Made available in DSpace on 2016-03-07T19:20:21Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-05-08. Added 1 bitstream(s) on 2016-03-07T19:23:59Z : No. of bitstreams: 1 000859337.pdf: 2201933 bytes, checksum: 55bd4532084ecdf72d36c645c536af43 (MD5) / Sistemas produtivos conservacionistas, como integração Lavoura-Pecuária (ILP) e plantio direto (SPD), proporcionam além de aumento na produtividade, a conservação do solo. Desta forma, objetivou em um LATOSSOLO VERMELHO Distroférrico sob condições irrigadas no Cerrado, avaliar: 1) o desempenho produtivo e a qualidade bromatológica das silagens produzidas nos diferentes sistemas de produção avaliados; 2) os componentes da produção e a produtividade do milho em consórcio, nos diferentes espaçamentos e da forragem remanescente; 3) em cortes do outono à primavera, a produtividade de forragem e a sua composição bromatológica após a colheita da silagem; 4) no último corte, verificar além da produtividade de forragem, os teores de macronutrientes e a decomposição da palhada das forrageiras após a dessecação na primavera e seu efeito na soja em sucessão; 5) analisar durante a condução dos sistemas de produção, as alterações nos atributos químicos e densidade do solo na camada de 0 a 0,10 e 0,10 a 0,20 m, ao final de cada ciclo produtivo, além da determinação do estoque de carbono; 6) avaliar o desempenho econômico da ILP sob SPD durante o período de estudo, visando constatar a sustentabilidade e lucratividade de cada sistema. Constatou-se que para produção de grãos ou silagem de grãos úmidos recomenda-se o consórcio do milho com capim-Xaraés, independentemente se em espaçamento entrelinhas de 0,90 ou 0,45 m. Enquanto que, para a produção de silagem de planta inteira, recomenda-se o consórcio do milho com o capim-Tanzânia. A variação de tempo para colheita do milho para produção de silagens ou grãos não interferiu na produção ou composição químico-bromatológica dos capins Xaraés e Tanzânia estabelecidos no consórcio com milho. A adubação nitrogenada das forrageiras após o consórcio com milho não refletiu em incremento na produtividade de... / Production systems that enable sustainability in agriculture as integration Crop-Livestock (ILP) and no-tillage (NT), as well as provide increased productivity, the full soil conservation. Thus, aimed in an Oxisol under irrigated conditions LATOSOL the Cerrado, to evaluate: 1) the productive performance and the chemical quality of the silage produced in different production systems; 2) the components of the production and productivity of maize in consortium in different spacing and the remaining forage; 3) to evaluate every autumn cut the spring, forage yield and its chemical composition after harvest of silage; 4) in the last cut, check beyond the forage yield, macronutrient contents and the decomposition of straw fodder after desiccation in the spring and its effect on soybean crop; 5) while driving in production systems, changes in chemical properties and density in the layer 0 to 0,10 and from 0,10 to 0,20 m at the end of each production cycle, in addition to the determination of stock carbon; 6) the ILP's economic performance under no till during the study period, in order to verify the sustainability and profitability of each system. It was found that for grain yield or silage moisture grains recommendes to the consortium of corn with Xaraés grass, whether in row spacing of 0,90 or 0,45 m. For the production of the whole plant silage, it is recommended consortium with corn Tanzaniagrass. The variation in time to harvest corn for silage or grain production did not affect the production or chemical composition of Xaraés and Tanzania grasses set out in consortium with corn. Nitrogen fertilization of forage after the consortium with corn not reflected in an increase in dry matter production and nutritional and chemical composition of grasses in area under nine years in no-tillage system. In irrigated conditions in the Cerrado, aiming increasing soybean yield in succession to tropical forages, ...

Ph.D. (Geography) / Skillful management and planning of the earth's natural resources and of agricultural production necessitates a great deal of Information regarding the resources and relevant soclo-economlc factors, as well as better Information on crop yield expectations throughout the year. These Intricate processes can often be simplified Into models. Most of Nature's systems (for example climatic systems) are, however, too complex to allow realistic models to be evaluated numerically and are therefore examined by means of simulation models through which the Interaction with time between physical processes Is established. The purpose Is to understand these processes In order to forecast the results of these changes and Interactions. The aim of this study Is to construct a composite climate model that (1) computes missing climate values, and (2) extrapolates climate values until the expected date of harvesting, by simulation using the random sampling of values from reference ("look-up") tables, In order that (3) the climate files, with simulated climate values, could be used with the parameter files as Input files for the CERES-Maize model. The CERES-Maize model uses dally values to simulate the growth, development and yield of the maize plant. The respective crop forecasting results obtained for actual and simulated climate values are then to be evaluated. Climate files, with four variables, were obtained on magnetic computer tape from the South African Weather Bureau for the study area In the Eastern Transvaal. The preliminary processing was done by the use of SA5-programmes and these files were then exported from the mainframe computer to a personal computer and stored on floppy disks. Climate reference flies were compiled from the original climate flies by sorting the climate data according to the Julian date. The missing values In the climate reference flies and the original climate files were restored from the files of neighbouring weather stations, as calculated orestimated values by.means of a suitable method of computation. Some of the methods used, were derived after comparing the graphs of the time-series of a number of climate files. Aclimate simulation model was compiled In which climatic elements were simulated by sampling values a set number of times randomly from the climate reference files. The mean of these sampled values were adjusted by multiplying It with a factor representing the climatic change over time. A climate file, also containing simulated values, and a theoretical parameter Input file were then used as the Input flies for a revised edition of the CERES-Maize model. A comparison of the results obtained for the 1986/87 growing season when the climate files, with actual and simulated values respectively, were used as Inputs for the CERES-Maize model, Indicated very promising results. The values predicted for two climate flies (1962-1987) differed by about 18%, whereas a difference of only about 8% between those predicted for two smaller climate files (actual and simulated values respectively), representing only the 1986/87 season, was recorded. The difference between values predicted for the climate file, mentioned last, and consisting only of simulated climate values, and those forecasted for the original and complete climate data file, was only 5%. As Indicated by the arithmetic mean, there is again a tendency towards the mean values.

The purpose of this study was to determine the uptake and distribution of nutrients during the growth of the Cayenne cultivar of Ananas comosus (L) Merr under field conditions in the Eastern Cape. The study was also done to help explain the apparent drop in the nutrient levels in the basal section of the "D"- leaf of the pineapple plant during the winter months and to determine the best part or parts of the plant to sample in order to measure the nutrient status of the pineapple plant at any stage of its growth. The investigation was conducted by selecting a plot within a production land on two farms in the pineapple growing region of the Eastern Cape. Plants were sampled from each plot at regular intervals from planting of the pineapple tops until the harvesting of the fruit of the first plant crop. Plant growth was measured and the nutrient concentrations in each section of the plant were determined. The total amounts of nutrients for each plant part were calculated and the nutrient uptake was compared and plotted on distribution diagrams.

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Agrivoltaic (AV) systems are dual-use land systems that consist of elevated solar panels with crops grown underneath. They offer a solution to the increasing demand for food production and clean renewable energy. The main concern regarding AV systems is the reduced availability of light to crops below the panels. Research to date shows that AV systems are quite productive with total energy and crop production exceeding the outputs of either solar farms or crop production alone. Research also shows that solar panels affect the microenvironment below the panels. The research on AV systems so far considers altering panel density to increase radiation to the crops by varying the distance between rows of panels in an AV solar array. This study examines the crop outputs for Swiss chard, kale, pepper, and broccoli in an AV system with different gap spacings of 2, 3, 4, or 5 feet (AV plots) between panel clusters within rows to determine how much spacing between solar panels is optimal for crop production by comparing these system yields to full sun crop production. This study also examines the effect of the AV system on crop nutrient levels, on soil water content, and crop leaf temperature below the panels. Ultimately, the biomass crop yields of AV plots are restricted significantly for Swiss chard, kale, or pepper compared against the full sun control plot yields but not for broccoli stem + leaf yields. The 4-ft or 5-ft gap distances between panels yield the highest crop biomass of the AV shaded plots. Nutrient levels tend to increase with more shade but the trend is only significant for Swiss chard nitrogen and phosphorus concentrations, pepper potassium concentrations, and broccoli phosphorus concentrations. For soil water content it is found that panels have some effect on evapotranspiration and rainfall redistribution at the soil level. Leaf temperatures in the AV plots are lower than leaf temperatures in the control plots on sunny days but not on cloudy days.

M.S.

To determine the most profitable rates of applying lime for different crops on different soil types in the State, and to determine if possible the hydrogen ion concentration for the most economic yields of the different crops on different soil types. Plots will be laid out at Blacksburg, Staunton, Williamsburg, Holland, and Martinsville, and limed at different rates, Yields will be kept of crops grown at each locality on limed plots and the hydrogen ion concentration will be determined for at least two localities. / M.S.

South Africa is the largest producer of sugar in Africa and one of the ten largest sugarcane producers in the world. Sugarcane in South Africa is grown under a wide range of agro-climatic conditions. Climate has been identified as the single most important factor influencing sugarcane production in South Africa. Traditionally, sugarcane mill committees have issued forecasts of anticipated production for a region. However, owing to several limitations of such committee forecasts, more advanced technologies have had to be considered. The aim of this study has been to develop, evaluate and implement a pertinent and technologically advanced operational sugarcane yield forecasting system for South Africa. Specific objectives have included literature and technology reviews, surveys of stakeholder requirements, the development and evaluation of a forecasting system and the assessment of information transfer and user adoption. A crop yield model-based system has been developed to simulate representative crops for derived Homogeneous Climate Zones (HCZ). The system has integrated climate data and crop management, soil, irrigation and seasonal rainfall outlook information. Simulations of yields were aggregated from HCZs to mill supply area and industry scales and were compared with actual production. The value of climate information (including climate station networks) and seasonal rainfall outlook information were quantified independently. It was concluded that the system was capable of forecasting yields with acceptable accuracy over a wide range of agro-climatic conditions in South Africa. At an industry scale, the system captured up to 58% of the climatically driven variability in mean annual sugarcane yields. Forecast accuracies differed widely between different mill supply areas, and several factors were identified that may explain some inconsistencies. Seasonal rainfall outlook information generally enhanced forecasts of sugarcane production. Rainfall outlooks issued during the summer months seemed more valuable than those issued in early spring. Operationally, model-based forecasts can be expected to be valuable prior to the commencement of the milling season in April. Current limitations of forecasts include system calibration, the expression of production relative to that of the previous season and the omission of incorporating near real-time production and climate information. Several refinements to the forecast system are proposed and a strong collaborative approach between modellers, climatologists, mill committees and other decision makers is encouraged. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2005.

Call number: LD2668 .T4 1985 L82 / Master of Science