Previous studies conducted in the study area recommended an irrigation scheme as a much desired intervention in order to reduce poverty levels, reduce unemployment, provide a livelihood for the households and trigger development. The Land Bank of South Africa has shown keen interest to provide funds to set up an irrigation scheme in Guquka. Absence of peoples’ involvement and farmer participation has been identified as one of the causes of poor performance of smallholder irrigation schemes in South Africa. The poor performance of smallholder irrigation projects in South Africa provided a good basis for exploring factors that could possibly affect farmer participation and the success of the proposed irrigation scheme. This knowledge would be useful to providers of extension services, capital providers, policy makers and the recipients of the proposed irrigation scheme. The main objective of this study was to investigate the factors affecting the willingness of farming households to participate in the proposed irrigation scheme. This investigation helped to analyse demographic; socio economic situation; farming practices; economic activities; water sources, uses and management in the study area. The major tool of enquiry in this study was the questionnaire which was used to collect data from the households. Household and farm characteristics were collected using structured questionnaires with the help of locally recruited and trained enumerators. The data used for the empirical analysis was obtained from a survey of 50 farming households in Guquka, in the Eastern Cape Province of South Africa. The following variables were selected to determine the scope of their influence on farmer willingness to participate in the proposed scheme: age; membership in local group; investment in agriculture, educational level of the farmers, knowledge, household size, labour and gender. A logit model was used to determine the extent to which these selected characteristics influence the willingness of farmers to participate in the proposed irrigation scheme. The results showed that willingness to participate in the scheme was significantly influenced by the afore mentioned variables as well as knowledge about the planned irrigation scheme which is mainly provided by extension agents; and total household income. Age was found to decrease the willingness of farmers to participate in irrigation. A positive association existed between participation and the following variables; membership in local group, investment in agriculture, educational level of the farmers and knowledge. On the other hand, household size, labour and gender were not significant variables affecting willingness to participate in the proposed irrigation scheme. Based on the results from the logit regression model, it can be concluded that membership in a local group, investment in agriculture, education, knowledge and total household income are responsible for increasing the probability of participation. The negative relationship on age and participation indicates that the older the person is, the lesser the chances of participation. It is recommended that stakeholders should improve access to education and farmer training programmes. Support systems to disseminate information, training and knowledge should be enhanced. Improving institutional support and access to financial services should be prioritised by the stakeholders in the study area. Further studies on building institutional capacity and a cost benefit analysis of irrigation options in the study area are recommended.

Identifying pathways of agricultural development that enable substantial productivity improvements is of prime importance for food security and human development across Sub-Saharan Africa. To ensure long-term welfare for its people and landscapes, it is imperative that such agricultural transformations are environmentally sustainable. This study explores the case of Ethiopia and aims to assess constraints and opportunities for a sustainable agricultural transformation, by analysing a) the governance context, b) narratives of agricultural development, and c) strategies employed by “green” non-state actors in the agricultural sector to lever change in the direction they perceive as desirable. By assessing the governance structure, the study finds that many non-state actors face significant legal and practical barriers to action, and that the strong government domination and rigid structures provide limited opportunities for influence. Further, the study finds that agricultural policy is dominated by a “Green Revolution”-inspired narrative focused on production and productivity, although food security and environmental rehabilitation narratives exist alongside. Issues of agricultural production and natural resource management are found to be largely decoupled in policy, which constitutes another barrier for green non-state actors working across the divide. Given these challenging conditions, green non-state actors in Ethiopia choose a strategy of close collaboration with government institutions, which, while offering the possibility of large-scale impact, may also reduce the prospects for more radical change. Applying current theories of sustainability transformations to a new type of system, the study concludes with a call for new conceptualisations of endogenous and exogenous change in future research to ensure that the theory fits a broader range of social-ecological realities.

Pour prévoir la production, les systèmes de surveillance de la sécurité alimentaire doivent être renseignés par des données sur les surfaces cultivées et sur le rendement. Ces données peuvent être estimées par les systèmes d'observations satellitaires à moyenne résolution spatiale, qui, par leur vision synoptique, constituent une source d'information particulièrement adéquate. En Afrique de l'Ouest, l'estimation des surfaces cultivées par télédétection reste cependant problématique en raison d'un domaine cultivé fragmenté, d'une grande hétérogénéité spatiale due aux conditions environnementales et aux pratiques culturales, et de la synchronisation des phénologies des agrosystèmes et des écosystèmes liée au régime des précipitations. Dans ce contexte, cette thèse présente, en trois volets, des développements méthodologiques originaux pour la caractérisation des systèmes agricoles d'Afrique de l'Ouest par télédétection. Les méthodes ont été développées à partir de séries temporelles MODIS (250 m à 500 m de résolutionspatiale) acquises sur le Mali. (i) La cartographie des surfaces cultivées a été réalisée à partir d'indices spectraux, spatiaux, texturaux et temporels dérivés des images. Deux approches ont été appliquées : une approche de type ISODATA consécutive à une segmentation du territoire basée sur les images MODIS et une approche de fouille de données basée sur des « motifs séquentiels ». Les produits cartographiques obtenus présentent une meilleure précision que les produits globaux « occupation du sol » existants (70% vs 50% en moyenne). Cependant, une part importante des erreurs d'omission et de commission (de 20% à 40%) reste incompressible en raison de la fragmentation du domaine cultivé. (ii) La cartographie des types de systèmes agricoles a nécessité un premier travail de typologie effectué à partir d'une BD d'enquêtes de terrain de l'Institut d' Economie Rurale de Bamako sur 100 villages. Trois types de systèmes agricoles ont été déterminés à l'échelle du village : céréales dominantes (mil, sorgho), cultures intensives dominantes (maïs, coton) et mélange de sorgho et de coton. La classification des systèmes agricoles à partir des indicateurs de télédétection précédemment cités a été produite par un algorithme de type Random Forest avec une précision globale de 60%. Les résultats mettent en évidence une combinaison optimale d'indicateurs comprenant le NDVI ainsi que la texture pour la caractérisation des systèmes agricoles. (iii) Enfin, pour le suivi des cultures, le produit phénologique MODIS a été testé et évalué à partir de variables phénologiques obtenues par simulations agro-météorologiques du modèle de plante SARRA-H. Les résultats montrent que ce produit comporte des incohérences dues au fort ennuagement de début de saison des pluies. Après suppression des données aberrantes, on montre que les dates de transition phénologique des surfaces cultivées issues de MODIS sont plus précoces de 20 jours comparées aux sorties du modèle de culture, en raison notamment de la nature mixte « agro-écosystème » des surfaces à l'échelle du pixel MODIS. Les résultats de cette thèse permettent de dégager de nouvelles pistes de couplage entre télédétection, données de terrain et modélisation agro-météorologique en apportant une information continue dans le temps et dans l'espace sur la caractérisation du domaine cultivé au « Sahel ». / For food security systems, data on cultivated surfaces and yields are a prerequisite for agricultural production forecast. Moderate resolution satellite remote-sensing systems offer a synoptic vision that makes them a particularly appropriate information source for the estimation of such data. However, the estimation of cultivated surfaces is still challenging in West Africa, because of highly fragmented farmland, specific weather conditions resulting in high regional variability in terms of agricultural systems and practices, and synchronized phenology of crops and natural vegetation due to the rainfall regime. In this context, this thesis presents three original methodological approaches for the characterization of agricultural systems in West Africa by remote sensing. These methods were developed using MODIS time series (from 250 to 500 m spatial resolution) acquired for Mali. (i) The mapping of cultivated areas was carried out with spectral, spatial and textural indices derived from the images. Two approaches were chosen: one of ISODATA type following a segmentation of the territory based on MODIS imagery, and the other of data mining type based on ‘sequential patterns'. The crop map obtained showed a better precision than that of the existing land cover global products (70% vs 50% in average). Furthermore, it was shown that a significant part of user and producer errors (20 to 40%) could not be compressed due to farmland fragmentation. (ii) The mapping of agricultural system types first required the definition of a typology derived from an IER (Institute of Rural Economy in Mali) field survey data base on 100 villages. Three types of agricultural systems were determined at the village scale: mainly cereals (millet, sorghum), mainly intensive crops (maize, cotton) and a mixture of sorghum and cotton. The classification of agricultural systems using the aforementioned remote sensing indicators was carried out by a Random Forest type algorithm with an overall accuracy of 62%. Results bring to light the important part played by temporal NDVI and texture in agricultural system characterization. (iii) Finally, for crop monitoring, the MODIS phenological product was tested and assessed using phenological variables obtained from agro-meteorological simulations made by the SARRA-H plant model. Results show that this product contains inconsistencies due to the significant cloud cover linked with the start of the raining season. After the suppression of incongruous data, the phenological transition dates for crop land derived from MODIS were shown to be earlier by 20 days than the SARRA-H-simulated transition dates, due mainly to the ‘agro-ecosystem' mixed nature of surfaces at MODIS pixels scale. The results of this thesis highlight new possibilities for the combinination of remote sensing, field data and agro-meteorological modelling, delivering nonstop information in time and space on the characterization of “Sahel” farmland.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / Este trabalho se propÃs a avaliar as alteraÃÃes nas atividades microbiana, quÃmica e fÃsica em solo sob sistemas agrÃcolas anuais e perenes na regiÃo da Chapada do Apodi - CE. Procurou-se testar a hipÃtese de que o uso agrÃcola de Ãreas sob sistemas anuais e perenes causam alteraÃÃes ambientais que influenciam a biomassa e a atividade microbiana do solo, reduzindo-a em relaÃÃo a Ãreas sob vegetaÃÃo natural. Foram selecionadas duas Ãreas com respectivas testemunhas (vegetaÃÃo natural); a primeira sob cultivo de bananeiras (Fazenda Frutacor) e a outra sob cultivo de rotaÃÃo milho e soja (Fazenda Faedo). Coletaram-se amostras compostas de solo em trÃs profundidades (0-5, 5-15 e 15-25 cm) com quatro repetiÃÃes. Nas amostras coletadas foram realizadas anÃlises fÃsicas, quÃmicas e microbiolÃgicas. Fisicamente, observou-se uma elevaÃÃo no teor de argila, com o aumento da profundidade na Ãrea cultivada com banana e na mata natural pivot. Em relaÃÃo aos atributos quÃmicos do solo, os riscos potenciais de salinidade e de saturaÃÃo por sÃdio aparentemente sÃo desprezÃveis. As prÃticas de manejo reduziram o N e o carbono orgÃnico total nos solos das Ãreas sob cultivo. Quanto à microbiologia dos solos, o carbono da biomassa microbiana e a populaÃÃo de fungos micorrÃzicos arbusculares foram mais elevados na profundidade de 0-5cm do solo. A respiraÃÃo basal do solo mostrou que os solos das Ãreas avaliadas tÃm baixa atividade microbiana quando comparados a solos do Cerrado. A atividade e produÃÃo da arilsulfatase e da fosfatase Ãcida foram estimuladas possivelmente, pela competiÃÃo dos Ãnions H2PO4 - e SO4 - pelos mesmos sÃtios de adsorÃÃo nos colÃides do solo, nas Ãreas de banana e rotaÃÃo milho e soja. A maior atividade da enzima β-glucosidase ocorreu nas Ãreas cultivadas, influenciada pela quantidade e qualidade do resÃduo vegetal retornado ao solo. / This work had the proposed to evaluate the alterations in the microbial activities, chemistry and physics in soil under annual and perennial agricultural systems in the area of the Chapada do Apodi - CE. It tried to test the hypothesis that the agricultural use of areas under annual and perennial systems causes environmental alterations that they influence the biomass and the microbial activity of the soil, reducing it in relation to areas under natural vegetation. Two areas were selected with respective witness (natural vegetation); the first under cultivation of banana trees (Fazenda Frutacor) and the other under cultivation of rotation corn and soy (Fazenda Faedo). Samples composed of soil were collected in three depths (0-5, 5-15 and 15-25 cm) with four repetitions. In the collected samples physical analyses, chemistries and microbiological were accomplished. Physically, an elevation was observed in the clay text, with the increase of the depth in the area cultivated with banana and in the forest natural pivot. In relation to the chemical attributes of the soil, the potential risks of salinity and of saturation for sodium seemingly are worthless. The handling practices reduced N and the total organic carbon in the soils of the areas under cultivation. With relationship to the microbiology of the soils, the carbon of the microbial biomass and the population of arbuscular mycorrhizal fungi were more elevated in the depth of 0-5cm of the soil. The basal breathing of the soil identified that the soils of the appraised areas have microbial when compared low activity the soils of the Cerrado. The activity and production of the arylsulphatase and of the acid phosphatase were stimulated possibly, for the competition of the anions H2PO4- and SO4- for the same ranches of adsorption in the coloides of the soil, in the banana areas and rotation corn and soy. The largest activity of the enzyme β-glucosidase happened in the cultivated areas, influenced by the amount and quality of the vegetable residue come back to the soil.

Made available in DSpace on 2017-07-10T19:25:02Z (GMT). No. of bitstreams: 1 Veruschka Rocha Medeiros Andreolla.pdf: 1722558 bytes, checksum: bb4f5cea73e94834a80a8b228456a12b (MD5) Previous issue date: 2005-08-03 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The objective of this work was to verify the influence of pasture in side of agriculture-cattle integration on the physical characteristics of the ground, to evaluate the influence of these parameters and the staggered of a planter (connecting rod and record of cut) on the grain yield of the soy and to quantify the energy performance of the planter in ground submitted to the trampling of animals. An experiment in Oxissol, situated was become fulfilled in the Santa Maria Farm, Santa Tereza do Oeste - PR, in the period of April of 2003 the April of 2004. The delineation in subdivided parcels "Split Plot" entirely randomized was used. The main treatments had been composed by pasture with the ground humid or wet, pasture with alone dry and without pasture, with a capacity of 26 U.A. ha 1. The secondary treatments had been composites for the mechanisms staggered of the planter (double connecting rod or records for deposition of the seasoning). Each plot with a area 1600 m2 (50 x 32 m) and the subparcels had dimensions of 20 x 8 m, with area of 160 m2. Physical properties of the ground, parameters of performance of the tractor-planter set and grain yield of the soy had been evaluated. The values gotten in the experiments had shown the effect of the cattle trampling in compacting the ground in the layer until the 10 cm initial. The sharp peak in the resistance to the penetration the 5 cm can be indicating that the maximum mobilization of the resistance of the ground occurred at the depth 5 cm. The root of the soy had promoted the decompaction of the ground, showing a trend of return to the initial structural condition of it. The tension-deformation analysis corroborated the results of the assays of compacting in laboratory, as well as the deformation curve revealed consistent with the profiles of resistance to the penetration in the field. The action of the cattle trampling on the ground modified the density conditions and cone index, however was not enough to intervene with the demand of power in the three studied conditions. The planter with staggered of records had exerted minor power and snatch force and the speed of displacement of the set was about 6,4 % greater in relation to the staggered connecting rod. The grain yield of the soy was not modified significantly by the handling systems, but when the mechanism was used connecting rod in the planter, the production of grains bigger when was compared with the planter equipped with staggered of records. / O objetivo deste trabalho foi verificar a influência do pastejo em área de integração lavoura-pecuária sobre as características físicas do solo, avaliar a influência desses parâmetros e dos elementos sulcadores de uma semeadora (haste e disco de corte) sobre a produtividade da soja e quantificar o desempenho energético da semeadora em solo submetido ao pisoteio do gado. Realizou-se um experimento em LATOSSOLO VERMELHO Eutroférrico, situado na Fazenda Santa Maria, em Santa Tereza do Oeste PR, no período de abril de 2003 a abril de 2004. Foi utilizado o delineamento em parcelas subdivididas Split Plot inteiramente casualizado. Os tratamentos principais foram compostos pelo pastejo com o solo úmido ou molhado, pastejo com solo seco e sem pastejo, com uma lotação de 26 U.A. ha 1 (unidade animal por hectare). Os tratamentos secundários foram compostos pelos elementos sulcadores da semeadora (haste ou discos duplo para deposição do adubo). Cada parcela com um total de 1600 m2 (50 x 32 m) e as subparcelas tinham dimensões de 20 x 8 m, com total de 160 m2. Foram avaliadas propriedades físicas do solo, variáveis de desempenho do conjunto trator-semeadora e rendimentos de grãos da soja. Os valores obtidos nos experimentos mostraram o efeito do pisoteio do gado em compactar o solo na camada até os 10 cm iniciais. O pico pronunciado na resistência à penetração a 5 cm pode ser indicador de que a máxima mobilização da resistência do solo ocorreu à profundidade 5 cm. Os sulcadores de haste promoveram a descompactação do solo conciliando assim com o efeito descompactador das raízes da aveia e da soja, mostrando uma tendência de retorno à condição estrutural inicial do mesmo. A análise tensão-deformação corroborou os resultados dos ensaios de compactação em laboratório, assim como a curva de deformação mostrou-se consistente com os perfis de resistência à penetração no campo. A ação do pisoteio do gado sobre o solo alterou as condições de densidade e resistência à penetração, entretanto não foi suficiente para interferir na demanda de potência nas três condições estudadas. A semeadora com sulcadores de discos exigiu menor força de tração e potência e a velocidade de deslocamento do conjunto foi cerca de 6,4 % maior em relação ao sulcador haste. O rendimentos de grãos da soja não foi alterado significativamente pelos sistemas de manejo, mas quando foi utilizado o elemento haste na semeadora, a produção de grãos foi maior quando comparada com a semeadora equipada com sulcadores de discos.

Made available in DSpace on 2017-05-12T14:48:24Z (GMT). No. of bitstreams: 1 Veruschka Rocha Medeiros Andreolla.pdf: 1722558 bytes, checksum: bb4f5cea73e94834a80a8b228456a12b (MD5) Previous issue date: 2005-08-03 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The objective of this work was to verify the influence of pasture in side of agriculture-cattle integration on the physical characteristics of the ground, to evaluate the influence of these parameters and the staggered of a planter (connecting rod and record of cut) on the grain yield of the soy and to quantify the energy performance of the planter in ground submitted to the trampling of animals. An experiment in Oxissol, situated was become fulfilled in the Santa Maria Farm, Santa Tereza do Oeste - PR, in the period of April of 2003 the April of 2004. The delineation in subdivided parcels "Split Plot" entirely randomized was used. The main treatments had been composed by pasture with the ground humid or wet, pasture with alone dry and without pasture, with a capacity of 26 U.A. ha 1. The secondary treatments had been composites for the mechanisms staggered of the planter (double connecting rod or records for deposition of the seasoning). Each plot with a area 1600 m2 (50 x 32 m) and the subparcels had dimensions of 20 x 8 m, with area of 160 m2. Physical properties of the ground, parameters of performance of the tractor-planter set and grain yield of the soy had been evaluated. The values gotten in the experiments had shown the effect of the cattle trampling in compacting the ground in the layer until the 10 cm initial. The sharp peak in the resistance to the penetration the 5 cm can be indicating that the maximum mobilization of the resistance of the ground occurred at the depth 5 cm. The root of the soy had promoted the decompaction of the ground, showing a trend of return to the initial structural condition of it. The tension-deformation analysis corroborated the results of the assays of compacting in laboratory, as well as the deformation curve revealed consistent with the profiles of resistance to the penetration in the field. The action of the cattle trampling on the ground modified the density conditions and cone index, however was not enough to intervene with the demand of power in the three studied conditions. The planter with staggered of records had exerted minor power and snatch force and the speed of displacement of the set was about 6,4 % greater in relation to the staggered connecting rod. The grain yield of the soy was not modified significantly by the handling systems, but when the mechanism was used connecting rod in the planter, the production of grains bigger when was compared with the planter equipped with staggered of records. / O objetivo deste trabalho foi verificar a influência do pastejo em área de integração lavoura-pecuária sobre as características físicas do solo, avaliar a influência desses parâmetros e dos elementos sulcadores de uma semeadora (haste e disco de corte) sobre a produtividade da soja e quantificar o desempenho energético da semeadora em solo submetido ao pisoteio do gado. Realizou-se um experimento em LATOSSOLO VERMELHO Eutroférrico, situado na Fazenda Santa Maria, em Santa Tereza do Oeste PR, no período de abril de 2003 a abril de 2004. Foi utilizado o delineamento em parcelas subdivididas Split Plot inteiramente casualizado. Os tratamentos principais foram compostos pelo pastejo com o solo úmido ou molhado, pastejo com solo seco e sem pastejo, com uma lotação de 26 U.A. ha 1 (unidade animal por hectare). Os tratamentos secundários foram compostos pelos elementos sulcadores da semeadora (haste ou discos duplo para deposição do adubo). Cada parcela com um total de 1600 m2 (50 x 32 m) e as subparcelas tinham dimensões de 20 x 8 m, com total de 160 m2. Foram avaliadas propriedades físicas do solo, variáveis de desempenho do conjunto trator-semeadora e rendimentos de grãos da soja. Os valores obtidos nos experimentos mostraram o efeito do pisoteio do gado em compactar o solo na camada até os 10 cm iniciais. O pico pronunciado na resistência à penetração a 5 cm pode ser indicador de que a máxima mobilização da resistência do solo ocorreu à profundidade 5 cm. Os sulcadores de haste promoveram a descompactação do solo conciliando assim com o efeito descompactador das raízes da aveia e da soja, mostrando uma tendência de retorno à condição estrutural inicial do mesmo. A análise tensão-deformação corroborou os resultados dos ensaios de compactação em laboratório, assim como a curva de deformação mostrou-se consistente com os perfis de resistência à penetração no campo. A ação do pisoteio do gado sobre o solo alterou as condições de densidade e resistência à penetração, entretanto não foi suficiente para interferir na demanda de potência nas três condições estudadas. A semeadora com sulcadores de discos exigiu menor força de tração e potência e a velocidade de deslocamento do conjunto foi cerca de 6,4 % maior em relação ao sulcador haste. O rendimentos de grãos da soja não foi alterado significativamente pelos sistemas de manejo, mas quando foi utilizado o elemento haste na semeadora, a produção de grãos foi maior quando comparada com a semeadora equipada com sulcadores de discos.

This thesis presents the findings of an investigation of the spatial and temporal distribution of soil macrofauna at multiple scales within smallholder agriforestry fields in a remote, mountainous area of western Honduras. Since 1990, smallholder farmers in the study area have switched from traditional slash-and-burn agriculture to a form of slash-and-mulch agriforestry based on cultivating maize, beans and sorghum amongst dispersed trees. The principal objective was to examine the influence of the slash-and-mulch agricultural system on soil macrofauna abundance, biomass and community composition, and relate soil macrofauna distribution patterns to environmental variables. The initial stage of the research comprised transect-based sampling of soil macrofauna and biophysical variables in four common land uses of the study area. All four land uses (secondary forest, young milpa (agriforestry), mature milpa, and pasture) supported abundant, diverse and heterogeneous soil macrofauna communities, with few notable differences in soil macrofauna distribution among land uses. The most abundant soil macrofauna taxa were termites, ants, earthworms and beetles. Of the 'explanatory' environmental variables that were measured (including land use and selected soil properties, vegetation characteristics and topographic variables), those that had the strongest relationships with soil macrofauna abundance were land use, tree density and soil organic matter content. The second stage of the research was spatially-orientated and used stratified sampling based on within-field differences in farmer-defined soil type, as well as grid-based sampling of soil macrofauna surface activity. There was substantial within-field variation in soil type and topography, which was related to distribution patterns of at least one agriculturally-important soil macrofauna taxon. Earthworm activity was higher in areas of fertile soil and lower slope positions. At a finer scale, there was a positive spatial correlation between tree distribution and earthworm casting activity. The final phase situated the biophysical research in the local socio-economic context through participant observation and interviews with farmers. The results of the three phases of the study were incorporated into an original conceptual model of the relationships among soil macrofauna and environmental variables in the study area across multiple spatial scales and along a chronosequence of land use changes. Specific pointers are provided for further research on the role of soil fauna in influencing soil structure, nutrient cycling and pest species abundance, and for further investigating local knowledge and the socio-economic and cultural drivers of land use change.

Identifier les « hotspots » environnementaux de l’agriculture est crucial dans un contexte où l’humanité doit produire plus et polluer moins. L’Analyse du Cycle de Vie (ACV) est un outil puissant pour évaluer les impacts environnementaux des systèmes agricoles, mais souffre encore de lacunes, notamment pour l’évaluation des impacts lies à la consommation d’eau douce et la salinisation des eaux et des sols. La complexité fondamentale réside dans le double statut de l’eau et du sol en ACV qui sont à la fois des ressources et des compartiments. Les trois questions auxquelles la thèse répond sont: Comment mieux évaluer les impacts associés aux flux d’eau et de sels? Quel modèle devrait être développé pour un inventaire pertinent des flux d’eau et de sels au champ? Le modèle développé est-il opérationnel pour une étude ACV d’une culture pérenne? La première question a été traitée grâce à une revue de la littérature sur les impacts salinisations en ACV. Cette revue détaille les principaux mécanismes environnementaux de la salinisation, les facteurs impliqués, et discute du statut du sol et de l’eau, notamment en définissant une frontière cohérente entre technosphère et écosphere. Pour répondre à la seconde question, une analyse critique des bases de données d’inventaire eau et ACV de produits agroalimentaires a montré leur inaptitude pour l’ecodesign basé sur l’ACV: elles fournissent des estimations d’eau consommée théorique, se basent sur des données et méthodes qui présentent des limites, et ne permettent pas le calcul des impacts liés à l’usage consommateur et dégradant de l’eau. Pour l’ecodesign des systèmes agricoles basé sur l’ACV, l’inventaire des flux d’eau et de sels devrait se fonder sur un modèle simulant l’évapotranspiration, la percolation profonde et le ruissèlement, prenant en compte les spécificités de la culture, les conditions pédoclimatiques et les pratiques agricoles. Le modèle Aquacrop de la FAO est un modèle pertinent et opérationnel pour les cultures herbacées, mais il n’existe pas de modèle dédié aux cultures pérennes pour le moment. Pour pallier à ce manque, un modèle simple et « sur mesure », appelé E.T., a été élaboré pour l’inventaire des flux d’eau et de sels au champ, pour les cultures annuelles et pérennes. Le modèle combine un bilan journalier de l’eau et des sels, prenant en compte le sol, le climat, les pratiques agricoles et d’éventuels stress salin ou hydrique. Un premier test du modèle a démontré son pouvoir discriminant des pratiques agricoles et sa robustesse. Son domaine de validité peut être étendu et sa précision augmentée grâce aux recommandations fournies. E.T. a aussi été appliquée dans une ACV de Mandarine cultivée au Maroc. Pour la plupart des catégories d’impacts, l’usage d’électricité pour l’irrigation était un contributeur majeur, révélant une forte connexion entre l’eau et l’énergie. L’usage d’eau avait une contribution majeure aux dommages sur les trois aires de protection. Dans l’ensemble, pour améliorer davantage la prise en compte des impacts liés à l’usage de l’eau (dont la salinisation) nous recommandons d’adopter une approche plus mécaniste et hydrologique. / 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.

Os estudos dos sistemas agrícolas em geral, incluindo os sistemas de produção frutícola, com freqüência abordam a sua configuração e dinâmica numa ótica ex-post à sua origem e formação. Neste trabalho os sistemas agrícolas foram analisados numa ótica ex-ante. As variáveis determinantes da emergência dos sistemas de produção frutícola foram identificadas, com vistas à construção de um modelo de emergência destes sistemas. Inicialmente, por meio de entrevistas com experts, foram identificadas as variáveis percebidas como determinantes da emergência de um sistema de produção frutícola consolidado, localizado no Vale do Rio São Francisco, na Região Nordeste do Brasil. A seguir, estas variáveis foram avaliadas, quanto à sua importância, na emergência de oito sistemas de produção frutícola menos desenvolvidos, localizados no estado do Rio Grande do Sul, sendo que destes, cinco sistemas são focalizados na citricultura e três na persicultura. Assim foi possível determinar um conjunto de variáveis que representam as condições básicas para a emergência de sistemas de produção frutícola. As condições edafoclimáticas, a demanda do mercado, o apoio tecnológico, a existência de mão-de-obra especializada, a infra-estrutura produtiva na região, as condições das estradas e a existência de uma liderança foram as variáveis que receberam os maiores escores de importância para a emergência. As variáveis relativas à logística, ao apoio governamental, ao envolvimento de múltiplos produtores, instituições e empresas complementares do sistema de produção frutícola, complementam os condicionantes da plena expressão das propriedades características dos sistemas emergentes. A identificação dessas variáveis pode ajudar nas decisões sobre iniciativas de estímulo de emergência de sistemas de produção frutícola desejados, embora a configuração do sistema resultante destas iniciativas não possa ser antevista. O próximo passo seria testar essas variáveis em outros tipos de sistemas agrícolas, para modelagem de uma equação da emergência dos sistemas agrícolas em geral. / General studies on agricultural systems, including fruit production systems, often approach their configuration and dynamics under an ex-post viewpoint to their origin and formation. In this work the agricultural systems were analyzed in their ex-ante aspects. The variables, which determine the emergence of fruit production systems were identified, and considered for the construction of a model of emergence of these systems. At first, through interviews with experts, it was possible to identify the variables perceived as determinant for the emergence of a consolidated fruit production system, located in the Sao Francisco River Valley, Brazilian northeastern region. Later, such variables were evaluated in terms of importance for the emergence of eight less developed fruit production systems located in the state of Rio Grande do Sul, of which five were focused on citrus culture, and three were focused on peach culture. A set of variables were determined that represent the basic conditions for emergence of fruit production systems, which might represent the bases for emergence and development of other fruit production systems. Edaphic-climatic conditions, market demand, technological support, availability of skilled labor force, productive infra-structure in the region, road conditions, and the existence of leadership were the variables that received the highest scores of importance for the emergence. The variables involving infrastructure and logistics, government support, market and participation of multiple producers, institutions and complementary companies of the fruit system complete the other conditioning aspects of the full expression of the characteristic properties of emerging systems. The identification of these variables could help in processes of decision making, regarding initiatives to stimulate emergence of the fruits production systems, although the resulting configuration of the systems cannot be forecasted for sure. The next step in this kind of study would be to test these variables in other agricultural systems types, for modeling of an equation of the agricultural systems emergence in general.

Os estudos dos sistemas agrícolas em geral, incluindo os sistemas de produção frutícola, com freqüência abordam a sua configuração e dinâmica numa ótica ex-post à sua origem e formação. Neste trabalho os sistemas agrícolas foram analisados numa ótica ex-ante. As variáveis determinantes da emergência dos sistemas de produção frutícola foram identificadas, com vistas à construção de um modelo de emergência destes sistemas. Inicialmente, por meio de entrevistas com experts, foram identificadas as variáveis percebidas como determinantes da emergência de um sistema de produção frutícola consolidado, localizado no Vale do Rio São Francisco, na Região Nordeste do Brasil. A seguir, estas variáveis foram avaliadas, quanto à sua importância, na emergência de oito sistemas de produção frutícola menos desenvolvidos, localizados no estado do Rio Grande do Sul, sendo que destes, cinco sistemas são focalizados na citricultura e três na persicultura. Assim foi possível determinar um conjunto de variáveis que representam as condições básicas para a emergência de sistemas de produção frutícola. As condições edafoclimáticas, a demanda do mercado, o apoio tecnológico, a existência de mão-de-obra especializada, a infra-estrutura produtiva na região, as condições das estradas e a existência de uma liderança foram as variáveis que receberam os maiores escores de importância para a emergência. As variáveis relativas à logística, ao apoio governamental, ao envolvimento de múltiplos produtores, instituições e empresas complementares do sistema de produção frutícola, complementam os condicionantes da plena expressão das propriedades características dos sistemas emergentes. A identificação dessas variáveis pode ajudar nas decisões sobre iniciativas de estímulo de emergência de sistemas de produção frutícola desejados, embora a configuração do sistema resultante destas iniciativas não possa ser antevista. O próximo passo seria testar essas variáveis em outros tipos de sistemas agrícolas, para modelagem de uma equação da emergência dos sistemas agrícolas em geral. / General studies on agricultural systems, including fruit production systems, often approach their configuration and dynamics under an ex-post viewpoint to their origin and formation. In this work the agricultural systems were analyzed in their ex-ante aspects. The variables, which determine the emergence of fruit production systems were identified, and considered for the construction of a model of emergence of these systems. At first, through interviews with experts, it was possible to identify the variables perceived as determinant for the emergence of a consolidated fruit production system, located in the Sao Francisco River Valley, Brazilian northeastern region. Later, such variables were evaluated in terms of importance for the emergence of eight less developed fruit production systems located in the state of Rio Grande do Sul, of which five were focused on citrus culture, and three were focused on peach culture. A set of variables were determined that represent the basic conditions for emergence of fruit production systems, which might represent the bases for emergence and development of other fruit production systems. Edaphic-climatic conditions, market demand, technological support, availability of skilled labor force, productive infra-structure in the region, road conditions, and the existence of leadership were the variables that received the highest scores of importance for the emergence. The variables involving infrastructure and logistics, government support, market and participation of multiple producers, institutions and complementary companies of the fruit system complete the other conditioning aspects of the full expression of the characteristic properties of emerging systems. The identification of these variables could help in processes of decision making, regarding initiatives to stimulate emergence of the fruits production systems, although the resulting configuration of the systems cannot be forecasted for sure. The next step in this kind of study would be to test these variables in other agricultural systems types, for modeling of an equation of the agricultural systems emergence in general.