O estabelecimento de balanços hídricos no campo é difícil e dispendioso, sendo a variabilidade de seus componentes o maior problema para se obter resultados confiáveis. Esta variabilidade dos componentes é aqui apresentada para uma cultura de café desenvolvida no hemisfério sul, em um solo tropical com 10% de declividade. É concluído que a chuva deve ser medida com um número apropriado de repetições, que a irrigação pode introduzir grande variabilidade dos cálculos, que a evapotranspiração calculada a partir da equação do balanço hídrico tem coeficientes de variação muito altos, que o componente armazenamento de água no solo é o que mais contribui na propagação dos erros e que a enxurrada pôde ser satisfatoriamente controlada nesse declive por meio de práticas de manejo. / The establishment of field water balances is difficult and costly, the variability of its components being the major problem to obtain reliable results. This component variability is here presented for a coffee crop grown in the Southern Hemisphere, on a tropical soil with 10% slope. It is concluded that rainfall has to the measured with an appropriate number of replicates, that irrigation can introduce great variability into calculations, that evapotranspiration calculated from the water balance equation has high coefficients of variation, that the soil water storage component is the major contributor in error propagation calculations, and that the run-off could be satisfactorily controlled through crop management practices.

Praticamente toda cana-de-açúcar produzida no Estado de São Paulo é cultivada em condições de sequeiro e o aproveitamento de novas áreas para a sua produção, nas quais haja necessidade de drenagem, torna-se importante. O dimensionamento de sistemas de drenagem agrícola baseado apenas na experiência prática do projetista tem levado a freqüentes insucessos. Para o dimensionamento racional, é necessário se conhecer a velocidade mínima de rebaixamento do lençol freático a ser proporcionado pelos drenos, o que depende da sensibilidade de cada cultura. Assim, este trabalho tem como objetivos determinar o efeito de diferentes velocidades de rebaixamento do NF, em diferentes estádios de desenvolvimento da cana-de-açúcar. O experimento foi conduzido em 64 lisímetros, em um delineamento experimental de blocos casualizados, arranjado em um fatorial de (3 x 5 + 1), sendo 3 estádios de desenvolvimento, 5 velocidades de rebaixamento do NF mais uma testemunha que não sofrerá estresse por excesso de umidade. Os resultados obtidos permitiram a obtenção de um critério de drenagem para o cálculo do espaçamento de drenos utilizando equações de movimento não permanente. A produtividade e seus componentes expressos em valores médios de massa verde de colmos, massa seca dos colmos, massa verde dos ponteiros, massa seca dos ponteiros, massa verde total e massa seca total não foram afetados pelas velocidades de rebaixamento de 0,30 m em 3, 6, 9, 12 e 15 dias. Entre os índices fisiológicos avaliados a condição de inundação das parcelas proporcionada pelas diferentes velocidades de rebaixamento do NF não interferiu nos valores médios da taxa de crescimento absoluto, taxa de assimilação liquida e na taxa de crescimento da cultura. Já a razão de área foliar, a taxa de crescimento relativo, e área foliar especifica apresentaram diferenças significativas para os períodos. O valor médio de Brix obtidos nas plantas que sofreram estresse pelo encharcamento no período de 305 DAP sob uma velocidade rebaixamento de 0,30 m em 12 dias apresentou valor médio de 16,03 % de brix, inferior e significativamente diferente dos demais períodos e velocidades. As parcelas inundadas aos 67 dias após o plantio apresentaram valores de pH no solo superiores aos demais períodos 210 e 305. Os valores médios de potenciais de oxiredução aumentam a medida que reduz o teor de umidade do solo. Os valores médios de oxigênio dissolvido aumentaram ao longo dos períodos de avaliação. Ocorreu uma redução e estabilização nos valores médios das leituras com o decorrer dos dias de avaliação. Em experimentos onde se tem uma limitação de material é possível utilizar uma mesma folha da canade- açúcar para determinar o potencial de água na folha. No entanto há a necessidade de proteger o local da fração foliar destacada com um papel alumínio. Os valores médios de potencial de água na folhas não se apresentaram diferentes estatisticamente entre as parcelas submetidas à inundação, assim como, quando comparados as parcelas sob irrigação. A severidade dos cincos velocidades de rebaixamentos não refletiu nos teores dos macronutrientes na folhas das plantas. / Almost all sugar cane produced in the State of Sao Paulo is grown under rainfed conditions and the exploration of new cultivated areas, were there is a need for drainage, becomes important. The design of agricultural drainage systems based only on practical experience of the designer has led to frequent failures. For the rational sizing, it is necessary to know the minimum speed of lowering the water table to be provided by the drains, which depends on the sensitivity of each crop. Thus, this study aims to determine the effect of different speeds of lowering the water table, at different development stages of sugar cane. The experiment was conducted in 64 lysimeters in a randomized blocks design, arranged in a factorial of (3 x 5 + 1), of three development stages, five speed of lowering the water table and a control that did not suffer stress by excess moisture. The results enabled to obtain a criteria of drainage for calculating the spacing of drains using no permanent motion equations. The yield and its components expressed in average values of green mass of stalks, dry weight of stalks, green mass of top, top of dry mass, total mass green and total dry mass were not affected by lowering speeds of 0,30 m 3, 6, 9, 12 and 15 days, no differences between them and not the control. Among the avaliated physiological indexes the flood condition of the plots provided by the different speeds of lowering of the water table did not interfere in the average values of absolute growth rate, net assimilation rate and growth rate of the crop. Whereas the leaf area ratio, the relative growth rate and specific leaf area showed significant differences for the periods. The average value of Brix obtained in plants that have suffered stress by flooding in the period of 305 DAP under lowering a speed of 0,30 m in 12 days showed a mean value of 16,03% of Brix, and significantly different than the other periods and speeds. The plots flooded for 67 days after planting showed pH values in soil higher than other periods 210 and 305. The average values of potential oxiredution increase with the reduction of the moisture content of soil. The average values of dissolved oxygen increased over the evaluation periods. And a reduction and stabilization in the average of the readings over the course of days evaluation. In experiments where there is a limitation of material one can use a single leaf sheet of sugar cane to determine the potential of water on the sheet. However there is a need to protect the site of the fraction leaf with an aluminum sheet. The average values of water potential in leaves did not show statistically different between plots subjected to flooding as well as, when compared to plots under irrigation. The severity of the five speeds, did not reflected in lower levels of macronutrients in the plant leaves.

Orientadores: Luiz Henrique Antunes Rodrigues, Maria Leonor Ribeiro Casimiro Lopes-Assad / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agrícola / Made available in DSpace on 2018-08-25T00:51:45Z (GMT). No. of bitstreams: 1 Boschi_RaquelStucchi_D.pdf: 2416172 bytes, checksum: 61a629e1b0d62348a6f99a7d4f6293dd (MD5) Previous issue date: 2014 / Resumo: O conhecimento das propriedades hidráulicas do solo é indispensável para modelagem do sistema solo-planta-atmosfera. A determinação destas propriedades de forma direta é problemática: ¬exigem métodos caros, laboriosos e grandes demandantes de tempo. O uso de funções, que estimam estas propriedades a partir de outras, facilmente obtidas, tem sido objeto de várias pesquisas. Estas funções são denominadas de funções de pedotransferência (PTF). As PTF são normalmente avaliadas em função dos valores observados e estimados; pouca atenção tem sido dada à análise do erro em função das propriedades do solo. Este tipo de análise pode revelar detalhes importantes sobre o desempenho de uma PTF, podendo contribuir para melhorar sua capacidade preditiva. A hipótese científica deste trabalho foi que é possível identificar e avaliar padrões nos erros das PTF utilizadas para estimar a retenção de água no solo, por meio de modelos baseados em árvore de decisão. Outra hipótese é que a identificação dos padrões nos erros das PTF fornecerá subsídios para o uso de tais funções de forma mais confiável e precisa. O objetivo geral deste trabalho, portanto, foi obter árvores de decisão capazes de auxiliar na compreensão de quais atributos do solo afetam o desempenho das PTF na estimativa de retenção de água no solo. A metodologia foi baseada no modelo CRISP-DM e foram avaliadas PTF disponíveis na literatura, com base na análise do erro, por meio de árvore de decisão. A metodologia foi dividida em duas partes. Na primeira parte, a PTF desenvolvida por Vereecken e colaboradores em 1989, foi avaliada no próprio conjunto de dados utilizado para sua geração. Na segunda parte, as PTF desenvolvidas por Vereecken e colaboradores em 1989, van den Berg e colaboradores em 1997 e Lopes-Assad e colaboradores em 2001, foram avaliadas em um conjunto de dados diferente do utilizado na sua geração. Os resultados mostraram que os erros inaceitáveis a -10 kPa (CC) se deram para as mesmas condições de erros aceitáveis a -1500 kPa (PMP) ; por outro lado, os erros inaceitáveis na estimativa de PMP, de modo geral, se deram para as mesmas condições de erros aceitáveis para estimativa de CC. A diferença entre o conjunto de dados utilizado para desenvolver uma PTF e o conjunto de dados utilizado para avaliá-la é um importante fator na incidência de erros. Na seleção de uma PTF deve-se considerar o maior número de fatores possíveis e não somente a distribuição granulométrica e a proximidade geográfica dos conjuntos de dados. A técnica de indução de árvore de decisão apresentou-se como uma alternativa complementar à avaliação da PTF, uma vez que permitiu uma avaliação detalhada dos erros nas estimativas. Este tipo de avaliação é interessante, pois permite a identificação de erros sistemáticos na aplicação destas funções. Pode, ainda, ser usada como uma forma de diagnóstico a ser explorada por desenvolvedores de PTF / Abstract: Knowledge of the soil hydraulic properties is essential for modeling the soil-plant-atmosphere system. Direct determination of these properties is problematic: the methods are expensive, laborious and time consuming. Therefore, the use of functions that estimate soil hydraulic properties from other more easily measurable soil properties has been the subject of several studies. These functions are called pedotransfer functions (PTF). Most studies have focused on the development of these functions; however, few have attempted to improve their implementation. PTF are usually evaluated in terms of the measured and predicted values; less attention has been given to the analysis of the error term in relation to soil properties such as texture, bulk density and organic matter. This type of analysis may reveal important details about the performance of PTF including options to improve their predictive capability. The hypothesis of this study was that it is possible to identify and evaluate patterns in the errors of PTF used to estimate soil water retention by using decision tree models. Another hypothesis is that the identification of PTF errors patterns will provide subsidies for the use of such functions more reliably and accurately. The objective of this study was to obtain a decision tree that can assist in understanding what soil properties affect the performance of PTF in estimating soil water retention. The methodology was based on the CRISP-DM model and refers to the evaluation of PTF available in the literature, based on an error analysis by means of decision tree induction. The PTF developed by Vereecken and coworkers in 1989 was evaluated the same data set as used for their development. Next, the PTF developed by Vereecken and coworkers in 1989, van den Berg and coworkers in 1997 and Lopes-Assad and coworkers 2001, were evaluated on a different dataset than the one used for their development. Results indicate that unacceptable errors at -10 kPa (CC) occurred for the same conditions that lead to acceptable errors at -1500 kPa (PMP); on the other hand the unacceptable errors at -1500 kPa (PMP) occurred for the same conditions that lead to acceptable errors at -10 kPa (CC). The difference between the data set used to develop a PTF and the data set used to evaluate is a factor of error incidence. In selecting a PTF should be considered the largest possible number of factors and not only the particle size distribution and the geographical proximity of the datasets. The decision tree induction technique provides a complement for evaluation of PTF, since the method is efficient in the detailed evaluation of PTF. This type of assessment is interesting because it allows identifying systematic errors in PTF applications. It can also be used as a diagnostic tool to be explored by PTF developers / Doutorado / Planejamento e Desenvolvimento Rural Sustentável / Doutora em Engenharia

Orientador: Hilton Silveira Pinto / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agricola / Made available in DSpace on 2018-08-03T21:59:17Z (GMT). No. of bitstreams: 1 Silva_FernandoAntonioMacenada_D.pdf: 6475935 bytes, checksum: 246f935053cc089136cbc1a9488498c7 (MD5) Previous issue date: 2004 / Doutorado / Agua e Solo / Doutor em Engenharia Agrícola

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The knowledge of soil moisture is quite important because it indicates soil hydric conditions and it can help on saving water and electric energy, given that monitoring of soil moisture allows controlled and timely applications of water pointing out how much and when to irrigate, according to the crop water requirements. Therefore, soil moisture should be determined before the irrigation and will serve as a parameter for the amount of water to be applied by the system. There are any methods used for determination of soil water content, in this way, the present study aimed to compare the results of soil moisture obtained by different methods for expeditious determination of the water content of the soil in different textural classes. The study was conducted in the Laboratório de Hidráulica Agrícola da Universidade Federal de Santa Maria . Four methods were tested (standard method, M0; electric oven method, M1, microwave oven method, M2; weighing method, M3) with three soil samples (S1, S2, S3) and three repetitions for each. The linear regression was made between the standard method and alternative methods, for obtaining the correlation coefficient (r), the linear coefficient and the slope, the Wilmott concordance index (Iw) and Performance Index (Id). From the results obtained can be stated that the electric oven method and the microwave oven method have excellent performance when compared to the standard method. The method of weighing presented a performance good and very good. In addition, it was concluded that the 20 minutes period for the electric oven method was efficient signifying a time reduction for the moisture content determination. For the microwave oven method the 5 minute drying period was sufficient and did not differ statistically from the standard method. The method of weighing was also reliable in determining soil moisture. Therefore, it is possible to use alternative methods to determine the soil moisture. / O conhecimento da umidade do solo é de fundamental importância, pois indica em que condições hídricas encontra-se o mesmo, podendo auxiliar na redução dos gastos com água e energia elétrica, haja vista que o monitoramento da umidade do solo possibilita aplicações controladas e pontuais de água, respondendo o quanto e quando irrigar em função das necessidades hídricas das culturas. Assim sendo, para a realização da irrigação, a umidade do solo deve ser determinada anteriormente e servirá de parâmetro para a quantidade de água a ser aplicada pelo sistema. Inúmeros são os métodos utilizados para a determinação do conteúdo de água no solo, dessa maneira, o presente trabalho objetivou comparar os resultados de umidade do solo obtidos pelos diferentes métodos expeditos para determinação do conteúdo de água no solo em diferentes classes texturais. O estudo foi desenvolvido no Laboratório de Hidráulica Agrícola da Universidade Federal de Santa Maria. Foram testados quatro métodos (método padrão de estufa, M0; método do forno elétrico, M1, método do forno de micro-ondas, M2; método das pesagens, M3), com três amostras de solo (S1, S2, S3) e três repetições para cada. Foi feita a regressão linear entre os métodos alternativos e o método padrão de estufa, com a finalidade de se obter o coeficiente de correlação (r), o coeficiente linear e o coeficiente angular, o índice de concordância de Wilmott (Iw) e o índice de desempenho (Id). Através dos resultados obtidos pode-se afirmar que o método do forno elétrico e o método do forno de micro-ondas apresentaram desempenho ótimo quando comparados ao método padrão. O método das pesagens apresentou desempenho bom e muito bom. Também concluiu-se que o tempo de 20 minutos para o método do forno elétrico foi eficiente, significando redução no tempo para determinação da umidade. Para o método do forno de micro-ondas o tempo de 5 minutos de secagem foi suficiente, não diferindo estatisticamente do método padrão. O método das pesagens também se mostrou confiável na determinação da umidade do solo. Portanto, existe a possibilidade de usar os métodos alternativos para a determinação da umidade do solo.

The disposal of fine-grained mining and industrial waste by formation of hydraulic-fill tailings dams is becoming a design and construction activity of increasing scale. In light of the increasing pressure on the mining industry to sustain stringent safety and environmental standards it is becoming more important to gain technical knowledge of the waste problem. The upper layers of the tailings residue dams are in the unsaturated state with the matric suction component contributing to the overall shear strength. The ability to incorporate the matric suction component in shear strength calculations is important to safe design. This research project investigates the use of the mid-plane suction probe to measure matric suction. The results obtained from the probe is used along with various tests to construct a complete soil-water characteristic curve for Mispah gold tailings as well as to investigate suction induced shear strength of drying tailings with depth. The tests were conducted on gold tailings from Vaal Operation’s Mispah tailings dam. The laboratory tests consisted of a trough test, to determine the soil-water characteristics of the gold tailing and also a drying box test that simulated the drying and desiccation of the gold tailings in the daywall. The project concluded that the mid-plane suction probe could be used with acceptable accuracy to determine soil suctions. The model for the prediction of the soil water characteristic curve, derived by Fredlund and Xing (1992), was used successfully to predict the complete soil water characteristics curve for Mispah gold tailings. The equation derived by Vanapalli et al. (1996) was successfully used to calculate both the normal and suction induced shear strength of gold mine tailings using either the volumetric water content from the extracted samples or from the soil water characteristic curve. / Dissertation (MEng (Geotechnical Engineering))--University of Pretoria, 2006. / Civil Engineering / unrestricted

The one-dimensional (1-D) potential heave (or swell strain) of expansive soil is conventionally estimated using the swelling pressure and swelling index values which are determined from different types of oedometer test results. The swelling pressure of expansive soils is typically measured at saturated condition from oedometer tests. The experimental procedures of oedometer tests are cumbersome as well as time-consuming for use in conventional geotechnical engineering practice and are not capable for estimating heave under different stages of unsaturated conditions. To alleviate these limitations, semi-empirical models are proposed in this thesis to predict the variation of swelling pressure of both compacted and natural expansive soils with respect to soil suction using the soil-water characteristic curve (SWCC) as a tool. An empirical relationship is also suggested for estimating the swelling index from plasticity index values, alleviating the need for conducting oedometer tests. The predicted swelling pressure and estimated swelling index are then used to estimate the variation of 1-D heave with respect to suction for expansive soils by modifying Fredlund (1983) equation. The proposed approach is validated on six different compacted expansive soils from US, and on eight field sites from six countries; namely, Saudi Arabia, Australia, Canada, China, US, and the UK. The proposed simple techniques presented in this thesis are friendly for the practitioners for using when estimating the heave in unsaturated expansive soils.

In many situations, the upper layers of soil above the ground water table are in a state of unsaturated condition. Although unsaturated soils are found throughout the world, they are predominant in arid or semi-arid regions. In these areas, the soil water characteristic curve (SWCC) which relates the water content to the matric suction could be used as key tool to implement the mechanics of unsaturated soils into the designs of geotechnical structures such as dams, embankments, pavements, canals, and foundations. Several experimental techniques are available for determining the SWCC in a laboratory environment. However, these experimental techniques are expensive, time consuming typically requiring days or weeks, depending on the soil type, and demanding intricate testing equipment. Due to these reasons, there has been a growing interest to find other means for estimating SWCC and encourage the adoption of unsaturated soils mechanics in geotechnical engineering practice. Several methods exist to indirectly estimate the SWCC from basic soil properties. Some may include statistical estimation of the water content at selected matric suction values, correlation of soil properties with the fitting parameters of an analytical equation that represents the SWCC, estimation of the SWCC using a physics-based conceptual model, and artificial intelligence methods such as neural networks or genetic programming. However, many studies have shown that environmental effects such as temperature, soil structure, initial water content, void ratio, stress history, compaction method, etc. can also affect the SWCC. This means that the estimation SWCC from set of conditions may not reliably predict the SWCC in other conditions. Due to this reason, it is crucial for engineers involved with unsaturated soils to take into account all the factors that influence the SWCC. The two key objectives of the present thesis are the development of a method based on first principles, using the capillary rise theory, to predict the variation of the SWCC as a function of temperature, as well as developing a technique for the prediction of the fixed parameters of a well-known function representing the SWCC based on basic soil properties together with the moisture profile of a soil column subjected to a known temperature gradient. A rational approach using capillary rise theory and the effect of temperature on surface tension and liquid density is developed to study the relation between temperature and the parameters of the Fredlund and Xing (1994) equation. Several tests, using a Tempe cell submerged in a controlled temperature bath, were performed to determine the SWCC of two coarse-grained soils at different temperatures. A good comparison between the predicted SWCC at different temperatures using the proposed model and the measured values from the Tempe cell test results is achieved. Within the scope of this thesis, a separate testing program was undertaken to indirectly estimate the SWCC of the same two coarse-grained soils from the measurement of their steady state soil-moisture profile while subjected to a fixed temperature differences. The water potential equation in the liquid and vapor phases is used to analyses the steady state flow conditions in the unsaturated soil. A good comparison is obtained for the SWCC estimated using this technique with the SWCC measured used a Tempe cell submerged in a controlled temperature bath. The results of this study indicate that knowledge of the moisture content of a soil specimen under a constant thermal gradient and basic soil properties can be used to estimate the SWCC of the soil at the desired temperature.

This study involves tracing inputs, partitioning, and outputs of phosphorus (P) through an aquaponics system. A mathematical model was developed to describe the dynamics of phosphorus in an aquaponics nutrient solution, and to maximize P use efficiency and minimize P waste. We assessed the influence of pH on the availability and speciation of phosphorus in an aquaponics nutrient solution. By using Visual MINTEQ, a freeware chemical equilibrium model for the calculation of element speciation, solubility equilibria, and sorption for natural waters, it was discovered that high pH values favor the formation of calcium phosphate complexes, decreasing the concentration of free phosphorus in aquaponics nutrient solutions. In addition, the mineralization of organic phosphorus in aquaponics systems was evaluated using treatments with phytase supplementation to fish diets, and incorporation of a microbial inoculant in the aquaponics nutrient solution. Overall, dietary phytase and microorganisms promoted phosphorus mineralization and enhanced phosphorus utilization in aquaponics systems. In the end, we conclude that aquaponics systems can keep the same growth performance and quality of vegetable crops grown in conventional systems when the availability and dynamics of phosphorus are well managed.

Landscape position and depth in the soil column influence the movement of microbial substrate throughout a catchment, from upslope areas to downslope areas, thereby impacting nutrient cycling rates and capabilities of the microbial communities in those areas. Wildfire also shapes the biogeochemistry of the landscape, creating a mosaic with variations in substrate type and concentration that also influence microbial communities and biogeochemical cycling. Nitrogen (N) in particular is altered by wildfire, as it is easily volatilized and the removal of organic matter (OM) reduces N inputs. We aimed to understand how landscape position and soil depth, first and foremost, influence microbial communities and their N-cycling, but also how this may differ from wildfires and their relative impacts on the soil microbial communities. Landscape position proved to influence few soil and microbial characteristics, while movement from soil surface to deep in the column and the incidence of wildfire caused many variations in soil physical and biogeochemical cycling properties. The interaction of landscape position and soil depth also showed little variation in any measurements, while wildfire and soil depth interactions showed drastic changes that indicate high order controls over the soil microbial community. It can be surmised that while landscape position is important for many soil properties, it is soil depth and wildfire that truly control the soil microbial communities and their N-cycling capabilities.