The population in the high mountains of the northwest provinces of Vietnam belongs to the poorest population in the country. Among the reasons behind this are the high frequency of minority groups in the region and the infertile soils of the steep slopes. As a result of the diversified elevation in northwest Vietnam, farmers are forced to cultivate fields with a gradient of more than 25 %. Additionally, the heavy rainfall events in the region increase the runoff, which is the main mechanism in erosion. Erosion leads to loss of bulk soil, and large losses of plant nutrients. In addition to erosion, nutrient leakage also occurs especially where a surplus of nutrients is applied. This is often the case when fertilizers are not applied with care. Nutrients are a limiting factor within agriculture, and with better nutrient management, the yield, and thus the farmers' economy, increases.The overall aim of this study was to locate and quantify sources and sinks of nutrients within the ten chosen farms. To achieve this aim, two specific objectives were researched. The first objective was to quantify the farm gate balance to get an overall idea of nutrient surplus and deficit and environmental risks. The second objective was to quantify and map out the internal flows i.e the field balances and the nutrients lost during manure storage. This will help locate sources and sinks of nutrients within each farm. Additionally, it will show if the grass strips help absorb nutrients lost through erosion.The study was carried out in Mai Son District in Son La Province in northwest Vietnam. The data was mainly collected through interviews with farmers on ten farms in the study area, as well as observations made during the field visit. Five farms with cows were chosen, while five farms had no cows. The farms mainly grew maize, longan, mango, and forage grass. Additionally, analyses were made on the nitrogen, phosphorous and potassium concentration in the compost, and the nitrogen concentration of the Guinea grass (Panicum maximum Jacq) which made up the grass-strips in the sloping land. The analysis of Guinea leaves was made to calibrate the SPAD-meter used in the field to gather nitrogen-values of the grass strips in the fields.The calculated balances indicated that the elements N, P and K on each farm varied between 32 to 580 kg/ha/year for N, -680 (16) to 53 kg/ha/year for P and -130 to 220 kg/ha/year for K. It also showed that Guinea grass, when grown along the contour lines, did as anticipated; absorb excess nutrients from the soil. However, the result shows that the forage grass mines the soil from potassium. Finally, the result showed that the farmers seem to over fertilize the plants. When estimating the nutrient lost from manure storage, the calculation showed significant losses of both nitrogen, phosphorus, and potassium during storage.The result of the study shows that the handling of manure, choice of compost or mineral fertilizer and fodder and use of grass strips on the farms affects the nutrient loss within the farm. It also shows that a system with forage grass on the contour is, above all, effective when used on farms with grass eating animals as the farmers otherwise don’t harvest the grass.

No description available.

L’effet des pratiques agroécologiques traditionnelles et innovantes sur les paramètres de fertilité des sols agricoles cultivés en grande culture a été étudié. L’étude a été réalisée en milieu paysan dans la zone agricole de Sampieri à l’Est du Burkina Faso en milieu soudano-sahélien sur des lixisols. La perception des agriculteurs sur la dégradation des sols et la pratique de l’agroécologie, les déterminants de l’adoption des pratiques agroécologiques et l'effet de ces pratiques sur les paramètres physiques, chimiques et microbiologiques ont été déterminés pour des parcelles sous pratiques agroécologiques, versus traditionnelles, comparés aux sols témoins. L’effet de ces pratiques sur le rendement (grains et pailles) du sorgho a également été évalué. L’étude a montré que les pratiques traditionnelles dans la zone sont progressivement remplacées par des pratiques de culture agroécologiques qui ont été enseignées aux producteurs par les partenaires intervenants dans la zone.Les déterminants de l'adoption de ces pratiques sont entre autres l'augmentation des rendements des cultures, l'amélioration du revenu des producteurs, la fourniture ou non de ressources matérielles et humaines et la formation des acteurs. On note également que les agriculteurs ont des indicateurs qui leur sont spécifiques pour apprécier et décrire la fertilité de leurs sols. L’effet des pratiques a été plus significatif pour la plupart des paramètres chimiques (C, N, CE,…) surtout pour la couche 0-10 cm.Les pratiques agroécologiques ont un effet significativement positif sur l'activité minéralisatrice des microorganismes du sol. En outre, il existait une corrélation entre la superficie des parcelles aménagées en cordon pierreux et la plupart des paramètres de fertilité du sol. Par contre aucun gradient de fertilité des sols n’apparait en fonction de la pente lorsqu’on s’éloigne de la première ligne de cordon pierreux. / The effect of traditional and innovative agroecological practices on the fertility parameters of agricultural soils grown in the field was studied. The study was carried out in a peasant environment in the agricultural area of Sampieri in eastern Burkina Faso in the Sudano-Sahelian environment onlixisols. Farmers' perception of soil degradation and the practice of agroecology, the determinants of the adoption of agroecological practices and the effect of these practices on physical, chemical and microbiological parameters were determined for plots under agroecological practices, versus traditional, compared to control soils. The effect of these practices on the yield (grains and straws) of sorghum was also evaluated. The study showed that traditional practices are being gradually replaced by agroecological cultivation practices that have been taught to producers by the partners involved in the area. The determinants of the adoption of these practices are among others the increase in crop yields, the improvement of producers' income, the supply or not of material and human resources and the training of actors. It is also noted that farmers have indicators specific to them to appreciate and describe the fertility of their soils. The effect of the practices was more significant for most chemical parameters (C, N, CE,...) especially for the 0-10 cm layer. Agroecological practices have a significantly positive effect on the mineralizing activity of soil microorganisms. In addition, there was a correlation between the area of stony cord parcels and most soil fertility parameters. On the otherhand, no gradient of soil fertility appears as a function of the slope when one moves away from the first line of stony cord.

O adequado deslocamento autônomo de robôs móveis entre fileiras de cultura agrícola implica a apropriada configuração estrutural do veículo, bem como considerar a detecção das filas de plantas ou árvores, e também o desenvolvimento de um sistema de controle de locomoção. Esta tese apresenta o desenvolvimento de um sistema de controle em malha fechada baseado na técnica de otimização H∞, que é aplicado no deslocamento entre fileiras de plantio de um robô móvel agrícola em escala reduzida. Mais especificamente, o foco deste trabalho é o seguimento de caminhos na cultura através da aplicação de técnicas de controle robusto. Duas questões foram fundamentais na elaboração da tese: 1) \"Quais são os métodos e procedimentos necessários para implementar a navegação autônoma de um protótipo de robô móvel entre fileiras de cultura agrícola?\" e, 2) \"É possível aplicar os conceitos relativos a sistemas de controle em malha fechada para solucionar o problema da navegação autônoma do robôs móveis entre fileiras de cultura agrícola?\". Primeiramente é apresentada uma revisão bibliográfica sobre robôs móveis agrícolas que tem locomoção baseada em rodas. Posteriormente, os conceitos relacionados com o projeto de controle baseado na técnica de otimização H∞ são fundamentados. Em seguida, são descritos os detalhes relacionados com a construção da plataforma robótica proposta, o projeto do controlador de caminho, as respectivas simulações e as especificações para a realização de testes em ambiente agrícola. Finalmente os resultados alcançados são apresentados. Conclui-se que o sistema de controle proposto se mostrou efetivo na realização da navegação autônoma do robô entre as fileiras da cultura previamente configuradas para a avaliação do seu desempenho. / Appropriate autonomous navigation of mobile robots between crop rows implies, besides appropriate structural configuration, considering detection of plants or trees in rows, as well as the development of a locomotion control system. Consequently, this thesis presents the development of a closed loop control system based on H∞ optimization technique, which is applied to control the navigation of a low scale car-like mobile robot between crop rows; more specifically, main focus of this work is tracking paths in the culture, by the application of robust control techniques. Two questions were fundamental in the development of the thesis: 1) which are the methods and procedures to implement the autonomous navigation of a mobile robot prototype between crop rows? And 2) is it possible to apply the concepts of closed-loop control systems to solve the problem of autonomous navigation of mobile robots between crop rows? Firstly, we provide a literature review on agricultural mobile robots whose mobility depends on wheels. Secondly, control systems design fundamentals based on the H∞ optimization technique are addressed. Thirdly, details related to the construction of the proposed robotic platform and also the design of the proposed path controller (including its simulation and specifications for testing within an agricultural environment) are described. Finally, results of our findings are presented. It is concluded that our control system showed to be effective in the realization of autonomous navigation between crop rows in agricultural environment, which was properly configured in order to evaluate the performance of our robot.

O adequado deslocamento autônomo de robôs móveis entre fileiras de cultura agrícola implica a apropriada configuração estrutural do veículo, bem como considerar a detecção das filas de plantas ou árvores, e também o desenvolvimento de um sistema de controle de locomoção. Esta tese apresenta o desenvolvimento de um sistema de controle em malha fechada baseado na técnica de otimização H∞, que é aplicado no deslocamento entre fileiras de plantio de um robô móvel agrícola em escala reduzida. Mais especificamente, o foco deste trabalho é o seguimento de caminhos na cultura através da aplicação de técnicas de controle robusto. Duas questões foram fundamentais na elaboração da tese: 1) \"Quais são os métodos e procedimentos necessários para implementar a navegação autônoma de um protótipo de robô móvel entre fileiras de cultura agrícola?\" e, 2) \"É possível aplicar os conceitos relativos a sistemas de controle em malha fechada para solucionar o problema da navegação autônoma do robôs móveis entre fileiras de cultura agrícola?\". Primeiramente é apresentada uma revisão bibliográfica sobre robôs móveis agrícolas que tem locomoção baseada em rodas. Posteriormente, os conceitos relacionados com o projeto de controle baseado na técnica de otimização H∞ são fundamentados. Em seguida, são descritos os detalhes relacionados com a construção da plataforma robótica proposta, o projeto do controlador de caminho, as respectivas simulações e as especificações para a realização de testes em ambiente agrícola. Finalmente os resultados alcançados são apresentados. Conclui-se que o sistema de controle proposto se mostrou efetivo na realização da navegação autônoma do robô entre as fileiras da cultura previamente configuradas para a avaliação do seu desempenho. / Appropriate autonomous navigation of mobile robots between crop rows implies, besides appropriate structural configuration, considering detection of plants or trees in rows, as well as the development of a locomotion control system. Consequently, this thesis presents the development of a closed loop control system based on H∞ optimization technique, which is applied to control the navigation of a low scale car-like mobile robot between crop rows; more specifically, main focus of this work is tracking paths in the culture, by the application of robust control techniques. Two questions were fundamental in the development of the thesis: 1) which are the methods and procedures to implement the autonomous navigation of a mobile robot prototype between crop rows? And 2) is it possible to apply the concepts of closed-loop control systems to solve the problem of autonomous navigation of mobile robots between crop rows? Firstly, we provide a literature review on agricultural mobile robots whose mobility depends on wheels. Secondly, control systems design fundamentals based on the H∞ optimization technique are addressed. Thirdly, details related to the construction of the proposed robotic platform and also the design of the proposed path controller (including its simulation and specifications for testing within an agricultural environment) are described. Finally, results of our findings are presented. It is concluded that our control system showed to be effective in the realization of autonomous navigation between crop rows in agricultural environment, which was properly configured in order to evaluate the performance of our robot.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / Irrigation is an alternative to minimize fluctuations in grain production and yield due to water deficiency. However, to prevent water losses and to improve the efficiency of this use, the irrigation management has to be sustainable. Therefore, the knowledge of the number of variables related with soil and crops, in response to different growing conditions is fundamental to have an adequate irrigation management. Thus, tere objective of tail study was made to evaluate water losses, variations in the soil temperature with different spacing between rows and the amount of plant residues on the surface of the soil during the cultivation of beans. This experiment was conducted in the experimental area of the Agricultural Engineering Department at the Federal University of Santa Maria, in 2010, under a rainout shelter. The experimental design was completely randomized bi-factorial with three replications. Factor A was consisted of three spacing rows between crops: 30, 50 and 70 cm. Factor B was consisted of two quantities of crop residues on soil surface: 1 Mg ha-1 of corn residues and 5 Mg ha-1 of corn + oat residues. The water content in the soil was determined by a FDR set (Frequency domain reflectometry, Campbell Scientific), in layers of the soil profile: 0-10, 10-25, 25-55 and 55-85 cm deep. Daily water storage in the soil (mm), daily and accumulated water losses in soil (mm) were evaluated. Soil temperature was mensured ussing thermocouples made of copper and constantan were installed at the depths of 3, 8, 15 and 35 cm. Morphological determination were conducted of the dry beans plants (leaf area and plant height) and the determination of the coverage fraction of the plants between the rows. The dry beans plants were 7cm higher in the plot with 5 Mg ha-1 of corn + oat residues on the surface. The full coverage of the dry beans plants between rows occurred primarily in the spacing of 30 cm at 47 days after sowing, and the spacing of 50 and 70 cm occurred at 61 days after sowing with a maximum leaf area index 6,8. Accumulated soil water losses during the development cycle of the dry beans, in the different layers of the soil profile down to 85 cm deep, were not affected by row spacing of cultivation from 30 to 70 cm. In the early stage of development of the dry beans plants, considering the period of 30 days after sowing, (104 mm of reference evapotranspiration accumulated) in the layer of the soil profile from 0-10 cm deep, using 5 Mg ha-1 of corn + oat residues on the soil surface reduced 26% of water losses in the soil, resulting in a better water storage and availability to plants. Using 5 Mg ha-1 of corn + oats residues on the soil surface caused reductions in soil temperature (minimum and maximum) up to 3oC. The soil temperature (minimum and maximum) increased linearly with the spacing between rows from 30 to 70 cm. The average values of yield components and yield of the beans of the treatments were 18 pods plant-1, 6 grains pod-1 and 3, 45 Mg ha-1. / A irrigação é uma alternativa para minimizar as oscilações na produção e produtividade de grãos devido à deficiência hídrica. Entretanto, para uma produção sustentável, a irrigação deve ser manejada de forma a evitar desperdícios de água e aumentar a eficiência deste recurso hídrico. Para isso, no manejo de irrigação tornase fundamental o conhecimento de uma série de variáveis, relacionadas ao solo e às culturas, em resposta a diferentes condições de cultivo. Dessa forma, o presente trabalho teve como objetivo avaliar as perdas de água e as variações na temperatura de um solo cultivado com feijão com diferentes espaçamentos entre linhas e quantidades de resíduos vegetais depositados na superfície do solo. O experimento foi realizado em área experimental do Departamento de Engenharia Rural da Universidade Federal de Santa Maria, RS, no ano agrícola de 2010/11, no interior de uma cobertura móvel. O delineamento experimental utilizado foi o inteiramente casualizado, bifatorial, com três repetições. O fator A foi constituído de três espaçamentos entre linhas de cultivo 30, 50 e 70 cm. O fator B constituiu-se de duas quantidades de resíduos vegetais na superfície do solo: 1 Mg ha-1 de resíduos de milho e 5 Mg ha-1 de resíduos de milho+aveia preta. O conteúdo de água do solo foi determinado por um conjunto FDR (Reflectometria no domínio de freqüência, Campbell Scientific), nas camadas do perfil do solo de: 0 a 10, 10 a 25, 25 a 55 e 55 a 85 cm de profundidade. Avaliou-se diariamente o armazenamento de água no solo, perdas diárias e perdas acumuladas de água do solo. Para avaliação da temperatura do solo foram utilizados termopares, constituídos de cobre e constantan, instalados nas profundidades de 3, 8, 15 e 35 cm do perfil do solo. Foram realizadas avaliações morfológicas das plantas de feijão (área foliar e altura de plantas) e determinado a fração de cobertura da entre linha pelo dossel vegetativo da cultura. As plantas de feijão foram, em média, 7 cm mais altas no solo mantido com 5 Mg ha-1 de resíduos de milho+aveia preta na superfície. A cobertura da entre linha pelo dossel vegetativo do feijoeiro ocorreu primeiramente no espaçamento entre linhas de 30 cm, aos 47 dias após a semeadura, e, nos espaçamentos entre linhas de 50 e 70 cm ocorreu aos 61 dias após a semeadura, com o máximo índice de área foliar das plantas de 6,8. As perdas de água do solo acumuladas durante o ciclo de desenvolvimento da cultura do feijão, nas diferentes camadas do perfil do solo, até 85 cm de profundidade, não foram afetadas pelos espaçamentos entre linhas de cultivo de 30 a 70 cm. Na fase inicial de desenvolvimento da cultura do feijão, período compreendido da semeadura até 30 dias após a semeadura (104 mm de evapotranspiração de referência acumulada), na camada do perfil do solo de 0-10 cm de profundidade, as perdas de água do solo acumuladas foram reduzidas em 26% com a utilização de 5 Mg ha-1 de resíduos de milho+aveia preta na superfície do solo, resultando em maior armazenamento de água no solo e disponibilidade de água às plantas. A utilização de 5 Mg ha-1 de resíduos de milho+aveia preta na superfície do solo causou reduções na temperatura do solo (média e máxima) de até 3oC. A temperatura do solo (média e máxima), dos 32 a 56 dias após a semeadura, aumentou linearmente com o incremento do espaçamento entre linhas de 30 para 70 cm. Os valores médios dos componentes do rendimento e rendimento de grãos da cultura do feijão para os tratamentos foram de 18 vagens planta-1, 6 grãos vagem-1 e 3,45 Mg ha-1.

Flow distribution has big importance in equipment with limited tube rows because it provides correct operation and sometimes specific flow distribution for technology purposes is needed. This thesis is focusing on flow analysis in these units using computational fluid dynamics (CFD). For analysis of such systems models with varying tube rows and varying perforated segment lengths were created. Analysis showed significant impact of flow manifold layout along with tube layout and number of tubes. Simplified 1D model using static pressure regain coefficient was created which provides much shorter computational times. Comparison of 1D and CFD models was made to determine field of their usage.

Ziel der Arbeit war die Beurteilung der räumlichen Verteilung und Struktur von Feldhecken hinsichtlich ihrer Wirkung für Hochwasser- und Naturschutz, sowie die Analyse von agrarökonomischen Faktoren, welche die Anlage von Hecken fördern beziehungsweise behindern. Folgende Fragen standen bei den Untersuchungen im Mittelpunkt: Wie muss eine Hecke sowohl aus naturschutzfachlicher als auch hydrologischer Sicht aufgebaut sein, um eine optimale Wirkung zu erzielen, und wie müssen die Rahmenbedingungen für Landwirte aussehen, damit Heckenstrukturen nicht nur erhalten, sondern auch neu angelegt werden können? Um diese komplexen Fragen zu beantworten, wurden verschiedene methodische Ansätze zur Analyse ökologischer, hydrologischer und entscheidungsbildender Prozesse gewählt. Um die Ergebnisse der verschiedenen Skalenarten (ordinal / kardinal) zu vergleichen und dabei aus verschiedenen Optionen eine für alle Ziele optimale Vorzugsvariante zu ermitteln, wurde am Ende eine Nutzwertanalyse durchgeführt. / There were two main purposes of the study; the evaluation of the spatial distribution and structural patterns of hedgerows in regard to their impact on flood prevention and nature conservation, and the investigation of factors facilitating or constraining the establishment of hedgerows. On the basis of this assessment, knowledge based recommendations were developed for the facilitation of hedgerows in agricultural landscapes in mountainous areas such as the Erzgebirge. The following questions were the main focus of the investigation: how should a hedgerow be composed to obtain the optimal effect from the nature conservation as well as the flood prevention point of view, and how should the general requirements for farmers be constructed so that hedgerows are not only maintained but also newly established. To answer these complex questions different methodologies were applied for analysing ecological, hydrological and decision-forming processes. In order to compare the results and hedgerow alternatives to determine the optimal choice, a value-benefit analysis was performed.

Ziel der Arbeit war die Beurteilung der räumlichen Verteilung und Struktur von Feldhecken hinsichtlich ihrer Wirkung für Hochwasser- und Naturschutz, sowie die Analyse von agrarökonomischen Faktoren, welche die Anlage von Hecken fördern beziehungsweise behindern. Folgende Fragen standen bei den Untersuchungen im Mittelpunkt: Wie muss eine Hecke sowohl aus naturschutzfachlicher als auch hydrologischer Sicht aufgebaut sein, um eine optimale Wirkung zu erzielen, und wie müssen die Rahmenbedingungen für Landwirte aussehen, damit Heckenstrukturen nicht nur erhalten, sondern auch neu angelegt werden können? Um diese komplexen Fragen zu beantworten, wurden verschiedene methodische Ansätze zur Analyse ökologischer, hydrologischer und entscheidungsbildender Prozesse gewählt. Um die Ergebnisse der verschiedenen Skalenarten (ordinal / kardinal) zu vergleichen und dabei aus verschiedenen Optionen eine für alle Ziele optimale Vorzugsvariante zu ermitteln, wurde am Ende eine Nutzwertanalyse durchgeführt. / There were two main purposes of the study; the evaluation of the spatial distribution and structural patterns of hedgerows in regard to their impact on flood prevention and nature conservation, and the investigation of factors facilitating or constraining the establishment of hedgerows. On the basis of this assessment, knowledge based recommendations were developed for the facilitation of hedgerows in agricultural landscapes in mountainous areas such as the Erzgebirge. The following questions were the main focus of the investigation: how should a hedgerow be composed to obtain the optimal effect from the nature conservation as well as the flood prevention point of view, and how should the general requirements for farmers be constructed so that hedgerows are not only maintained but also newly established. To answer these complex questions different methodologies were applied for analysing ecological, hydrological and decision-forming processes. In order to compare the results and hedgerow alternatives to determine the optimal choice, a value-benefit analysis was performed.