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1
Madeira, Nogueira Filipe. "Movement of predators in arable crop systems." Doctoral thesis, Universitat de Lleida, 2014. http://hdl.handle.net/10803/285265.
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L`abundància i dispersió d`O. majusculus no va ser diferent entre parcel-les de panís amb moderadament alta o baixa densitat de males herbes. Els caràbids, C. fuscipes, P. rufipes, P. cupreus i Metallina sp. i l`antocòrid O. majusculus presenten moviment bidireccional entre cultius adjacents de alfals i panís durant l'estació. En contrast, C. septempunctata només es va moure des de l`alfals cap al panís. Els individus d'O. majusculus i C. septempunctata que van colonitzar el panís a l'estadi vegetatiu provenien de l`alfals, indicant que l`alfals va ser la font d'aquests depredadors. No obstant, en el període reproductiu, el panís va actuar com una font de C. fuscipes, P. rufipes, P. cupreus, Metallina sp. i O. majusculus cap a l`alfals, principalment després de dall. El moviment de caràbids, estafilínids i aranyes va ser més intens des dels cereals d'hivern cap als hàbitats semi naturals que des dels prats cap als hàbitats semi naturals, indicant que l'hàbitat adjacent modela el moviment dels depredadors cap als hàbitats semi naturals.La abundancia y dispersión de O. majusculus no fué diferente entre parcelas de maíz con moderada alta o baja densidad de las malas hierbas. Los carábidos, C. fuscipes, P. rufipes, P. cupreus y Metallina sp. y el anthocorido O. majusculus presentan movimiento bidireccional entre cultivos adyacentes de alfalfa y maíz durante la estación. En contraste, C. septempunctata sólo se movió desde la alfalfa hacia al maíz. Los individuos de O. majusculus y C. septempunctata que colonizaron el maíz en el estadio vegetativo provinieron de la alfalfa, indicando que la alfalfa actúo como fuente de estos depredadores. Sin embargo, en el período reproductivo, el maíz actuó como una fuente de C. fuscipes, P. rufipes, P. cupreus, Metallina sp. y O. majusculus hacia la alfalfa, principalmente después de corte. El movimiento de carábidos, estafilínidos y arañas fué más intenso desde los cereales de invierno hacia los hábitats seminaturales que desde los prados hacia a los hábitats semi-naturales, indicando que el hábitat adyacente moldea el movimiento de los depredadores hacia los hábitats seminaturales adyacentes.
The abundance and dispersal activity of O. majusculus were not different in maize plots with moderately high or low weed density. The carabids C. fuscipes, P. rufipes, P. cupreus and Metallina sp. and the anthocorid O. majusculus presented bidirectional movements between adjacent alfalfa and maize crops during the season. In contrast, C. septempunctata only moved from alfalfa to maize. The plant-dwelling O. majusculus and C. septempunctata that colonized maize at early vegetative stages came from alfalfa, indicating that alfalfa acted as a source of predators towards maize. However, in the reproductive growth stage period, maize acted as a source for C. fuscipes, P. rufipes, P. cupreus, Metallina sp. and O. majusculus moving to alfalfa, mainly after cuttings. After an alfalfa cutting, margins also acted as a refuge for carabids. Spillover of carabids, rove beetles and spiders was stronger from winter cereals to semi-natural habitats than from meadows to semi-natural habitats, indicating that neighbourhood identity shapes spillover effects to adjacent semi-natural habitats.
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Nogueira, Madeira Filipe José. "Movement of predators in arable crop systems." Doctoral thesis, Universitat de Lleida, 2014. http://hdl.handle.net/10803/285265.
Full textAbstract:
L`abundància i dispersió d`O. majusculus no va ser diferent entre parcel-les de panís amb moderadament alta o baixa densitat de males herbes. Els caràbids, C. fuscipes, P. rufipes, P. cupreus i Metallina sp. i l`antocòrid O. majusculus presenten moviment bidireccional entre cultius adjacents de alfals i panís durant l'estació. En contrast, C. septempunctata només es va moure des de l`alfals cap al panís. Els individus d'O. majusculus i C. septempunctata que van colonitzar el panís a l'estadi vegetatiu provenien de l`alfals, indicant que l`alfals va ser la font d'aquests depredadors. No obstant, en el període reproductiu, el panís va actuar com una font de C. fuscipes, P. rufipes, P. cupreus, Metallina sp. i O. majusculus cap a l`alfals, principalment després de dall. El moviment de caràbids, estafilínids i aranyes va ser més intens des dels cereals d'hivern cap als hàbitats semi naturals que des dels prats cap als hàbitats semi naturals, indicant que l'hàbitat adjacent modela el moviment dels depredadors cap als hàbitats semi naturals.La abundancia y dispersión de O. majusculus no fué diferente entre parcelas de maíz con moderada alta o baja densidad de las malas hierbas. Los carábidos, C. fuscipes, P. rufipes, P. cupreus y Metallina sp. y el anthocorido O. majusculus presentan movimiento bidireccional entre cultivos adyacentes de alfalfa y maíz durante la estación. En contraste, C. septempunctata sólo se movió desde la alfalfa hacia al maíz. Los individuos de O. majusculus y C. septempunctata que colonizaron el maíz en el estadio vegetativo provinieron de la alfalfa, indicando que la alfalfa actúo como fuente de estos depredadores. Sin embargo, en el período reproductivo, el maíz actuó como una fuente de C. fuscipes, P. rufipes, P. cupreus, Metallina sp. y O. majusculus hacia la alfalfa, principalmente después de corte. El movimiento de carábidos, estafilínidos y arañas fué más intenso desde los cereales de invierno hacia los hábitats seminaturales que desde los prados hacia a los hábitats semi-naturales, indicando que el hábitat adyacente moldea el movimiento de los depredadores hacia los hábitats seminaturales adyacentes.
The abundance and dispersal activity of O. majusculus were not different in maize plots with moderately high or low weed density. The carabids C. fuscipes, P. rufipes, P. cupreus and Metallina sp. and the anthocorid O. majusculus presented bidirectional movements between adjacent alfalfa and maize crops during the season. In contrast, C. septempunctata only moved from alfalfa to maize. The plant-dwelling O. majusculus and C. septempunctata that colonized maize at early vegetative stages came from alfalfa, indicating that alfalfa acted as a source of predators towards maize. However, in the reproductive growth stage period, maize acted as a source for C. fuscipes, P. rufipes, P. cupreus, Metallina sp. and O. majusculus moving to alfalfa, mainly after cuttings. After an alfalfa cutting, margins also acted as a refuge for carabids. Spillover of carabids, rove beetles and spiders was stronger from winter cereals to semi-natural habitats than from meadows to semi-natural habitats, indicating that neighbourhood identity shapes spillover effects to adjacent semi-natural habitats.
3
Nyamai, D. O. "Crop production in an intercropping system with tropical leguminous trees." Thesis, University of Oxford, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382474.
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Ayre, Kevin. "Evaluation of carabids as predators of slugs in arable land." Thesis, University of Newcastle Upon Tyne, 1995. http://hdl.handle.net/10443/946.
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An Enzyme-Linked Immunosorbent Assay (ELISA) was developed which detected slug antigens in postmortem gut analysis of carabid beetles. The ELISA was used to identify beetles which fed on slugs in three fields of oilseed rape and winter wheat in the Tyne valley, Northumberland. Generalist species such as Harpalus rufipes, Pterostichus melanarius, Pterostichus nladidus, Anlara silnilata and Nebria brevicollis fed on slugs in the field. Molluscan specialists such as Carabus violaceus and Cychrus caraboides also fed on slugs in the field. Laboratory studies indicated that many large and medium sized carabids were able to predate small slugs. Some beetle species did not eat slugs but exposure to the beetles increased slug mortality. Therefore, postmortem investigations may underestimate the impact that carabids exert on slugs as they do not measure the number of slugs killed. Slug mucus affected the locomotory activity of generalist and specialist beetle species. Beetles foraged longer, covered greater distances, made more turns, walked slower and spent more time stationary on soil covered in slug mucus compared to control areas. Abax parallelepipedus, P.melanarius, Pterostichus niger and H.rufipes all reduced slug damage to a chinese cabbage crop in a miniplot experiment compared with unprotected plots. However, these differences were not significant. A.parallelepipedus was most effective at reducing slug damage to the chinese cabbage but was rare in arable land. H.rufipes was least effective at reducing slug damage but was abundant in arable land in both years of the study. A high proportion of H.rufipes beetles fed on slugs in the field. None of these four species occurred at densities in the field which reduced slug damage in the miniplot experiment.
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Jamir, Chubamenla. "Assessing ozone impacts on arable crops in South Asia : identification of suitable risk assessment methods to improve crop biotechnology." Thesis, University of York, 2011. http://etheses.whiterose.ac.uk/1958/.
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This study has applied a number of different O3 risk assessment methods in South Asia to assess the extent and magnitude of O3 risk to crops and investigate how appropriate different methods are in identifying local environmental conditions and crop physiological traits that might alter crop sensitivity to O3. Concentration based methods are used in combination with tools and datasets tailored for South Asian conditions to investigate O3 impacts on wheat, rice, soybean and potato. Relative yield losses are substantially smaller (0.1 to 11.5 %) than those found in previously conducted global modelling studies (3 to 30 %) which is attributed to the improved resolution of the O3 photochemical model and crop distribution datasets used in this South Asian analysis. For the first time O3 flux based risk assessment methods are also applied for wheat in India. The stomatal conductance component of this flux method has been parameterised for Indian wheat based on available crop physiology data. Comparisons show that flux based methods tend to estimate larger relative yield losses than concentration based methods (16 % compared to 0.6 to 11.5 % for India). There are also differences in the spatial pattern of estimated risk though both methods clearly identify the Indo-Gangetic Plains as a high O3 risk region. The co-variation in O3 concentrations, crop distribution (both growth periods and geographical location), local meteorology (especially temperature and VPD) and crop physiology are all important in determining flux estimated O3 sensitivity. Finally, the flux based method is used to assess phenological traits (sowing times and maturing periods) introduced in new Indian wheat cultivars. This highlights the importance of crop phenology in determining O3 sensitivity as a function of both O3 concentration and environmental conditions and emphasises the potential application of flux based approaches as a tool capable of informing future crop biotechnology efforts.
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Sharpe, Lorna. "Geophysical, geochemical and arable crop responses to archaeological sites in the Upper Clyde Valley, Scotland." Thesis, University of Glasgow, 2004. http://theses.gla.ac.uk/1162/.
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This thesis considers the geochemical links between geophysical survey results from, and responses of barley crop growth to, the existence of plough-levelled archaeological sites. It takes as a starting point the results of magnetic and resistivity surveys undertaken at three sites in the Upper Clyde Valley, Lanarkshire, Scotland. Two of the three sites produced geophysical results that closely matched the evidence for archaeological remains recorded using oblique aerial photography. The third site was largely unresponsive to geophysical prospection techniques. These mixed responses prompted a closer examination of why barley crops respond to plough-levelled remains, and why the geophysical data gathered tend to correlate with the growth responses. To allow an examination of the growth responses, a series of pot-based growth experiments were carried out under glasshouse conditions, and these were followed up by ICP-MS analysis of the plants and the archaeological soils in which they had grown, in an attempt to link any changes in elemental compositions with the growth responses, and to the geophysical responses recorded at the soil sampling points or for the features from which the soils were taken. The results of the experimental work revealed that although soil moisture content has a role in the development of both crop marks and geophysical anomalies, other factors are also involved, including changes in elemental concentrations in soils and plant material, soil pH changes and the redox potential of the archaeological soils.
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Mendi, Ebrahim M. "Biological control of Chenopodium album by Ascichyta caulina." Thesis, Available from the University of Aberdeen Library and Historic Collections Digital Resources, 2001. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?application=DIGITOOL-3&owner=resourcediscovery&custom_att_2=simple_viewer&pid=59743.
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Kyllmar, Katarina. "Nitrogen leaching in small agricultural catchments : modelling and monitoring for assessing state, trends and effects of counter-measures /." Uppsala : Dept. of Soil Sciences, Swedish Univ. of Agricultural Sciences, 2004. http://epsilon.slu.se/a485.pdf.
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Metcalfe, Carol. "New ash glazes from arable crop waste : exploring the use of straw from Pisum sativum (combining pea) and Vicia faba (field bean)." Thesis, University of Sunderland, 2008. http://sure.sunderland.ac.uk/3657/.
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The Chinese first developed stoneware ash glazes about 3500 years ago, when their kiln technology progressed sufficiently to reach temperatures high enough to fuse such glazes. More than 2000 years went by before this knowledge reached Japan and Korea, where ash glazes were also subsequently produced. In Britain, the advent of studio pottery in the 20th century led to interest in oriental approaches to ceramics, including ash glazes. A number of studio potters used and indeed continue to use ash glazes in their work. The great majority of these glazes have, throughout history, been made of wood ash and are mainly fired to high stoneware temperatures of at least 1280°C, Cone 10. Worldwide interest in this subject continues today; however, a general increase in environmental concern, especially fuel economy, raises a number of issues for contemporary ceramic practitioners. This research addresses these issues by employing multiple methods in a „composite‟ methodology, rooted in art practice, the aims being: To develop a range of new glazes, for lower stoneware temperature (1240°C, Cone 7) oxidised firings, using ash from arable crop waste as an environmentally sensitive ingredient. To demonstrate and articulate the possible creative, practical and environmental benefits of the new glazes for contemporary ceramic practitioners, principally through artworks. To offer a model for investigating the potential of a new source of ash, as a glaze material. The plant species explored are the Combining pea and Field bean, neither of which is documented in any of the contextual sources located. Both plants are widely grown as protein crops in many countries of the world and were available in North Yorkshire for this research. Glaze calculation methods and empirical approaches to glaze development have been investigated and the ashes have been analysed. From this information, glaze recipes have been developed and tested. Since the appearance of a glaze is affected by the clay body to which it is applied, the compositions of available clays have been studied and four widely differing examples chosen for the tests. Case studies have been undertaken of contemporary ceramic practitioners, whose approaches to ash glazing vary widely. These studies further develop the context for the new glazes and provide a framework within which to assess their significance. The creative potential of the glazes developed has been explored through their application in ceramic artworks, exhibited both during and at the end of the research. During the creation of these artworks, a theme emerged, closely linking them to their place of origin. In addition to the new artworks, the research contributes both a range of new ash glaze recipes and a model for exploring the potential of ash from a new source.
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Kleftodimos, Georgios. "Economic valuation of bees’ pollination services in arable crop farms : the role of Public Policy regulations towards the provision of pollination services." Thesis, Toulouse 2, 2019. http://www.theses.fr/2019TOU20101.
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L’objectif principal de l'étude réalisée est d'évaluer l'importance économique des interactions entre les abeilles sauvages et domestiques, appelées « complémentarité », dans les exploitations agricoles. Une emphase particulière a été mise en examinant la manière dont l'importance économique de la complémentarité devrait affecter le règlement de politique publique afin de préserver la fourniture de services de pollinisation. Le premier chapitre fournit le cadre théorique sur lequel repose cette évaluation économique. Le chapitre 2 fournit un modèle éco-économique montrant les décisions des agriculteurs entre deux intrants, les services de pollinisation et les pesticides. Deux sources de pollinisation avec des caractéristiques différentes sont considérées; les abeilles domestiques, qui peuvent être remplacées à un certain coût, et les abeilles sauvages, dont la population est supposée d’être soutenue au paysage. En plus, nous prenons pour acquis que les services entre les deux abeilles ont une relation complémentaire. Le troisième chapitre intègre les résultats du chapitre 2 dans une modélisation éco-économique territoriale plus sophistiquée afin d'explorer les impacts potentiels des changements de politique sur la protection des services de pollinisation et sur les revenus des agriculteurs pour différents taux de coopération entre eux. Enfin, le chapitre 4 évalue l’efficacité des mesures prises par la politique française en matière de protection des services de pollinisation et examine en quoi les résultats de nos analyses peuvent contribuer à l’amélioration de l’efficacité de ces mesures. Le résultat majeur de nos recherches est double. Premièrement, la connaissance de la complémentarité des abeilles peut offrir aux agriculteurs une stratégie alternative de gestion optimale. Deuxièmement, l’inclusion de ces connaissances dans les mesures politiques mises en œuvre peut faciliter le processus d’adoption par les agriculteurs en faveur de pratiques à faibles intrants et conséquemment accroître leur efficacité sur la durabilité des services de pollinisation pour les systèmes agricoles et alimentairesThe principal objective of the realized study is to evaluate the economic importance of the behavioral interactions which emerge from managed and wild bees, called bees’ complementarity in arable crop farms. A particular emphasis was placed on examining how the economic importance of bees’ complementarity should affect the public policy regulation in order to safeguard the provision of pollination services. The first Chapter of this Ph.D. thesis provides the theoretical framework on which this economic valuation is based. Chapter 2, provides an ecological-economic model displaying farmer’s decisions between two agricultural inputs, pollination services and pesticides, and two sources of pollination with different characteristics; managed bees, which can be replaced at a cost, and wild bees, which rely on a population being sustained within the farmland. Moreover, we take as a given that the services of wild and managed bees are in a complementary relationship. The third Chapter of this thesis, integrates the findings of Chapter 2 in a Mathematical-Programming territorial ecological-economic modeling in order to explore the potential impacts of policy changes on the provision of pollination services and on farmers’ incomes for different rates of farmers’ cooperation. Finally, Chapter 4, evaluates the effectiveness of French policy measures towards the provision of pollination services and it discusses how the results of our analyses may contribute towards the amelioration of the effectiveness of these measures. The major result of our research is twofold. Firstly, the knowledge of bees’ complementarity may offer to farmers an alternative optimum management strategy. Secondly, the inclusion of this knowledge in the implemented policy measures may facilitate farmers’ adoption process towards low-input practices and, consequently, increase their effectiveness towards the sustainability of pollination services for the agricultural and food systems
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Frank, Tina [Verfasser], Rainer [Akademischer Betreuer] Horn, and Rainer [Gutachter] Duttmann. "Optimization of the soil structure in arable crop production by means of lime (CaCO3) application / Tina Frank ; Gutachter: Rainer Duttmann ; Betreuer: Rainer Horn." Kiel : Universitätsbibliothek Kiel, 2021. http://nbn-resolving.de/urn:nbn:de:gbv:8:3-2021-00562-5.
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Xu, Jialu [Verfasser], and Sabine [Akademischer Betreuer] Gruber. "Effects of woody plants and their residues on crop yield, weedsand soil carbon fractions in selected arable cropping systems / Jialu Xu ; Betreuer: Sabine Gruber." Hohenheim : Kommunikations-, Informations- und Medienzentrum der Universität Hohenheim, 2018. http://d-nb.info/1155237161/34.
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Hama-Aziz, Zanist Qader. "Assessment of the application of a cover crop and conservation tillage on soil and water properties and on dissolved nitrous oxide in an arable system." Thesis, University of East Anglia, 2016. https://ueaeprints.uea.ac.uk/59671/.
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Agriculture is a major contributor to environmental pollution. About quarter of water bodies in England are classified as being good ecological and chemical status. To tackle agricultural pollution, a range of on-farm mitigation measures are recommended. The overall aim of this study was to assess the effectiveness of cover cropping and reduced cultivation methods as infield mitigation measures to reduce diffuse water pollution, improve soil quality and reduce nitrous oxide greenhouse gas emissions. These mitigation measures were applied to seven fields within the intensive arable River Wensum catchment, eastern England, with a further two fields kept under conventional cultivation as a control. Soil and water chemistry, principally water discharging from subsurface agricultural field drains, were regularly sampled and analysed from these fields over a two-year period. The results revealed the mitigation measures had no positive impact on soil quality. The soil chemical condition, including soil organic carbon, phosphorus, magnesium and sulphate concentrations were not improved by the use of a cover crop or reduced cultivation, whilst soil physical condition deteriorated through increased compaction, as highlighted by increased bulk density, penetration resistance and lower infiltration rates. Conversely, field drain water quality improved markedly. The presence of a winter cover crop significantly reduced mean dissolved nitrate concentrations from 13.9 mg N L-1 to 2.5 mg N L-1, an 82% reduction. Different inversion intensity of the soil tended to have no effect on nitrate concentrations. Regarding dissolved N2O, a slightly higher N2O concentration was recorded in field drains under a cover crop than without cover crop. This finding suggests that whilst the use of a winter cover crop is highly effective at reducing soil nitrate losses to rivers, it does not represent an effective strategy for reducing N2O emissions. Indirect nitrous oxide emission factors (EF5g and EF5r) were calculated using two approaches (IPCC 2006 and the N2O-N/NO3̄-N ratio) for both field drain and stream water samples. Values for these two EFs obtained were found to be below the IPCC default value of 0.0025. If the IPCC were to revise EF5 values in future then, regardless of soil type, crop type, and land use practices, a value of 0.0009 (about one third of the current value) for EF5g and a value of 0.0002 (one order of magnitude lower than the current value) for EF5r may be a more reasonable estimates. Such radical downward revision would at least halve the current estimates of N2O emissions associated with N leaching and runoff from agriculture for both the UK and globally.
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Mary, Sébastien. "A dynamic stochastic farm household model with occasionally binding debt constraints and investment adjustment costs : assessing the impacts of direct farm payments and common agriculture policy reforms in French arable crop farms." Thesis, University of Aberdeen, 2010. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=158412.
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Traditionally, the Common Agricultural Policy has used minimum intervention prices and coupled payments to support farmers in Europe. These highly trade-distorting instruments have received much criticism. Following the Uruguay Round, a major reform process started in the EU. In 2003, the EU decoupled farm support by introducing Single Farm Payments. However, economic theory has shown that such payments may lead to increases in farm output because of the existence of market imperfections or risk. This thesis explores the issue of farm support for the case of crops farm households in France. It develops and applies a stochastic dynamic farm household model for a representative crops farm household. The farm household faces occasionally binding debt constraints and investment adjustment costs. The model is specified and parameterized to a sample of French crops farms using Farm Accountancy Data Network (FADN) data observed between 1996 and 2003. Simulations with various policy scenarios show the extent to which farm support and especially decoupled payments affect the farm household’s decisions. First, the thesis examines the impact of CAP reforms on farm behaviour. Then, the thesis compares the impacts of different farm payments, i.e. Single Farm Payments, farm payments coupled to production and Counter-cyclical Payments, to explore the link between investment and farm payment. Further, the thesis highlights that the degree of decoupling of farm payments depends on the farm household’s access to credit. Although Single Farm Payments may potentially affect output decisions, given the relatively low impacts found in the thesis, it is reasonable to consider that the Single Farm Payment is effectively decoupled in this French FADN sample of arable crops farms. The introduction of decoupled direct payments in the EU appears to be an efficient step towards reducing trade distortions.
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Kapal, Debbie B. "Influence of a legume green manure crop on barley straw/stubble decomposition, and soil nitrogen retention and availability." Lincoln University, 2008. http://hdl.handle.net/10182/701.
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The incorporation of cereal straw/stubble often immobilises nitrogen (N). This can help conserve N in soil in organic forms, thus reducing loss through leaching over dormant winter periods. However, N-depressions that arise during decomposition can reduce crop yield. The inclusion of a legume green manure can supply fixed-N, thus alleviating the low N availability to crops. In this study, the effect of lupin (Lupinus angustifolius L.) green manure incorporation on barley (Hordeum vulgare L.) straw/stubble decomposition, and N availability was investigated. A field experiment was used to determine the effects of the green manure on decomposition. Decomposition of straw/stubble was monitored using the litterbag technique. Following green manure incorporation, soil cores were incubated in a glasshouse to determine mineral-N availability. Though not significant, the inclusion of lupin green manure seemed to increase the decomposition of straw/stubble during the growth period, then slowing it after its incorporation at 110 d. This was described by a logarithmic pattern of loss of - 4.97 g AFDW residue day⁻¹, with 60% remaining after 140 d. Treatments without lupin had a linear decomposition of - 0.12 g AFDW residue day⁻¹, with 49% remaining after 140 d. The loss of cellulose confirmed the differences in decomposition with the inclusion of lupin resulting in 2.79% less cellulose remaining in straw/stubble after 140 d compared to its exclusion. Lupin significantly increased pot oat N uptake and DM yield by 55 % and 46 %, respectively, compared to its exclusion. However, this effect was not observed in field sown wheat yields and the soil mineral-N measurements made. This study showed that the potential of lupin to increase straw/stubble decomposition by improving the retention and availability of N, leading to long-term yield benefits, needed further investigation.
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Lefrancq, Marie. "Transport and attenuation of pesticides in runoff from agricultural headwater catchments : from field characterisation to modelling." Phd thesis, Université de Strasbourg, 2014. http://tel.archives-ouvertes.fr/tel-01037928.
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Understanding pesticide transport is crucial to evaluate their ecological impact on ecosystems. Current knowledge on the spatial variability of pesticide deposition, the impact of erosion on pesticides export and the in situ pesticide degradation is very limited at the catchment scale. In this thesis, characterisation and modeling at two scales, the plot and catchment, were combined in two agricultural contexts. A formalism was developed to predict pesticide transport in runoff and was integrated in LISEM (LImbourg Soil Erosion Model). The results show that impermeable roads contributed to more than 40% to the overall load of fungicides exported via runoff from the vineyard. Pesticide partitioning between suspended solids and runoff water differed largely according to the molecules and the hydrological dynamics. The occurrence of degradation products and the enrichment of one enantiomer were observed suggesting the potential of chiral analyses for assessing biodegradation of chiral pesticides at such scale. Overall, the investigation demonstrated that combining different approaches enable a better understanding of pesticide transport.
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Lundqvist, Maja. "Ny tid över tegarna : Nyodling och skifte i Torstuna härad 1750-1914." Thesis, Uppsala universitet, Ekonomisk-historiska institutionen, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-338237.
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The purpose of this thesis is to elucidate the importance of the enclosure movement for the agricultural development in the area of Mälardalen, Sweden. This is done through a case study of Torstuna härad between the years 1750-1914 by sampling five points in time. By studying the long term development of land reclamation and its correlation with meadow acreage, crop rotation and animal stock the thesis argues that the the radical enclosures in the 1850’s was a course of action to regain opportunities for agricultural expansion. The most intense period of land reclamation was after the implementation of radical enclosure which brought with it a change from communal land use to private ownership. Private property rights meant a new set of advantages for the individual farmer to plan and invest and balance the arable and the meadow.
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Reed, L. E. "Mycorrhizal effects in arable crops." Thesis, University of Leeds, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.371057.
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Morrison, Eilidh Christina. "Methyl halide and biogenic volatile organic compound fluxes from perennial bioenergy crops and annual arable crops." Thesis, University of Edinburgh, 2013. http://hdl.handle.net/1842/8279.
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The depletion of fossil fuel resources, pollution concerns and the challenge of energy security are driving the search for renewable energy sources. The use of lignocellulosic plant biomass as an energy source is increasing in the United Kingdom and worldwide. In the UK, up to 0.35MHa (6% of total arable land) may be planted with perennial bioenergy crops by 2020 in order to meet renewable energy and CO2 reduction targets. Several plant species that produce high biomass from low inputs have been identified. The most promising for the UK climate are the genus Miscanthus, a perennial rhizomatous grass which can grow up to 3.5m in a year, and short rotation coppice (SRC) willow (Salix spp.), plantations of which can remain viable for up to 30 years. Although bioenergy crops are perceived as “carbon neutral”, changes in land use can have a wider impact on atmospheric composition than through CO2 alone. This study compares vegetation fluxes of methyl halides (CH3Br and CH3Cl) and biogenic volatile organic compounds (BVOCs) from perennial bioenergy crops and annual arable crops at three sites in the UK. Methyl halides are the most abundant natural vectors of bromine and chlorine into the stratosphere and play an important role in stratospheric ozone destruction. BVOCs affect atmospheric oxidising capacity and are a major precursor to the formation of ozone and secondary organic aerosols in the troposphere. Although terrestrial vegetation is an important source of these trace gases there are very few previous measurements of these reactive gases from bioenergy crops. This study describes measurements conducted at two SRC willow sites in Scotland, and one site in England planted with adjacent perennial bioenergy crops and annual arable crops, to quantify and characterise natural methyl halide and BVOC fluxes from vegetation. Measurements were conducted with branch chambers, using static enclosure techniques to measure methyl halide fluxes and dynamic enclosures to measure BVOCs such as isoprene and -pinene. Fluxes were calculated from the concentration difference between background/inlet samples and after enclosure/outlet samples. Methyl halide concentrations were determined by sampling gas from static enclosures followed by analysis using an oxygen-doped GC-ECD with a custom-built pre-concentration unit. Samples for BVOC analysis were collected onto adsorbent tubes and a thermal desorption GC-MS was used to determine BVOC concentrations. Potentially influential environmental variables such as photosynthetically active radiation (PAR), total solar radiation, air temperature, soil temperature, internal chamber temperature and soil moisture were recorded in parallel to the enclosures to determine their potential relationships to fluxes. Long-term environmental data was also available from on-site or nearby weather stations. Long-term measurements were carried out for 2 1 2 years at a site in Lincolnshire, England where adjacent fields are planted with Miscanthus, SRC willow and annual arable crops (wheat and oilseed rape crop rotation). Vegetation measurements were made almost every month throughout the period, with more intensive measurements such as full diurnal cycle carried out during the summer. Ten sampling points are sampled in each field and semi-diurnal measurements are taken regularly. Long-term measurements were also carried out at two sites in Scotland planted with SRC willow, one in Arnot, Perth & Kinross which was sampled for a year and one in East Grange, Fife which was sampled for half a year. Up to 30 sampling points were employed in Arnot and another 10 in East Grange. The bioenergy crops and wheat emitted low fluxes of methyl halides in comparison to the oilseed rape. Mean annual net fluxes of CH3Br and CH3Cl from Miscanthus were 1.8 ng g (dry weight)-1 h-1 and 11 ng g-1 h-1, respectively. At the three willow sites, mean annual net fluxes of CH3Br and CH3Cl ranged between 0.6 - 1.7 ng g-1 h-1, and 1.7 - 12 ng g-1 h-1, respectively. Negligible fluxes of methyl halides were measured from wheat but oilseed rape was found to emit large fluxes of methyl halides with mean annual net fluxes of CH3Br and CH3Cl of 20 ng g-1 h-1and 144 ng g-1 h-1, respectively. The largest BVOC fluxes were measured from SRC willow at the Brattleby site, with high mean annual net fluxes of isoprene (77 μ g g-1 h-1), α -pinene (46 g μg-1 h-1), β -pinene (5.5 μ g g-1 h-1), limonene (3.7 μ g g-1 h-1) and δ -3-carene (11 μ g g-1 h-1). However, mean annual net BVOC fluxes measured at Arnot and East Grange were much lower. High fluxes of - pinene were measured from Miscanthus in 2010 (giving a mean annual net flux of 65 μ g g-1 h-1) but no other significant BVOC fluxes were distinguished. Negligible fluxes of isoprene were measured from wheat but fluxes of monoterpenes were high with mean annual net fluxes of 65 μ g g-1 h-1 and 25 μg g-1 h-1 for α -pinene and limonene, respectively. No significant fluxes of BVOCs were measured from the oilseed rape. All fluxes demonstrated a strong seasonal trend with higher emissions during the summer growing season and low to zero emissions over winter. The high spatial variability was captured by sampling from many points in each field. Some diurnal measurements exhibited a clear pattern of higher emissions during the day and low to zero emissions at night. Some positive correlations between fluxes and environmental variables such as PAR and air temperature were observed. An experiment carried out on willow cuttings in the greenhouse found no clear increase or decrease in fluxes of BVOCs in response to N fertiliser treatment, instead fluxes were found to vary significantly with some of the observed environmental variables. UK estimates were derived by extrapolating measured fluxes using the current respective land cover areas for Miscanthus and SRC willow. Estimated UK annual fluxes of CH3Br and CH3Cl from Miscanthus were 0.01Mgy-1 and 0.05Mgy-1, respectively and from SRC willow were 0.06Mgy-1 and 0.4Mgy-1, respectively, accounting for a very small percentage of total global annual turnover of CH3Br and CH3Cl. Estimated UK annual fluxes of the BVOCs isoprene and α -pinene from Miscanthus were 0.01Mgy-1 and 0.4Mgy-1, respectively and from SRC willow were 3Mgy-1 and 1Mgy-1, respectively. Future planting of SRC willow to meet the UKs energy needs could lead to a potential annual isoprene flux of 150 MgMgy-1.
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Xing, Ying [Verfasser]. "Iron isotope fractionation in arable soil and graminaceous crops / Ying Xing." Bonn : Universitäts- und Landesbibliothek Bonn, 2020. http://d-nb.info/1224270398/34.
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Robson, Melissa. "The potential of break crops for ley/arable rotations in organic agriculture." Thesis, University of Aberdeen, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.274840.
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This thesis examines the potential of nine break crops (bean, carrot, swede, hemp, sugar beet, potato, lupin, oilseed rape and linola), against an oat control crop. Seven rotational field trails were carried out at five sites across the UK. The most profitable break crops in this study were carrot and potato in terms of direct economic return to the farmer. Mean annual returns were £5175 and £3668 respectively. Cereal yields following break crops were found to be more affected by the soil fertility before the break crops were planted, than the actual break crop. Studies on the nutrient concentration of break crops showed that by the second year of the experiment, over 50% of the break crops were deficient in either N, P or K, with N deficiency being most common. Subsequent cereal crops mostly had adequate nutrient concentrations. Break crop and cereal yields were more strongly correlated with soil nutrient concentrations at the start of the experiment that previous crop. Root crops showed a strong N response, sugar beet had a strong Mg response, linola, oilseed rape and oat had strong K responses, and wheat and barley yields were strongly influenced by soil N, P and Cu. In general soil nutrients decreased over the experiment as did pH and soil organic matter. In general there was an inverse relationship between the crops yield and the crop’s nutrient concentration, so as the yield of a crop increases, the concentration of nutrients in the plant matter, or quality, decrease. The break crops, hemp, linola and carrot generally had positive effects on reducing weed populations during growth and in the subsequent cereal crop compared with the control crop. In additional these break crops were pest- and disease-free during growth. Other break crops, such as bean, swede and oilseed rape were shown to suffer from many weed, pest or disease problems, which may limit their potential for inclusion in an organic rotation.
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Morris, Nathan. "The establishment of arable crops in UK cereal stubbles using strip tillage." Thesis, University of Reading, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.486352.
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Recent advances in crop establishment techniques have led to the introduction of conservation tillage systems that enables a reduction in the number of field operations and associated costs whilst maintaining or increasing financial margins. A recent development in conservation tillage systems in the United States was the adoption of strip tillage that was defined as the disturbance of less than one-third of a total field by cultivation. The aim of strip tillage is to produce a narrow, residue free, cultivated zone that is suitable for drilling crops into whilst leaving a significant area uncultivated that maintains crop residue on the soil surface with benefits both to soil stability and biodiversity. This study reported in this thesis focuses on the use ofa strip tillage implement to establish Brassica napus and Beta vulgaris in two soil types found in the United Kingdom. Crop residue has been reported to reduce crop emergence and this study found a reduction in percentage emergence by up to 40% when straw was mixed into the top 5 cm of soil or when straw and seed was placed on the soil surface. The strip tillage unit using a tine and disc combination operating in a range of light soil types gave disturbance patterns that were independent of forward speed in the range of 6.0 to 12.0 km/h but tine penetration was often limited. The star wheel was found to remove up to 80% of straw residue from within row. Using strip tillage was found to create a tilth either similar to, or finer than, plough tillage but initially gave poorer emergence and growth. Overall performance of using strip tillage to establish Brassica napus and Beta vulgaris was found to be equivalent to a conventional plough tillage system resulting in no penalties to crop yield or quality.
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Weinberg, Naomi Hélène. "Improving nitrogen fertilizer recommendations for arable crops in the Lower Fraser Valley." Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/26664.
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A two year field study located in Delta Municipality, British Columbia, was conducted to investigate the possible improvement of nitrogen (N) fertilizer recommendations for arable crops in the Lower Fraser Valley (LFV).
After reviewing current N fertilizer recommendation systems in other humid regions, the approach taken in the study was to determine the applicability of a spring soil test and/or a N Index system for the LFV region. The project, which used sweet corn (Zea Mays saccharata) as the trial crop, consisted of two interconnected parts:
1) A 'Replicated Fertilizer Response Trial' which aimed to; a) Monitor soil N0₃-N and NH₄-N during spring to a depth of 80cm, using intervals of 0-20, 20-50, and 50-80cm. b) Investigate yield response and N uptake efficiency at four different rates of sidedress applied urea, 0, 50, 100 and 200 kg ha⁻¹ N. c) Compare the effectiveness of urea applied broadcast preplant, and applied by sidedressing, when the crop was approximately 30cm tall.
2) A 'Multifarm Survey' at 28 locations, comparing plots sidedressed with 135 kg ha⁻¹ N, to control plots containing only starter N. The aim of this survey vas to establish the range of N supplying capacities in some LFV soils and relate these capacities to other soil properties and site history.
Monitoring mineral N in the soil demonstrated that soil N0₃-N increased during the spring, reaching a peak 5-6 weeks after planting. Maximum N0₃-N levels in the 0-80cm profile were 90 and 135 kg ha⁻¹ in 1984 and 1985 respectively. NH₄-N levels tended to be low compared to NO₃-N. As a proportion of total mineral N, NH₄-N decreased from approximately 25% at the beginning of May, to between 10 and 15% by mid June. Large amounts of spatial and temporal variability in both N0₃-N and NH₄-N were observed on the two sites studied. The difference in magnitude of mineral N between the years was due to a large number of site and weather factors which could not be separated.
No significant differences in corn yield or crop N content were found between any of the four fertilizer treatments in the Replicated Response Trial. Similarly, no significant differences were found in the comparison of urea N applied by broadcasting before planting and urea N applied by sidedressing. Two reasons for this lack of response were suggested, one, that the soil plus starter N provided sufficient N for the crop's needs, and two, that the fertilizing techniques were inefficient considering the soil and weather conditions.
The Multifarm Survey provided the greatest amount of information relevant to the project's objectives. It showed that the range of soil types and cropping regimes on corn fields in Delta Municipality was too narrow to have a direct influence on N supplied by the soil. Soil N supplying capacity was shown to be weakly related to organic matter, the study results suggested that a knowledge of site history was necessary before this relationship could be assumed to be positive. Such findings favoured the implementation of a spring soil test rather than a N Index system. Various approaches to estimating N fertilizer requirements using a spring soil sample were examined.
In conclusion, the project showed that substantial amounts of N vere made available by the soil and that these should be taken into consideration when fertilizer recommendations are made. The study suggested that in a small agricultural region such as Delta Municipality, spring soil N0₃-N appeared to be sufficiently well correlated with total soil plus crop nitrogen to warrant the further investigation of a soil test for N. This test, for corn, should be as close as possible to sidedress time and the ideal sampling depth would be to 80cm. Anomalous sites with adverse soil conditions, such as poor drainage, marine influences, low pH or compaction should not be included in the test.Land and Food Systems, Faculty of
Graduate
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Rydberg, Ingrid. "Breeding of catch crops : a way to reduce nitrate leaching from arable land /." Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 1998. http://epsilon.slu.se/avh/1998/91-576-5525-1.gif.
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Macdonald, Andrew James. "The effects of cover crops soil N transformations and losses from arable land." Thesis, University of Reading, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326592.
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Cilgi, Tamer. "Effects of pesticides on non-target invertebrates in arable crops and field boundaries." Thesis, University of Southampton, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.295247.
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Alyemeny, Mohammed N. "Water use of the alfalfa crop under desert conditions in Saudi Arabia." Thesis, University of Edinburgh, 1989. http://hdl.handle.net/1842/11973.
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Bradley, Bo Dylan. "The impacts of farm finances of substituting mechanical for chemical weed control in arable crops." Thesis, Imperial College London, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.263299.
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Reverte, Rocio Alarcon. "Understanding and combating the threat posed by Lolium multiflorum as a weed of arable crops." Thesis, University of Reading, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.525129.
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McClatchie, Meriel. "Arable agriculture and social organisation : a study of crops and farming systems in Bronze Age Ireland." Thesis, University College London (University of London), 2009. http://discovery.ucl.ac.uk/17260/.
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This thesis will present the results of an investigation into arable crops and farming systems of Bronze Age Ireland. Earlier studies have suggested that barley - particularly the naked variety - was the predominant crop of this period, with wheat playing a very minor role in farming economies. These studies relied heavily upon evidence from plant impressions on ceramic vessels. The research presented here will explore the production and consumption of crops in Bronze Age Ireland through the examination of an alternative dataset – the evidence from charred plant macro-remains recovered from archaeological excavations. Investigations are focused upon evidence from the Middle and Late Bronze Age in Ireland, due to a relative dearth of Early Bronze Age material. The collation and analysis of mainly unpublished data from more twenty sites provide a strong contrast to the evidence from the seed impressions record. Clear differences can also be observed when comparing data from the Middle and Late Bronze Age periods. Investigation of the types of contexts in which these remains were recorded has revealed new insights into deposition processes and activities at this time. Analysis of the arable weeds accompanying the cereals has also enabled an exploration of cultivation, harvesting and crop-processing activities. Investigation of the scale of agricultural production suggests the mobilisation of communities for agricultural work, as well as the accumulation of agricultural surpluses. The record from Bronze Age Ireland does, however, indicate that a variety of agricultural strategies could have been deployed, and a progressive or 'evolutionary' trend towards agricultural intensification is unlikely to have occurred in all areas.
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Day, Robyn Linda. "The use of model flowers to enhance oviposition by aphidophagous hoverflies (Diptera: Syrphidae) in arable crops." Thesis, University of Southampton, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.479140.
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Kirkland, Dean Lee. "The use of semiochemicals to enhance the natural control of pests of arable crops by invertebrate predators." Thesis, University of Edinburgh, 1999. http://hdl.handle.net/1842/28368.
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The electrophysiological and behavioural responses of the aphidophagous hoverfly Episyrphus balteatus Degear, and polyphagous ground beetles Pterostichus melanarius Illiger and Nebria brevicollis Linneaus, to a range of volatile semiochemicals were studied. Phacelia tanaectfiolia flower extract, Nepeta cataria whole plant extract, and (E)-β-farnesene where found to be attractive to the predators in laboratory and windtunnell assays. Field trials demonstrated that the attractive semiochemicals could be placed in dispensers in arable crops to increase the amount of predators present throughout the field system. There was also a corresponding decrease in the number of pest species present in the treated field plots relative to the control plots. Phacelia flower extract was found to have the greatest effects on predator and prey numbers. The mechanisms of the reduction in prey numbers were studied using exclusion experiments in the field and enzyme linked immunosorbant assays on the gut contents of the predators. There was found to be a link between the increased rates of predation in the field and the decline in pest numbers. The potential of semiochemicals to enhance natural control of crop pests is discussed.
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Kielty, Jonathan Peter. "The effects of field margins on the distribution and biocontrol potential potential of polyphagous predatory arthropods in arable crops." Thesis, University of Hertfordshire, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314623.
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Pattichis, Charalambos Athanasiou. "Cyprus and the Common Agricultural Policy : a quantitative analysis, with special reference to arable crops, livestock and dairy products." Thesis, University of Cambridge, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.624196.
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Sänger, Anja [Verfasser]. "Application of biogas slurries from energy crops to arable soils and their impact on carbon and nitrogen dynamics / Anja Sänger." Kassel : Universitätsbibliothek Kassel, 2012. http://d-nb.info/1029215154/34.
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Gabriel, Doreen. "Plant communities in organic and conventional agriculture comparing local, landscape and regional effects /." Doctoral thesis, [S.l.] : [s.n.], 2006. http://webdoc.sub.gwdg.de/diss/2006/gabriel.
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Creel, Sarah Frances. "Effect of acacia gum on bare root nursery crops and in cutting propagation." Auburn, Ala., 2006. http://repo.lib.auburn.edu/2006%20Summer/Theses/CREEL_SARAH_14.pdf.
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Gayer, Christoph [Verfasser], and Martin [Akademischer Betreuer] Dieterich. "Suitability of conventional flowering fields and organic lentil mixed-crops to promote biodiversity on arable land / Christoph Gayer ; Betreuer: Martin Dieterich." Hohenheim : Kommunikations-, Informations- und Medienzentrum der Universität Hohenheim, 2020. http://d-nb.info/1223981924/34.
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MARTANI, ENRICO. "Conversion of perennial cropping systems to arable land: keyelements for an ecologically sustainable transition." Doctoral thesis, Università Cattolica del Sacro Cuore, 2021. http://hdl.handle.net/10280/96576.
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La coltivazione dei sistemi colturali poliennali su terreni marginali combina la produzione sostenibile di biomassa per diversi utilizzi a benefici di carattere ambientale come il sequestro del C atmosferico nel suolo. La limitata longevità di questi sistemi colturali (10-20 anni), fornisce la possibilità di sfruttarli come una tecnica temporanea per rigenerare la fertilità dei terreni marginali e di studiare il loro effetto nel lungo periodo sul carbonio del suolo. Con questa tesi, avevo l'obiettivo di studiare l'effetto della riconversione a coltura annuali dei sistemi agricoli poliennali sul carbonio del suolo: per raggiungere questo obiettivo, ho combinato ad una meta-analisi di letteratura sull'effetto della riconversione, con un esperimento di campo di lungo periodo, un esperimento di incubazione in laboratorio e l'uso di un modello matematico del carbonio del suolo. L'uso combinato di questi approcci mi ha permesso di mostrare il potenziale che i sistemi colturali poliennali hanno nel sostenere il sequestro del C ne suolo anche dopo la loro riconversione. Quindi i sistemi colturali poliennali sono una pratica sostenibile promettente che può essere integrata in rotazioni agricole di 13 anni sui terreni marginali del nord d'Italia per ripristinare il carbonio del suolo.The cultivation of perennial cropping systems on marginal lands combines the production of sustainable biomass for multiple uses with environmental benefits such as carbon (C) sequestration in soil. In this thesis, we studied the effect of perennial cropping system on soil C considering the scenario of perennial cropping systems reversion to arable land. The limited longevity (10-20 years) of perennial cropping systems, gives the possibility of using these crops as a temporary- option to restore soil fertility of marginal lands and to study the long-term legacy of these cropping systems on soil C. In this thesis I aimed to study the effect of perennial cropping systems reversion to arable land on soil C: to achieve this objective, I combined a literature meta-analysis on the effect of reversion of perennial cropping systems on soil C, with a long-term field experiment on perennial cropping systems, an incubation experiment and the use of a process-based soil C model. The combined use of these approaches gave me the chance to show the potential of perennial cropping systems to support C sequestration even after their reversion. Therefore, perennial cropping systems are a promising sustainable practice which could be integrated on a 13-year agricultural rotation on marginal lands of northern Italy to restore soil C.
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Catalogna, Maxime. "Expérimentations de pratiques agroécologiques réalisées par des agriculteurs : proposition d’un cadre d’analyse à partir du cas des grandes cultures et du maraîchage diversifié dans le département de la Drôme." Thesis, Avignon, 2018. http://www.theses.fr/2018AVIG0705/document.
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L’intensification des processus écologiques proposée par l’agroécologie est très dépendante du contexte agricole. Un renouvellement des savoirs sur l’exploitation agricole est nécessaire pour adapter chaque pratique agroécologique. Dans cette thèse, nous avons étudié l'activité d'expérimentation des agriculteurs, définie comme un processus de mise à l’épreuve de pratiques embarquant des hypothèses tant sur leur mise en œuvre que sur les processus agroécologiques que ces pratiques visent à induire. Notre travail est basé sur des enquêtes auprès de 17 agriculteurs majoritairement drômois, étant soit en maraîchage diversifié, soit en grandes cultures.Nous avons formalisé l'activité d'expérimentation des agriculteurs avec deux notions : la situation expérimentale (SE) et l'itinéraire d'expérimentation (ITE). Elles concernent respectivement le temps court (annuel ou infra-annuel) et le temps long (pluri-annuel) et font l'objet des deux premiers chapitres de résultat. Dans le premier, nous avons construit un cadre d’analyse des SEs comprenant des phases de conception, de réalisation et d’évaluation. A partir de ce cadre, nous avons étudié la diversité d’un échantillon de 181 SEs et identifié 10 groupes de SEs organisés en 4 clusters. La typologie obtenue dépend d'une variable particulière qui est le type de lien aux SEs précédentes. Dans le deuxième chapitre de résultat, nous avons approfondi ces liens en nous intéressant aux ITEs, définis comme la combinaison de différentes SEs portant sur une thématique agroécologique particulière. Nous avons identifié 4 types d'ITE qui diffèrent par leur intensité expérimentale, les liens entre SEs et l'émission ou non de nouvelles branches expérimentales.Le troisième chapitre de résultat traite la question du développement des connaissances des agriculteurs grâce à leurs expérimentations. Après avoir caractérisé différentes formes de connaissances, plus ou moins stabilisées, nous proposons trois processus de développement de connaissances avancées grâce aux expérimentations menées.Le modèle SE/ITE est prometteur pour accompagner les agriculteurs. La frise chronologique des SEs organisées en ITE représente un outil de réflexivité potentielThe intensification of ecological processes proposed by agroecology is highly dependent on the agricultural context. A renewal of farming knowledge is necessary to adapt each agro-ecological practice. In this thesis, we studied farmers’ experiments, defined as a process of testing practices that embody hypotheses both on their implementation and on the targeted agro-ecological processes. Our work is based on surveys of 17 farmers, mainly Drôme farmers, who were either diversified market gardeners or cereal farmers.We have formalized the farmers’ experiments with two notions: the experimental situation (SE) and the experimentation itinerary (ITE). They concern respectively short time (annual or infra-annual) and long time (multi-year) and are the subject of the first two chapters of the results. In the first one, we built an analytical framework that includes design, implementation and evaluation phases. From this framework, we studied the diversity of a sample of 181 SEs and identified 10 groups of SEs organized into 4 clusters. The typology obtained depends on a particular variable which is the type of link to previous SEs. In the second chapter of the result, we have deepened these links by focusing on ITEs, defined as the combination of different SEs on a particular agro-ecological theme. We identified 4 types of ITEs that differ in their experimental intensity, the links between SEs and the emission or not of new experimental branches.The third chapter of the result deals with the question of farmers developing knowledge through their experiments. After having characterized different forms of knowledge, more or less stabilized, we propose three processes for the development of advanced knowledge through experimentation.The SE/ITE model is promising to support farmers. The chronological timeline of SEs organized in ITEs represents a potential reflexivity tool
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Fritsch, Sebastian [Verfasser], and Christopher [Akademischer Betreuer] Conrad. "Spatial and temporal patterns of crop yield and marginal land in the Aral Sea Basin: derivation by combining multi-scale and multi-temporal remote sensing data with alight use efficiency model / Sebastian Fritsch. Betreuer: Christopher Conrad." Würzburg : Universität Würzburg, 2013. http://d-nb.info/1111815038/34.
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Rakotovololona, Lucia. "Quantification expérimentale et modélisation de la production, des flux d'eau et d'azote en systèmes de culture biologiques." Thesis, Paris, Institut agronomique, vétérinaire et forestier de France, 2018. http://www.theses.fr/2018IAVF0024.
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Dans le contexte actuel de changements globaux, faire face au défi multiple et interconnecté de la sécurité alimentaire et des impacts environnementaux s’avère fondamental pour la durabilité des systèmes agricoles. La thèse s’attache ainsi à évaluer les performances agronomiques et environnementales des systèmes en AB, en couplant un suivi expérimental réalisé sur un réseau de 35 parcelles agricoles dans la région Hauts-de-France, avec la modélisation du continuum sol-plante-atmosphère afin de mieux comprendre les processus expliquant les dynamiques de l’eau et de l’azote dans ces systèmes, en vue de promouvoir des pratiques de gestion durables.Dans un premier temps, le drainage d’eau et la lixiviation d’azote ont été quantifiés en couplant les données sol-culture-climat et le modèle LIXIM. L’analyse de la lixiviation des parcelles agricoles a permis de déterminer que les facteurs qui expliquent la variabilité. Outre le fort effet sol et l’importance des conditions climatiques sur le drainage, ils sont principalement liés à la combinaison de précédent cultural et de gestion de la couverture du sol en automne. Ces deux derniers jouent en effet sur la quantité d’azote minéral présent avant la période de drainage et expliquent la position du nitrate dans le profil de sol. Nos résultats ont montré le rôle dichotomique des légumineuses dans les systèmes de grandes cultures en AB, et la faible performance des cultures intermédiaires car semées tardivement en automne dans ce contexte.Dans un second temps, le diagnostic des déterminants de l’écart au rendement des cultures ou yield gap a été réalisé via une approche par modélisation déterministe. Le modèle sol-culture STICS a servi à estimer les différents niveaux de rendement potentiel et décomposer le yield gap, en s’appuyant sur le cas du blé tendre et du triticale. Les résultats montrent que le stress en azote permet d’expliquer la majeure partie du yield gap survenant en AB, et dans une moindre mesure les facteurs liés à la pression biotique, pour des systèmes recourant à peu ou pas d’apport azoté exogène.Finalement, le défi de la fourniture en azote dans les systèmes de grandes cultures en AB a été abordé afin de contribuer à une meilleure efficience d’utilisation de l’azote et une amélioration de la productivité des parcelles. Le modèle STICS a permis de simuler l’impact de pratiques de gestion alternatives de l’azote, par expérimentation numérique menée dans le cadre d’une approche participative, mobilisant les agriculteurs, les conseillers techniques et les chercheurs. Les résultats indiquent l’importance de la succession et des pratiques culturales, en particulier la mise en place de cultures intermédiaires et la gestion du retournement des luzernières. L’optimisation des pratiques des agriculteurs restent ainsi possible, en réduisant les émissions potentielles d’azote par lixiviation ou par pertes gazeuses, sans léser la fourniture en N pour les cultures.Dans les contextes pédo-technico-climatiques étudiés, les systèmes de grandes cultures en AB peuvent ainsi combiner performance agronomique et faibles impacts environnementaux, lorsque la gestion de l’azote est bien maîtriséeNowadays, in a context of global changes, addressing the interlinked challenges of food security and environmental impacts is fundamental for the sustainability of agricultural systems. Therefore, the thesis aimed to assess agronomic and environmental performances of organic systems, by coupling the experimental monitoring of a 35 organic fields network in the Northern region of France with modeling the soil-crop continuum, to better understand the underlying processes in water and nitrogen dynamics within those systems, and to promote a more sustainable management.Water drainage and nitrate leaching were assessed by coupling soil, crop and climate data within LIXIM model. Then we analyzed N leaching pattern under diverse organic arable fields to explain its main driving factors. Leaving aside the strong soil type effect and the importance of climatic conditions on drainage, the combination of previous crops and autumn field management appeared to be a key determinant of nitrate leaching in the studied organic systems, as they both drive the amount of soil mineral nitrogen before draining period and explain the position of nitrate in the soil profile. We also showed the dichotomous role of legumes as preceding crop in organic cropping systems and the poor performance of the standard catch crops, sown in late summer in this context.Yield gap of cereals was investigated using a deterministic modeling approach as a diagnosis tool, to contribute in improving the productivity of organic agriculture. The soil-crop model STICS was used to estimate the potential yields of each studied winter wheat and winter triticale crop fields in their given soil and climate conditions. Our results reasserted how nitrogen stress could explain a major part of the yield gap occurring in organic crops and outweigh biotic limiting factors impacts, for cropping systems relying on few or no manures for nitrogen supply.Lastly, we aimed to address the challenge of nitrogen supply in organic arable systems for a better nitrogen use efficiency and improved crop yields. We used the model STICS to simulate the impact of alternative nitrogen management practices by carrying out a numerical experiment in a participatory approach involving farmers, technical advisors and researchers. The findings emphasized the importance of crop succession design and management practices, particularly the implementation of catch crops and the timing of the destruction of perennial legume crops. Optimizing the farmer’s actual practices could then be possible, reducing the potential emissions of nitrogen via leaching or gaseous losses, without decreasing the nitrogen supply for the following crop.Organic arable cropping systems, within the studied soil, technics and climate contexts, can achieve agronomic performances combined with low environmental impacts, with well-managed nitrogen practices
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Wietzke, Alexander. "Arable plant diversity in conventionally managed farmland of Northwest Germany - Current state and a participative approach to increase farmland biodiversity." Doctoral thesis, 2020. http://hdl.handle.net/21.11130/00-1735-0000-0005-14A8-7.
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Schmidt, Martin H. "Spinnen in Agrarlandschaften und die biologische Kontrolle von Getreideblattläusen." Doctoral thesis, 2004. http://hdl.handle.net/11858/00-1735-0000-0006-AB40-C.
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Fritsch, Sebastian. "Spatial and temporal patterns of crop yield and marginal land in the Aral Sea Basin: derivation by combining multi-scale and multi-temporal remote sensing data with alight use efficiency model." Doctoral thesis, 2013. https://nbn-resolving.org/urn:nbn:de:bvb:20-opus-87939.
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Irrigated agriculture in the Khorezm region in the arid inner Aral Sea Basin faces enormous challenges due to a legacy of cotton monoculture and non-sustainable water use. Regional crop growth monitoring and yield estimation continuously gain in importance, especially with regard to climate change and food security issues. Remote sensing is the ideal tool for regional-scale analysis, especially in regions where ground-truth data collection is difficult and data availability is scarce. New satellite systems promise higher spatial and temporal resolutions. So-called light use efficiency (LUE) models are based on the fraction of photosynthetic active radiation absorbed by vegetation (FPAR), a biophysical parameter that can be derived from satellite measurements. The general objective of this thesis was to use satellite data, in conjunction with an adapted LUE model, for inferring crop yield of cotton and rice at field (6.5 m) and regional (250 m) scale for multiple years (2003-2009), in order to assess crop yield variations in the study area. Intensive field measurements of FPAR were conducted in the Khorezm region during the growing season 2009. RapidEye imagery was acquired approximately bi-weekly during this time. The normalized difference vegetation index (NDVI) was calculated for all images. Linear regression between image-based NDVI and field-based FPAR was conducted. The analyses resulted in high correlations, and the resulting regression equations were used to generate time series of FPAR at the RapidEye level. RapidEye-based FPAR was subsequently aggregated to the MODIS scale and used to validate the existing MODIS FPAR product. This step was carried out to evaluate the applicability of MODIS FPAR for regional vegetation monitoring. The validation revealed that the MODIS product generally overestimates RapidEye FPAR by about 6 to 15 %. Mixture of crop types was found to be a problem at the 1 km scale, but less severe at the 250 m scale. Consequently, high resolution FPAR was used to calibrate 8-day, 250 m MODIS NDVI data, this time by linear regression of RapidEye-based FPAR against MODIS-based NDVI. The established FPAR datasets, for both RapidEye and MODIS, were subsequently assimilated into a LUE model as the driving variable. This model operated at both satellite scales, and both required an estimation of further parameters like the photosynthetic active radiation (PAR) or the actual light use efficiency (LUEact). The latter is influenced by crop stress factors like temperature or water stress, which were taken account of in the model. Water stress was especially important, and calculated via the ratio of the actual (ETact) to the potential, crop-specific evapotranspiration (ETc). Results showed that water stress typically occurred between the beginning of May and mid-September and beginning of May and end of July for cotton and rice crops, respectively. The mean water stress showed only minor differences between years. Exceptions occurred in 2008 and 2009, where the mean water stress was higher and lower, respectively. In 2008, this was likely caused by generally reduced water availability in the whole region. Model estimations were evaluated using field-based harvest information (RapidEye) and statistical information at district level (MODIS). The results showed that the model at both the RapidEye and the MODIS scale can estimate regional crop yield with acceptable accuracy. The RMSE for the RapidEye scale amounted to 29.1 % for cotton and 30.4 % for rice, respectively. At the MODIS scale, depending on the year and evaluated at Oblast level, the RMSE ranged from 10.5 % to 23.8 % for cotton and from -0.4 % to -19.4 % for rice. Altogether, the RapidEye scale model slightly underestimated cotton (bias = 0.22) and rice yield (bias = 0.11). The MODIS-scale model, on the other hand, also underestimated official rice yield (bias from 0.01 to 0.87), but overestimated official cotton yield (bias from -0.28 to -0.6). Evaluation of the MODIS scale revealed that predictions were very accurate for some districts, but less for others. The produced crop yield maps indicated that crop yield generally decreases with distance to the river. The lowest yields can be found in the southern districts, close to the desert. From a temporal point of view, there were areas characterized by low crop yields over the span of the seven years investigated. The study at hand showed that light use efficiency-based modeling, based on remote sensing data, is a viable way for regional crop yield prediction. The found accuracies were good within the boundaries of related research. From a methodological viewpoint, the work carried out made several improvements to the existing LUE models reported in the literature, e.g. the calibration of FPAR for the study region using in situ and high resolution RapidEye imagery and the incorporation of crop-specific water stress in the calculationDie vorliegende Arbeit beschäftigt sich mit der Modellierung regionaler Erntemengen von Baumwolle und Reis in der usbekischen Region Khorezm, einem Bewässerungsgebiet das geprägt ist von langjähriger Baumwoll-Monokultur und nicht-nachhaltiger Land- und Wassernutzung. Basis für die Methodik waren Satellitendaten, die durch ihre großflächige Abdeckung und Objektivität einen enormen Vorteil in solch datenarmen und schwer zugänglichen Regionen darstellen. Bei dem verwendeten Modell handelt es sich um ein sog. Lichtnutzungseffizienz-Modell (im Englischen Light Use Efficiency [LUE] Model), das auf dem Anteil der photosynthetisch aktiven Strahlung basiert, welcher von Pflanzen für das Wachstum aufgenommen wird (Fraction of Photosynthetic Active Radiation, FPAR). Dieser Parameter kann aus Satellitendaten abgeleitet werden. Das allgemeine Ziel der vorliegenden Arbeit war die Nutzung von Satellitendaten für die Ableitung der Erntemengen von Baumwolle und Reis. Dazu wurde ein Modell entwickelt, das sowohl auf der Feldebene (Auflösung von 6,5 m) als auch auf der regionalen Ebene (Auflösung von 250 m) operieren kann. Während die Ableitung der Erntemengen auf der Feldebene nur für ein Jahr erfolgte (2009), wurden sie auf der regionalen Ebene für den Zeitraum 2003 bis 2009 modelliert. Intensive Feldmessungen von FPAR wurden im Studiengebiet während der Wachstumssaison 2009 durchgeführt. Parallel dazu wurden RapidEye-Daten in ca. zweiwöchentlichem Abstand aufgezeichnet. Aus den RapidEye-Daten wurde der Normalized Difference Vegetation Index (NDVI) berechnet, der anschließend mit den im Feld gemessenen FPAR-Werten korreliert wurde. Die entstandenen Regressionsgleichungen wurden benutzt um Zeitserien von FPAR auf RapidEye-Niveau zu erstellen. Anschließend wurden diese Zeitserien auf die MODIS-Skala aggregiert um damit das MODIS FPAR-Produkt zu validieren (1 km), bzw. eine Kalibrierung des 8-tägigen 250 m NDVI-Datensatzes vorzunehmen. Der erste Schritt zeigte dass das MODIS-Produkt im Allgemeinen die RapidEye-basierten FPAR-Werte um 6 bis 15 % überschätzt. Aufgrund der besseren Auflösung wurde das kalibrierte 250 m FPAR-Produkt für die weitere Modellierung verwendet. Für die eigentliche Modellierung wurden neben den FPAR-Eingangsdaten noch weitere Daten und Parameter benötigt. Dazu gehörte z.B. die tatsächliche Lichtnutzungseffizienz (LUEact), welche von Temperatur- und Wasserstress beeinflusst wird. Wasserstress wurde berechnet aus dem Verhältnis von tatsächlicher (ETact) zu potentieller, feldfruchtspezifischer Evapotranspiration (ETc), die beide aus einer Kombination von Satelliten- und Wetterdaten abgeleitet wurden. Der durchschnittliche Wasserstress schwankte nur geringfügig von Jahr zu Jahr, mit Ausnahmen in den Jahren 2008 und 2009. Die Modellschätzungen wurden durch feldbasierte Ernteinformationen (RapidEye-Ebene) sowie regionale statistische Daten (MODIS-Ebene) evaluiert. Die Ergebnisse zeigten, dass beide Modellskalen regionale Ernteerträge mit guter Genauigkeit nachbilden können. Der Fehler für das RapidEye-basierte Modell betrug 29,1 % für Baumwolle und 30,4 % für Reis. Die Genauigkeiten für das MODIS-basierte Modell variierten, in Abhängigkeit des betrachteten Jahres, zwischen 10,5 % und 23,8 % für Baumwolle und zwischen -0,4 % und -19,4 % für Reis. Insgesamt gab es eine leichte Unterschätzung der Baumwoll- (Bias = 0,22) und Reisernte (Bias = 0,11) seitens des RapidEye-Modells. Das MODIS-Modell hingegen unterschätzte zwar auch die (offizielle) Reisernte (mit einem Bias zwischen 0,01 und 0,87), überschätzte jedoch die offiziellen Erntemengen für die Baumwolle (Bias zwischen -0,28 und -0,6). Die Evaluierung der MODIS-Skala zeigte dass die Genauigkeiten extrem zwischen den verschiedenen Distrikten schwankten. Die erstellten Erntekarten zeigten dass Erntemengen grundsätzlich mit der Distanz zum Fluss abnehmen. Die niedrigsten Erntemengen traten in den südlichsten Distrikten auf, in der Nähe der Wüste. Betrachtet man die Ergebnisse schließlich über die Zeit hinweg, gab es Gebiete die über den gesamten Zeitraum von sieben Jahren stets von niedrigen Erntemengen gekennzeichnet waren. Die vorliegende Studie zeigt, dass satellitenbasierte Lichtnutzungseffizienzmodelle ein geeignetes Werkzeug für die Ableitung und die Analyse regionaler Erntemengen in zentralasiatischen Bewässerungsregionen darstellen. Verglichen mit verwandten Studien stellten sich die ermittelten Genauigkeiten sowohl auf der RapidEye- als auch auf der MODIS-Skala als gut dar. Vom methodischen Standpunkt aus gesehen ergänzte diese Arbeit vorhanden LUE-Modelle um einige Neuerungen und Verbesserungen, wie z.B. die Validierung und Kalibrierung von FPAR für die Studienregion mittels Feld- und hochaufgelösten RapidEye-Daten und dem Einbezug von feldfrucht-spezifischem Wasserstress in die Modellierung