Master of Science / Department of Agronomy / Scott A. Staggenborg / Irrigated cropping systems on the High Plains are dominated by water intensive continuous corn (Zea mays L.) production, which along with other factors has caused a decline in the Ogallala aquifer. Potentially demand for water from the aquifer could be decreased by including drought tolerant crops, like grain sorghum (Sorghum bicolor L.) and cotton (Gossypium hirsutum L.), in the cropping systems. This study calibrated the CERES-Maize, CERES-Sorghum, and CROPGRO-Cotton models for the High Plains and studied the simulated effects of different irrigation amounts and initial soil water contents on corn, cotton, and grain sorghum. Input files for calibration were created from irrigated and dryland research plots across Kansas. Information was collected on: soil physical properties, dry matter, leaf area, initial and final soil water content, management, and weather. CERES-Maize simulated grain yield, kernel number, ear number, and seed weight across the locations with root mean square errors (RMSE) of 2891 kg ha-1, 1283 kernels m-2, 1.6 ears m-2, and 38.02 mg kernel-1, respectively. CERES-Sorghum simulated grain yield, kernel number, head number, and seed weight with RMSEs of 2150 kg ha-1, 5755 kernels m-2, 0.13 heads m-2, and 4.51 mg kernel-1. CROPGRO-Cotton simulated lint yield and boll number with RMSEs of 487 kg ha-1 and 25.97 bolls m-2. Simulations were also conducted with CERES-Maize, CERES-Sorghum, and CROPGRO-Cotton to evaluate the effects of irrigation amounts and initial soil water content on yield, evapotranspiration (ET), water use efficiency (WUE), available soil water at maturity, and gross income per hectare. Simulations used weather data from Garden City, KS from 1961 to 1999. Irrigation amounts were different for all variables for corn and grain sorghum. For cotton, yield, WUE, soil water, and gross income were not different between the top two irrigation amounts. For corn and grain sorghum, initial soil water content was only different at 50% plant available water. Initial soil water had no affect on cotton, except for ET at 50%. Simulations showed that cotton yields are similar at lower irrigation. Also, cropping systems that include cotton have the potential to reduce overall irrigation demand on the Ogallala aquifer, potentially prolonging the life of the aquifer.

Made available in DSpace on 2014-07-29T15:32:13Z (GMT). No. of bitstreams: 1 Dissertacao Lara Cristine Gomes Ferreira.pdf: 3398874 bytes, checksum: eca827e932ec567a736addd2fdf5a3cb (MD5) Previous issue date: 2010-03-30 / The national and international demand for ethanol has grown in recent years, due mainly to search for new energy sources and cheaper. In this context, Brazil has been increasing and is currently the largest producer of ethanol (from cane sugar) the world. In recent expansion of sugar cane, the state of Goiás is configured in an area favorable for growing cane, is the geoenvironmental characteristics and / or existing infrastructure and cheaper land, compared to southeastern Brazil. In some regions of São Paulo stand out in sugar cane production and sugar and alcohol projects implementation, the micro Ceres is the center of the Goiás region with increased production of cane sugar and quantity of plants in operation and in the process of implementation / registration, are eleven to total. These plants socio-economically streamline the region's economy moving, creating new jobs and bringing new relations between the enterprise and the residents, merchants / service providers and farmers (landowners). However, these complex developments in a series of negative effects such as seasonality in employment generation due to the inter-harvest period, the precariousness of work, especially related to cutting and manual harvesting of sugar cane, also found in plants as most of the micro-Ceres, the system of concessions, which often "force" the owner to lease their land for plants (as the production of sugarcane as a monoculture, it requires a large amount of land for cultivation, as plants have little land is necessary to lease land from other owners, putting together various properties, are small, medium and / or large), the owner if it is a small owner does not have much booty for the payment relates to the size of the land, in addition to expropriation and consequent rural exodus, which in this case is very common. This study aimed to contribute to the theme of expansion of the sugar industry and its dynamics and impacts associated, especially in the cities of Ceres microregion plants that have deployed, but realizing that this dynamic goes through the fronts of those municipalities, host plants, and end up involving municipalities neighbors, then tried to understand the issues proposed using the regional level. It is understood the relevance of this theme, considering the importance to continue this study to other regions and municipalities of Goiás, especially in this time of growing sugarcane for the state, as each place has its own dynamics and therefore different impacts could arise. / A demanda nacional e internacional por etanol cresceu muito nos últimos anos, devido principalmente a busca por novas fontes de energia renováveis e mais baratas. Neste contexto, o Brasil vem se destacando, sendo atualmente o maior produtor de etanol (de cana-de-açúcar) do mundo. Nessa recente expansão canavieira, o Estado de Goiás configura-se em área favorável ao cultivo de cana, seja pelas caracteristicas geoambientais e/ou infraestrutura existente e terras mais baratas, se comparado a região sudeste brasileira. Em Goiás algumas regiões se destacam na produção canavieira e implantação de empreendimentos sucroalcooleiros; a microrregião Ceres é a região do centro goiano com maior produção de cana-de-açúcar e quantidade de usinas em funcionamento e em processo de implantação/cadastro, são onze ao total. Essas usinas dinamizam sócio-economicamente essa região movimentando a economia, gerando novos empregos e trazendo novas relações entre o empreendimento e os moradores, os comerciantes/prestadores de serviço e produtores rurais (proprietários de terras). Contudo, esses complexos empreendimentos trazem uma série de impactos negativos, como a sazonalidade na geração de empregos, devido ao período da entressafra; a precarização do trabalho, sobretudo, relacionado ao corte e colheita manual da cana, ainda verificado como maioria nas usinas da microrregião Ceres; ao sistema de arrendamentos de terras, que muitas vezes força o proprietário a arrendar suas terras para as usinas (já que a produção canavieira, como uma monocultura, necessita de uma grande extensão de terras para o cultivo, como as usinas possuem poucas terras próprias é preciso arrendá-las de outros proprietários, aglutinando várias propriedades, sejam pequenas, médias e/ou grandes), o arrendador se for um pequeno proprietário não terá muitos ganhos, pois o pagamento está ligado ao tamanho das terras, além da expropriação e consequente êxodo rural, que nesse caso é muito comum. Este trabalho buscou contribuir com a temática de expansão do setor sucroalcooleiro e suas dinâmicas e impactos relacionados, principalmente, nos municípios da microrregião Ceres que possuem usinas implantadas, porém entendendo que esta dinâmica perpassa as fronterias desses municípios, sede das usinas, e acabam envolvendo municípios vizinhos, tentou-se então, compreender a problemática proposta utilizando-se do recorte regional. Entende-se a relevância dessa temática, considerando a importancia de continuar este estudo a outros municípios e regiões de Goiás, sobretudo, neste momento de expansão sucroalcooleira para o Estado, já que cada lugar possui sua própria dinâmica e consequentemente diferentes impactos poderão surgir.

Made available in DSpace on 2016-04-28T20:12:53Z (GMT). No. of bitstreams: 1 2007- Marcos Botton Piccin.pdf: 3891788 bytes, checksum: 50ac5d427e99048c73b932fdad6563b0 (MD5) Previous issue date: 2007-08-23 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / This work consists of a research that analyzes the underlying sociocultural logics to the productive strategies developed by the landless farmers settled in the rural Settlement called Ceres, RS. That Settlement was formed in the end of 1996 and it received landless farm workers of several areas and municipal districts of Rio Grande do Sul, having different paths and acquired social experiences in the different busy social positions in the structure of relationships of the society. Hence the occupation of the territory and the social-historical development of that state have conformed certain social positions to the poor rural workers as small farmers, temporary and permanent workers, millers, lacemakers, among other generating potentially different principles of action, behaviors, codes and operational modalities that provide a group of knowledge, creeds and a certain practical sense, working as social habitus. In this sense, this sociocultural heterogeneity tends to compose the social processes as much of the camps as of the rural settlements and it can be expressed by the different situations that took the rural workers to the fight for the land, for the different objectives related to the ownership of a lot, as well as for the differentiated projects and future dreams elaborated among those individuals. Then, when in the establishment of awareness, knowledge, projects and future dreams which have been built along the social paths tend to make present and updated face of the found circumstances regarding the differential of powers among the different social agents of the local and regional environment. Like this, the cultivations, handlings and several forms of productive occupation of the land lots for the farmer-seated can also represent that social-cultural heterogeneity forged by the socialhistorical process. In that sense, the research classified the farmer-seated in three productive systems considered as diversified, soy-milk, and soy farmers through a survey questionnaire and it was opted for living the daily of them starting from an interview of a pre-selected sample of seated families. The analysis of the data and information allow considering that the interactions and reactions from those environments do not occur in the same way by the group of the farmer-seated in the establishment of the strategies of social reproduction. The existence of three productive systems in the Settlement tends to correspond to the sociocultural internal factors along the social paths. As a result, the significances attributed to the differentiated forms of productive occupation of the land lots reveal desires and life projects longed for and also differentiated and such objectives are believed to be possible to achieve in the Settlement. . / Este trabalho consiste em uma pesquisa que analisa as l?gicas socioculturais subjacentes ?s estrat?gias produtivas desenvolvidas pelos agricultores-assentados no Assentamento rural Ceres, RS. Esse Assentamento foi formado no final de 1996 e recebeu agricultores sem-terra de v?rias regi?es e munic?pios do Rio Grande do Sul, com diferentes trajet?rias e experi?ncias sociais adquiridas nas diferentes posi??es sociais ocupadas na estrutura de rela??es da sociedade. A ocupa??o do territ?rio e o desenvolvimento s?cio-hist?rico desse estado conformaram determinadas posi??es sociais aos trabalhadores rurais pobres como pequenos agricultores, trabalhadores tempor?rios e permanentes, meeiros, rendeiros, entre outras, gerando, potencialmente, distintos princ?pios de a??o, comportamentos, c?digos e modalidades operacionais que conferem um conjunto de saberes, cren?as e um senso pr?tico determinado, funcionando como habitus sociais. Esta heterogeneidade sociocultural tende a compor os processos sociais tanto dos acampamentos quanto dos assentamentos rurais e pode ser expressada pelas diferentes situa??es que levaram os trabalhadores rurais ? luta pela terra, pelos diferentes objetivos para com a posse de um lote, assim como pelos diferenciados projetos e sonhos de futuro elaborados entre esses indiv?duos. Quando em assentamento os saberes, conhecimentos, projetos e sonhos de futuro constru?dos ao longo das trajet?rias sociais tendem a ser presentificados e atualizados frente ?s circunst?ncias encontradas dos diferenciais de poderes entre os distintos agentes sociais que figuram a ambi?ncia local e regional. Assim, os cultivos, manejos e formas diversas de ocupa??o produtiva dos lotes de terra pelos agricultores-assentados tamb?m podem representar aquela heterogeneidade sociocultural forjada pelo processo s?cio-hist?rico. Nesse sentido, a pesquisa classificou os agricultores-assentados em tr?s sistemas produtivos considerados como diversificado, sojaleite e soja atrav?s de um question?rio tipo survey e optou-se pela viv?ncia do cotidiano dos mesmos a partir do qual se procedeu a entrevista de uma amostra pr?-selecionada de fam?lias assentadas. A an?lise dos dados e informa??es permite considerar que as intera??es e rea??es a essas ambi?ncias n?o se d?o da mesma forma pelo conjunto dos agricultores-assentados no estabelecimento das estrat?gias de reprodu??o social. A exist?ncia de tr?s sistemas produtivos no Assentamento tende a corresponder aos fatores socioculturais internalizados ao longo das trajet?rias sociais. As significa??es atribu?das ?s formas diferenciadas de ocupa??o produtiva dos lotes de terra revelam desejos e projetos de vida almejados tamb?m diferenciados e que se julga poss?vel alcan?ar no Assentamento.

<p>The dynamical evolution of the spin axis direction due to gravitational and thermal factors is examined. It is found that the spin axis variations generally are regular and relatively small for the bodies in the asteroid main belt. There are also reasons to believe that this is the case for minor objects beyond the main belt. However, it is found that these regular variations are larger when the orbital inclination of the objects is increased. This effect may explain certain features in the spin vector distribution of the main belt asteroids, not possible to explain by collisional factors. The spin vector evolution of the asteroids in the inner solar system, including the Earth- and Mars-crossing objects, is often subjected to strong forces related to frequencies in the orbital evolution. The variations in the spin vector direction are then very large and often subjected to chaos. The larger frequency related obliquity zones of the Mars-crossers are usually regular while the zones of the Earth-Mars-crossers often are of a chaotic nature. The spin vector evolution of asteroids with comet-like orbits is often chaotic regardless of initial obliquity. For the inner solar system asteroids, it is often possible for an initial prograde spin to turn into a retrograde one, or vice versa, due to the frequency related phenomena. Though some spin vector directions seem to be more probable than other ones over time, there are no indications for an evolution towards a more prograde or a more retrograde spin vector distribution.</p><p>The effects on the spin vector evolution from the thermal Yarkovsky force are examined for objects with radii larger than 50 m. This force will affect the orbital evolution and thus indirectly affect the spin vector evolution. However, it is found that the studied effects are minor as compared to the gravitationally related ones. This is true both for the diurnal and the seasonal variants of the Yarkovsky force.</p>

The dynamical evolution of the spin axis direction due to gravitational and thermal factors is examined. It is found that the spin axis variations generally are regular and relatively small for the bodies in the asteroid main belt. There are also reasons to believe that this is the case for minor objects beyond the main belt. However, it is found that these regular variations are larger when the orbital inclination of the objects is increased. This effect may explain certain features in the spin vector distribution of the main belt asteroids, not possible to explain by collisional factors. The spin vector evolution of the asteroids in the inner solar system, including the Earth- and Mars-crossing objects, is often subjected to strong forces related to frequencies in the orbital evolution. The variations in the spin vector direction are then very large and often subjected to chaos. The larger frequency related obliquity zones of the Mars-crossers are usually regular while the zones of the Earth-Mars-crossers often are of a chaotic nature. The spin vector evolution of asteroids with comet-like orbits is often chaotic regardless of initial obliquity. For the inner solar system asteroids, it is often possible for an initial prograde spin to turn into a retrograde one, or vice versa, due to the frequency related phenomena. Though some spin vector directions seem to be more probable than other ones over time, there are no indications for an evolution towards a more prograde or a more retrograde spin vector distribution. The effects on the spin vector evolution from the thermal Yarkovsky force are examined for objects with radii larger than 50 m. This force will affect the orbital evolution and thus indirectly affect the spin vector evolution. However, it is found that the studied effects are minor as compared to the gravitationally related ones. This is true both for the diurnal and the seasonal variants of the Yarkovsky force.

In order to reduce the vulnerability of wheat production to drought, a calibrated and validated CERES Wheat crop simulation model was used to predict wheat yields on major soil textural groups using historical weather data at Swift Current, Saskatoon and Melfort. Yields were predicted using a run-out technique which involved the use of actual weather data to the prediction date and historical weather data from 1960 to 1990 for the remainder of the growing season. Yield predictions were made at five Julian dates during the crop calendar and these dates coincided with crop emergence, terminal spikelet initiation, end of the vegetative growth, heading and start of grain filling. Three sample years were used as case studies to test the applicability of the run-out method in making yield predictions. Sample base years were those with the lowest, medium and highest yields between 1960 and 1990 and these were selected from ranked yield values using quartiles. Test years were termed base years and weather files that were joined with the test years were run-out years. Each base year had 30 run-out years (1960-1990) and the mean of each run-out year was compared with the observed yield at the end of the season. Run-out yields for each base year were summarised as simple probability distributions so that yields exceeding certain values could be selected. Run-out yields at five prediction dates were found to be in close agreement with observed yields at the end of the growing season. To account for the variability in yields that can be found between places within the same climatic zone, simulated yields were re-classified by soil type and water stress level. These modifiers (soil type and water stress level) showed that chances of getting high yields diminish from Melfort to Swift Current at all prediction points due to the high variability of yield factors. Yield predictions that were made as above suggested that if historical weather records are combined with available weather data during the growing season, a good indication of yields can be obtained ahead of the harvest time and this could allow producers and those in the agri-business to decide on alternative actions of minimizing losses when prospects of getting a good yield are poor.

Clear-sky top-of-atmosphere (TOA) fluxes are important in estimating the impact of clouds on our climate. In this study, we quantitatively compare the clear-sky fluxes measurements of the Clouds and the Earths Radiant Energy System (CERES) instrument to clear-sky fluxes from two reanalysis, NASA's Modern Era Retrospective-analysis for Research and Application (MERRA), and the European Center for Medium Range Weather Forecast Interim reanalysis (ERA-Interim). In the first comparison, we compare observed fluxes from individual cloud-free field-of- views to the reanalyses. In the second comparison, we compare monthly averaged observed clear-sky fluxes to those from the reanalyses. Monthly clear-sky fluxes are calculated by averaging fluxes from cloud-free regions. In both comparisons, the fluxes generally agree within +/- 10 W/m^2. Finally, we show that, while the differences between the fluxes of observations and the reanalyses are several W/m2, the inter-annual anomalies agree much better, with zonal and global average inter-annual anomalies typically agreeing within 1 W/m^2. The longwave clear-sky anomalies show excellent agreement even when comparing individual grid points, whereas the shortwave clear-sky anomalies are generally smaller at individual grid points.

Crop simulation models (CSMs) are used to evaluate management and environmental scenarios on crop growth and yields. Two corn (Zea Mays L.) crop growth simulation models, Hybrid-Maize, and CERES-Maize were calibrated and validated under Virginia conditions with the goal of better understanding corn response to variable environmental conditions and decreasing temporal yield variation. Calibration data were generated from small plot studies conducted at five site-years. Main plots were plant density (4.9, 6.2, 7.4, and 8.6 plants m-2); subplots were hybrids of differing relative maturity (RM) [early = Pioneer® Brand "34B97" (108 day RM); medium = Pioneer® Brand "33M54" (114 day RM); and late = Pioneer® Brand "31G66" (118 day RM)]. Model validation was generated from large scale, replicated strip plot trials conducted at various locations across Virginia in 2005 and 2006. Prior to model adjustments based on calibration data, both CSMs under predicted corn grain yield in calibration and validation studies. CERES-Maize grain yield prediction error was consistent across the range of tested plant density while accuracy of Hybrid-Maize varied with plant density. Hybrid-Maize-estimated biomass production was highly accurate. Greater leaf area index (LAI) and biomass production were measured than was predicted by the CERES-Maize CSM. Both CSMs were modified based on calibration data sets and validated. Validation results of the calibrated CSMs showed improved accuracy in simulating planting date and environmental effects on a range of corn hybrids grown throughout Virginia over two years. We expect that both modified models can be used for strategic research and management decisions in mid-Atlantic corn production. / Master of Science