Dissertations / Theses on the topic 'Sown area of crops'

En l’actual situació de creixement continuat de la població mundial, la producció suficient d’aliments no pot ser garantida sense l’ús de productes fitosanitaris (PF). No obstant, el seu ús no resta exempt de notables dificultats com l’elevat cost dels programes de lluita química pel control de les plagues i malalties que, en el cas de la fructicultura i la viticultura, representen fins al 30% dels costos totals de producció. A més a més, l’ús de PF comporta riscs importants per la salut humana i el medi ambient. A tot això, s’hi ha de sumar la creixent desconfiança, quan no el rebuig, d’amplis sectors de la societat. Per tal de reduir el seu impacte, la Comissió Europea mitjançant el pacte verd i, en concret, a través de l’estratègia de la granja a la taula, pretén reduir el consum i el risc associat als PF en un 50% en l’any 2030. En aquest context, són necessàries eines cientificotècniques validades per reduir de les dosis a les mínimes imprescindibles sense comprometre la collita. En aquesta Tesi es presenta i valida el sistema d'ajuda a la presa de decisió DOSA3D, el qual permet ajustar el volum de caldo i la dosi de PF en cultius arboris (cultius 3D) a partir de les característiques del cultiu (àrea foliar objectiu i geometria ), el polvoritzador i la plaga o malaltia a controlar. La validació del sistema DOSA3D s’ha dut a terme en tractaments uniformes i en tractaments zonals en base a mapes de vigor atenent a dos criteris, les deposicions sobre l’objectiu tractat i l’eficàcia en el control de plagues i malalties. En base a això, les hipòtesis contrastades han estat: i) el “Leaf Area Index” (LAI) o índex d’àrea foliar (paràmetre més rellevant per l’ajust de la dosis) és estimat correctament a partir de la geometria de la vegetació i de l’estat fenològic de la vinya; ii) l’eficiència del tractament calculada mitjançant el sistema DOSA3D s’ajusta a la realitat operativa dels tractaments; iii) la deposició a les fulles és un paràmetre que es relaciona bé amb l’eficàcia biològica del tractament; iv) el volum de caldo establert pel sistema DOSA3D permet obtenir deposicions similars a l’objectiu llindar (1.2 µl cm-2) i, conseqüentment, obtenir l’eficàcia adequada; i, v) el tractament zonal de la vinya a partir de mapes de vigor, ajustant la dosi mitjançant el sistema DOSA3D, permet assolir deposicions optimes i l’eficàcia biològica esperada en els diferents vigors. El cos de la Tesi Doctoral es divideix en tres blocs. El primer està dedicat a la revisió de l’estat de l’art en matèria d’expressió i l’ajustament de la dosi i a la comparació entre els diferents sistemes existents per a la presa de decisió en l’ajustament de la dosi. El segon bloc de la Tesi inclou dos capítols dedicats als fonaments del sistema DOSA3D i a la seva validació en el cultiu de la de vinya. això Amb aquesta finalitat, s’han practicat defoliacions de trams de vinyes en espatllera, donant-se per vàlid el model d’estimació del LAI del sistema DOSA3D vinyes de fins a 1.25 m d’amplada. També, mitjançant la metodologia descrita a la norma ISO 22522:2007, s’ha determinat la deposició foliar en tractaments ajustats, posant-se de manifest la marcada tendència a la uniformització de les deposicions en la mesura que incrementa el LAI. També, el sistema DOSA3D ha estat validat al llarg de tota la campanya per l’eficàcia en el control de l’oïdi (Erysiphe necator Schw.) en quatre assajos independents en els que les dosis de PF s’han reduït fins al 60% respecte a l’estratègia realitzada per l’agricultor. En el tercer bloc s’han validat els tractaments zonals a dosis ajustades mitjançant el sistema DOSA3D en vinyes espacialment variables. Mitjançant l’índex de vigor “Plant Cell Density” (PCD), establert a partir d’imatges multiespectrals adquirides des d’un avió, s’han confeccionat mapes de dos vigors i els consegüents mapes de prescripció. En tots els casos, la deposició foliar no ha presentat diferencies significatives entre classes de vigor i l’eficàcia dels tractaments en el control del àcar groc (Eotetranychus carpini Oud.) i el mosquit verd (Empoasca vitis G. y Jacobiasca lybica Berg. & Zanon) ha permès situar la densitat de la plaga per sota dels llindars econòmics de danys en ambdues classes de vigor, comportant estalvis de PF entre el 16,6 i el 24,8% en les zones de baix vigor. Les conclusions obtingudes en la present Tesi Doctoral proporcionen les evidències cientificotècniques necessàries per utilitzar el sistema DOSA3D de manera sanitàriament segura (garantint l’eficàcia biològica). El sistema es mostra com una eina a ser considerada pels seus efectes beneficiosos per part dels agents interessats (agricultors, assessors en sanitat vegetal, indústria química, constructors d’equips de tractaments i autoritats reguladores) així com per la seva contribució a la consecució dels objectius de la Comissió Europea en matèria de reducció de l'ús dels PF.<br>En la situación de crecimiento continuado de la población mundial, la producción suficiente de alimentos no puede ser garantizada sin los productos fitosanitarios (PF). No obstante, su empleo no está exento de graves dificultades como el elevado coste de los programas de lucha química contra las plagas y enfermedades que, para el caso de la producción frutal y el viñedo, pueden representar hasta el 30% del total de los costes de producción. Además, el uso de PF conlleva riesgos importantes para la salud humana y el medio ambiente. A todo ello hay que añadir la desconfianza creciente, cuando no el rechazo, de amplias capas de la sociedad en relación a los PF. Para reducir su impacto, la Comisión Europea mediante el pacto verde y, en concreto, a través de la estrategia de la granja a la mesa, pretende reducir el consumo y el riesgo asociado a los PF en un 50% para el año 2030. En este contexto, se hacen necesarias herramientas científico-técnicas validadas para el ajuste de las dosis a las mínimas imprescindibles sin comprometer la cosecha. En esta Tesis se presenta y valida el sistema de ayuda a la toma de decisión DOSA3D, el cual permite ajustar el volumen de caldo y la dosis de PF en cultivos arbóreos (o cultivos 3D) a partir de las características del cultivo (área foliar objetivo y geometría), el pulverizador y la plaga o enfermedad a controlar. La validación del sistema DOSA3D se ha llevado a cabo en tratamientos uniformes y en tratamientos zonales en base a mapas de vigor atendiendo a dos criterios, las deposiciones sobre el objetivo tratado y la eficacia en el control de plagas y enfermedades. A tal fin, las hipótesis contrastadas han sido: i) el Leaf Area Index (LAI) o índice de área foliar (parámetro más relevante para el ajuste de la dosis) es estimado correctamente a partir de la geometría de la vegetación y del estado fenológico del viñedo; ii) la eficiencia del pulverizador calculada mediante el sistema DOSA3D se ajusta a la realidad operativa de los tratamientos; iii) la deposición en hojas es un parámetro que se relaciona bien con la eficacia biológica del tratamiento; iv) el volumen de caldo establecido por el sistema DOSA3D permite obtener deposiciones similares al objetivo umbral (1.2 µl cm-2) y, consecuentemente, conseguir la eficacia adecuada; y, v) el tratamiento zonal en viñedo a partir de mapas de vigor, ajustando la dosis mediante el sistema DOSA3D, permite alcanzar deposiciones óptimas y la eficacia biológica esperada en los distintos vigores. El cuerpo de la Tesis se divide en tres bloques. El primero está dedicado a la revisión del estado del arte en materia de la expresión y ajuste de la dosis y a la comparación entre los diferentes sistemas al uso para el ajuste de la dosis. El segundo bloque de la tesis incluye dos capítulos dedicados a los fundamentos del sistema DOSA3D y a su validación en viñedo. Para ello se han practicado defoliaciones de tramos de vides en espaldera, dándose por válido el modelo de estimación del LAI del sistema DOSA3D para espalderas de hasta 1.25 m de anchura. Asimismo, mediante la norma ISO 22522:2007, se ha determinado la deposición foliar, lo que ha puesto de manifiesto la tendencia marcada a la homogenización de las deposiciones en la medida que incrementa el LAI. También, el sistema DOSA3D ha sido validado a lo largo de toda la campaña por eficacia en el control de oídio (Erysiphe necator Schw.) en cuatro ensayos independientes en los que se ha reducido la dosis entre 0% y 60% respecto a la aplicada por el agricultor. En el tercer bloque se han validado los tratamientos zonales a dosis ajustadas mediante el sistema DOSA3D en viñedos espacialmente variables. Mediante el índice de vigor Plant Cell Density (PCD), establecido a partir de imágenes multiespectales adquiridas desde avión, se han confeccionado mapas de clasificación zonal en dos vigores y el consiguiente mapa de prescripción. La deposición foliar no ha presentado diferencias significativas entre clases de vigor y la eficacia de los tratamientos en el control de ácaro amarillo (Eotetranychus carpini Oud.) y mosquito verde (Empoasca vitis G. y Jacobiasca lybica Berg. & Zanon) han permitido situar la densidad de las plagas por debajo de los umbrales económicos de daño en ambas clases de vigor, comportando ahorros de PF entre el 16.6 y el 24.8% en las zonas de bajo vigor.<br>In the current situation of a growing world population, it is not possible to ensure the production of sufficient food without phytosanitary products (PPs). However, their use has considerable drawbacks such as high costs of chemical control programs against pests and diseases. For instance, in the integrated pest control strategies implemented in orchards and vineyards they may represent up to 30% of the total production costs. Furthermore, the use of PPs can pose important risks to human health and to the environment. In addition, broad sectors of society increasingly distrust and reject the use of PPs. In order to reduce the negative impacts of PPs, the European Union developed the green deal and, through the implementation of the “from farm to fork” strategy, aims to reach a 50% reduction of the consumption and risks associated to PPs for the year 2030. In this context, reliable scientific and technical tools are needed to allow adjustment of application doses to the minimum doses required for effective control, that is without reducing the harvest. Throughout this thesis, the DOSA3D decision support system is presented and validated, this system allows to adjust the volume and dose rates of the PPs for fruit crops (3D crops) according to the characteristics of the crop (leaf area and geometry), the sprayer and the target pest or disease. The validation of the DOSA3D system has been carried out for both uniform applications and zonal applications based on vigour maps, according to the following two criteria: on-target product deposition and efficacy of pest and disease control. In order to do so, the following hypothesis were tested: i) the LAI or leaf area index (the most relevant parameter for adjusting the dose) is estimated correctly from the geometry of the vegetation and the phenological stages of the vineyard; ii) the efficiency of the sprayer, calculated by means of the DOSA3D system is adjusted to the operational reality of the applications; iii) deposition on leaves is a parameter that correlates well to the biological efficacy of the application; iv) the volume rate established by the DOSA3D system allows to obtain leaf depositions close to the objective threshold (1.2 µl cm-2) and, consequently, achieve the appropriate efficacy; and v) the zonal application in vineyards based on vigour maps, after adjusting the dose by means of the DOSA3D system, allows to achieve optimal depositions and therefore the expected biological efficacy for the different vigour zones. The body of this thesis is divided into three parts. The first part consists of a revision of the state of the art regarding dose expression and adjustment and different existing dose adjustment decision support systems. The second part of the thesis includes two chapters dedicated to the technical rationale of the DOSA3D system and its validation in vineyards. Sections along the vine trellis were defoliated in order to validate the LAI estimation model of the DOSA3D system for trellises up to 1.25 m wide. Likewise, the ISO standard 22522:2007 was used to determine the foliar deposition, this evidenced a marked tendency to the homogenisation of the depositions as LAI increases. In addition, the DOSA3D system has been validated throughout the entire season for the control of powdery mildew (Erysiphe necator Schw.), in four independent trials in which the dose was reduced up to 60%, compared to the doses used by the farmer. In the third part of the thesis, the DOSA3D system is validated for zonal applications of adjusted doses in spatially variable vineyards. Zonal classification maps, and the corresponding prescription maps, were built based on the Plant Cell Density (PCD) vigour index, established from aerial multispectral images. Leaf deposition did not present significant differences between vigour classes and the reduced-dose applications for control of yellow spider-mite (Eotetranychus carpini Oud.) and leafhoppers (Empoasca vitis G. and Jacobiasca lybica Berg. & Zanon) allowed to reduce pest density bellow the economic damage thresholds in both vigour classes, resulting in PPs reductions between 16.6 and 24.8% in low vigour zones. The conclusions reached in this thesis provide the scientific and technical evidences required for the safe use of the DOSA3D system for delivery of reliable control of pests and diseases. The system has proved to be a useful tool due to its benefits for stakeholders (farmers, advisors in plant protection, the chemical industry, constructors of application equipment and regulatory authorities) and its contribution to the achievement of European Commission objectives regarding reduction in the use of PPs.

[Abstract]: Since early settlement, agriculture has been one of the main industries contributing to the livelihoods of most rural communities in Australia. The wheat grain industry is Australia’s second largest agricultural export commodity, with an average value of $3.5 billion per annum. Climate variability and change, higher input costs, and world commodity markets have put increased pressure on the sustainability of the grain industry. This has lead to an increasing demand for accurate, objective and near real-time crop production information by industry. To generate such production estimates, it is essential to determine crop area planted at the desired spatial and temporal scales. However, such information at regional scale is currently not available in Australia.The aim of this study was to determine broadacre crop area estimates through the use of multi-temporal satellite imagery for major Australian winter crops. Specifically, the objectives were to: (i) assess the ability of a range of approaches to using multi-temporal Moderate Resolution Imaging Spectroradiometer (MODIS) imagery to estimate total end-of-season winter crop area; (ii) determine the discriminative ability of such remote sensing approaches in estimating planted area for wheat, barley and chickpea within a specific cropping season; (iii) develop and evaluate the methodology for determining the predictability of crop area estimates well before harvest; and (iv) validate the ability of multi-temporal MODIS approaches to determine the pre-harvest and end-of-season winter crop area estimates for different seasons and regions.MODIS enhanced vegetation index (EVI) was used as a surrogate measure for crop canopy health and architecture, for two contiguous shires in the Darling Downs region of Queensland, Australia. Multi-temporal approaches comprising principal component analysis (PCA), harmonic analysis of time series (HANTS), multi-date MODIS EVI during the crop growth period (MEVI), and two curve fitting procedures (CF1, CF2) were derived and applied. These approaches were validated against the traditional single-date approach. Early-season crop area estimates were derived through the development and application of a metric, i.e. accumulation of consecutive 16-day EVI values greater than or equal to 500, at different periods before flowering. Using ground truth data, image classification was conducted by applying supervised (maximum likelihood) and unsupervised (K-means) classification algorithms. The percent correctly classified and kappa coefficient statistics from the error matrix were used to assess pixel-scale accuracy, while shire-scale accuracy was determined using the percent error (PE) statistic. A simple linear regression of actual shire-scale data against predicted data was used to assess accuracy across regions and seasons. Actual shire-scale data was acquired from government statistical reports for the period 2000, 2001, 2003 and 2004 for the Darling Downs, and 2005 and 2006 for the entire Queensland cropping region.Results for 2003 and 2004 showed that multi-temporal HANTS, MEVI, CF1, CF2 and PCA methods achieved high overall accuracies ranging from 85% to 97% to discriminate between crops and non-crops. The accuracies for discriminating between specific crops at pixel scale were less, but still moderate, especially for wheat and barley (lowest at 57%). The HANTS approach had the smallest mean absolute percent error of 27% at shire-scale compared to other multi-temporal approaches. For early-season prediction, the 16-day EVI values greater than or equal to 500 metric showed high accuracy (94% to 98%) at a pixel scale and high R2 (0.96) for predicting total winter crop area planted.The rigour of the HANTS and the 16-day EVI values greater than or equal to 500 approaches was assessed when extrapolating over the entire Queensland cropping region for the 2005 and 2006 season. The combined early-season estimate of July and August produced high accuracy at pixel and regional scales with percent error of 8.6% and 26% below the industry estimates for 2005 and 2006 season, respectively. These satellite-derived crop area estimates were available at least four months before harvest, and deemed that such information will be highly sought after by industry in managing their risk. In discriminating among crops at pixel and regional scale, the HANTS approach showed high accuracy. Specific area estimates for wheat, barley and chickpea were, respectively, 9.9%, -5.2% and 10.9% (for 2005) and -2.8%, -78% and 64% (for 2006). Closer investigation suggested that the higher error in 2006 area estimates for barley and chickpea has emanated from the industry figures collected by the government.Area estimates of total winter crop, wheat, barley and chickpea resulted in R2 values of 0.92, 0.89, 0.82 and 0.52, when contrasted against the actual shire-scale data. A significantly high R2 (0.87) was achieved for total winter crop area estimates in Augusts across all shires for the 2006 season. Furthermore, the HANTS approach showed high accuracy in discriminating cropping area from non-cropping area and highlighted the need for accurate and up-to-date land use maps.This thesis concluded that time-series MODIS EVI imagery can be applied successfully to firstly, determine end-of-season crop area estimates at shire scale. Secondly, capturing canopy green-up through a novel metric (i.e. 16-day EVI values greater than or equal to 500) can be utilised effectively to determine early-season crop area estimates well before harvest. Finally, the extrapolability of these approaches to determine total and specific winter crop area estimates showed good utility across larger areas and seasons. Hence, it is envisaged that this technology is transferable to different regions across Australia. The utility of the remote sensing techniques developed in this study will depend on the risk agri-industry operates at within their decision and operating regimes. Trade-off between risk and value will depend on the accuracy and timing of the disseminated crop production forecast.

The topics of the PhD thesis have the objective of assessing three different aspects of the renewable energy sector: i) sizing of plants for the production of biogas through anaerobic digestion of agricultural waste and by-products of agro-industries; ii) evaluation of the mechanization and energetic aspects of the cultural practices and the harvesting of oil crops; iii) assessment of the sustainability of biodiesel production from Linum usitatissimum L. and Camelina sativa, with particular attention to the pressing of the seeds and the trans-esterification of vegetable oils. As regards the first topic the aim of the work was to develop a procedure for verifying the availability of biomass for biogas production in a territory of Ragusa province (south-east Sicily) and to calculate the power of a co-generator engine for a biogas plant taking in consideration the quantity and the biogas yields of this biomass. In order to assess the quantity of biogas and electricity production per year two hypothesis have been evaluated. The first examines the available biomass for only some months of the year and the second examines the available biomass all the year round. With regard to the second and third topic, the purpose of the research activities was primarily concerned with the following aspects: to calculate the quantitative parameters of mechanization such as work capacities, unitary time, fuel consumptions of farming practices to calculate the qualitative parameters of the work done during the seeding and harvesting such as the product obtained in respect of the product expected; to assess the cultivation sustainability of unconventional oil crops as Linum usitatissimum L. and Camelina sativa, in south-eastern Sicily for biodiesel production in terms of energy used compared to that obtained, by means of EROI index; to analyse the mechanical pressing of seeds in terms of a) vegetable oil yields and chemical characteristics; b) machine work capacity; c) energy consumptions; d) characterization of the operating parameters of the screw press plant; to evaluation the trans-esterification process in terms of a) yield into biodiesel by varying the temperature of the process; b) yield into biodiesel by varying the amount of methanol and potash; c) physical-chemical characteristics of FAME according to EN 14214

This study was born out of the desire to analyze the complex soil management problem faced by individual economic agents as well as society. The focus of this study, however, was on the theoretical formulation and estimation of partial equilibrium dynamic economic models directed toward optimizing the private use of the soil resource. In particular, four empirical representative farm models were formulated. Solutions to the four representative farm models showed that sizable reductions in topsoil loss, which contributes to non-point source pollution, and aggravates the crop productivity impacts of soil erosion, can be accomplished by adopting alternative support practices. Because of the change in support practices, reductions in the present value of net returns are expected, but this decrease in return was found to be minimal when compared to reductions in topsoil loss. Policy implications as well as several policy recommendations stemming from those results, with respect to soil conservation, are outlined and analyzed.<br>Ph. D.