Dissertations / Theses on the topic 'Pedotransfer function'

Soil hydraulic properties are very time-consuming and expensive to measure directly. Conversely, routinely collected soil survey parameters (e.g. soil texture, dry bulk density and organic matter content) are relatively cheap and easy to collect. Fortunately, mathematical regression models called Pedotransfer Functions (PTFs) allow the transfer of data we have (soil survey parameters) into the data we need (soil hydraulic properties), and this thesis focusses on the potential and modelling methodologies of Artificial Neural Network (ANN) ensembles as a means by which to construct PTFs. The individual processes of the ensemble modelling procedure are examined herein, and suggestions as to how they may be improved upon, by mathematical, conjectural and empirical means, are discussed. Ultimately, it will show that more accurate, robust and efficient PTFs may be constructed by incorporating these into such models. An ensemble is a collection of individual ANNs, each of which provides an independent solution to the same problem. Thus, the combined strengths of the individual models are augmented, whilst their weaknesses are diminished. For any modelling methodology, a trade-off exists between the bias and variance components of the model error - decreasing the bias results in higher variance, and vice versa. However, for the ensemble method, combining ensemble members results in the reduction or elimination of the variance, whilst leaving the bias unaltered. Thus, the aim of the ensemble modeller is to determine an optimum balance between achieving low bias (regardless o f the consequences to the variance) and conserving data - a trade-off between the amount of data used and the value of that data. It has been empirically demonstrated here that by training ANNs using data selected such that all parts of the dataspace are equally represented, bias in ANN-PTF ensembles may be reduced to negligible levels. In addition, results showed that, using one-third or less the amount of data, the ensemble method yields results that are at least as accurate as single ANN methods.

The most important characteristics of each soil is its hydro-physical properties, which include retention curve. Retention curve expresses the relationship between humidity and pressure head. It is course affected by many factors such as grain size and mineralogical composition, humus content, structure and bulk density of dry soil. This thesis deals with direct and indirect determination of one of the basic hydraulic characteristics of the soil, soil moisture retention curve. For laboratory determination of moisture retention curves were used for sand tank and pressure instruments. Measured body retention curves were optimized RETC program.For indirect determination of retention curves were used Pedotransfer function by Wösten et . al .(1998 ) , derived from the European soils and under HYPRES Šútora and Štekauerová (2000). As in the project Wösten et al . (1998), PTF were processed for arable land in the area. The accuracy of both models PTF was assessed by the correlation coefficient R and standard error RMSE. Simple models PTF provide estimates of retention curves with sufficient accuracy for practical use in the locality.

Both empirical and process-simulation models are useful for evaluating the effects of management practices on environmental quality and crop yield. The use of these models is limited, however, because they need many soil property values as input. The first step towards modelling is the collection of input data. Soil properties can be highly variable spatially and temporally, and measuring them is time-consuming and expensive. Efficient methods, which consider the uncertainty and cost of measurements, for estimating soil hydraulic properties form the main thrust of this study. Hydraulic properties are affected by other soil physical, and chemical properties, therefore it is possible to develop empirical relations to predict them. This idea quantified is called a pedotransfer function. Such functions may be global or restricted to a country or region. The different classification of particle-size fractions used in Australia compared with other countries presents a problem for the immediate adoption of exotic pedotransfer functions. A database of Australian soil hydraulic properties has been compiled. Pedotransfer functions for estimating water-retention and saturated hydraulic conductivity from particle size and bulk density for Australian soil are presented. Different approaches for deriving hydraulic transfer functions have been presented and compared. Published pedotransfer functions were also evaluated, generally they provide a satisfactory estimation of water retention and saturated hydraulic conductivity depending on the spatial scale and accuracy of prediction. Several pedotransfer functions were developed in this study to predict water retention and hydraulic conductivity. The pedotransfer functions developed here may predict adequately in large areas but for site-specific applications local calibration is needed. There is much uncertainty in the input data, and consequently the transfer functions can produce varied outputs. Uncertainty analysis is therefore needed. A general approach to quantifying uncertainty is to use Monte Carlo methods. By sampling repeatedly from the assumed probability distributions of the input variables and evaluating the response of the model the statistical distribution of the outputs can be estimated. A modified Latin hypercube method is presented for sampling joint multivariate probability distributions. This method is applied to quantify the uncertainties in pedotransfer functions of soil hydraulic properties. Hydraulic properties predicted using pedotransfer functions developed in this study are also used in a field soil-water model to analyze the uncertainties in the prediction of dynamic soil-water regimes. The use of the disc permeameter in the field conventionally requires the placement of a layer of sand in order to provide good contact between the soil surface and disc supply membrane. The effect of sand on water infiltration into the soil and on the estimate of sorptivity was investigated. A numerical study and a field experiment on heavy clay were conducted. Placement of sand significantly increased the cumulative infiltration but showed small differences in the infiltration rate. Estimation of sorptivity based on the Philip's two term algebraic model using different methods was also examined. The field experiment revealed that the error in infiltration measurement was proportional to the cumulative infiltration curve. Infiltration without placement of sand was considerably smaller because of the poor contact between the disc and soil surface. An inverse method for predicting soil hydraulic parameters from disc permeameter data has been developed. A numerical study showed that the inverse method is quite robust in identifying the hydraulic parameters. However application to field data showed that the estimated water retention curve is generally smaller than the one obtained in laboratory measurements. Nevertheless the estimated near-saturated hydraulic conductivity matched the analytical solution quite well. Th author believes that the inverse method can give a reasonable estimate of soil hydraulic parameters. Some experimental and theoretical problems were identified and discussed. A formal analysis was carried out to evaluate the efficiency of the different methods in predicting water retention and hydraulic conductivity. The analysis identified the contribution of individual source of measurement errors to the overall uncertainty. For single measurements, the inverse disc-permeameter analysis is economically more efficient than using pedotransfer functions or measuring hydraulic properties in the laboratory. However, given the large amount of spatial variation of soil hydraulic properties it is perhaps not surprising that lots of cheap and imprecise measurements, e.g. by hand texturing, are more efficient than a few expensive precise ones.

Both empirical and process-simulation models are useful for evaluating the effects of management practices on environmental quality and crop yield. The use of these models is limited, however, because they need many soil property values as input. The first step towards modelling is the collection of input data. Soil properties can be highly variable spatially and temporally, and measuring them is time-consuming and expensive. Efficient methods, which consider the uncertainty and cost of measurements, for estimating soil hydraulic properties form the main thrust of this study. Hydraulic properties are affected by other soil physical, and chemical properties, therefore it is possible to develop empirical relations to predict them. This idea quantified is called a pedotransfer function. Such functions may be global or restricted to a country or region. The different classification of particle-size fractions used in Australia compared with other countries presents a problem for the immediate adoption of exotic pedotransfer functions. A database of Australian soil hydraulic properties has been compiled. Pedotransfer functions for estimating water-retention and saturated hydraulic conductivity from particle size and bulk density for Australian soil are presented. Different approaches for deriving hydraulic transfer functions have been presented and compared. Published pedotransfer functions were also evaluated, generally they provide a satisfactory estimation of water retention and saturated hydraulic conductivity depending on the spatial scale and accuracy of prediction. Several pedotransfer functions were developed in this study to predict water retention and hydraulic conductivity. The pedotransfer functions developed here may predict adequately in large areas but for site-specific applications local calibration is needed. There is much uncertainty in the input data, and consequently the transfer functions can produce varied outputs. Uncertainty analysis is therefore needed. A general approach to quantifying uncertainty is to use Monte Carlo methods. By sampling repeatedly from the assumed probability distributions of the input variables and evaluating the response of the model the statistical distribution of the outputs can be estimated. A modified Latin hypercube method is presented for sampling joint multivariate probability distributions. This method is applied to quantify the uncertainties in pedotransfer functions of soil hydraulic properties. Hydraulic properties predicted using pedotransfer functions developed in this study are also used in a field soil-water model to analyze the uncertainties in the prediction of dynamic soil-water regimes. The use of the disc permeameter in the field conventionally requires the placement of a layer of sand in order to provide good contact between the soil surface and disc supply membrane. The effect of sand on water infiltration into the soil and on the estimate of sorptivity was investigated. A numerical study and a field experiment on heavy clay were conducted. Placement of sand significantly increased the cumulative infiltration but showed small differences in the infiltration rate. Estimation of sorptivity based on the Philip's two term algebraic model using different methods was also examined. The field experiment revealed that the error in infiltration measurement was proportional to the cumulative infiltration curve. Infiltration without placement of sand was considerably smaller because of the poor contact between the disc and soil surface. An inverse method for predicting soil hydraulic parameters from disc permeameter data has been developed. A numerical study showed that the inverse method is quite robust in identifying the hydraulic parameters. However application to field data showed that the estimated water retention curve is generally smaller than the one obtained in laboratory measurements. Nevertheless the estimated near-saturated hydraulic conductivity matched the analytical solution quite well. Th author believes that the inverse method can give a reasonable estimate of soil hydraulic parameters. Some experimental and theoretical problems were identified and discussed. A formal analysis was carried out to evaluate the efficiency of the different methods in predicting water retention and hydraulic conductivity. The analysis identified the contribution of individual source of measurement errors to the overall uncertainty. For single measurements, the inverse disc-permeameter analysis is economically more efficient than using pedotransfer functions or measuring hydraulic properties in the laboratory. However, given the large amount of spatial variation of soil hydraulic properties it is perhaps not surprising that lots of cheap and imprecise measurements, e.g. by hand texturing, are more efficient than a few expensive precise ones.

This thesis deals with direct and indirect determination of soil hydraulic characteristics (retention curve and hydraulic conductivity) in the locality of Bohaté Málkovice. For laboratory determination of soil moisture retention curve is used sand tank and pressure relief device. For the indirect determination of soil hydraulic characteristics is used computer software Rosetta, which includes 5 models of pedotransfer functions. For estimatiton of retention curves are applied previously derived pedotransfer function (continuous parametric PTF and point PTF).

Cette thèse a été effectuée dans le cadre du projet ANCRES. Son rôle est d'assurer la compréhension physique du milieu récepteur, le sol, alors qu'une autre équipe étudie l'impact physico-chimique des eaux usées traitées sur le sol. Pour cela, il faut connaître ses propriétés texturales et structurales contrôlant ses fonctions d'épuration et d'évacuation. La problématique est donc de comprendre le processus de l'infiltration imposée par un dispositif d'ANC dans un sol caillouteux. D'abord, suite au positionnement du site pilote d'ANC au pied d'un versant au cœur du plateau portlandien dans le département de l'Yonne en France, on a identifié là un type de sol hétérogène et complexe, caillouteux, une colluvion qui n'était pas cartographiée sur la carte géologique BRGM de cette région et sur laquelle on focalise la thèse. Ensuite, dans le sol complexe du site pilote, on a d'abord mesuré la conductivité hydraulique du sol par l'appareil Guelph sur 15 m² de la fouille de l'ANC à une profondeur de 120 cm : au total, on a fait 15 essais d'infiltration. De plus, on a récupéré 15 échantillons du sol accompagnant ses essais de Guelph pour la caractérisation physique au laboratoire. On a mesuré la texture, l'humidité résiduelle (HR), la teneur en cailloux (Rw) et la matière organique (MO) des échantillons au laboratoire. Ensuite, pour l'étude du processus d'infiltration, on a instrumenté ce site par un dispositif de surveillance hydrique (tensiométrie, teneur en eau, piézométrie) et de prélèvement d'eau interstitielle du sol. De plus, la masse volumique (densité) apparente d'un sol hétérogène a été déterminée. Parmi les paramètres mesurés, certains sont choisis comme indicateurs pour caractériser un sol comme milieu récepteur potentiel des eaux usées traitées en ANC. Puis, en utilisant la MO et la texture des échantillons, on a estimé la masse volumique apparente de la matrice du sol du site piloteau moyen de fonctions de pédotransfert appelées BD-FPTs et on a testé la relation entre la conductivité hydraulique à saturation Ks et la texture de ce sol complexe. Pour cela, une méthodologie en quatre phases a été développée pour évaluer la capacité prédictive des fonctions Ks-FPTs. Cette méthodologie de sélection n'a pas été trouvée dans la littérature mais est élaborée pour les besoins de la thèse. On a déduit les meilleures Ks-FPTs pour ce type de sol. Enfin, avec les données d'humidité volumique et du potentiel matriciel du sol, acquises par une centrale d'acquisition des données, le régime hydrodynamique du sol sous le massif filtrant de l'ANC a été étudié et on a mis en évidence l'écoulement préférentiel dans un sol caillouteux. Les résultats ont montré que dans la colluvion, bien que la matrice du sol soit fine, la conductivité hydraulique mesurée est plus élevée qu'attendu. Cela démontre que la fraction des cailloux dans le sol joue un rôle essentiel en accélérant l'évacuation des eaux usées traitées et aussi l'eau pluviale vers les couches sous-jacentes, et finalement vers la nappe. Cette propriété serait un point fort pour la fonction de transfert du sol et on peut en déduire une méthode pour améliorer la capacité de transfert de l'eau des sols lourds dans les projets d'aménagement urbain ou périurbain : l'ajout de graviers et graves calcaires par mélange au sol en place. On conclut que cette expérimentation, unique en son genre, a été utile pour évaluer la fonction de rétention / transfert de l'eau dans le sol recevant les eaux usées traitées. On a identifié les paramètres prédicteurs pertinents et les relations empiriques qui permettent de faire l'économie de nombreux essais in situ d'eau
The soil is an essential compartment in hydrologic cycle of water in the nature. Therefore, it is clear that taking into account the properties and organization of the soil is essential to the understanding and management of flows involved in the development of the quality of groundwater and surface water. The on-site sanitation (ANC) is a management method of domestic wastewater, by which the water is sent into the soil after settling and filtration liquefaction / aerobic degradation. The second step was often provided by the top soil in place himself, and this continues to this day on many plots of on-site sanitation.This thesis was carried out under ANCRES project. Its role was to ensure the physical understanding of the receptor medium, soil, while another research team was investigating the physico-chemical impact of treated wastewater on the sol. To ensure it, we have to understand its textural and structural properties controlling its purifying power and hydrodynamic processes. So, the problematic is to understand the process of infiltration imposed by an ANC in a heterogeneous stony soil. At first, due to the positioning of the pilot ANC site, at the foot of a slope in the Yonne department in France, a type of complex and heterogeneous soil, a colluvion, was identified. This soil has not been mapped on the BRGM (Bureau de recherches géologiques et minières) geological map of the area. So, the thesis was focalised on this soil. Then, in this soil complex at a depth of the 120 cm of the excavation of the ANC, the soil hydraulic conductivity was first measured by a Guelph apparatus on 15 m². We totally made 15 infiltration tests. Furthermore, we have collected 15 soil samples with each Guelph test for physics laboratory physical characterization. Then, in order to study the soil functions, this site was instrumented by the water monitoring devices (tensiometers, water content probes, and piezometer) and the interstitial water sampling device from the soil. In addition, the bulk of this heterogeneous soil was determined. Among the measured parameters, a series of indicators chosen to characterize the soil as a potential receptor medium of treated wastewater of the ANC. Then, the bulk density of the soil matrix using pedotransfer functions called BD-FPTs was estimated and the relationship between saturated hydraulic conductivity Ks and the texture of the soil complex (by Ks-FPT function) was tested. For this aim, a four-phase methodology was developed to assess the predictive ability of Ks- FPTs functions. This methodology in four phases is not found in the literature but was prepared for the purposes of the thesis. We concluded the best Ks- FPTS for this type of soil. Finally, with the volumetric water content and soil matrix potential data acquired by a the data loggers, the hydrodynamic regime of the soil under the sand pack of the ANC has been studied and demonstrated the preferential flow in a stony soil was demonstrated. The results showed that in the colluvion, although the soil matrix is fine, the measured hydraulic conductivity is higher than expected. This shows that the stone fraction in the soil plays an important role in accelerating the evacuation of treated wastewater and also rainwater to the underlying layers, and finally to the water table. This property would be a strong point for the transfer function of the soil and we can deduce a method to improve the transfer function of heavy soils in urban or peri-urban development projects. This could be possible by adding the gravel and -limestone to soil matrix and mixing them. It has been concluded that this experiment, unique in its kind, has been useful in evaluating the function of retention / transfer of water in the soil receiving treated wastewater. In addition, the relevant predictor parameters and empirical relationships that make the economy of many water tests were identified

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Soil water retention stems from the action of attractive forces manifested by adsorption and capillary phenomena. Matric potential (ψ) expresses the soil water retention energy, which varies according to water content and is described by soil water retention curve (SWRC). The experimental obtainment of SWRC is difficult and costly, therefore, the use of pedotransfer functions (PTF) is preferred, because PTF estimate SWRC (or part of it) from other soil properties related to water retention. The use of available PTFs is limited for being calibrated from a particular set of soils and/or for not being able to represent the effect of structural changes (e. g. bulk density (Bd)) on water retention. Thus, the aim of this study is to propose and evaluate a mathematical model to estimate the volumetric moisture based on the specific surface area (SSA) and on the integration of the effect of the Bd with a physicoempirical parameter (fa). SWRCs were obtained experimentally from soils with different particle size and Bd variations were simulated by samples prepared in metal cylinders. The SSA was estimated by particle size distribution curve. Dependence of fa on ψ, SSA and Bd was described by Van Genuchten (1980) sigmoidal model, while the effect of SSA and Bd was incorporated in parameters of this same sigmoidal model by graphical and sensibility analysis. The estimates of the model were compared with the literature FPTs estimates for the same data set. Initially, the results showed that samples prepared in the laboratory did not ensure consistent experimental data of SWRC. This finding masked the model predictive ability. However, it is clear that the proposed FPT coherently described the effect of SSA and Bd with adsorption and capillarity phenomena, complying with the study purpose. In addition, the physicoempirical consistency of SSA and Bd with parameters of the Van Genuchten (1980) sigmoidal model allowed a better predictive performance compared to literature PTFs. In a broader sense, results reinforce the idea that models which mechanistically explore the relationship between predicted and predictor variables are more efficient in estimating the magnitude of the natural soil processes. and Bd was incorporated in parameters of this same sigmoidal model by graphical and sensibility analysis. The estimates of the model were compared with the literature FPTs estimates for the same data set. Initially, the results showed that samples prepared in the laboratory did not ensure consistent experimental data of SWRC. This finding masked the model predictive ability. However, it is clear that the proposed FPT coherently described the effect of SSA and Bd with adsorption and capillarity phenomena, complying with the study purpose. In addition, the physicoempirical consistency of SSA and Bd with parameters of the Van Genuchten (1980) sigmoidal model allowed a better predictive performance compared to literature PTFs. In a broader sense, results reinforce the idea that models which mechanistically explore the relationship between predicted and predictor variables are more efficient in estimating the magnitude of the natural soil processes.
A retenção de água no solo decorre da atuação de forças atrativas que se manifesta por meio dos fenômenos de adsorção e capilaridade. O potencial matricial (ψ) expressa a energia com que a água está retida no solo, que varia com a umidade volumétrica (Uv) e é descrita pela curva de retenção de água no solo (CRAS). A obtenção experimental da CRAS é difícil e onerosa, o que motiva o uso de funções de pedotransferência (FPT), que estimam a CRAS (ou parte dela) a partir de propriedades do solo ligadas à retenção de água. As FPTs disponíveis são limitadas quanto à aplicação para solos diferentes dos quais foram calibradas ou por não conseguirem representar o efeito de mudanças estruturais (variação na densidade do solo (Ds)) sobre a retenção de água. Portanto, o objetivo deste estudo é propor e avaliar um modelo matemático para estimar a umidade volumétrica, baseado na área superficial específica (ASE) e na integração do efeito da Ds a partir de um parâmetro físico-empírico (fa). Experimentalmente, CRAS foram obtidas a partir de solos com diferente granulometria, para os quais variações de Ds foram simuladas por meio da confecção de amostras em cilindros metálicos. A ASE foi estimada por meio da curva granulométrica. A dependência de fa em relação às variáveis ψ, ASE e Ds, foi descrita pelo modelo sigmoidal de Van Genuchten (1980), enquanto o efeito da ASE e Ds foi incorporado aos parâmetros desse modelo sigmoidal por meio de análise gráfica e de sensibilidade. As estimativas do modelo proposto foram comparadas com estimativas de FPTs da literatura para o mesmo conjunto de dados. Inicialmente, verificou-se que, mesmo utilizando amostras confeccionadas em laboratório, a obtenção experimental da CRAS demonstrou-se, por vezes, inconsistente, o que mascarou a capacidade preditiva do modelo. Contudo, é possível afirmar que a FPT proposta foi capaz de descrever o efeito da ASE e da Ds de forma fisicamente coerente com os fenômenos de adsorção e capilaridade, cumprindo com a proposta deste estudo. Além disso, a consistência física-empírica entre ASE e Ds e os parâmetros de ajuste do modelo sigmoidal de Van Genuchten (1980) permitiram melhor desempenho preditivo comparado às FPTs da literatura. De forma mais ampla, os resultados reforçam a ideia de que modelos que explorem mecanisticamente a relação entre variáveis preditas e preditoras são mais eficientes na estimativa da magnitude dos processos naturais ligados ao solo.

Characterization of heterogeneous soil hydraulic parameters of deep vadose zones is often difficult and expensive, making it necessary to rely on other sources of information. Pedotransfer functions (PTFs) based on soil texture data constitute a simple alternative to inverse hydraulic parameter estimation, but their accuracy is often modest. Inverse modeling entails a compromise between detailed description of subsurface heterogeneity and the need to restrict the number of parameters. We propose two methods of parameterizing vadose zone hydraulic properties using a combination of k-means clustering of kriged soil texture data, PTFs, and model inversion. One approach entails homogeneous and the other heterogeneous clusters. Clusters may include subdomains of the computational grid that need not be contiguous in space. The first approach homogenizes within-cluster variability into initial hydraulic parameter estimates that are subsequently optimized by inversion. The second approach maintains heterogeneity through multiplication of each spatially varying initial hydraulic parameter by a scale factor, estimated a posteriori through inversion. This allows preserving heterogeneity without introducing a large number of adjustable parameters. We use each approach to simulate a 95 day infiltration experiment in unsaturated layered sediments at a semiarid site near Phoenix, Arizona, over an area of 50 x 50 m(2) down to a depth of 14.5 m. Results show that both clustering approaches improve simulated moisture contents considerably in comparison to those based solely on PTF estimates. Our calibrated models are validated against data from a subsequent 295 day infiltration experiment at the site.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
In recent years, Brazil has proposed policies to reduce emissions of greenhouse gases (GEE). In this context, the aim of this study was to estimate the carbon stock (EC) from different Brazilian soils under different agricultural uses and propose strategies that contribute to mitigation of GEE emissions. The research was conducted in four stages: i) organization of a soil database; ii) development of a pedotransfer function (PTF) for the estimation of bulk density (DS) and evaluate the effect on estimate of EC; iii) estimation of the EC; and iv) evaluation of potential EC by Brazilian agriculture. Data from 38.456 soil samples were performed and, after standardization, they formed a database with 10.445 data samples corresponding to 5.823 data for the 0-30 cm layer. These data covered all Brazilian states, all classes of the Brazilian System of Soil Classification and nine types of land use: annual crop in no-tillage system (SPD), annual crop in conventional tillage system, perennial crop, planted forest, integrated crop-livestock (ILP) system, integrated crop-livestock-forest (ILPF) system, pasture, uncovered soil and native vegetation. Many samples had no DS record, then 12 PTF for DS estimation were developed using 974 soil samples. The performance of PTFs was assessed by R2, and in the validation, the accuracy of prediction was measured based on the mean error (ME), the mean absolute error (MAE), and the root mean squared error (RMSE). All functions overestimated DS values and one of them (PTF 5) presented the best performance. The evaluation of the estimated EC was made with 926 samples layer 0-30 cm, using observed data DS (ECobs), estimated data DS from the PTF5 (ECest) and estimated data DS from the null model (ECnull), in which the DS was given by the mean value of DS observed. Based on the calculation of ME, MAE, the RMSE and comparison with ECobs values, it was found that the ECnull values were overestimated and dispersed. It was concluded at this stage that the null model was not a reliable alternative and PTF5 was applied in 4.540 samples from 0-30 cm layer with missing DS. The estimated DS values ranged from 0,10 kg dm-3 at 1,92 kg dm-3 with a mean of 1,39 kg dm-3 and standard deviation of 0,19 kg dm-3. The coefficient of variation was less than 15% configuring a homogeneous data. It was made the EC calculation for 5.823 EC data for the layer 0-30 cm and these values were grouped by types of land use and soil types. In grouping by type of land use, the lowest EC values were observed in annual crop and native vegetation (0,10 Mg ha-1) and the largest maximum values were observed in annual crop, pasture and native vegetation, with 297,3 Mg ha-1, 259,9 Mg ha-1 and 253,6 Mg ha-1 respectively. In grouping by type of soil, it was observed that a minimum value of 0,10 Mg ha-1 in an Argisol while maxima were observed in a Cambisol (297,3 Mg ha-1) and an Argisol (265,8 Mg ha-1). Three scenarios were developed to estimate the potential increase of EC, from changes in management practices and land use. In a scenario where 18% of the areas of annual crops adopt SPD, the increase in EC was 73,6 Gg. If 15 million hectares of degraded pastures were recovered with ILP system in 20% of the area, and ILPF system in 10% of the area, the potential for increasing the EC would be 88.13 Gg. These values could represent an addition of 59,6 Gg of CO2, which could offset the 472,1 Gg CO2 emitted by the Brazilian agricultural sector in 2010, according to estimates by the Ministry of Science, Technology and Innovation. It concludes that: i) the absence of DS data, using a simple PTF is more appropriate than the use of the null model; ii) the detected errors in the estimation of DS by PTF not propagate the EC calculation; iii) the proposed changes would offset emissions from the Brazilian agricultural sector; and iv) the estimates presented highlight the role of the agricultural sector in mitigating GEE emissions.
Nos últimos anos, o Brasil tem proposto políticas para diminuir as emissões de gases de efeito estufa (GEE). Nesse contexto, o objetivo geral deste trabalho foi estimar o estoque de carbono (EC) de diferentes solos brasileiros com diferentes usos agrícolas e propor estratégias que contribuam para mitigação das emissões de GEE. A pesquisa foi desenvolvida em quatro etapas: i) organização de um banco de dados de solos; ii) desenvolvimento de função de pedotransferência (PTF) para a estimativa de densidade do solo (DS) e avaliação do efeito na estimativa de EC; iii) estimativa do EC; e iv) potencial de EC pela agricultura brasileira. Foram levantados dados de 38.456 amostras de solos que, após padronização, constituíram um banco com dados de 10.445 amostras, que corresponderam a 5.823 dados para a camada 0-30 cm. Esses dados recobriram todos os estados brasileiros, todas as classes do Sistema Brasileiro de Classificação de Solos e nove tipos de uso do solo: cultura anual em sistema de plantio direto (SPD), cultura anual sem SPD, cultura perene, floresta plantada, integração lavoura-pecuária (ILP), integração lavoura-pecuária-floresta (ILPF), pastagem, solo descoberto e vegetação nativa. Como muitas amostras não apresentavam registro de DS, 12 PTF foram desenvolvidas em um subconjunto de 974 amostras do banco de dados, sendo 664 amostras utilizadas para o desenvolvimento das PTFs e 310 utilizadas para teste. O desempenho de cada PTF foi avaliado através do R2, e na validação, a acurácia da predição foi medida pela comparação dos valores estimados com os observados, com base no cálculo de erro médio (ME), do erro absoluto médio (MAE) e da raiz quadrada do erro quadrático médio (RMSE). Todas as PTFs testadas superestimaram os valores de DS, porém, a PTF5 apresentou o melhor desempenho. A avaliação da estimativa de EC foi feita com 926 amostras da camada 0-30 cm, usando-se dados de DS observados (ECobs), dados de DS estimados a partir da PTF5 (ECest) e dados de DS estimados a partir do modelo nulo (ECnulo), no qual a DS é dada pelo valor médio das DS observadas. Com base no cálculo do ME, da MAE, da RMSE e da comparação com os valores de ECobs, constatou-se que os valores de ECnulo foram superestimados e dispersos. Concluiu-se nesta etapa que o modelo nulo não era uma alternativa confiável e a PTF5 foi aplicada em 4.540 amostras de camada 0- 30 cm com DS faltante. Os valores de DS estimados variaram de 0,10 kg dm-3 a 1,92 kg dm-3, com média de 1,39 kg dm-3 e desvio padrão de 0,19 kg dm-3. O coeficiente de variação foi menor que 15%, configurando dados homogêneos. Foi feito o cálculo de EC para 5.823 dados de EC referentes à camada 0-30 cm e esses valores foram agrupados por tipos de uso do solo e por classes de solo. No agrupamento por tipos de uso do solo, os menores valores de EC foram observados em cultura anual e vegetação nativa (0,10 Mg ha-1) e o maiores valores máximos foram observados em cultura anual, pastagem e vegetação nativa, com 297,3 Mg ha- 1, 259,9 Mg ha-1 e 253,6 Mg ha-1 respectivamente. No agrupamento por tipos de solo, observou-se que um valor mínimo de 0,10 Mg ha-1 em um Argissolo enquanto que valores máximos foram observados em um Cambissolo (297,3 Mg ha-1) e em um Argissolo (265,8 Mg ha-1). Foram elaborados três cenários para estimar o potencial de aumento de EC, a partir de mudanças nas práticas de manejo e de uso do solo. Em um cenário de adoção de SPD em 18 % das áreas de culturas anuais, o aumento do EC seria de 73,6 Gg. Se 15 milhões de hectares de pastagens degradadas forem recuperados com ILP, em 20% da área, e com ILPF, em 10% da área, o potencial de aumento do EC seria de 88,13 Gg. Esses valores somados representariam 593,6 Gg de CO2, que poderiam compensar os 472,1 Gg de CO2 emitidos pelo setor agropecuário brasileiro em 2010, conforme estimativas do Ministério da Ciência, Tecnologia e Inovação. Conclui-se que: i) na ausência de dados de DS, o uso de uma PTF simples é mais indicado do que o uso do modelo nulo; ii) os erros detectados na estimativa de DS por meio de PTF não se propagam no cálculo de EC; iii) as mudanças propostas compensariam emissões do setor agrícola brasileiro; e iv) as estimativas apresentadas ressaltam o papel do setor agropecuário na mitigação das emissões de GEE.

We use geostatistical and pedotrasnfer functions to estimate the three-dimensional distributions of soil types and hydraulic properties in a relatively large volume of vadose zone underlying the Maricopa Agriculture Center near Phoenix, Arizona. Soil texture and bulk density data from the site are analyzed geostatistically to reveal the underlying stratigraphy as well as finer features of their three-dimensional variability in space. Such fine features are revealed by cokriging soil texture and water content measured prior to large-scale long-term infiltration experiments. Resultant estimates of soil texture and bulk density data across the site are then used as input into a pedotransfer function to produce estimates of soil hydraulic parameter (saturated and residual water content θs and θr, saturated hydraulic conductivity Ks, van Genuchten parameters αand n) distributions across the site in three dimensions. We compare these estimates with laboratory-measured values of these same hydraulic parameters and find the estimated parameters match the measured well for θs, n and Ks but not well for θr nor α, while some measured extreme values are not captured. Finally the estimated soil hydraulic parameters are put into a numerical simulator to test the reliability of the models. Resultant simulated water contents do not agree well with those observed, indicating inverse calibration is required to improve the modeling performance. The results of this research conform to a previous work by Wang et al. at 2003. Also this research covers the gaps of Wang’s work in sense of generating 3-D heterogeneous fields of soil texture and bulk density by cokriging and providing comparisons between estimated and measured soil hydraulic parameters with new field and laboratory measurements of water retentions datasets.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
The preconsolidation pressure (σp) is obtained from the curve of the soil compression visual graphical form, mathematical or associating both and is an estimate of its load-bearing capacity. In order to remove the subjectivity of the visual graphical method is need for mathematical description (models using) of the compression curve. However, research results do not provide subsidies for the choice of a model whose σp represents well the resulting load-bearing capacity of soil, but if some model to represent, the σp should be a function of density and water content soil, other properties remain constant. The objective of this study was to understand the variability in the preconsolidation pressure caused by different models and options to adjust these models to the compression curve and evaluate the relationship of preconsolidation pressure with bulk density (Ds), volumetric water content (θ) and macroporisity (Ma) . For this, we performed the uniaxial compression test of 300 samples from a Hapludox, clayey, with wide variation Ds and θ. The preconsolidation pressure was determined by strictly mathematical, from the set of ten models, where seven of them consisted of variations of the model van Genuchten (1980) and others have been proposed by Friton (2001), Assouline (2002) and Gregory et al. (2006). The model proposed by Gregory and Friton possible to obtain the σp for only 62 and 56% of the curves, respectively, the variations of the model van Genuchten were enable the calculation of σp at least 90% of the curves. In three of the variations of the van Genuchten model, it was possible to get σp in 100% of the curves. The range of σp produced by the various options described in compression curve affects the physical significant of σp to represent the load bearing capacity of the soil. Likewise, Ds, θ and Ma, which influence the same load bearing capacity of the soil, not explained more than 58% of the variation of σp produced using different models. With the criteria used, it is not possible to choose one model over the other which allows to estimate more adequately by σp, the load bearing capacity of the soil, which limits the use of this parameter as an indicator for soil management agricultural. Given this result, it was investigated whether the percentage of deformation of the sample as a function of the applied loads would be more closely related to Ds, θ, and Ma was considered a safe limit of deformation of the physical viewpoint, that Ma deformation where the remains higher than 10%. The use of maintenance limit of 80% of voids index (Mεi) displaces the deformation to the plastic region of the curves of all the density ranges and therefore cannot be used for soil with structure more affected by compaction. The load to achieve a certain percentage (Mεi) is best explained by the variation of Ds and θ. The pedotransfer functions to load in Mεi between 85 and 87.5% resulted in higher coefficients of determination (0.74), having potential use of such values as critical limits to maintenance of porosity without degradation of soil physical quality.
A pressão de preconsolidação (σp) é obtida da curva de compressão do solo de forma gráfica visual, matemática ou associando ambas e é uma estimativa de sua capacidade de suporte de carga. A fim de se retirar a subjetividade do método gráfico visual, há necessidade de descrição matemática (uso de modelos) da curva de compressão. Porém, os resultados de pesquisa não fornecem subsídios para a escolha de um modelo cuja σp resultante represente, de maneira confiável, a capacidade de suporte de carga do solo. Entretanto, se algum modelo a representar, a σp deverá ser uma função da densidade e conteúdo de água do solo, mantidas constantes outras propriedades. O objetivo deste trabalho foi conhecer a variabilidade na pressão de preconsolidação provocada por diferentes modelos e opções de ajuste desses modelos à curva de compressão e avaliar a relação da pressão de preconsolidação com a densidade do solo (Ds), conteúdo volumétrico de água (θ) e macroporosidade do solo (Ma). Para isso, foi realizado o ensaio de compressão uniaxial para 300 amostras provenientes de um Latossolo Vermelho Distroférrico típico, com textura argilosa, com ampla variação Ds e θ. A pressão de preconsolidação foi determinada por meio estritamente matemático, a partir do ajuste de dez modelos, onde sete deles consistiram em variações do modelo de van Genuchten (1980) e os demais foram propostos por Friton (2001), Assouline (2002) e Gregory et al. (2006). Os modelos propostos por Gregory e Friton possibilitaram a obtenção da σp para apenas 62 e 56 % das curvas, respectivamente, já as variações do modelo de van Genuchten viabilizam o cálculo da σp para no mínimo 90 % das curvas. Em três das variações do modelo de van Genuchten, foi possível obter a σp em 100% das curvas. A variação da σp produzida pelas diferentes opções de descrição da curva de compressão compromete o significado físico da σp para representar a capacidade de suporte de carga do solo. Da mesma forma, Ds, θ e Ma, mesmo que influenciem a capacidade de suporte de carga do solo, não explicaram mais que 58% da variação da σp produzida com o uso de diferentes modelos. Com os critérios utilizados, não é possível eleger um modelo em relação aos demais que possibilite estimar de maneira mais adequada, através da σp, a capacidade de suporte de carga do solo, o que limita o uso desse parâmetro como um indicador para o manejo dos solos agrícolas. Diante desse resultado, foi investigado se a porcentagem de deformação da amostra em função das cargas aplicadas estaria melhor relacionada com Ds, θ e Ma. Considerou-se um limite de deformação prudente do ponto vista físico, aquela deformação onde a Ma permaneça maior que 10%. O uso do limite de manutenção de 80 % do índice de vazios inicial (Mεi) desloca as deformações para a região plástica das curvas de todas as faixas de densidade e, por isso, não pode ser utilizado para solos com estrutura mais comprometida pela compactação. A carga para atingir determinada porcentagem de Mεi é melhor explicada pela variação da Ds e θ. As funções de pedotransferência da carga para a Mεi entre 85 e 87,5% resultaram em maiores coeficientes de determinação (0,74), havendo potencial da utilização destes valores como limites críticos de manutenção da porosidade sem haver degradação da qualidade física do solo.

Doutoramento em Engenharia dos Biossistemas - Instituto Superior de Agronomia
Modeling has become an essential tool for implementing better irrigation and fertilization practices. The HYDRUS software package is currently one of the few models capable of considering multicomponent geochemistry and evaluating multiple environmental problems in an integrated way. The model was used to simulate water movement and solute transport in two complex experiments carried out under field conditions, between 2004 and 2010. The field experiments were helpful to identify the main physical and chemical processes influencing soil water flow and multicomponent solute transport in soils irrigated with saline waters. They were further useful for evaluating different irrigation water quality and fertilization scenarios while considering soil salinization/sodification risks, root nutrient uptake, nutrient leaching, and crop yield. HYDRUS proved to be a powerful tool for establishing sound irrigation policies. However, the considerable demand on input data, namely, soil hydraulic properties, has been limiting its use (and other reactive transport models). Different pedotransfer functions (PTFs) were thus established to indirectly estimate soil hydraulic properties from the soil information available in the PROPSOLO database. A set of class-PTFs were developed to estimate water retention properties after grouping data by soil texture, soil horizon, and bulk density. A different procedure was also presented to estimate water retention properties from particle size distribution using the soil texture triangle and ordinary kriging. Finally, a set of PTFs were established for Cape Verde soils. All these PTFs may have multiple applications in irrigation management and watershed modelling. However, it is still necessary to further extend those PTFs to other regions of Portugal and Cape Verde, and to gain more knowledge on the hydraulic conductivity functions of those soils so that they can be used in reactive transport modeling

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
The soil management systems involve changes in soil physico-hydrical properties. The objective of this study was (i) characterize the soil physico-hydrical properties in the layer 0-5 cm for different soil management systems in the Cândido Brum watershed, (ii) build a map with the spatial variability of soil saturated hydraulic conductivity (Ks), (iii) estimate the Ks from other soil physico-hydrical properties and (iv) test the reliability of others pedotransfer functions for Ks found in the literature. The study was conducted in the watershed Cândido Brum, Brazil, which predominate the soil management systems native pasture, native forest, conventional tillage, minimum tillage and no-tillage. Orthogonal contrasts were performed between groups of soil management systems, which compared the effect of soil cultivation, the type of vegetation and bovine trampling, conservation practice and permanent soil cover. Determinations of soil bulk density, porosity, size particles, organic carbon, degree of flocculation, aggregate stability, Ks, air permeability, retention and availability of water and shear stress of the soil were made. Besides being used for the comparison of management systems, the water-physical properties used as input variables for the development of pedotransfer functions for Ks, which used the stepwise method in the selection of variables, and to test the reliability of pedotransfer functions found in the literature. The map of spatial variability of Ks was constructed from data interpolation using kriging. The soils of the watershed under crops had degraded structure, with low organic matter and low aggregates stability. Soil with native pasture had reduced the macroporosity, the Ks and air permeability in relation to other soil management systems. Conservation practices were effective in increasing the retention and vailability of soil water in relation to conventional tillage. The variables that represent the structure of the soil were more accurate in estimating the Ks that the size particle variables. The pedotransfer functions found in the literature, usually developed for soils of temperate climate, were not reliable in the estimation of Ks of soils watershed. The range of spatial dependence of the values of Ks was 141 m. The map of spatial variability allowed the visualization of areas that need management practices and conservation of soil and water.
Os sistemas de manejo do solo implicam em mudanças nas suas propriedades físico-hídricas. O objetivo do estudo foi (i) caracterizar as propriedades físico-hídricas do solo na camada 0-5 cm para diferentes sistemas de manejo da microbacia hidrográfica Cândido Brum, (ii) construir um mapa com a variabilidade espacial da condutividade hidráulica do solo saturado (Ks), (iii) estimar a Ks a partir de outras propriedades físicohídricas do solo e (iv) testar a confiabilidade de funções de pedotransferência para a Ks encontradas na literatura. O estudo foi conduzido na microbacia Cândido Brum, em Arvorezinha-RS, em que predominam os sistemas de manejo campo nativo, mata nativa, preparo convencional, plantio direto e preparo mínimo. Foram realizados contrastes ortogonais entre grupos de sistemas de manejo do solo, em que se comparou o efeito do cultivo, do tipo de vegetação natural e pisoteio animal, das práticas conservacionistas e da cobertura permanente do solo. Foram realizadas determinações de densidade do solo, porosidade, granulometria, carbono orgânico, grau de floculação, estabilidade de agregados, Ks, permeabilidade ao ar, retenção e disponibilidade de água e tensão de cisalhamento do solo. As propriedades físico-hídricas serviram também como variáveis de entrada para a elaboração de funções de pedotransferência para a Ks e para testes de confiabilidade de funções de pedotransferência encontradas na literatura. O mapa de variabilidade espacial da Ks foi construído a partir da interpolação dos dados com o método da krigagem. Os solos cultivados da microbacia apresentaram estrutura degradada, com pouca matéria orgânica e baixa estabilidade de agregados. O uso com campo nativo reduziu a macroporosidade, a Ks e a permeabilidade ao ar em relação aos outros sistemas de manejo do solo. As práticas conservacionistas foram eficientes em aumentar a retenção e a disponibilidade de água no solo em relação ao preparo convencional. As variáveis que representam a estrutura do solo foram mais precisas em estimar a Ks que as variáveis granulométricas. As funções de pedotransferência encontradas na literatura, geralmente elaboradas para solos de clima temperado, não foram confiáveis na estimativa da Ks da microbacia. O alcance da dependência espacial dos valores de Ks foi de 141 m. O mapa de variabilidade espacial possibilitou a visualização de áreas que necessitam de práticas de manejo e conservação do solo e da água.

Thesis (MScAgric)--Stellenbosch University, 2011.
ENGLISH ABSTRACT: Increased pressure on groundwater sources due to increased population size and threats of climate change is driving research to better understand the process of aquifer recharge. Soil pattern is of interest as it serves to partition rainwater into different flowpaths destined for surface runoff, evapotranspiration and deep percolation. The challenges inherent to studying these flowpaths are almost universal as uncertainties concerning spatial and temporal heterogeneity in catchments make the upscaling of models complex. This research addresses these challenges as it aims to improve the catchment scale hydrological models of two aquifer systems: One a fractured bedrock system at the Kogelberg Nature Reserve, Kleinmond, and the other a cover sand system in Riverlands Nature Reserve, Malmesbury. This study focussed on strengthening the link between what is known about a given soil form and the hydrological assumptions that can be drawn from that classification, and formulating the results so that they may ultimately be used to calibrate the recharge prediction models for the respective catchments. The research was done in two parts: The first phase was to conduct soil surveys in both reserves during which soils were classified according to South African Soil Classification. Samples were collected at representative observation points which provided textural data for use in pedotransfer functions (PTFs). These PTFs were used to estimate plant available water (PAW) and hydraulic conductivity (K) for the observed profiles. Infiltration experiments were subsequently done to investigate the infiltration patterns of distinctly different soil forms at two sites from each reserve. The experiments included double ring and mini disc infiltration, volumetric water content determination and flow path visualisation using a staining dye. A statistical comparison between the hydrological properties (K and PAW) of the different soil forms suggest that hydraulic properties differed between the deep sandy soil forms (Fernwood, Pinegrove and Witfontein in Kogelberg and Witfontein, Concordia and Lamotte in Riverlands) and the shallow rocky soil forms (Cartref and Glenrosa in Kogelberg). Thus grouping of hydrological similar units (HSUs) could be done on the basis of the soil forms present within the given catchments. The infiltration study showed that shallow, rocky soils that grade into bedrock would have infiltration rates far greater than those estimated using PTFs in Kogelberg. This is due to the prevalence of continuous preferential flow (PF) of water between coarse fragments in these profiles. Recharge estimates would thus be inaccurate in such soils and calibration using locally derived data is recommended. On the contrary, PTFs produced accurate infiltration estimates relative to measured infiltration rates in deep sandy soils in Kogelberg and Riverlands. The Lamotte soil form is an example of such a soil form. It should however be noted that an increase in PF in these soils had subsequently higher K values than estimated, thus illustrating the link between PF and accelerated infiltration rates. These results confirm that using soil survey information, in the form of a soil map, and calibrated hydrological properties, one can delineate HSUs that encompass a large degree of heterogeneity in a given catchment.
AFRIKAANSE OPSOMMING: Verhoogde druk op grondwaterhulpbronne weens die groeiende bevolking en klimaatsverandering dryf tans navorsing om akwifeer hervulling beter te verstaan. Die grondlaag is van belang sienend dat dit reënwater verdeel in oppervlak afloop, evapotranspirasie en diep dreinering. Die uitdagings in hidrologiese navorsing is universeel as gevolg van onsekerhede oor ruimtelike en tydelike variasie wat lei tot komplekse grondwatermodelle. Diè navorsing mik om die tekortkominge in akwifeer hervulling aan te vul deur groundwatermodelle van twee akwifeersisteme te verbeter: Die een is 'n gebroke rots sisteem in die Kogelberg Natuur Reservaat, Kleinmond, en die ander is 'n sand-bedekde sisteem in Riverlands Natuur Reservaat, Malmesbury. Die navorsing streef om die verhouding tussen 'n spesifieke grondvorm en sy hidroliese vloeipaaie te bestudeer en om die gevolgtrekkings so te formuleer dat dit kan gebruik word om die onderskeie grondwatermodelle te kalibreer. Die eerste fase van die navorsing was om 'n grondopname van die onderskeie reservate te doen waartydens die gronde geklassifiseer was volgens die Suid Afrikaanse Grondklassifikasie Sisteem. Grondmonsters is by verteenwoordigende observasiepunte geneem en geanaliseer om tekstuurdata vir pedo-oordraagbare-funksies (PTFs) te kry. Die PTFs was gebruik om plant beskikbare water (PBW) en hidrouliese geleiding (K) te voorspel vir die verskeie observasiepunte. Infiltrasie eksperimente was daarna gedoen om die infiltrasie patroon van twee verskillende grondvorms van elke reservaat te bestudeer. Die eksperimente sluit dubbel- en minidisk-infiltrasie, volumetriese waterinhoud bepaling en vloeipad visualisering met die gebruik van 'n kleurstof in. Die statistiese vergelyking van die hidrouliese eienskappe (K en PBW) en grondvorm dui aan dat die hidrouliese eienskappe verskil tussen die diep, grondvorms met 'n oorwegende sand tekstuur (Fernwood, Pinegrove en Witfontein in Kogelberg en Witfontein, Concordia en Lamotte in Riverlands) en die vlakker, klipperige grondvorms (Cartref en Glenrosa in Kogelberg). Groepering van hidrologies soortgelyke eenhede (HSE's) kan dus op die basis van die teenwoordige grondvorms in 'n opvangsgebied gedoen word. Die infiltrasie studie het bewys dat vlak, klipperige gronde wat tot die rotsbodem gradueer 'n baie hoër infiltratsie tempo sal hê as die PTF voorspelde waardes. Dit is as gevolg van die voorkoms van aaneenlopende voorkeurvloei (VV) van water tussen die growwe materiaal in die profiele, veral die gebroke rots ondergorond. Voorspellings van akwifeer hervulling sal dus onakkuraat wees en kalibrasie met plaaslike data word dus aanbeveel. In teendeel met die begenoemde, het die PTFs akkurate voorspellings gemaak relatief tot die gemete infiltrasie tempo's in die diep sanderige grondvorms in Kogelberg en Riverlands. Dit was duidelik met metings dat 'n toename in aaneenlopende VV hoër gemete K waardes getoon as die voorspelde waardes. Die verband tussen VV en verhoogde infiltrasie tempo word dus hiermee geillustreer. Die resultate bevestig dus dat grondopname data, in die vorm van 'n grondkaart en gekalibreerde hidrouliese eienskappe gebruik kan word om hidrologies soortgelyke eenhede uiteen te sit wat die meerderheid van die variasie in 'n gegewe opvangsgebied insluit. Die HSE's kan gebruik word om grondwatermodelle meer akkuraat te laat funksioneer en dus beter voorspellings te genereer.

Conselho Nacional de Desenvolvimento Científico e Tecnológico
The present study aimed to contribute, in the methodological way, to the field of Soil Science and Irrigation, more specifically Micro-Irrigation (Targeted Irrigation), by in situ to obtain physical and hydric parameters, specially the hydrodynamic functions of a Paleudalf soil. A multi-drip system, whose application is linked to the Drip Method principles, was designed to obtain hydraulic conductivity K(h) and soil-water retention curve θ(h). The system applied flow rates of 2, 4 and 8 L h-1 and, their respective areas of wetting and saturation in the dynamic balance moment were measured and worked as basis for the adjustment of a regression function, so as the saturated flow was estimated in dynamic balance. With the pairs of values to the advances in wetting and time fronts, the declivity of the respective regression line was determined considering the three flow rates tested in the study. The average value of sorptivity calculated was 2.68 cm h-0,5, with values of η = 2.22, β = 0.44 e hw = −2.29 cm H2O. By using these values of soil parameters, the soil-water retention characteristic curve (SWRCC) and the hydraulic conductivity function as function of the water content in the soil were estimated and graphically represented. The retention curve obtained through field experimental data does not match to the one obtained in laboratory according to standard methodology, but it was possible to build an exponential function which allows the correction of the volumetric soil moisture values.
O presente estudo visou contribuir no âmbito metodológico, nas áreas da ciência do solo e da irrigação, notadamente a microirrigação (irrigação localizada), na obtenção in situ de parâmetros físicos e hídricos, em especial as funções hidrodinâmicas do Argissolo Vermelho Distrófico Arênico (PVd). Foi projetado um sistema multi-gotejador , cuja aplicação está vinculada aos princípios do Método do Gotejador , na obtenção da condutividade hidráulica e da curva de retenção de água no solo . Vazões aplicadas de 2, 4 e 8 L h-1 e suas respectivas áreas de molhamento e de saturação no momento do equilíbrio dinâmico serviram de base para o ajuste de uma função de regressão, estimou-se o fluxo saturado em equilíbrio dinâmico. Com os pares de valores do avanço da frente de molhamento e de tempo determinou-se a declividade da respectiva reta de regressão para as três vazões testadas no trabalho. O valor médio de sorptividade calculado foi de 2,68 cm h-0,5, sendo obtidos os valores de η = 2,22, β = 0,44 e hw = −2,29 cm de H2O. Usando estes valores dos parâmetros do solo, a curva característica de retenção de água no solo (CCRAS) e a função da condutividade hidráulica em função do conteúdo de água do solo foram estimados e representados graficamente. A curva característica obtida com dados experimentais de campo não foi igual àquela obtida em laboratório conforme metodologia padrão, mas foi possível obter uma função exponencial que permite corrigir os valores de umidade volumétrica do solo.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
This work is related to knowledge of Pedotransfer functions (PTF), enabling an understanding about water soil content influenced by soil properties and analyzes to generate PTFs. This study aimed was proposed pedotransfer functions (PTF) based on hydro-physical soil properties and organic carbon to estimate soil moisture. The study was conducted in the area owned by Santa Teresa Plant in Goiana City, PE (7º36'56 "S 34º59'19" W) with sugarcane crop (Saccharum spp) irrigated by Lateral Move System. Field capacity (θfc) and wilting point (θwp) were assumed by dependent variables. Sand, silt, clay, soil bulk density and organic carbon were adopted as independent variables. Pedotransfer functions generated in this study estimate soil moisture to matric potential at -10 kPa, equivalent to θfc, in sandy soils and at -33 kPa to clay soils and matric potential at -1.500 kPa to θwp in 0-20; 20-40 e 40-60cm soil depth. These functions were classified as “Point PTF”, since estimated specific points to matric potential to soil water retention. Statistical indices and graphic analyses (1:1 ratio) between model-predicted and observed data were used to evaluate PTFs performance. The following statistical indices were used: Correlation coefficient (r), Concordance index (d), Maximum error (ME), Square root mean squared error normalized (RMSE), Coefficient of residual mass (CRM), Mean absolute error (MAE), Performance Index (c) and Determination coefficient (R²). Statistical indices that evaluate generated models to estimate soil water content indicated high performance for most of PTFs and good correlation between observed and estimated values at matric potential studied in all soil layers analyzed. Thus, retention water estimated by PTFs can be an interesting alternative to support irrigation management at sugarcane.
Esta dissertação é referente aos conhecimentos sobre Funções de Pedotransferência (FPT), possibilitando um entendimento relacionado ao conteúdo de água no solo a partir das influências nas propriedades do solo e nas análises estabelecidas para gerar as FPTs. O objetivo deste trabalho foi gerar funções de pedotransferência com base em atributos físico-hídricos do solo e a relação do carbono orgânico para estimar a umidade do solo. O trabalho foi realizado na área pertencente à Usina Santa Teresa localizada no município de Goiana, PE (7º36’56”S 34º59’19”W), em área cultivada com cana-de-açúcar (Saccharum spp) irrigada por sistema Lateral Móvel Linear. As variáveis adotadas como dependentes foram umidade na capacidade de campo (θcc) e umidade no ponto de murcha permanente (θpmp) e as variáveis independentes foram areia, silte, argila, densidade do solo e carbono orgânico. As funções de pedotransferência foram geradas a partir do método de regressão linear múltipla aplicando a técnica de stepwise backward elimination para seleção das variáveis candidatas ao modelo. Assim, as FPT geradas estimam o conteúdo de água no solo equilibrada nos potenciais mátricos equivalentes à umidade na capacidade de campo de -10kPa para solos arenosos, -33kPa para solos argilosos e ao ponto de murcha permanente de -1500kPa, nas camadas de 0-20; 20-40 e 40-60cm, totalizando 99 amostras. Essas funções foram classificadas como FPT pontuais, uma vez que, estima pontos específicos aplicados nas tensões de interesse para retenção de água no solo. O desempenho das Funções de pedotransferência foram analisadas graficamente pela relação 1:1, entre os dados estimados versus dados observados e por meio dos seguintes indicadores estatísticos: Coeficiente de correlação (r), Índice de concordância (d), Erro máximo (ME), Raiz quadrada do erro médio quadrático normalizado (RMSE), Coeficiente de massa residual (CRM), Erro absoluto médio (EAM), Índice de desempenho (c) e coeficiente de determinação (R²). Os índices estatísticos, que avaliam os modelos gerados para estimar a umidade volumétrica no solo estudado, apresentaram valores que indicam elevado desempenho para a maioria das FPTs e boa correlação entre os valores observados e estimados nas tensões estudadas e em todas as camadas de solo analisadas. Assim, a estimativa da retenção de água no solo por meio da FPTs apresenta-se como uma alternativa para auxiliar as técnicas adotadas no manejo de irrigação da cana-de-açúcar.

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CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
O fósforo remanescente consiste na concentração de fósforo que permanece em solução após a agitação por 1 hora de uma amostra de solo com solução de CaCl2 0,01 mol L-1 contendo 60 mg L-1 P. O valor de fósforo remanescente pode ser utilizado como um bom indicador da capacidade de sorção aniônica de um solo haja vista ser mais sensível a sua composição mineralógica do que ao teor de sua fração argila. No Brasil, a utilização agronômica do fósforo remanescente é contemplada no sistema oficial de recomendação de fertilizantes e corretivos do Estado de Minas Gerais. O objetivo principal deste estudo foi o de desenvolver uma função de pedotransferência que permitisse estimar com razoável exatidão o valor de fósforo remanescente de solos representativos do Estado de São Paulo, a partir de outros atributos químicos de mais simples e/ou rotineira determinação laboratorial. Nesse contexto, duas funções de pedotransferência foram desenvolvidas com base em redes neurais artificiais (RNA) e análises de regressão linear múltipla (RLM), utilizando um banco de dados constituído por propriedades físicas e químicas de solos amostrados em diferentes localidades do Estado de São Paulo. As redes alimentadas adiante com múltiplas camadas foram utilizadas para desenvolver a função de pedotransferência baseada em RNA e a topologia foi determinada a partir de experimentos sucessivos. Os critérios de escolha da melhor rede neural foram, simultaneamente, o desempenho na etapa de treinamento, medido por meio do erro quadrático médio, e a capacidade de generalização, avaliada por meio de análises estatísticas entre os valores de Prem estimados e determinados analiticamente. A topologia da rede que melhor estimou o fósforo remanescente foi [3 14 1], ou seja, três neurônios na camada de entrada, quatorze em uma única camada intermediária e um na camada de saída; a função de ativação utilizada foi a sigmoidal logística, os valores de entrada foram normalizados entre [0;1] e o algoritmo de aprendizagem utilizado foi o resilient backpropagation. As três variáveis da camada de entrada foram o valor de pH medido em solução de NaF 1 mol L-1 (pH NaF), a soma de bases trocáveis (SB) e o teor de alumínio trocável (Al3+), sendo as duas últimas determinadas rotineiramente em análises de solo e a primeira de mais fácil e rápida obtenção que o fósforo remanescente. A função de pedotransferência baseada em RLM foi desenvolvida considerando as mesmas variáveis de entrada utilizadas na função de pedotransferência baseada em RNA. A comparação entre os desempenhos obtidos, para um mesmo conjunto de validação, mostrou que as funções de pedotransferência baseadas em redes neurais apresentam estimativas mais exatas do fósforo remanescente. Apesar do conjunto de dados utilizado não ser suficientemente abrangente para o estabelecimento de uma função de pedotransferência definitiva para a estimativa do fósforo remanescente, os resultados do presente trabalho indicam como promissor o desenvolvimento de um massivo banco de dados por meio do aproveitamento dos resultados analíticos continuamente gerados pelos vários laboratórios brasileiros dedicados à avaliação da fertilidade do solo e que contemple os valores de fósforo remanescente e pH NaF. Tal banco de dados permitirá o desenvolvimento de uma função de pedotransferência baseada em redes neurais artificiais cuja utilização possibilitará o cálculo imediato de valores suficientemente exatos de fósforo remanescente com razoável economia de recursos financeiros que seriam empregados na análise de um grande número de amostras.
The remaining phosphorus consists of the P concentration that remains in solution after shaking for 1 hour a soil sample with 0.01 mol L-1 CaCl2 containing 60 mg L-1 P. The remaining phosphorus values can be used as suitable indicators of the soil capacity of anion sorption due to be more dependable on the soil mineralogy than on the soil clay content. In Brazil, the remaining phosphorus is used as an ancillary variable in the official guidelines for determining fertilizer and amender requirements of agricultural soils of the Minas Gerais state. The main goal of this research was to develop a pedotransfer function (PTF) capable of providing fairly accurate estimates of remaining phosphorus values of representative soils of the São Paulo state from often-determined soil chemical properties and/or from other ones of easier determination. In this context, two pedotransfer functions were developed by using artificial neural networks (ANN) and multiple regression analysis (MRA) applied to a database formed by values of soil chemical and physical properties derived from soil surveys previously carried out in different locations of the São Paulo state. The multi-layer feedforward neural networks approach was used for the development of the ANN-based PTF being its topology determined from successive experiments. The simultaneous criteria adopted for choosing the best neural network were the performance during the training stage, measured by the mean squared error, and its capacity of providing accurate Prem values, which was evaluated by using a validation database in which statistical comparisons were done between the measured and estimated Prem values. The topology of the network that provided the most accurate estimates of the remaining phosphorus was [3 14 1], i.e., three neurons at the input layer, fourteen at a unique hidden layer and one neuron at the output layer; further development features included the use of the sigmoid logistic model as activation function, the input of data normalized in the [0;1] interval and the use of the resilient backpropagation learning algorithm. The three variables at the input layer were the soil pH value measured in 1 mol L-1 NaF (pH NaF), the sum of exchangeable bases (SB) and the soil content of exchangeable aluminum (Al3+), being the two last ones usually determined in soil test laboratories whereas the pH NaF determination is easier than the remaining phosphorus one. The MRA-based PTF was developed considering the same input variables of the ANN-based one, i.e., pH NaF, SB and Al3+. The comparisons performed with a same validation database showed that the pedotransfer function developed from artificial neural networks provided more accurate estimates of remaining phosphorus values. Despite the database used for the PTF development not be so comprehensive for the establishment of a definitive pedotransfer function for estimating remaining phosphorus values, the results of the present research indicate as promising the development of a massive database from chemical results often obtained by the Brazilian laboratories dedicated to soil fertility evaluation and that includes Prem and pH NaF values. This database will allow the development of a comprehensive ANN-based pedotransfer function capable of not only calculating suitable Prem values for practical applications but also reducing the expenses related to the analyses of a great number of soil samples.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
O presente trabalho tem como objetivos: i) caracterizar a mineralogia da fração argila e estudar a variabilidade espacial dos atributos granulométricos, químicos e mineralógicos do solo com base em informações geológicas, pedológicas e geomorfológicas; ii) avaliar o potencial de utilização da espectroscopia de reflectância difusa (ERD) e suscetibilidade magnética (SM) na estimação dos óxidos de ferro hematita (Hm) e goethita (Gt), atributos granulométricos e químicos do solo nos compartimentos da paisagem; iii) utilizar a ERD e a SM no estudo da quantificação e variabilidade espacial da emissão de CO2 do solo (FCO2) e iv) investigar a eficiência da utilização da SM e dos óxidos de ferro em funções de pedotransferência (FPTs) que sejam capazes de estimar a FCO2. A área de estudo, de 870 ha, está localizada no município de Guatapará – São Paulo, e é cultivada com cana-de-açúcar manejada com palha. A área está inserida na província geomorfológica do Planalto Ocidental Paulista, apresentando três materiais de origem relacionados à transição entre Basaltos Serra Geral, Depósito Colúvio Eluvionar e Depósito Aluvionar, quatro tipos de Latossolos e um Neossolo, além de geomorfologia caracterizada por áreas côncavas e convexas. Foram coletadas 372 amostras na profundidade de 0,00-0,25 m para a avaliação dos atributos do solo. Para o estudo da FCO2 foi delimitada uma área de 90 ha. Para avaliar os métodos indiretos ERD e SM, os dados foram comparados com os resultados de análises químicas, granulométricas e mineralógicas. Todos os dados foram submetidos à análise estatística clássica e geoestatística para avaliar a dependência e variabilidade espacial. A variabilidade de alguns atributos do solo foi estratificada por compartimentos (geologia, pedologia e geomorfologia), com o intuito de entender a influência de cada compartimento na variabilidade dos atributos estudados. A estratificação dos atributos do solo por compartimento geológico, pedológico e geomorfológico é eficaz para o estudo da variação dos atributos estudados. A ERD é uma ferramenta eficaz na caracterização de óxidos de ferro e na identificação das diferentes classes de solos. A SM é útil tanto para melhor detalhamento e readequação das classes de solo, quanto ao conteúdo de ferro e aos intervalos de classe textural, auxiliando na identificação de zonas de manejo. Todos os atributos estudados têm dependência espacial. Os mapas interpolados com base na predição dos atributos por SM e ERD apresentam padrão de variabilidade semelhante aos mapas baseados nos dados observados. No entanto, para solos com altos teores de óxidos de ferro, como os Latossolos férricos, a SM mostrou-se mais indicada para predizer os atributos estudados. Dentre os atributos estudados, os óxidos de ferro e a SM foram os principais preditores da FCO2, provando a eficiência destes como pedoindicadores dos fatores e processos de formação do solo.
This study aims: i) to characterize the clay mineralogy and study the spatial variability of the granulometric, chemical and mineralogical attributes of the soil based on geological, pedological and geomorphological information; ii) to evaluate the potential of diffuse reflectance spectroscopy (DRS) and magnetic susceptibility (MS) in the estimation of hematite (Hm) and goethite (Gt) iron oxides, granulometric and chemical attributes in the landscape compartments; iii) to use DRS and MS in the study of the quantification and spatial variability of soil CO2 emission (FCO2); and iv) to investigate the efficiency of the use of MS and iron oxides in pedotransfer functions (PTFs) for estimate the FCO2. The study area, 870 ha, is located in the municipality of Guatapará-São Paulo, and is cultivated with sugar cane managed with straw. The area is located in the geomorphological province of Plateau Western Paulista, presenting three materials of origin related to the transition between Serra Geral Basalts, Eluvial-Colluvial Deposit and Alluvial Deposit, four types of Oxisols and one Entisols, besides geomorphology characterized by concave and convex areas. A total of 372 samples were collected at a depth of 0.00-0.25 m for soil attributes. For the FCO2 study, an area of 90 ha was delimited. In order to evaluate the indirect methods DRS and MS, the data were compared with the results of chemical, granulometric and mineralogical analyzes. All data were submitted to classical and geostatistical statistical analysis to evaluate spatial dependence and variability. The variability of some soil attributes was stratified by compartments (geology, pedology and geomorphology), in order to understand the influence of each compartment on the variability of the attributes studied. The stratification of soil attributes for geological, pedological and geomorphological compartment is effective to study the variation of the attributes. DRS is an effective tool in the characterization of iron oxides and in the identification of different soil classes. MS is useful both for better detailing and re-adjustment of soil classes, iron content and textural class intervals, helping to identify management zones. All attributes studied have spatial dependence. The interpolated maps based on attribute prediction by MS and DRS show pattern of variability similar to maps based on observed data. However, for soils with high levels of iron oxides, such as ferric Oxisols, the MS was more indicated to predict the attributes studied. Among the attributes studied, iron oxides and MS were the main predictors of FCO2, proving their efficiency as pedoenvironmental of soil formation factors and processes.
FAPESP: 2013/17552-6

Hydraulic characteristics are the most important properties of soil, i.e. retention curve of soil moisture and hydraulic conductivity. Hydraulic conductivity of soil characterizes the ability of the soil to conduct water. Retention curve expresses the relationship between moisture and moisture potential of soil. The running of retention curve is influenced by many factors, eg. grain size and mineralogical composition, content of humus, reduce bulk density and structure of soil. Measurement of retention curves takes a lot of time and money in laboratory conditions therefore pedotransfer functions seem to be an alternative solution. The thesis aims to estimate moisture retention curves of soil in a selected area of interest in South Moravia using program Rosetta (Schaap, 2003). Data of granularity (% content of clay, sand and dust), bulk density of soil and hydrolimits field water capacity and wilting point were used as predictors in individual models of program Rosetta. Data of grain were matched by FAO / USDA system. Retention curves of soil moisture were measured on a sand tank and overpressure devices. The measured retention curves were parameterized by RETC program. Estimated retention curves were graphically compared with measured to determine the quality of the estimate. The accuracy of the estimate was assessed by correlation coefficient R of determination coefficient R2 and standard error SMRE. Usability own derivatives pedotransfer functions is hard to say due to the size of the input data file. I would recommend further verification of data at the other localities in south Moravia.

The diploma thesis is focused on issues of measurement and evaluation of hydraulic characteristics of soil. In the literary research, the definitions of hydraulic conductivity and retention curve of soil moisture, their measurements in laboratory and field conditions and the prediction of these characteristics by using of pedotransfer functions. In the practical part of the diploma thesis, an evaluation of the hydraulic conductivity of soil from the experimental areas near the village Bohaté Málkovice. Two-cylindrical and mini-disc infiltration meters were used for field measurements, and a constant-gradient permeameter was used in the laboratory. Physical and empirical equations were used to evaluate the hydraulic conductivity. The results were processed numerically, tabulated and then compared.

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Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPq
Financiadora de Estudos e Projetos - Finep
For any study involving the movement of soil water becomes essential to know the physical and hydraulic properties and their correlations. Both proprieties are of fundamental importance in the storage and transport of water and nutrients, in controlling infiltration and runoff, as well as soil conservation. In this context, this study aimed to do a physical-water characterization of three experimental basins (Jatoba and Mimoso / Pesqueira-PE and Xaréu / Fernando Noronha-PE) in the semiarid, in order to generate information for hydrological modeling and subsidies for soil and water management and conservation. It has been evaluated the physical and hydraulic behavior of soil at different depths and vegetation cover. Physical characterization of soils was carried out by laboratory tests on disturbed and undisturbed samples. The hydraulic characterization was conducted through moisture retention curves and through of hydraulic conductivity (K) tests in the field with the Guelph permeameter. Possession of physical variables and soil organic matter pedotransfer functions (PTF) have been tested to estimate the K0 and moisture in particular tensions in order to compare field and laboratory measurements. Among the attributes analyzed, the organic matter was the one with the highest coefficient of variation in depth in the basins and Mimoso Jatoba. There was also high variability of saturated hydraulic conductivity (K0) in depth, in the three basins. It was concluded that the hydraulic conductivity no significant difference in hydraulic conductivity means has been verified for the different vegetation covers. Among soils, the Vertisol presented the highest capacity to retain water. It is concluded that the proposed PTF showed low prediction of K0. The PTF for estimatingsoil moisture, also showed low prediction for soils at Xaréu Basins. In the Jatoba and Mimoso Basins, the best prediction for soil moisture at field capacity was obtained by the model proposed by Meng et al. (1987) and the humidity at wilting point, the equation based on the mean texture proposed by Oliveira et al. (2002) showed the best performance. For the water available content for the equation based on unique data set proposed by Oliveira et al. (2002), and Massuti (1997) model showed a good prediction.
Para qualquer estudo que envolva o movimento da água no solo torna-se imprescindível o conhecimento das propriedades físicas e hidráulicas, bem como suas correlações. Ambas têm fundamental importância no armazenamento e transporte de água e de nutrientes, no controle da infiltração e escoamento superficial, bem como na conservação do solo. Nesse contexto, o presente estudo buscou realizar uma caracterização físico-hídrica de três bacias experimentais (Jatobá e Mimoso/Pesqueira-PE e Xaréu/Fernando Noronha-PE) do semiárido, a fim de gerar informações para suporte à modelagem hidrológica e subsídios para o gerenciamento e conservação do solo e da água. Avaliou-se o comportamento físico-hídrico dos solos em diferentes profundidades e coberturas vegetais. A caracterização física dos solos se deu por análises de laboratório com amostras indeformadas e deformadas. A caracterização hidráulica foi realizada por meio de curvas de retenção de umidade e através de testes de condutividade hidráulica (K) em campo com permeâmetro de Guelph. De posse das variáveis físicas e da matéria orgânica do solo, foram testadas funções de pedotransferência (FPT) para estimativa da K0 e umidade em tensões específicas, a fim de comparar com as medidas em campo e laboratório. Dentre os atributos do solo analisados, a matéria orgânica foi o que apresentou o maior coeficiente de variação, em profundidade, nas Bacias do Jatobá e do Mimoso. Verificou-se também, alta variabilidade da condutividade hidráulica do solo saturado (K0) em profundidade, nas três bacias. Concluiu-se que a condutividade hidráulica não apresentou diferença significativa entre médias, para as diferentes coberturas vegetais. Dentre os solos estudados, o Vertissolo foi o que apresentou a maior capacidade de retenção de água. Conclui-se que as FPT propostas apresentaram baixa predição da K0. As FPT para estimativa da umidade retida a potenciais específicos, também apresentaram baixa predição para os solos da Bacia do Xaréu. Nas Bacias do Jatobá e do Mimoso a melhor predição para umidade na capacidade de campo foi obtida pelo modelo de Meng et al. (1987) e para a umidade no ponto de murcha permanente, a equação baseada na textura média proposta por Oliveira et al. (2002) mostrou o melhor desempenho. Para água disponível a equação baseada no conjunto único de dados proposta por Oliveira et al. (2002), e o modelo de Massuti (1997) apresentaram boa predição.

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The understanding of the dynamics of the water in the soil-plant-atmosphere system, including the water availability to the crops, soil water infiltration, drainage and soil solute movement, depends on the knowledge of the relation between the soil water content and the matric potential, represented by the soil water retention curve (SWRC). However, the establishment of SWRCs is laborious and time consuming, besides being costly. A alternative is its estimate through statistical equations called Pedotransfer Functions (PTFs). The aim of this study was to evaluate the ability of some existing PTFs, in predicting the soil water retention and to capture its spatial variability structure, using geostatistical tools, when applied in a lowland soil of the south region of Brazil. For this, an experimental 10 x 10 m grid was established and soil disturbed and undisturbed samples were collected in the 0-0.20 m soil depth, totaling 100 experimental points. The following soil attributes were determined in each point: soil texture, soil organic carbon, pH, cation exchange capacity, soil bulk density, and the soil water retention curve. Eight developed PTFs for estimating gravimetric soil water content, eight for estimating volumetric water content and five for estimating the van Genuchten model parameters were evaluated using the statistical measures mean error (ME), and the root mean square error (RMSE). Results indicated that the Oliveira et al. (2002) PTF presented the best performance for estimating the gravimetric soil water content at the tension of 33kPa, with mean error (ME) value of 0.0136g.g-1, while for the gravimetric water content at tension of 1500kPa the Pidgeon (1972) FPT was the best, with ME value of -0,0054g.g-1. Concerning to the potential of describing the spatial variability structure the Bell & van Keulen (1995 and 1996) and of Urach (2007) PTFs presented the best performance based on the results from the cross validation technique. For estimating the soil water volumetric content at the tension of 10kPa the Tomasela et al. (2002) was the best (ME of 0.019cm3.cm-3), while Rawls et al. (1982) and van den Berg et al. (1997) PTFs were the best for estimating soil water content at the tension of 33kPa (ME of 0.001cm3.cm-3) and 1500kPa (ME of -0.008cm3.cm-3), respectively. The range and sill geostatistical parameters for the tension of 33kPa were reasonable estimated, while for the tension of 1500kPa they were underestimated by the evaluated PTFs. The Parametric Pedotransfer Function constructed by Vereecken et al.(1989) presented the lowest value of ME (0.0247cm3.cm-3), while the Hodnett and Tomasella (2002) PTF presented the lowest value of RMSE (0.0367 cm3.cm-3). Both PTFs well described the experimental semivariograms of the soil water content at the tensions of 10kPa and 33kPa, however their performance was not good for the tension of 1500kPa.
Estudos que envolvem a dinâmica da água no sistema solo-planta-atmosfera tais como disponibilidade de água no solo para as culturas, infiltração, drenagem e movimento de solutos no solo necessitam do conhecimento da relação entre o conteúdo de água no solo e o potencial matricial, representada pela curva de retenção de água no solo. No entanto, sua execução é laboriosa, demanda considerável tempo e custos. Uma alternativa é sua estimativa através de equações estatísticas denominadas Funções de Pedotransferência (FPTs). O objetivo deste estudo foi avaliar o desempenho de funções de pedotransferência em estimar a retenção de água no solo e capturar a sua estrutura de variabilidade espacial, usando ferramentas geoestatísticas, quando aplicadas em um solo de várzea da região sul do Brasil. Para isto, uma malha experimental de 10m x 10m foi estabelecido e amostras deformadas e indeformadas do solo foram coletadas representativas da camada de 0 0,20m, totalizando 100 pontos amostrais. Os seguintes atributos do solo foram determinados em cada ponto: textura, carbono orgânico, pH, capacidade de troca de cátions, densidade do solo e a curva de retenção de água no solo. Oito FPTs desenvolvidas para estimar o conteúdo gravimétrico de água no solo, oito para estimar o conteúdo volumétrico e cinco para estimar os parâmetros do modelo de van Genuchten foram avaliadas, usando as medidas estatísticas erro médio (ME) e raiz quadrada do erro médio ao quadrado (RMSE). Os resultados obtidos para a estimativa do conteúdo de água gravimétrico mostram que a FPT de Oliveira et al. (2002) apresentou o melhor desempenho para a tensão de 33kPa, com erro médio (ME) de 0,0136g.g-1, enquanto para a tensão de 1500kPa a FPT de Pidgeon (1972) foi melhor, com ME de -0,0054g.g-1. Com relação ao potencial de descrever a estrutura de variabilidade espacial do conjunto de dados medidos, as FPTs desenvolvidas por Bell & van Keulen (1995 e 1996) e Urach (2007) foram as que apresentaram melhor desempenho baseado nos resultados da validação cruzada. Para o conteúdo volumétrico de água retida no solo, os melhores desempenhos foram obtidos pela FPT de Tomasela et al.(2003) para a tensão de 10kPa, Rawls et al. (1982) para 33kPa e van den Berg et al.(1997) para 1500kPa, com ME iguais a 0,019cm3.cm-3, 0,001cm3.cm-3 e -0,008cm3.cm-3, respectivamente. Os parâmetros da estrutura de dependência espacial, alcance e patamar, para a tensão de 33kPa foram razoavelmente estimados, enquanto para a tensão de 1500kPa foram subestimados pelas FPTs avaliadas. A FPT paramétrica desenvolvida por Vereecken et al. (1989) apresentou o menor valor de ME (0,0247cm3.cm-3), enquanto a FPT de Hodnett e Tomasella (2002) apresentou o menor valor de RMSE (0,0367 cm3.cm-3). Ambas FPTs descreveram bem os semivariogramas experimentais do conteúdo de água retido no solo a 10kPa e 33kPa, entretanto para a tensão de 1500kPa nenhuma das FPTs testadas apresentou bom desempenho.

L'augmentation de la mécanisation lors de l'exploitation forestière combinée aux changements climatiques augmente le risque de circuler dans les mauvaises conditions et donc de dégrader les sols. C'est pourquoi il est nécessaire de développer des outils d'aide à la décision capables de prédire la praticabilité des sols forestiers. Cependant, évaluer la praticabilité avec des outils simples et des données facilement accessibles est complexe. En effet, elle dépend de multiple facteurs : la susceptibilité du sol à se déformer, la charge appliquée, le seuil de déformation toléré et l'état hydrique du sol. Ce travail vise à mieux comprendre et prévoir la dynamique hydrique des sols forestiers et des cloisonnements (i.e. chemins dédiés à la circulation des engins forestiers). Les objectifs sont les suivants : (i) améliorer notre compréhension de l'effet du tassement sur la teneur en eau des sols forestiers, (ii) paramétrer un modèle de fonctionnement hydrique en contexte forestier et (iii) être capable de prédire l'humidité des sols dans un contexte opérationnel. Nous avons mis en place un observatoire des cloisonnements qui a permis de fournir une base de données sur les propriétés hydrodynamiques des sols forestiers et sur l'évolution de la teneur en eau. Nous avons estimé les paramètres hydrodynamiques (PH) avec la méthode BEST sur des binômes de sols circulés-non circulés. Nous avons développé une loi de passage prédisant les valeurs de la teneur en eau à saturation et de la conductivité hydraulique à saturation des sols circulés à partir de ceux non circulés. Ensuite, nous avons paramétré un modèle de fonctionnement hydrique mécaniste basé sur l'équation de Richards en contexte forestier. Nous avons évalué la capacité du modèle à prédire la teneur en eau selon différents jeux de PH estimés par : la méthode BEST, une fonction de pédotransfert FPT ou calage. Le modèle combiné aux PH estimé par la méthode BEST mène à des problèmes de dessèchement de la couche intermédiaire en période estivale. L'utilisation d'une FPT conduit à un plus faible pouvoir prédictif mais ne simule la phase de dessèchement. La stratégie choisie consiste à utiliser la méthode BEST comme première estimation des PH et ensuite d'en caler certains par inversion. Enfin, nous avons développé un modèle empirique utilisable en conditions opérationnelles. Nous avons utilisé le modèle mécaniste pour générer une base de données virtuelle permettant (i) d'identifier les principaux mécanismes impliqués dans la dynamique de dessèchement des sol à prendre en compte et (ii) de caler et valider le modèle empirique. Il est capable de prédire le "jour de praticabilité" avec une résolution de 1.5 à 2.5 jours en période estivale. En période hivernale, sa précision n’est pas satisfaisante (rmse = 8.4 j), elle s'explique par la sensibilité du modèle aux évènements pluvieux fréquents et rapprochés. Le modèle empirique s'applique pour une seule configuration "sol x peuplement x climat x seuil" et mérite d'être calé dans d'autres contextes
The increase of the mechanization during logging combined with climate changes increases the risk of driving in not suitable conditions and thus degrading soils. This is why it is necessary to develop decision support tools capable of predicting the practicability of forest soils. However, assessing practicability with simple tools and easily accessible data is complex. It depends on the susceptibility of the soil to deformation, the load applied, the accepted threshold of soil deformation and the water state of the soil. This work aims to better understand and predict the water dynamics of forest soils and of the skid trails (i.e. roads dedicated to the circulation of forest machines). The objectives are: (i) to improve our knowledge of the compaction effect on forest soil water dynamic, (ii) to parametrize a model predicting the soil water flow under forest context and (iii) to be able to predict the soil water content of forest soils in an operational context. This work was carried out in three stages. First, we established an observatory of skid trails that has provided a data base on forest soil hydraulic properties and water dynamic. We estimated the hydraulic properties with the BEST method on circulated and non-circulated soils. We have developed a law predicting the values of the saturation water conten and the saturation hydraulic conductivity of circulated soils from those not circulated. Then, we have parametrized in forest context a mechanistic model based on Richards equation. We evaluated the ability of the model to predict the soil water content according to different hydraulic parameters: BEST method, pedotransfert function PTF and optimization. With the hydraulic parameters estimated from BEST method, the model leads to problem of middle layer drying during the summer period. With pedotransfer function, the model leads to a poorer prediction but does not simulate the drying phase. The strategy chosen is to use the BEST method as the first estimate of the hydraulic parameters and then to calibrate some of them by inversion. Finally, we have developed an empirical model that can be used in operational conditions. We used the mechanistic model to generate a virtual data set to (i) identify the main mechanisms involved in soil drying dynamics that need to be taking into account and (ii) calibrate and validate the empirical model. It is able to predict the "day of traffic" with accuracy of 1.5 to 2.5 days in summer. In winter, its accuracy is not satisfactory (rmse = 8.4 days) and is explained by the model sensitivity to weather sequences composed of frequent and nearby rainfall events. The empirical model is applicable to a single configuration "soil x stand x climate x threshold" and should be calibrated in other contexts

碩士
中興大學
水土保持學系所
99
The soil water characteristic curves(SWCC) is one of the important soil hydraulic property, however the experiment is time-consuming. In recent years the scholars propose pedotransfer function one after another, predicting the soil water characteristic curve by using common property. To provide a convenient method for later study. This study analysis 22 samples which were collected around Taiwan. Predicting the basic soil properties and soil water characteristics curve, 12 samples were chosen randomly as training set and estimate the hydraulic parameters α and n by curve fitting technique of the van Genuchten Model. Laters using principle components analysis summarize the regression of α and n in training set. The accuracy of the equations were validated by other 10 soil samples. The regression equations were as follows: ln⁡(α)=-0.06458×BD+0.001045×Sa-0.01297×C-0.11505×FC+0.106199×OM ln⁡(n)=0.7138-0.26254×BD-0.0002×Sa+0.00058×C -0.00527×FC-0.0113×OM The results shows that the coefficient of determination (R2) of the parameter ln(α)、ln(n) of the estimating equations are 0.996 and 0.842. The root mean square error (RMSE) of parameter ln(α) 、ln(n) are 1.333 and 0.093 respectly, . In the estimation of water characteristic curve, the sampling location and the soil information were randomly chosen when validated the regression equation, the range of RMSE is 0.021~0.063. The applicability is better than previous study in different texture.

碩士
國立屏東科技大學
環境工程與科學系所
95
In the survey reports of rural soils in Taiwan, 68 soil series have been established in Tainan county. According to parent materials in Tainan County, the rural soils were divied into six types including Sandstone-shale lime new-alluvial soils, sandstone-shale lime-nodule new-alluvial soils, non-lime sandstone-shale new-alluvial soils, lime-nodule Taiwan clays, non-lime Taiwan clays and sandstone-shale old-alluvial soils. Based on Soil Taxonomy, they include Entisoils, Inceptisoils and Alfisoils. However, the dominant Soil Orders are Entisols and Inceptisols, and Alfisols were only found in local Taiwan clays. Pedotransfer function (PTF) has been used to predict soil properties, which were determined costly. Therefore, this study applied PTF to predict cation exchange (CEC) for the rural soils in Tainan county by the variables of pH, organic matter (OM) and clay, and further verify the predicted CEC values with measured CEC. The study results showed that the variables of pH, OM and clay corrected well with CEC (r2> 0.77 (n=411). Moreover, r2 were more than 0.80 under variables of OM and clay. Therefore, the differences between predicted and measured CEC are lower than 10% evaluated by OM and clay. Based on the above analysis, clay can be effectively predicted CEC for the rural soils in Tainan county, and their relationship is CEC=0.47×clay(%).

Modeling the seedling recruitment microsite involves characterization of the soil environment of the shallow profile from which weed seedlings recruit. Understanding the environment of the seedling recruitment microsite is the prelude to weed emergence studies. Because of spatial and temporal heterogeneity of the recruitment microsite, sufficient measurements are often not feasible. An experiment was established in 2003 and 2004 across topography within an annually cropped field in south-central Manitoba to determine the effect that hillslope aspect and position, and soil residue and depth would have on microsite environment within the shallow seedling recruitment zone. Microclimatic, topographic, soil surface and soil properties were assessed in the context of the weed recruitment microsite. The soil water retention characteristic was measured by pressure plate to determine water availability to germinating seeds at the various topographic positions. The soil water characteristic was evaluated across topography and soil depth. Evaluation of the soil water characteristic by pedotransfer function indicated that a single soil water characteristic is representative of the recruitment zone. Field and laboratory experimental measurements were used as parameterization for the simultaneous heat and water (SHAW) model to generate continuous water and temperature profiles for the recruitment zone. Soil temperature and temperature fluctuation decreased with depth in the recruitment zone. Despite differences of texture, bulk density, and organic matter across topography and soil depth, the soil water characteristic differed only across topography. Soil water potential fluctuated considerably at the soil surface due to numerous precipitation events and direct evaporation. Implications for germinating seeds is that the seedling recruitment zone is influenced by spatial effects of topography and the vertical location of the seed microsite. Physical process based modeling used in this study to predict temperature and water within the seedling recruitment zone enables better understanding of interactions between above-ground microclimate and the recruitment microsite. Such interactions enable linkage between atmospheric models and recruitment models that can enhance our ability to evaluate crop management decisions.

This thesis presents a comparison of Ks estimates obtained by three classical devices, namely the double ring infiltrometer (DRI), the Guelph version of the constant-head well permeameter (GP) and the CSIRO version of the ten- sion permeameter (CTP). A distinguishing feature of this study is the use of steady deep flow, obtained from controlled rainfall-runoff experiments, as a benchmark of Ks at "local" and field/plot scales to assess the reliability of the above methods. Spatially representative estimates of Ks are needed for simulating catchment scale surface runoff and infiltration. Classical methods for measuring Ks at the catchment scale are time-consuming. Important insights can be obtained by experiments aimed at understanding the controls of Ks in an agricultural setting and identifying the minimum number of samples required for estimating representative plot scale Ks values. This thesis presents results from a total of 131 double-ring infiltrometer measurements at 12 plots in a small Austrian catchment. Classical field techniques to determine Ks at the plot and catchment scales are complex and time-consuming, therefore the development of pedotransfer functions, PTFs, to derive Ks from easily available soil properties is of utmost importance. However, PTFs have been generally developed at the point scale, while application of hydrological modeling requires field scale estimates. In this thesis, values of field-scale saturated hydraulic conductivity, K ̄s , measured in a number of areas within the Austrian catchment, have been used to derive two PTFs by multiple linear regression (PTFMLR) and ridge regression (PTFR). Two alternative approaches have been used: (A) soil properties have been first interpolated with successive application of the PTFs, (B) the PTFs have been first applied in the sites where soil properties were available and then interpolated.

碩士
國立中興大學
水土保持學系所
100
The purpose of this study is developing pedotransfer functions (PTFs) which were based on soil texture to derive parameters of van Genuchten Model(vG-Model). The study focused on loamy soil, because it is the main type of soil in Taiwan. Determining variables in PTFs by collecting literatures widely, then K-Means cluster analysis was used to classify samples according to the content of sand and clay. All samples were derived into two groups, multiple linear regression analysis was used to develop model for each group, and then compared the predictive ability with the model which was developed from all samples. By the calculation of root mean square error and the point distribution of unbiased estimate line which produced from validations showed that PTFs developed according to texture could surely improve the prediction of the parameter α. Further investigation showed that there might be linear relationship between soil gravity water and parameter α. There was no improvement in the prediction of parameter n. However, the result of observing the model showed that the parameter n might be affected by the content of clay. Taking validations to regroup according to the content of clay, and then put them in the model again. The result of root mean square error and the point distribution of unbiased estimate line showed that when the content of clay was greater than 8%, the improvement of the model was obvious, but when the contents of clay were less than 8%, it didn’t have any effect. This phenomenon was related with that the previous studies which pointed out there was uncertainty in developing the model of n, but the effect of clay was undeniable. This study further compared two PTFs which were developed according to texture and region, and the result showed that in prediction of parameter α and n, the former was better than the latter. And the result proved that it was necessary to classify samples by texture. PTFs were as follows: ln(α)=-3.2110-0.1871∙(BD∙FC)-1423.24∙〖FC〗^(-2) +0.14523∙(BD∙f)-0.1525∙〖OM〗^(-2) ln(n)=-0.0605+407.7189∙f^(-2)+0.0227∙〖OM〗^(-2) +0.00013∙(Sa∙C) ln(α)=-4.3389-0.1572∙(BD∙FC)+0.1259∙(BD∙f) -0.2197∙〖OM〗^(-2) ln⁡(n)=-0.1049+0.0272∙〖OM〗^(-2)+437.1857∙f^(-2) +0.00052∙(C∙FC) ln(α)=-5.6336- 0.0058∙〖FC〗^2+0.0052∙(f∙FC) ln⁡(n-1)=8.6704+5.1255∙〖BD〗^2+850.0738∙〖FC〗^(-2) -16.5089∙BD+0.01316∙(BD∙FC) +0.4315∙(C∙BD)-0.5646∙C

碩士
國立屏東科技大學
環境工程與科學系所
95
The Contents of Abstract in this Thesis： Soil attributes can be estimated from current data base by pedotransfer function (PTF). Namely、unknown soil properties can be transformed from PTF by equations and models based on present analysis data according to basic theories. A total of 57 soil series has been established for the arable soils of Hualian and Taitung counties including shist and igneous parent materials with minor quaternary alluvial red earth. They are classified as Entisols、Inceptisols、Mollisols、Ultisols and Vertisols in Soil Taxonomy. The variables of pH、organic matter、Clay、free Fe and cation exchange capacity (CEC) were subjected to predict the available P for these soils in this study、and further verify the differences between the estimation and practical values. Experimental results indicate that the correlation (r2) between available P and free Fe and CEC is 0.15 (p < 0.05、n=163). However、the addition of variables in organic matter and pH causes the r2 up to 0.16. If all the above 5 variables are involved、the r2 value will not clearly increase. Therefore、free Fe and CEC are the best both variables in this PTF model. Overall、the estimated available P is generally lower than the practical value about 20%、respectively. Keywords: Soil pedotransfer function; available P; Clay; free Fe; organic matter; cation exchange capacity.

Due to climate change there is a growing concern for soil organic carbon reservoires. The soil is the largest terrestrial pool of organic carbon and its balance is being increasingly disturbed by conversion of natural to managed ecosystem (for agriculture, forestry and urbanization). There are still large uncertainities with estimating real amount of organic carbon sequestrated in soils. Therefore a number of regional and national soil inventories and monitoring networks are currently established or tested to verify soil carbon changes. Thesis is focused on estimation of soil organic carbon pools in the area of Czech basic map Beroun 12-41-08. It evaluates available soil data and restrictions of their use. Especially is focused on comprehensive soil survey undertaken between 1961 and 1970, on soil properties change in time and how to get missing bulk densities of the soil, particularly through pedotransfer functions. Powered by TCPDF (www.tcpdf.org)