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La productivité à l'hectare des céréales est plus importante dans les exploitations agricoles de grande taille au Burkina Faso. Cette relation positive va à l'encontre du constat dominant estampillé dans la littérature économique comme la " relation inverse entre taille et productivité ". Cet article analyse l'interdépendance entre les productions de maïs et de coton pour l'accès à l'engrais comme facteur explicatif de la relation positive. Un modèle de production inspiré de Feder (1985) est appliqué à la production du maïs sous contrainte de crédit. Il établit que le rendement du maïs augmente avec la surface totale de l'exploitation, à condition que cet accroissement se traduise par une levée de la contrainte de terre cultivable en coton. La validité empirique de ce modèle est testée par la mobilisation de données ménages, de prix et de données pluviométriques au Burkina Faso sur la période 1995-2012.

After many years of decline, hunger in Africa is growing again. This represents a global societal issue that all disciplines concerned with data analysis are facing. The rapid and accurate identification of food insecurity situations is a complex challenge. Although a number of food security alert and monitoring systems exist in food insecure countries, the data and methodologies they are based on do not allow for comprehending food security in all its complexity. In this study, we focus on two key food security indicators: the food consumption score ( F C S ) and the household dietary diversity score ( H D D S ). Based on the observation that producing such indicators is expensive in terms of time and resources, we propose the F S P H D (Food Security Prediction based on Heterogeneous Data) framework, based on state-of-the-art machine and deep learning models, to enable the estimation of F C S and H D D S starting from publicly available heterogeneous data. We take into account the indicators estimated using data from the Permanent Agricultural Survey conducted by the Burkina Faso government from 2009 to 2018 as reference data. We produce our estimations starting from heterogeneous data that include rasters (e.g., population density, land use, soil quality), GPS points (hospitals, schools, violent events), line vectors (waterways), quantitative variables (maize prices, World Bank variables, meteorological data) and time series (Smoothed Brightness Temperature — SMT, rainfall estimates, maize prices). The experimental results show a promising performance of our framework, which outperforms competing methods, thus paving the way for the development of advanced food security prediction systems based on state-of-the-art data science technologies.

International audience; Identifying food insecurity situations timely and accurately is a complex challenge. To prevent food crisis and design appropriate interventions, several food security warning and monitoring systems are very active in food-insecure countries. However, the limited types of data selected and the limitations of data processing methods used make it difficult to apprehend food security in all its complexity. In this work, we propose models that aim to predict two key indicators of food security: the food consumption score and the household dietary diversity score. These indicators are time consuming and costly to obtain. We propose using heterogeneous data as explanatory variables that are more convenient to collect. These indicators are calculated using data from the permanent agricultural survey conducted by the Burkinabe government and available since 2009. The proposed models use deep and machine learning methods to obtain an approximation of food security indicators from heterogeneous explanatory data. The explanatory data are rasters (population densities, rainfall estimates, land use, etc.), GPS points (of hospitals, schools, violent events), quantitative economic variables (maize prices, World Bank variables), meteorological and demographic variables. A basic research issue is to perform pre-processing adapted to each type of data and then to find the right methods and spatio-temporal scale to combine them. This work may also be useful in an operational approach, as the methods discussed could be used by food security warning and monitoring systems to complement their methods to obtain estimates of key indicators a few weeks in advance and to react more quickly in case of famine.

Digital innovations are central to the transformation of food systems, from production and processing through to distribution. While they have the potential to enhance environmental and social sustainability across the value chain, they could also have disruptive effects on organisations and come with huge uncertainties in terms of access to these technologies, working conditions ('Uberisation') and governance. This chapter aims to briefly address the challenges associated with the diffusion of these technologies in developing countries. We focus on the examples of digital agriculture and blockchains.

In January 2013, we collected data from 653 farmers in Burkina Faso, who were asked hypothetical questions about risk aversion and time discounting. Ten months later, these farmers were offered the opportunity to participate in an inventory credit system, also called warrantage, in which they receive a loan in exchange for storing a portion of their harvest as a physical guarantee in one of the newly‐built warehouses of the program. We found that a significant number of farmers chose to store grain in the warehouse without taking the maximum amount allowed for a loan in return, and that farmers who exhibit a stronger present bias were significantly more likely to participate in the warrantage system than other, otherwise similar, farmers. We interpret these results as evidence that farmers use warrantage as a means to commit to saving a portion of their crop until the lean season. These results are in line with the main predictions of our theoretical model, which explicitly takes the hyperbolic nature of farmers' time preferences into account.

International audience; This paper investigates whether Burkinabe maize farmers’ fertiliser-use decisions are correlated with their risk and time preferences. We conducted a survey and a series of hypothetical experiments on a sample of 1500 farmers. We find that more patient farmers do use more fertiliser, but it is only because they plant more maize (a fertiliser-intensive crop) rather than because they use more fertiliser per hectare of maize planted. Conversely, we find no statistically significant link between risk aversion and fertiliser use. We use a simple two-period model, which suggests that risk aversion may indeed have an ambiguous effect on fertiliser use.

We analyze the role of farm stock management on price volatility under liquidity constraints and heterogeneous price expectations. In commodity markets, speculative behaviors by stockholders tend to reduce price volatility, but this is not the case in certain agricultural markets, where speculation by farmers regarding decisions to sell or store grain are subject to liquidity constraints and heterogeneous price expectations. Like stockholders, most farmers sell grain if they expect a price drop in the near future, but unlike stockholders, they are not necessarily able to purchase grain if they expect a price increase in the next period. Heterogeneous price expectations can also lead to suboptimal storage decisions, further increasing price volatility. For these reasons, the storage management behavior of farmers often fails to mitigate price drops in the way that speculation by stockholders does. We merge historical data on maize prices and household storage collected in Burkina Faso in order to build a dynamic panel over the 2005–2012 period. We show that carry-over from one season to the next is associated with unexpected price drops during the preceding lean season and that carry-over is associated with more frequent unexpected price drops following the subsequent post-harvest season. This article is protected by copyright. All rights reserved

Stylized facts set agendas and shape debates. In rapidly changing and data scarce environments, they also risk being ill-informed, outdated and misleading. So, following higher food prices since the 2008 world food crisis, robust economic growth and rapid urbanization, and climatic change, is conventional wisdom about African agriculture and rural livelihoods still accurate? Or is it more akin to myth than fact? The essays in “Agriculture in Africa” Telling Myths from Facts aim to set the record straight. They exploit newly gathered, nationally representative, geo-referenced information at the household and plot level, from six African countries. In these new Living Standard Measurement Study-Integrated Surveys on Agriculture, every aspect of farming and non-farming life is queried—from the plots farmers cultivate, the crops they grow, the harvest that is achieved, and the inputs they use, to all the other sources of income they rely on and the risks they face. Together the surveys cover more than 40 percent of the Sub-Saharan African population. In all, sixteen conventional wisdoms are examined, relating to four themes: the extent of farmer's engagement in input, factor and product markets; the role of off-farm activities; the technology and farming systems used; and the risk environment farmers face. Some striking surprises, in true myth-busting fashion, emerge. And a number of new issues are also thrown up. The studies bring a more refined, empirically grounded understanding of the complex reality of African agriculture. They also confirm that investing in regular, nationally representative data collection yields high social returns.

In recent decades, policies in many countries have been shaped by the implementation of economic liberalization, characterized by state withdrawal from marketing operations and control of trade. In this era of liberalization, policies regulating commodity marketing and trade were expected to disappear, but, in fact, this has hardly occurred. A comparative study is carried out of three farm sectors in Costa Rica, based on a dynamic analysis of behaviour in the context of the institutional change brought about by liberalization. The capacity of farmers' organizations to adapt and contribute to institutional change through their control over economic activity and their participation in policymaking processes is highlighted. In so doing, it is shown that, even in a liberalized era, policies regulating marketing and trade still exist and affect the functioning of agricultural markets. These policies differ according to the farm sector and can be linked directly to the influence of farmers' organizations within these sectors. It is shown that organizations play a key role in the regulation of farm sectors, and that their success depends on the institutional and organizational "thickness" to which they have contributed in each sector. Differences in historical trajectories can explain differences in the capacity of organizations to influence policymaking and to gain market share.

The authors thank the two anonymous referees for their very useful comments. We are grateful to Valérie Reboud and Dominique Rojas for their support and the numerous discussions we had concerning the neo-caledonian economic situation.; International audience; Standard economic indexes intending to capture the wealth of nations fail to capture the importance of natural resources for national economic development. In order to overcome this shortcoming, the World Bank have implemented an analytical framework taking account of natural capital as a component of the total wealth of countries. In this paper we implement the accounting framework of the World Bank for the evaluation of new-Caledonia natural capital and of its contribution to the total wealth of this island. Following our computations, new-Caledonia has a strong natural capital endowment, making it similar to other rental economies. In order to capture the peculiarities of the natural capital of new-Caledonia, this paper also expand the World Bank methodology and deliver a new extended evaluation of new-Caledonia natural capital.; Les indicateurs économiques standard, mis en place pour appréhender la richesse des pays, se révèlent insuffisants pour saisir l’importance qu’occupent les ressources naturelles dans le développement économique des nations. Pour faire face à cette insuffisance, la Banque Mondiale a développé un cadre analytique dans lequel le capital naturel est une des composantes de la richesse totale des pays. Dans cet article, nous appliquons le cadre comptable développé par la Banque Mondiale pour évaluer le capital naturel néo-calédonien et sa contribution à la richesse de la Nouvelle-Calédonie. Les résultats décrivent une économie fortement dotée en capital naturel et qui, dans une perspective internationale, se rapproche des autres économies rentières. Pour intégrer les spécificités du capital naturel de la Nouvelle-Calédonie, cet article propose également une extension de la méthode Banque Mondiale et procède à une nouvelle évaluation étendue du capital naturel néo-calédonien

L'economie neo-institutionnelle a developpe le concept de modeles mentaux, defini comme la facon dont les agents percoivent leur environnement, pour analyser les comportements strategiques. Cependant, peu de travaux portent explicitement sur la demonstration empirique de l'influence des modeles mentaux. Cet article analyse le role que jouent les modeles mentaux des leaders paysans dans les processus de negociation de politiques agricoles pendant le contexte de la liberalisation economique au Costa Rica. Les modeles mentaux sont caracterises par une analyse statistique textuelle des discours des leaders. Le poids des modeles mentaux dans les negociations est ensuite analyse, relativement a d'autres facteurs explicatifs, par l'approche des moindres carres ordinaires. Le principal resultat est que les modeles mentaux influencent l'issue des negociations, avec un poids comparable a celui des ressources financieres, techniques et humaines.

International audience; The 2007-2008 food crisis and current food price swings led economists to re-evaluate the potential for policy instruments to manage food price volatility. When world prices are unstable, the use of import tariffs in importing countries to stabilize price is theoretically not the first best policy. But in practice many countries use import tariffs with intention to stabilize price - and other reasons-, which sometimes achieve some price stabilization, sometimes not. We address the question why is this policy sometimes a success and sometimes a failure? In the context of Kenya, we show that while domestic price levels are mainly explained by seasonal cycles, pluri-annual cycles, and international prices, domestic price volatility is mainly explained by inconsistent moves of trade policy. Thus, the ability of a policy regime to lower food price volatility does not depend on the nature of the policy instrument only, but also on the government ability to implement it. We define a consistent policy adjustment as a tariff decrease when world price increases and a tariff increase when world price is decreasing. We use an autoregressive conditionally heteroskedastic model of price determination in which prices and prices volatility are jointly estimated, using monthly data over the 1994-2009 period in Kenya.

International audience; The 2007-2008 food crisis and current food price swings led economists to re-evaluate the potential for policy instruments to manage food price volatility. Many developing countries recently pursued price regulation policies, but the difficulties of these policies in promoting price stability is not fully understood. In particular, the ability of a stabilization policy to lower food price volatility does not depend on the nature of the policy instrument only, but also on the institutional conditions of its implementation. Kenya is a particularly interesting case as it is characterized by a rather long tradition of public intervention, and by the persistence of highly volatile prices. The consistency of the policy use appears to be key factor influencing the degree of price volatility. Applied to trade policies, this consistency is defined by the temporal relationship between the tariff level and the international price changes. To test the influence of policy consistency on price volatility, we develop an autoregressive conditionally heteroskedastic model of price determination in which prices and prices volatility are jointly estimated, using monthly data over the 1994-2009 period in Kenya.

Cet article porte sur la faisabilite des politiques destinees a limiter l'instabilite des prix agricoles dans les pays en developpement. En analysant l'experience recente de Madagascar, du Mali et de la Zambie, nous montrons que la capacite des politiques a contenir l'instabilite des prix depend des conditions dans lesquelles ces politiques sont definies et mises en oeuvre, et notamment de : l'appui sur des capacites d'expertise solides ; la maitrise des couts ; la previsibilite des politiques ; et, enfin, du controle de la mise en oeuvre des politiques. Le papier ouvre une reflexion sur le caractere plus ou moins risque des interventions envisagees et sur la replicabilite de ces interventions d'un pays a un autre, dans un contexte ou des recettes " one size fits all " sont privilegiees. (Resume d'auteur)

International audience; Soaring agricultural prices in 2007/2008, followed by decreasing prices in 2009/2010 then a new surge in late 2010/ 2011, have placed the management of agricultural price volatility at the heart of policy debates. Many developing countries have implemented policies to limit agricultural price volatility and its adverse effects, without always achieving the expected results. Analysis of recent experiences in Africa shows that in order to be effective, a policy measure must meet four conditions: it must be based on robust knowledge; it must be predictable; its funding must be secured; and its enforcement must be monitored.; La flambée des prix des produits agricoles de 2007/2008, suivie d'une baisse en 2009/2010, puis d'une nouvelle hausse en 2010/2011, a placé la gestion de l'instabilité des prix agricoles au coeur des débats politiques. De nombreux pays en développement ont mis en oeuvre des politiques pour limiter l'instabilité des prix agricoles et ses effets préjudiciables, sans toujours atteindre les résultats escomptés. L'analyse d'expériences récentes en Afrique montre que, pour être efficace, chaque mesure politique suppose de satisfaire quatre conditions : elle doit s'appuyer sur des connaissances solides ; elle doit être prévisible ; son financement doit être assuré ; et sa mise en oeuvre contrôlée.

L’objectif de cet article est d’etudier la vulnerabilite du developpement de la Nouvelle-Caledonie, a partir de l’analyse de son epargne veritable. Si le calcul de l’epargne veritable ne fait pas apparaitre de signe particulier de vulnerabilite sur la periode 1970-2007, l’analyse de sa trajectoire demontre cependant l’existence d’effets de seuil dans l’activite du secteur nickel pour lesquels la trajectoire de developpement suivie par la Nouvelle-Caledonie ne parait plus soutenable.

Au cours des vingt dernières années, l’évolution des politiques économiques au Nord comme au Sud a été marquée par la mise en place de processus de libéralisation. Selon les contextes institutionnels, la libéralisation peut prendre des formes très contrastées. Au Costa Rica, suite à l’adhésion du pays à l’OMC, la libéralisation de la filière haricot a été très marquée, du fait d’une protection tarifaire basse, alors que celle de la filière lait n’a pas été effective, du fait d’une protection tarifaire élevée, notamment. Ces différences de traitement entre sous-secteurs ont eu un impact direct sur le développement et la durabilité des filières. Cet article éclaire les processus qui conduisent à ces différences par l’analyse des modalités de participation des organisations professionnelles agricoles à la négociation des politiques tarifaires. Les approches du changement institutionnel et de l’action collective sont mobilisées pour mettre en évidence des capacités différentes d’action et d’influence sur le contenu des politiques économiques, selon les filières. Les conditions de réussite de ces processus d’action collective s’inscrivent dans une logique de dépendance de sentier mais aussi dans le cadre d’apprentissages individuels et collectifs qui déterminent les possibilités de changer les règles du jeu. During the last twenty years, the evolution of economic policies in the southern countries has been characterized by the implementation of liberalization processes. According to the institutional contexts, these reforms can show different faces. In Costa Rica, the bean subsector liberalization has experienced a tough process due to a low tariff policy; while in the milk subsector liberalization is not yet effective mainly due to a high tariff policy. These differences have direct impacts on the subsectors’ sustainability. In this paper, we highlight the different processes at work through the analysis of the ways the agricultural organizations’ participate in the definition of tariffs policies. Following the institutional change approach that we combine with an analysis of collective action, we underline differentiated capacities of influencing policy outcomes across the subsectors. We show that the conditions for the success of these collective action processes are in line with a path dependent logic, but also with both individual and collective learning processes among the organisations that determine collective capabilities to chape the rules of the game.

Nous étudions le processus de transfert politique selon lequel les idées et valeurs du développement durable, mûries et véhiculées au niveau international, donnent lieu au niveau national à une recomposition des modes publics d’intervention en milieu rural. Au Mali et à Madagascar, les politiques de développement durable recouvrent des expressions différentes. Nous interprétons ces différences par une analyse comparative des stratégies des acteurs intervenant dans le jeu politique. Nous montrons que ces stratégies renvoient à des processus historiques. L’analyse sur le temps long des processus de construction et de mise en oeuvre des politiques agricoles et rurales dans ces pays permet de mieux comprendre les expressions que revêt aujourd’hui le développement durable. Ideas and values of "sustainable development" are transferred from the international to the national level in policy-making processes and give way to a reshaping of rural development policies: we study this policy transfer in Mali and Madagascar, two countries where sustainable development policies are quite different. We give an interpretation of these differences through a comparative analysis of strategies of actors involved in policy-making processes. We show that these strategies are related to historical processes. In Mali and Madagascar, the long run analysis of agricultural and rural policy making allows us to reach a better understanding of current sustainable development policies.

Au cours des cinq dernieres annees, les prix des matieres premieres agricoles ont ete a la fois hauts et instables. L'augmentation concomitante du niveau des prix et de leur instabilite ravive des inquietudes sur le developpement agricole et la securite alimentaire des pays en developpement, dans les institutions internationales (FAO, G8, G20, OCDE), comme dans les instances en charge des politiques nationales. Dans la foulee des hausses des cours du debut 2011, une declaration ministerielle du G20 appelait fin juin 2011 a limiter la volatilite des prix alimentaires. Ainsi, la question des politiques de stabilisation a fait un retour remarquable dans les arenes internationales de negociation, reprenant les debats consecutifs a la hausse des cours des matieres premieres de la deuxieme moitie de la decennie 1970. Les contributions rassemblees dans ce numero de la Revue Tiers Monde font etat des principaux elements des debats actuels sur la nature et les enjeux des evolutions recentes des cours des matieres premieres pour les pays en developpement les plus pauvres. (Resume d'auteur)

Les organisations de producteurs agricoles sont souvent considérées comme un moyen de permettre un meilleur accès des producteurs aux marchés agricoles. Notre étude montre que cette affirmation n’est valable que dans le cas de filières présentant des caractéristiques techniques relativement complexes, nécessitant une coordination entre producteurs et opérateurs aval pour la commercialisation. Dans le cas de filières à caractéristiques techniques plus simples, la coordination par le marché permet un accès facile des petits producteurs. Dans les filières où les exigences des opérateurs aval sont élevées, on peut observer une exclusion de toute une frange de producteurs, même en présence d’organisations de producteurs agricoles. Nos résultats militent ainsi pour une attention accrue des pouvoirs publics aux formes collectives d’organisation et le développement de politiques publiques à même de faciliter l’accès des producteurs familiaux aux marchés agricoles., Agricultural producer organizations are often considered as a way of enabling producers to gain better access to agricultural markets. Our study shows that this claim is only valid in product chains with relatively complex technical characteristics that require coordination between producers and downstream operators for marketing products. In product chains with simpler technical characteristics, the coordination by the market enables easy access for small producers. In product chains where downstream operators have greater requirements, we find a whole group of producers are excluded even when there are agricultural producer organizations. Our findings suggest that government needs to pay closer attention to collective forms of organization and policies need to be developed to help small producers gain better access to agricultural markets.