or resilience of farming systems in the face of environmental disruptions. From Northern Senegal to Southern Benin, the research group explores a wide range of ecoregions and socio-ecological contexts, including stakeholders and their objectives, land use and agricultural practices, and management of biodiversity for enhancing biological control. Main challenges to be turned into opportunities include (i) encouraging collaborations amongst researchers from different scientific fields, (ii) fostering interactive research and synergies among research institutions and among countries, and (iii) developing an ecological engineering approach for the design of sustainable agricultural systems for smallholder farmers.

A aussi fait l'objet d'une présentation à: Environment Workshop, Toulouse School of Economics ; Toulouse - (2014-11-24 - 2014-11-24) / Workshop; The scientific, political and societal debate on how to prevent the erosion of the world biodiversity has largely concentrated on the effects of two alternative types of agricultural production, land sparing (intensive farming leaving more land for natural spaces) and land sharing (extensive farming richer in biodiversity).For a given production target, Green et al. (2005) conclude in favor of land sparing if the relation between biodiversity and yield is decreasing and convex. Indeed, with a shift to extensive farming, biodiversity then increases little on already cultivated land, while it decreases strongly on newly cultivated land. According to these authors and to Phalan et al. (2011a), available empirical data are in favor of a land sparing strategy.We extend the model of Green et al. (2005) by adding the reaction of supply and demand to prices. We show that extensive farming is more interesting than intensive farming for biodiversity if the relation between biodiversity and yield does not have a very high degree of convexity, if demand reacts to prices and if the profitability of extensive farming is lower. Therefore, we do not obtain the result of Green et al. (2005) when production results from market equilibrium. Besides, extensive farming is detrimental to consumers when their surplus is evaluated in a restrictive way as increasing in quantities consumed and decreasing in prices. Its effect on agricultural producers is indeterminate.Distinguishing food demand in vegetal and animal products, we show that extensive farming reduces mostly the size of the animal product market, which demand is more price elastic. Integrating demand for animal products increases the advantage of extensive farming towards biodiversity by increasing the price elasticity of demand. The opposite result is obtained when we consider the introduction of policies for the mandatory incorporation of biofuels in fuel. Indeed, the demand for biofuels varies little with prices, to the detriment of extensive farming as far as biodiversity conservation is concerned.We discuss the implications of this model on the social pressure on protected areas, on the relations between different outlets and on welfare and food security. We also discuss its contribution to the analyses notably of Perfecto and Vandermeer (2010) and Tscharntke et al. (2012) on this topic. Finally, we discuss how to take into account innovations like ecologically intensive farming.

14th International Symposium on Water-Rock Interaction (WRI); International audience; Geochemical and crop models allow for simulating the concentration of irrigation water (Durance River) by evapotranspiration, equilibration with soil pCO2, dissolution / precipitation of calcite, dissolution of fertilizers (P-K, no N), and apatite precipitation. Nutrient absorption is simulated as removal of the corresponding ions from the solution. The results show that the crop system in the Crau plain has thus protected and ameliorated soils since the XVIth century, while sustaining production of high quality crops and a correct income for farmers. This has been made possible by investments in water control (irrigation and drainage). It is now endangered by urban sprawl.

Chapitre 6; International audience; Community and ecosystem ecology are paying increasing attention to evolutionary dynamics, offering a means of attaining a more comprehensive understanding of ecological networks and more efficient and sustainable agroecosystems. Here, we review how such approaches can be applied, and we provide theoretical models to illustrate how eco-evolutionary dynamics can profoundly change our understanding of agricultural issues. We show that community evolution models can be used in several contexts: (1) to improve the selection of agricultural organisms within the context of their ecological networks; (2) to predict and manage the consequences of agricultural disturbances on the ecology and evolution of ecological networks; and (3) to design agricultural landscapes that benefit from network eco-evolutionary dynamics, but without negative impacts. Manipulation of landscape structure simultaneously affects both community ecological dynamics (e.g., by modifying dispersal and its demographic effects) and co-evolution (e.g., by changing gene flows). Finally, we suggest that future theoretical developments in this field should consider appropriate co-evolutionary models and ecosystem services.

Dans de nombreux pays en voie de développement où l'usage agricole des eaux souterraines a conduit à une surexploitation des nappes, il est difficile d'organiser un contrôle direct de l'usage par les agriculteurs des eaux souterraines. Il est alors possible de mettre en place à court terme de politiques influençant de façon indirecte cet usage, mais leur efficacité dépendra des stratégies des agricultures. Les différentes stratégies adoptées par les agriculteurs pour faire face à une crise d'accès à l'eau souterraine ont été analysées dans la région de la Chaouia côtière au Maroc. Dans cette région, l'usage agricole intensif de l'aquifère a mené à l'intrusion saline dans la partie littorale et une baisse des niveaux piézométriques dans la partie interne de l'aquifère. Des stratégies, que l'on peut qualifier de 'chasse' à l'eau souterraine, se fondent sur un approfondissement des forages, l'amenée d'eau de l'extérieur vers l'exploitation agricole, et la location de parcelles dans des zones riches en eau souterraine douce. Ces stratégies permettent aux agriculteurs de maintenir des systèmes de production nécessitant une forte consommation d'eau douce. D'autres stratégies, que l'on peut qualifier d'adaptatives, visent à adapter les systèmes de production à l'eau disponible sur l'exploitation compte-tenu des puits et forages existants. La plupart des stratégies analysées ne sont pas durables simultanément du point de vue économique et environnemental. Les politiques publiques pour favoriser de telles activités durables à la fois d'un point de vue économique et environnemental, diffèrent non seulement quant à leur difficulté de mise en oeuvre,mais aussi quant aux types d'exploitations agricoles qui seront le mieux enmesure d'en bénéficier.

Diffusion du document : Pubique; This paper develops an analytical model of a REDD+ mechanism with an international payment tier and a national payment tier, and calibrates land users' opportunity cost curves based on data from Sumatra, Indonesia. We compare the avoided deforestation and cost- effciency of government purchases across two payment types (fixed price_ and _opportunity cost_), and across two government types (_benevolent_ and _budget maximizing_). Our pa- per shows that fixed-price payments are likely to be more effcient than opportunity-cost compensation payments at low international carbon prices, when the government is _benevolent,_ or when variation in opportunity cost within land users is high relative to variation in opportunity cost across land users. Thus, a program which pays local communities or land users based on the value of the global climate service provided by avoided deforestation may not only distribute REDD revenue more equitably than an opportunity cost-based payment system, but may be more cost-effcient as well

On the tropical island of La Reunion, population growth, increasing demand in food products, agricultural densification, and the resulting pressure on the environment are representative of what is expected to happen in the majority of the world's regions in the next decades. Crop-livestock integration is a possible solution for the sustainable intensification of farming systems. GAMEDE, a whole-farm model, was designed and used with six representative dairy farmers on the island to ex-ante assess differences in farm sustainability of various degrees of crop-livestock integration and to support discussions with farmers about these options. The model details the dynamics of the main biophysical and decisional processes affecting labour, gross margin, and energy and nutrient flows within the farm. We propose a method based on typology, modelling and participatory techniques to support policy making. All its methodological stages integrate both quantitative and qualitative data. The large majority of farm model implementation cases reported in the literature refers to constructed synthetic farms. However, in our case, actual farm simulation was particularly useful for capturing farmers' expert knowledge and providing insights into how agro-ecosystems are really managed. This approach enabled taking farm diversity into account in defining relevant interventions. The reliability of extrapolations and recommendations for policy formulation based on farm-level simulation were verified by a rigorous evaluation of the representativeness of the farm sample, crossing expert data with data stemming from a multi-variate analysis. Our research indicates that actual farms can also be typical. (Resume d'auteur)

International audience; Pest resistance and water pollution are major issues caused by the excessive use of pesticides in intensive agriculture. The concept of integrated production system (IPS) has been thus designed to solve those issues and also to meet the need for better food quality and production. Methodologies such as agronomic diagnosis-based design, prototyping, and model-based design have been developed. Here we review the model-based design of IPS. We identify tools for the development of comprehensive models. Once comprehensive models have been developed, model-based design of IPS can be formulated as an optimization problem to be solved using different approaches. Thus, we review the choice of corresponding criteria, constraints, and mathematical formulations found in the literature. We analyze successful model-based design in transportation and drug development. We learn from these areas to overcome the inherent difficulties involved in the model-based design of IPS. We recommend the following major points: IPS model-based design should use integrative modeling platforms, process-oriented modeling, and object-oriented techniques to improve the genericity, modularity, reuse of crop models, and the data sharing. The spatial dimension of IPS has to be accounted for by making crop models spatially explicit. The design evaluation criteria have to be standardized and carefully chosen by promoting stakeholders involvement. The design of IPS should be formulated as a multiobjective optimization problem, for which non-aggregative approaches should be preferred. Finally, it is necessary to establish a true dialogue between prototyping and model-based design practitioners in order to test, and if necessary to improve, the proposed systems.

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.

International audience; Organic agriculture offers an attractive framework for sustainable farming in terms of the environment, socio-economic and institutional aspects (Capitaine et al., 2009). In spite of the advantages, farmers are more often than not reluctant to convert fully to organic vineyard for they consider that, over and above any technical constraint, farm subsidies do not sufficiently compensate for the uncertain yields and market prices for their products. The purpose of this paper is to evaluate, at short-term and long-term, using a bio-economic approach, the farmer strategies in terms of production system (conventional or organic farming) given uncertainties related to prices, yields and subsidies granted to organic agriculture.

Transport-chemistry models are useful and well-used tools in the environmental assessment of impacts of atmospheric N on Natura 2000 sites. Impacts arise from two groups of reactive nitrogen compounds: reduced nitrogen compounds (NH3 and its reaction product NH4+) and oxidised nitrogen compounds (NO, NO2 and their reaction products). Often the contributions from these two groups are of the same magnitude, but close to intensive livestock farms, the contribution from NH3 may dominate. Oxidised nitrogen compounds contribute to the long-range transport component of nitrogen deposition, but may for most practical purposes be disregarded in local scale assessments. Local scale assessments, therefore, concentrate on the assessment of NH3 deposition from local agricultural sources.

ridaura@supagro.inra.frSAD CT1; This paper reports on a six-year study in Cuba that has shown that increasing a farm's diversity, for example with a mixed crop-livestock system, increases its overall productivity, energy efficiency and nutrient management. Equally important, it reduces risks, in particular when compared to simplified and homogeneous systems. Mixed systems draw various ideas and lessons from traditional farming systems found in many parts of the world. The Cuban case, at the same time, provides many lessons, especially when regarding the design and management of diverse systems.

International audience; Pour optimiser les rendements (agricoles), l'agriculture intensive nécessite une utilisation massive d'intrants agricoles dont les engrais chimiques, potentiellement sources de pollution des ressources en eau. La région du Sud - Ouest du Burkina, dont font partie les zones concernées par la présente étude, connaît une agriculture intensive du coton. Il est fait usage dans les champs de coton, d'engrais à base essentiellement d'azote, de phosphate, de potassium, mais également d'urée, de chlorure de potassium et de nitrate d'ammonium. Un total de 42 échantillons d'eau de surface, de puits et de forages ont fait l'objet d'analyses, afin d'évaluer l'impact de ces engrais sur la qualité des ressources en eau de consommation des populations sur une année. Eu égard à la nature des fertilisants utilisés, les paramètres essentiels suivants ont été ciblés : Nitrates, nitrites, ortho-phosphates, ammonium, potassium, conductivité électrique et dureté totale. Il ressort de ces investigations que les eaux de puits, pendant la saison hivernale, présentent des teneurs plus importantes en nitrates et potassium avec des valeurs maximales respectives de 178 mg/L (plus de 3 fois la valeur limite admise par l'OMS pour les eaux de consommation) et 55 mg/L pour une norme admise par l'OMS de 10 mg/L en potassium. Les ortho-phosphates, forme soluble du phosphore et les nitrites, présentent des teneurs inférieures aux normes admises. S'agissant des ions ammonium, un seul puits par sa position en aval d'un WC et d'un parc d'animaux, a donné des valeurs supérieures à la norme qui est fixée à 1,5 mg/L, atteignant ainsi 20 mg/L de N-NH+4. Les échantillons d'eau de forages sont exempts de toute contamination, alors que 33% des prélèvements d'eau de surface ont donné des teneurs dépassant la valeur limite admise seulement en potassium. Globalement, 61% des échantillons d'eau de puits sont contaminés par les nitrates, 67% par le potassium et 17% donnent des teneurs supérieures à la norme en ammonium. Ce qui permet d'en déduire qu'il y a une infiltration de pollution dans la nappe superficielle qui alimente les puits. La conductivité électrique et la dureté totale sans être excessives présentent les valeurs les plus importantes pour les mêmes sites que sont les puits, avec des valeurs maximales respectives de 1252 μS/cm et 202 mg/L de CaCO3.

Colloque conjoint ERSA/ASRDLF; L’agriculture française et occidentale des dernières décennies est souvent perçue comme trop artificialisée, trop coupée des territoires et du milieu naturel. De nombreuses critiques présentent cette séparation comme non durable et soulignent la nécessité pour l’agriculture d'être mieux reliée au milieu naturel pour une plus grande durabilité. L'article analyse les processus et les déterminants de l'affranchissement de l'agriculture envers les territoires. Il revient sur les diagnostics faits en la matière, notamment sur l'intensification et ses facteurs. Une dernière partie envisage diverses solutions pour une meilleure intégration de l'agriculture dans le milieu naturel et le territoire.

International audience

Agricultural growth rates of about 6% are required in sub-Saharan Africa to fuel economic growth. It is generally acknowledged that this will require sustainable agricultural intensification through the increased use of external inputs, in combination with locally available soil amendments, i.e., integrated soil fertility management (ISFM).

The intensity of agricultural production was assessed in 25 landscape test sites across temperate Europe using a standardised farmer questionnaire. The intensity indicators, nitrogen input (to arable crops and to permanent grassland), density of livestock units and number of pesticide applications (herbicides, insecticides, fungicides and retardants), were recorded and integrated into an overall intensity index. All three components were needed to appropriately characterise the intensity of agricultural management. Four hypotheses were tested. (i) A low diversity of crops is related to higher intensity. The contrary was observed, namely because diverse crop rotations contained a higher share of crops which are more demanding in terms of nitrogen and of plant protection. (ii) Intensity decreases when there is more permanent grassland. This was confirmed by our study. (iii) Large farms are managed more intensively. There was no relation between farm size and intensity. (iv) Large fields are managed more intensively. There was a tendency towards higher nitrogen input and livestock density in landscapes with larger fields but only a few of the results were statistically significant. The aggregated overall intensity index was of limited usefulness mainly because of limitations in interpretability.

This paper focuses on agricultural activities and horticultural practices and their impact on the local development of a typical town in south-west Cameroon. The chosen town, Muea, is one of many in the South-West Province of the country where favourable weather and soil conditions promote agricultural production and regional trade with the neighbouring towns and Nigeria. A total of 26 food crops and cash crops were recorded in the economy of Muea, of which 13 are horticultural. Two censuses conducted in the town in 1995 and in 2004 have revealed that agricultural incomes have declined by one third during this period. It appears that more people are now focusing primarily on urban rather than farming activities. Farming is still practised by much of the population but as a secondary activity; farmers in Muea have diversified agricultural production into horticultural crops. Not only have horticultural practices spread among farmers but most farmers now derive ten times more income from horticulture in 2004 than in 1995. This increase in horticultural activity now provides over half the total income derived from all agricultural activities. (Resume d'auteur)

Nitrogen loading to the Bassin d'Arcachon coastal lagoon (SW France) was evaluated by studying land-use and nitrogen output in its 3001 km(2) catchment. At present, the catchment is dominated by forestry (79%), while intensive agriculture occupies 9% of the surface. The N-output of two hydrological subunits, i.e. the Tagon subunit dominated by pine forestry and the Arriou 11 subunit comprising both forestry and intensive agriculture, were monitored for a seven year period (1996-2002). From these observations it was calculated that forestry contributes on average 1.6 kg total N ha(-1) yr(-1), which is dominated by organic nitrogen (DON+PON are 70% of N). On an areal basis, intensive agriculture contributes 26 times more than forestry, i.e. 41.6 kg total N ha(-1) yr(-1), which is mainly in the form of nitrate (65% of N). These data were upscaled to the catchment and the upscaling was validated by comparison to gauged nitrogen throughputs for the catchment of the Leyre river that is the major tributary to the system. Taking into account the other known N sources and the interannual variability in the catchment it was estimated that nitrogen loading to the lagoon was on average 90 kg ha(-1) yr(-1) (range from 54 to 126 kg ha(-1) yr(-1)). The sandy soils of the catchment have a clear potential for denitrification, but anoxic conditions (waterlogged) and input of organic matter to fuel this process are required. Currently, agricultural practices and spatial planning do not make use of this potential. Nitrogen loading in the Bassin d'Arcachon is reflected by 10-40 muM nitrate concentrations in winter, which became depleted during spring as a result of uptake by vegetation. Short-term uptake experiments showed that the macroalga Monostroma obscurum is well adapted to temperatures between 10 to 20degreesC and competitive with respect to the seagrass Zostera noltii when the nitrate concentrations are above 10 muM. Spring conditions with high nitrate and high insolation are therefore favourable for M. obscurum and this species presents a high risk for algal blooming. In contrast, the macroalga Enteromorpha clathrata well adapted to summertime temperatures around 25degreesC, forms occasionally blooms in the lagoon. This phenomenon is limited due to the low DIN concentrations in summer.

Ressource électronique ; Special issue ; Guest editors : Alexandra Hughes, Nicholas Atampugre ; Texte intégral accessible à partir de l'adresse suivante : http://www.planotes.org/pla_backissues/51.html; International audience