Dissertations / Theses on the topic 'Soil physics'

The aim of the thesis is to find a method, in conjunction with the ordinary differential equation (ODE) based method of lines (MOL) solution of Richards’ equation, to model the steep wetting front infiltration in very dry soils, accurately and efficiently. Due to the steep pressure head or steep water volumetric content gradients, highly nonlinear soil hydraulic properties and the rapid movement of the wetting front, accurate solutions for infiltration into a dry soil are usually difficult to obtain. Additionally, such problems often require very small time steps and large computation times. As an enhancement to the used ODE/MOL approach, Higher Order Finite Differencing, Varying Order Finite Differencing, Vertical Scaling, Adaptive Schemes and Non-uniform Stretching Techniques have been implemented and tested in this thesis. Success has been found in the ability of Vertical Scaling to simulate very steep moving front solution for the Burgers’ equation. Unfortunately, the results also show that Vertical Scaling needs significant research and improvement before their full potential in routine applications for difficult nonlinear problems, such as Richard’s equation with very steep moving front solution, can be realized. However, we have also shown that the use of the composed form of RE and a 2nd order finite differencing for the first order derivative approximation is conducive for modelling steep moving front problem in a very dry soil. Additionally, with the combination of an optimal influx value at the edges of the inlet, the ODE/MOL approach is able to model a 2-D infiltration in very dry soils, effectively and accurately. Furthermore, one of the strengths of this thesis is the use of a MATLAB PDE template. Implementing the ODE/MOL approach via a MATLAB PDE template has shown to be most suitable for modelling of partial differential equations. The plug and play mode of modifying the PDE template for solving time-dependent partial differential equations is user-friendly and easy, as compared to more conventional approaches using Pascal, Fortran, C or C++. The template offers greater modularity, flexibility, versatility, and efficiency for solving PDE problems in both 1-D and 2-D spatial dimensions. Moreover, the 2-D PDE template has been extended for irregular shaped domains.
Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Australian School of Environmental Studies
Full Text

The aim of the thesis is to find a method, in conjunction with the ordinary differential equation (ODE) based method of lines (MOL) solution of Richards’ equation, to model the steep wetting front infiltration in very dry soils, accurately and efficiently. Due to the steep pressure head or steep water volumetric content gradients, highly nonlinear soil hydraulic properties and the rapid movement of the wetting front, accurate solutions for infiltration into a dry soil are usually difficult to obtain. Additionally, such problems often require very small time steps and large computation times. As an enhancement to the used ODE/MOL approach, Higher Order Finite Differencing, Varying Order Finite Differencing, Vertical Scaling, Adaptive Schemes and Non-uniform Stretching Techniques have been implemented and tested in this thesis. Success has been found in the ability of Vertical Scaling to simulate very steep moving front solution for the Burgers’ equation. Unfortunately, the results also show that Vertical Scaling needs significant research and improvement before their full potential in routine applications for difficult nonlinear problems, such as Richard’s equation with very steep moving front solution, can be realized. However, we have also shown that the use of the composed form of RE and a 2nd order finite differencing for the first order derivative approximation is conducive for modelling steep moving front problem in a very dry soil. Additionally, with the combination of an optimal influx value at the edges of the inlet, the ODE/MOL approach is able to model a 2-D infiltration in very dry soils, effectively and accurately. Furthermore, one of the strengths of this thesis is the use of a MATLAB PDE template. Implementing the ODE/MOL approach via a MATLAB PDE template has shown to be most suitable for modelling of partial differential equations. The plug and play mode of modifying the PDE template for solving time-dependent partial differential equations is user-friendly and easy, as compared to more conventional approaches using Pascal, Fortran, C or C++. The template offers greater modularity, flexibility, versatility, and efficiency for solving PDE problems in both 1-D and 2-D spatial dimensions. Moreover, the 2-D PDE template has been extended for irregular shaped domains.

Orientadores: Zigomar Menezes de Souza, Edson Eiji Matsura
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agrícola
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Resumo: É crescente a demanda global por fontes de energia renováveis, tais como o etanol, o qual no Brasil, possui como principal matriz energética a cultura da cana-de-açúcar. Neste contexto faz-se necessário a incorporação de novas tecnologias, como a mecanização da colheita, para o uso racional das áreas manejadas com cana-de-açúcar. O acúmulo superficial de resíduos vegetais da cana-de-açúcar na superfície do solo promove o enriquecimento das camadas superficiais com matéria orgânica bem como o incremento do intervalo hídrico ótimo, mitigando os efeitos da compactação do solo causados pelo tráfego de máquinas no sistema de cana colhida mecanicamente sem queima. Portanto, o objetivo deste trabalho foi estudar as alterações no comportamento físico e mecânico de um Latossolo Vermelho produzido pelo enriquecimento do conteúdo de matéria orgânica e, ainda, a capacidade dos resíduos vegetais acumulados na superfície do solo dissiparem cargas aplicadas sobre o mesmo, em áreas cultivadas com cana-de-açúcar colhidas com e sem queima. O projeto foi desenvolvido em três áreas cultivadas com cana-de-açúcar: 1- cana-de-açúcar sem queima e corte mecanizado, desde 1996 (com 16 anos de implantação do sistema de cana crua); 2- cana-de-açúcar sem queima e corte mecanizado, desde 2004 (com 8 anos de implantação do sistema de cana crua); 3- cana-de-açúcar com queima e corte manual, desde 1973 (cana queimada). Os atributos físicos avaliados foram: análise granulométrica, consistência do solo, densidade do solo, estabilidade de agregados, porosidade do solo e resistência do solo à penetração nas profundidades de 0,00-0,10 m, 0,10-0,20 m e 0,20-0,30 m. Determinou-se ainda o intervalo hídrico ótimo para desenvolvimento das plantas. Foram avaliadas as relações entre o teor de matéria orgânica e a compressibilidade do solo, as relações entre teor de matéria orgânica do solo e a umidade crítica para a compactação e as relações entre quantidade de resíduos vegetais na superfície e a densidade do solo obtida pelo teste Proctor. Os atributos de solo estudados apresentam estrutura de dependência espacial. O intervalo hídrico ótimo e ?p mostraram-se sensíveis as alterações ocorridas no solo em detrimento dos sistemas de manejo estudados. A área sob colheita manual da cultura da cana-de-açúcar apresentou menor valor de densidade crítica para o intervalo hídrico ótimo, sendo que a maior produtividade da cultura concentrou-se nas regiões de maior amplitude do intervalo hídrico ótimo e maior capacidade suporte de carga do solo
Abstract: An increasing global demand for renewable energy sources such as ethanol, which in Brazil, has as its primary energy matrix culture of sugar cane. In this context it is necessary to incorporate new technologies, mechanization of the harvest, for the rational use of managed areas with cane sugar. The accumulation of surface plant residues of sugar cane on the soil surface promotes the enrichment of the surface layers with organic matter as well as increasing the optimal water, mitigating the effects of soil compaction caused by machinery traffic on the system cane mechanically harvested without burning. Therefore, the aim of this work was to study the changes in physical and mechanical behavior of soil produced by enriching the content of organic matter, and also the ability of plant debris accumulated on the soil surface dissipate loads applied on it, in cultivated areas sugar cane harvested with and without burning. The project was developed in three areas cultivated with sugar cane: 1 - harvested with manual cutting and burning since 1973; 2 - mechanically harvested without burning since 2004 (8 years of implantation of sugarcane), 3 - mechanically harvested unburned since 1996 (16 years of implantation of sugarcane). The physical attributes were: particle size analysis, soil consistency, soil bulk density, and aggregate stability, soil porosity and soil resistance to penetration depths of 0.00 to 0.10 m, 0.10-0.20 me 0.20-0.30 m. It was determined the optimal water yet to identify the critical limits of soil density where resistance to penetration and aeration porosity are restrictive to plant development. We evaluated the relationship between the organic matter content and soil compressibility, the relationships between organic matter content and soil moisture critical for the compression and the relationship between the amount of crop residue on the surface and soil density obtained by the Proctor test. The soil attributes have studied the spatial dependence structure. The least limiting water range and ?p were sensitive to changes in the soil instead of studied treatments. The area under cultivation of manual harvesting cane sugar showed a lower value of the critical density for optimal water, and the greater crop concentrated in regions of higher altitude and lower load-bearing capacity
Doutorado
Agua e Solo
Doutor em Engenharia Agrícola

Thesis (Ph. D.)--Kongelige Veterinær - og Landbohøjskole, 1988.
Summary in English. NAL copy missing pages from p. 113-128. English summary "Energy requirements by soil tillage with dual-driven harrow tines"): p. 120-124. Includes bibliographical references.

[Truncated abstract] Root-induced changes to soil hydraulic properties (SHP) are an essential component in understanding the hydrology of an ecosystem, and the resilience of these to climate change. However, at present our capacity to predict how roots will modify SHP and the consequences of this is limited because our knowledge of the processes and effects are highly fragmented. Also, current models used to investigate the relationship between plants and root-induced changes to SHP are based on empirical relationships which have limited applicability to the various and often contrasting ecosystems that occur. This thesis focuses specifically on the quantifying the processes by which roots modify SHP and developing models that can predict changes to these and the water balance. Both increase and decreases in saturated hydraulic conductivity have been attributed to the presence of roots. In general, decreases occur when the root system is relatively young, and increases occur when the roots senesce and begin to decay, creating voids for water flow. The evidence available suggests that the change in pore geometry created by roots is the dominant process by which roots modify SHP because they are more permanent and of a greater magnitude than changes to fluid properties or soil structure. We first quantified the effects of wheat roots on SHP of a coarse sand with a laboratory experiment where we measured changes in both SHP and the root system at 3, 5, 7 and 9 weeks after sowing (weeks). ... The main message that can be drawn from this thesis is that root-induced changes to SHP are dynamic, and dependent upon the combination of soil texture, connectivity of root-modified pores and the ratio of root radius to pore radius. Consequently, root-induced changes to the water balance have the same dependencies. The work in this thesis provides a significant first step towards improving our capacity to predict how roots modify soil hydraulic properties. By defining the range for the parameters used to predict how the soil is modified by roots, we are able to make quantitative assessments of how a property such as hydraulic conductivity will change for a realistic circumstance. Also , for the first time we have measured changes in soil hydraulic properties and roots and have been able to establish why a rapid change from a root-induced decrease to increase in Ks occurred. The link between physiological stage of the root system, and the changes that are likely to occur has implications for understanding how roots modify SHP: it may provide an effective tool for predicting when the switch from a decrease to increase occurs. Further work is required to test the validity of the assumptions we have made in our models that predict changes to SHP. While we have endeavoured to define the parameter space for those parameters that we have introduced, there is still some uncertainty about the connectivity of root-modified pores. Also, the parameterisation of the soil domain with roots is based upon work that measures 'fine' roots only which may not provide a true representation of the effect trees and perennial shrubs have on SHP. It is inevitable that root-induced changes to SHP will affect the fate of solutes in the soil, and temporal dynamics of root-induced changes to these may be particularly important for the timing of nutrient and pesticide leaching.

In soil, where trees and crops grow, heavy vehicles shear and compact the soil, leading to reduced plant growth and diminished nutrient recycling. Computer simulations offer the possibility to improve the understanding of these undesired phenomena. In this thesis, soils were modelled as large collections of contacting spherical particles using the Discrete Element Method (DEM) and the physics engine AGX Dynamics, and these entities were analyzed. In the first part of the thesis, soils, which were considered to be continua, were subjected to various controlled deformations and fields for quantities such as stress and strain were visualized using coarse graining (CG). These fields were then compared against analytical solutions. The main goal of the thesis was to evaluate the usefulness, accuracy, and precision of this plotting technique when applied to DEM-soils. The general behaviour of most fields agreed well with analytical or expected behaviour. Moreover, the fields presented valuable information about phenomena in the soils. Relative errors varied from 1.2 to 27 %. The errors were believed to arise chiefly from non-uniform displacement (due to the inherent granularity in the technique), and unintended uneven particle distribution. The most prominent drawback with the technique was found to be the unreliability of the plots near the boundaries. This is significant, since the behaviour of a soil at the surface where it is in contact with e.g. a vehicle tyre is of interest. In the second part of the thesis, a vehicle traversed a soil and fields were visualized using the same technique. Following a limited analysis, it was found that the stress in the soil can be crudely approximated as the stress in a linear elastic solid.

Thesis (PhD (Physics))--University of Stellenbosch, 2011.
ENGLISH ABSTRACT: Radioactivity is well known and well understood, but its usefulness in industrial applications to optimise processes or increase economic viability is not yet fully utilised by many industries. This study focuses on the measurement of natural radioactivity and its application in heavy mineral separation and vineyard soil classification. The gamma radiometry set-up consisted of a high purity germanium detector, a Marinelli beaker as sample container and associated electronics. It was calibrated for laboratorybased measurements by minimising the background radiation with the use of lead castle and energy and resolution calibrations. Furthermore, detection parameters were optimised; these included the counting time, the selection of gamma rays used for analysis of a sample, the peak area calculation for the detector dead time and the detector efficiency. Given that the samples had different densities and volumes, the detector efficiency had to be corrected for volume and density effects. After implementation of the corrections and optimisations the detection system was tested and found able to accurately measure radioactivity concentrations. The systematic measurement errors for 238U were 5.1 % in the case of the heavy mineral sands and 34.3 % for the vineyard soils, 4.5 % for the 232Th concentrations and 4.7 % for 40K concentrations. Statistical errors were kept below 2 %. The application of radiometry has not been done before at any South African heavy mineral separation plant. For this reason radiometry is suggested as an easier, faster and cheaper alternative to X-ray fluorescence (XRF) for effective implementation of grade control for zircon to improve the cost benefit of the heavy mineral separation process. Zircon is an example of a heavy mineral that is worldwide in demand with a consumption of more than a million tonnes per year. It is used in a wide range of industrial applications and products that include tiles, sanitary ware and plasma displays. South Africa is the second largest producer of zircon in the world and also has the second largest reserve of available zircon, making this mineral a viable source of income for several years to come. Radioactivity, in the form of uranium and thorium, and other impurities such as iron oxide and titanium oxide are found in the crystal lattice of zircon. For it to be a sellable product, the sum of the uranium and thorium concentrations must be less than 500 parts per million for prime or first grade zircon and less than 1000 parts per million for second grade zircon. At present the concentrations of uranium and thorium in zircon concentrates are measured on a whole rock basis by XRF during and at the end of the processing cycle before the final products are ready to be shipped. This is not an ideal situation as the grab samples are taken periodically and are not necessarily representative of the stream or final assignment and has resulted in significant losses by the producer. The solution is to accurately measure the uranium and thorium concentrations fast or immediately, preferably the measurements must be made online and in real time so that processing decisions can be implemented quickly to optimise the final product. Heavy mineral sand samples were obtained from the various separation processes in a Mineral Separation Plant and their 238U and 232Th concentrations determined. The results indicated that the samples’ uranium to thorium ratios together with their total concentrations can be used to differentiate between the samples (i.e. separation processes). The measurement results were compared with those obtained with XRF. The correlations with radiometry were excellent for the uranium (r2 = 0.992), thorium (r2 = 0.998) and total concentrations (r2 = 0.998). Radiometric measurements were also conducted by decreasing the counting time from 3600 s to 1 s to investigate its effect on the accuracy of the results. Correlations between the different times and 3600 s ranged from excellent to good. The obtained results are then used to recommend that radiometry is used in a Mineral Separation Plant to verify that the zircon and zirkwa meet the specifications, to optimise the entrance feed and the other separation processes and to monitor the tailings streams. Finally the practical aspects of the implementation of radiometry are discussed. As a second application was radiometry applied in an agricultural pilot study to demonstrate the applicability of radiometry as a possible useful tool in soil classification. The creation of a vineyard is a long term and expensive investment and its yield and quality will be influenced by many factors such as the type of soil, viticultural preparations and climate. Information on the different soil types in a vineyard is therefore indispensable for the optimisation of land use with respect to vine cultivar, wine quality and production. Soil samples were obtained from Kanonkop, Simonsig and Spier vineyards and their 238U, 232Th and 40K concentrations determined, assuming that fertilisers would have no effect on the results. The difference in 40K concentrations were related to the clay fraction of the soil and demonstrated that the Kanonkop and Simonsig soils are fine-grained and clay-rich compared to the sandy coarse-grained soils of Spier. The uranium and thorium concentrations were indicators of whether the mineralogy of the soil is the same as the underlying bedrock as well as soil maturity. The measurement results were compared with those obtained with XRF. The correlation with radiometry were poor for the uranium concentrations (r2 = 0.314), as many of the samples concentrations were below the XRF detection limit. The correlations were excellent for both thorium (r2 = 0.985) and potassium (r2 = 0.999). As a positive result from the findings of the study was an in-situ measurement performed by Newman et al. for the radiometric mapping of a Simonsig vineyard for soil classification.
AFRIKAANSE OPSOMMING: Radioaktiwiteit is wel bekend en word goed verstaan, tog is die gebruik daarvan in industriele toepassings om prosesses te optimiseer of winsgrense te verhoog nog nie deur baie industrië ten volle benut nie. Hierdie studie fokus op die meting van natuurlike radioaktiwiteit en die toepassing daarvan in swaar mineraal skeiding en wingerd grond klassifikasie. Die gamma radiometrie opstelling het bestaan uit ‘n hoë suiwerheid germanium detektor, 'n Marinelli beker as monster houer en verwante elektronika. Dit was gekalibreer vir laboratorium gebaseerde metings deur die vermindering van die agtergrondstraling met die gebruik van lood kasteel en energie en resolusie kalibrasies. Verder was deteksie parameters geoptimaliseer, dit sluit in die teltyd, die keuse van gammastrale wat gebruik word vir die ontleding van 'n monster, die piek area berekening, die korreksie vir die detektor se dooie tyd en die detektor doeltreffendheid. Gegee dat die monsters van mekaar verskil het in terme van dighteid en volume was dit nodig om die detektor doeltreffendheid te korrigeer vir volume en digtheid effekte. Na die implementering van die korreksies en optimalisasie was die detektor stelsel getoets en was gevind dat radioaktiwiteit konsentrasies akkuraat gelewer kan lewer. Die sistematiese meet foute vir 238U was 5.1 % vir die mineraal sand en 34.3 % vir wingerd grond, 4.5 % vir 232Th konsentrasies en 4.7 % vir 40K konsentrasies. Statistiese foute was onder 2 % gehou. Die toepassing van radiometrie was nog nie voorheen by enige Suid-Afrikaanse swaar mineraal skeidings aanleg gedoen nie. Vir die rede is radiometrie voorgestel as ‘n makliker, vinniger en goedkoper alternatief teenoor XSF vir effektiewe implementering van graad beheer vir zirkon om die koste voordeel van die swaar mineral skeiding proses te verbeter. Zirkon is ‘n voorbeeld van ‘n swaar mineraal wat wêreldwyd in aanvraag is met ‘n verbruik van meer as ‘n miljoen ton per jaar. Dit word in ‘n wye reeks van industriele toepassings en produkte gebruik onder andere teëls, sanitêre ware en plasma skerms. Suid Afrika is die tweede grootste vervaardiger van zirkon in die wêreld en het ook die tweede grootste reserwe van besikbare zirkon. Dit veroorsaak dat die mineraal ‘n lewensvatbare brom van inkomste is vir nog etlike jare. Radioaktiwiteit, in die vorm van uraan en thorium, word tesame met ander onsuiwerhede soos ysteroksied en titaanoksied in zirkon se kristal rooster gevind. Om ‘n verkoopbare produk te wees moet die som van die uraan en thorium konsentrasies minder wees as 500 dele per miljoen vir prima en eerste graad zirkon en minder wees as 1000 dele per miljoen vir tweede graadse zirkon. Huidiglik word die uraan en thorium konsentrasies in die zirkon konsentraat gemeet op ‘n heel gesteente basis met X-straal fluoroskopie (XSF) gedurende en op die einde van die prosesering siklus net voor die finale produk reg is om versend te word. Dit is nie die ideale situasie nie, want die monsters word periodies geneem en is nie noodwendig verteenwoordigend van die stroom of die finale produk nie en het al tot beduidende verliese deur die vervaardiger gelei. Die oplossing is om die uraan en thorium konsentrasies vinnig of onmiddelik te meet, verkieslik moet die metings inlyn en intyds gedoen word om verwerkings besluite vinnig geimplementeer kan word om die finale produk te optimaliseer. Swaar mineraal sand monsters was verkry van die verskeie skeidingsprosesse in ‘n Mineraal Skeidings Aanleg en hul 238U en 232Th konsentrasies bepaal. Die resultate het aangetoon dat die monsters se uraan en thorium verhoudings saam met hul totale konsentrasies gebruik kan word om te onderskei tussen die monsters (oftewel die skeiding prosesse). Die meting resultate was vergelyk met dié verkry met XSF. Die korrelasies met radiometrie was uitstekend vir die uraan (r2 = 0.992), thorium (r2 = 0.998) en totale konsentrasies (r2 = 0.998). Radiometriese metings was ook uigevoer deur die teltyd te verminder van 3600 s tot 1 s om die uitwerking daarvan op die akkuraatheid van die resultate te ondersoek. Korrelasies tussen die verskillende tye en 3600 s het gewissel van uitstekend tot goed. Die bevindinge was dan gebruik om aan te beveel dat radiometrie in a Mineraal Skeidings Aanleg gebruik kan word om te verifeer dat daar aan die zirkon en zirkwa spesifikasies voldoen word, om die begin voer en ander skeidings prosesse te optimaliseer en ook die uitskot strome te monitor. Laastens is die praktiese aspekte van die implementering van radiometrie bespreek. Vir die tweede toepassing was radiometrie toepgepas in ‘n loods studie in die landbou om die toepaslikheid van radiometrie as ‘n moontlike nuttige instrument in grond klassifikasie te demonstreer. Die skepping van ‘n wingerd is ‘n lang termyn en duur belegging waarvan die opbrengs en kwaliteit beinvloed sal word deur vele faktore, onder andere die tipe grond, wynbou voorbereidings en die klimaat. Inligiting oor die verskillende grond tipes in ‘n wingerd is daarom onmisbaar vir die optimalisering van land gebruik in betrekking tot die wingerdstok kultivar, wyn kwaliteit en produksie. Radiometrie is toegepas om te demonstreer die toepaslikheid daaran as ‘n moontlike nuttige instrument in grond klassifikasie. Grondmonsters was verkry vanaf Kanonkop, Simonsig en Spier wingerde en hul 238U, 232Th en 40K konsentrasies bepaal met die aanname dat kunsmis nie ‘n uitwerking op die resultate sou hê nie. Die verskil in 40K konsentrasies was verwant aan die kleifraksie van die grond en het getoon dat die Kanonkop en Simonsig gronde is fyn korrelrig en kleiryk is in vergelyking met die sanderige growwe korrel grond van Spier. Die uraan en thorium konsentrasies het gedui op die samestelling van die grond en ook aangedui watter grond dieselfde is as die onderliggende rots. Die meting resultate was vergelyk met dié verkry met XSF. Die korrelasie met die radiometrie was sleg vir die uraan konsentrasies (r2 = 0.314) aangesien baie van die monster konsentrasies laer was as die XSF deteksie limiet. Die korrelasies was uitstekend vir beide thorium (r2 = 0.985) en kalium (r2 = 0.999). As ‘n positiewe resultaat van die studie se bevindinge was ‘n in-situ meting gedoen deur Newman et al. om ‘n Simonsig wingerd radiomeries te karteer vir grond klassifasie.

Thesis (MScAgric)--Stellenbosch University, 2012
ENGLISH ABSTRACT: Biochar has been labelled to be a key factor in the global carbon mitigation act and has been described as the modern day equivalent (terra nova) to the terra preta dark earth soils of the Brazilian Amazon. Globally biochar has been evaluated as a means to improve soil fertility and to mitigate greenhouse gases (GHGs). Little research has however been published on the effects of biochar incorporation on soil physical properties. The objective of this study was to evaluate the effect of pine sawmill waste derived biochar (locally-produced via slow pyrolysis – 450°C) on selected soil physical properties, soil-water dynamics and crop production and- performance, when amended to a Kroonstad (Kd 1000 – Morgendal) soil form. This soil form is commonly found in the Western Cape area (South Africa) and can be classified as having low agricultural suitability for perennial- and annual crop species. Two pot trials were carried out in an atmospheric controlled greenhouse, where winter wheat and green beans respectively were planted, with five different application levels of biochar (0t/ha, 1t/ha, 10t/ha, 50t/ha and 200t/ha). Soil physical properties namely, water-stable aggregates, bulk density and water-retention capacity along with physiochemical characterisation of the sandy soil and biochar was determined. The water-use was monitored throughout the trials (evapotranspiration, volumetric water content and biomass water use efficiency, BWUE). The above- and below ground (specific leaf traits for the green bean and the root structural development for the winter wheat) biomass was collected and analysed at harvest. There was significantly higher volumetric water content measured for the 50t/ha and 200t/ha biochar treatments. This effect can be ascribed due to a change in the soil’s tortuosity and porosity where more meso- and micro-pores were present as the biochar rate increased. The same results were evident when a water-retention curve was established in vitro by means of the sandbox method. The bulk densities were only significantly lower for the 200t/ha biochar treatments. The wheat root systems differed greatly among the fertilised biochar treatments: the 50t/ha and 200t/ha treatments had a more complex fibrous root system (more extensive branching and thinner roots) than 0t/ha, 1t/ha and 10t/ha application levels. This is attributed to the increased water-holding capacity along with a reduction of N- and P availability with increasing addition of biochar. Several leaf traits were measured for the green bean crops; however the leaf nitrogen- and carbon content, chlorophyll content index (CCI) and carbon isotope fractionation yielded the most interesting findings. Concerning the fertilised biochar treatments, there was established that the 10t/ha treatments had the highest leaf nitrogen- and carbon content. The leaf chlorophyll content did not differ significantly between the fertilised biochar treatments; however a very interesting observation was evident regarding the measured leaf CCI for the unfertilised treatments. A decreasing trend and lower leaf CCI was measured as the biochar application levels increased. This effect was ascribed to be due to a decrease in N uptake by the plants as the biochar application increased, the C/N ratio also increased, and this leading to N immobilisation. The lowest leaf carbon isotope fractionation was measured for the 10t/ha fertilised treatments and is inversely correlated with BWUE and therefore endorses the conclusion that the 10t/ha biochar application had a positive effect on the long term water use efficiency for the green bean plants. Biochar promoted aggregation in the sand-rhizosphere interface for winter wheat, increased water-holding capacity and enhanced crop performance for green beans. The findings reported here provide new information on the effect of biochar on the structural development of sandy soil, combined with biochar- and root growth effects for winter wheat; along with detailed interpretations of specific leaf traits associated with crop production for commercial green beans. The addition of biochar at low application levels (approximately 1-10t/ha to 15 cm depth) increased the biomass yield and water use efficiency of the crop species. Besides long term carbon storage, biochar can have immediate positive effects on the physical properties of sand and plant growth.
AFRIKAANSE OPSOMMING: Biokoolstof word beskou as ‘n sleutel komponent rakende die wet op globale koolstofvermindering en is al beskryf as die moderne ekwivalent (terra nova) van die terra preta donker-aardgronde wat aangetref word in die Brasiliaanse Amasone. Wêreldwyd word biokoolstof tans geëvalueer met die doel om grondvrugbaarheid te verbeter asook kweekhuisgasse (KHG) se nadelige gevolge te verlig. Min navorsing was tot dus ver gedoen rakende die uitwerking met toediening van biokoolstof op grondfisiese-eienskappe. Die doel van hierdie studie was om die effek van biokoolstof, wat afkomstig is van denne-saagmeul-afval (plaaslik geproduseer is en d.m.v. stadige perolise - 450°C) te evalueer aangaande die volgende faktore: geselekteerde grondfisiese-eienskappe, grond-waterdinamika interaksie en die uitwerking op gewasproduksie; met toediening aan 'n Kroonstad (Kd 1000 - Morgendal) grondvorm. Hierdie grondvorm word as algemeen in die Wes-Kaap (Suid-Afrika) bestempel en kan geklassifiseer word as ‘n lae-geskiktheid landbougrond vir meerjarige- en eenjarige gewasse. Twee potproewe is uitgevoer onder beheerde atmosfeer in ‘n kweekhuis, waar winter koring en groenbone geplant is, met vyf verskillende behandelings van biokoolstof (0t/ha, 1t/ha, 10t/ha, 50t/ha en 200t/ha). Die volgende grondfisiese-eienskappe is ondersoek, naamlik water-stabiele aggregaat formasie, bulkdigtheid en waterhouvermoë, asook die fisiochemiese karakterisering van die sanderige grond en biokoolstof wat gebuik is. Waterverbruik is gedurende die proewe gekontroleer (evapotranspirasie, volumetriese waterinhoud en die biomassa se water verbruiksdoeltreffendheid, BWVD). Die bo- en ondergrondse biomassa, spesifiek die blaareienskappe van die groenboontjie en die strukturele ontwikkeling van die winter koring se wortels, is tydens die oes ondersoek en ontleed. Die volumetriese waterinhoud was betekenisvol, asook hoër vir die 50t/ha en 200t/ha behandelings. Hierdie effek word toegeskryf as gevolg van 'n verandering in die grond se kronkeligheid en porositeit; waar meer meso- en mikroporieë teenwoordig was soos die biokoolstof inhoud toegeneem het. Dieselfde resultate was verkry met die opstelling van ‘n water-retensie kurwe in vitro d.m.v. die Sandboks metode. Bulkdigtheid was slegs betekenisvol verskilled asook aansienlik laer vir die 200t/ha biokoolstof behandelings. Die koring se wortelstelsel het drasties verskil tussen die verskillende bemeste biokoolstof behandelings: die 50t/ha en 200t/ha behandelings het 'n meer komplekse en veselagtige wortelstelsel gevorm (hoër graad van vertakking en dunner wortels was aanwesig) as die 0t/ha, 1t/ha en 10t/ha behandelings. Die effek word toegeskryf aan die toenemende waterhouvermoë, tesame met 'n tekort aan N- en P-beskikbaarheid soos die biokoolstof toedieningshoeveelhede verhoog het. Verskeie blaareienskappe is gemeet vir die groenboon gewasse, maar die blaar stikstof- en koolstof-inhoud, chlorofil inhoud indeks (CII) en koolstof-isotoop fraksionering het die mees interessante bevindinge opgelewer. Die hoogste blaar stikstof-en koolstof-inhoud is gemeet vir die 10t/ha bemeste biokoolstof behandelings. Die blaar chlorofil inhoud het nie beduidend verskil tussen die bemeste biokoolstof behandelings nie, maar daar was egter 'n baie interessante waarneming vir die onbemeste biokoolstof behandelings. ‘n Tendens was aanwesig waar die CII afgeneem het soos die biokoolstof toedieningshoeveelheid ook afgeneem het vir die onbemeste behandelings. Die effek word toegeskryf as gevolg van 'n afname in N-opname deur die plant soos die biokoolstof toedieningshoeveelheid verhoog is en tot gevolg gehad het dat die C/N-verhouding ook toegeneem het, wat gelei het tot N-immobilisasie. Die laagste blaar koolstof-isotoop fraksionering was geassioseer met die 10t/ha bemeste biokoolstof behandelings en is omgekeerd gekorreleerd met BWVD en onderskryf dus die gevolgtrekking dat die 10t/ha biokoolstof behandeling 'n positiewe uitwerking het op die langtermyn waterverbruiksdoeltreffendheid vir groenboontjie plante. Biokoolstof het aggregasie bevorder binne die wortelsone, asook deurgans die waterhouvermoë verhoog en gewasproduksie verbeter. Hierdie bevindinge lewer nuwe inligting oor die effek van biokoolstof op die strukturele ontwikkeling van sanderige grond en die gekombineerde interaksie met biokoolstof toediening en hoe dit wortegroei beïnvloed van winter koring; asook 'n gedetailleerde interpretasie van spesifieke blaareienskappe wat verband hou met die produksie van gewasse vir kommersiële verbouing soos die groenboontjie. Die toediening van biokoolstof by die lae hoeveelhede (ongeveer 1-10t/ha tot op 15 cm diepte) het die opbrengs en waterverbruiksdoeltreffendheid van die gewasse verbeter. Behalwe vir die langtermyn koolstofvaslegging, kan biokoolstof toediening onmiddellike positiewe resultate teweeg bring aangaande die fisiese eienskappe van sandgronde en plantegroei.

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.

Bibliography: p. 182-197. The objectives of this study are: selection and construction of four narrow sowing points, evaluation of these points in terms of draught requirements and wear rates, comparison of the points in direct drilling systems and their effects on soil physical properties.

The objective of this study is to integrate a continuum-based deformable tire and terrain interaction model into a general-use physics-based simulation environment capable of off-road vehicle mobility analysis and high-performance computing potential. Specifically, the physics-based deformable tire and terrain models which were recently proposed and validated by Yamashita, et al. will be implemented into the structure of the multi-physics simulation engine Chrono. In off-road vehicle mobility analysis, empirical and analytical models have been commonly used for vehicle-terrain interaction. While these models utilize experimental data or terramechanics theories to create quick predictive mobility models, they are unable to capture the highly nonlinear behavior of soft soil deformation, which can lead to inaccurate or unreliable results. In order to resolve these limitations, the use of physics-based numerical approaches have been proposed. These methods make use of finite element and discrete element simulations to describe the interaction between the vehicle and deformable terrain. Continuum-based finite element models transfer tire forces to the terrain and model the deformation with elasto-plastic constitutive models. Discrete element soil uses a large number of small rigid body particles to describe the microscale behavior of granular terrain, with the deformation of the soil represented by the motion and contact of the particles. While these physics-based models offer a more accurate vehicle-terrain interaction model, the solution procedure can become complex and computationally expensive since co-simulation techniques are often used. To address these issues, the analysis of physics-based full vehicle dynamics simulations utilizing high-fidelity deformable tire and terrain models in a multi-physics engine with high-performance computing capability is desired. To this end, a continuum mechanics based shear deformable laminated composite shell element proposed by Yamashita, et al. was integrated into the flexible body dynamics simulation framework of Chrono. This element was based on the absolute nodal coordinate formulation and is defined by the global position coordinates and the transverse gradient coordinates of its four nodes. Element lockings are eliminated with the incorporation of the enhanced assumed strain (EAS) and assumed natural strain approaches (ANS). The element formulation includes an extension to model laminated composite materials. Additionally, a locking-free 9-node brick element was integrated into the Chrono framework that makes use of the curvature coordinates at the center of the element. This element is formulated with the Hencky strain measure such that multiplicative finite strain plasticity theory can be used to incorporate soil plasticity models, such as the capped Drucker-Prager failed criterion. With the shear deformable laminated composite shell element and plastic soil brick element integrated into the Chrono multi-physics simulation engine, an off-road deformable tire and terrain interaction model was developed using the vehicle dynamics simulation module Chrono::Vehicle. An off-road deformable tire model was parameterized based on commercial tire properties and generated as an interchangeable tire model option in the full vehicle dynamics system. Benchmark verification tests were performed to ensure the accuracy of tire deformation and tire force characteristics. Further tests were performed to validate a deformable tire model with a deformable tread pattern constructed from shear deformable shell elements and co-rotational tetrahedral elements. The deformable soil model was also integrated as a terrain option in Chrono::Vehicle and numerical tests were carried out to demonstrate its interaction with rigid and deformable tire models. To make use of the computational performance enhancements available in Chrono, Open Multi-Processing (OpenMP) and Advanced Vector Extensions (AVX) were applied to the evaluation of the elastic force/Jacobian matrix and large matrix operations of flexible bodies, respectively, in order to reduce the computation time by nearly 60%.

Forest ecosystems undergo both natural and human induced disturbances. Depending on disturbance type, soil physical and chemical parameters show different response patterns during the recovery phase. An added level of complication is the ecological site types occurring throughout a forested area. The identification of indicators of soil fertility and the successful emulation of a natural disturbance regime were the scope of this research.
The research presented herein took place in the Manitoba Model Forest (MBMF), located in eastern Manitoba, where the natural disturbance regime is wildfire. Timber harvest strategies used in the area are designed to emulate a wildfire (5% retention of standing timber and extensive slash inputs) and clearcut harvesting. The objective of this study was to document changes in forest floor and soil properties prior to and following harvesting, and to compare these properties to those found in a small wildfire that burned in the MBMF in late summer 1998, which serves as a benchmark to the harvest. In the two study areas, both thin mineral soil (5--20 cm) and moderately deep mineral soil (20--100 cm) ecosite types were monitored at four dates over a two year period for soil physical and nutritional response patterns.

A compactação devido ao tráfego agrícola tem se tornado um dos grandes problemas de degradação do solo. Os modelos de predição vêm sendo utilizados para investigar o impacto do tráfego sobre atributos físicos do solo. Neste estudo, relações entre parâmetros mecânicos que descrevem a compressão do solo e atributos físicos são estabelecidas, a precisão das estimativas são testadas em campo, limitações físicas do solo são quantificadas por efeito do tráfego, a sensibilidade de indicadores de compactação é avaliada, e um sistema de predição de resistência à compactação para solos brasileiros é descrito, implementado e proposto. Regressões foram usadas estimar os parâmetros mecânicos do solo, e simples modelos foram propostos em função da densidade inicial sucção matricial. Teste de campo foram usados para avaliar a precisão das estimativas, e boa concordância foi observada entre medições e simulações. Em cenários simulados, solos compactados mostraram-se bastante sensíveis a variação de fatores limitantes para as plantas, medidos pelo intervalo hídrico ótimo. Medidas de resistência à penetração e sucção matricial pós-tráfego não substituíram avaliações diretas de variação de volume no diagnóstico de compactação do solo. Um fundamental modelo de resistência à compactação em função da tensão aplicada foi proposto, e parâmetros de máquina, pneu e solo podem ser utilizados para predição do risco de compactação em Latossolos brasileiros.
Compaction due to agricultural field traffic has become one of the major problems of soil degradation. Prediction models have been used to investigate the impact of the traffic on physical soil attributes. In this study, relationships among mechanical parameters which describing soil compression and physical attributes are established, the accuracy of the estimation are field-tested, physical soil limitations are quantified due to the traffic effect, the sensitivity of compaction indicators are evaluated, and a soil strength prediction system for Brazilian soils is described, implemented and proposed. Regression were used to estimate the soil mechanical parameters, and simple models were proposed as a function of the initial bulk density and matric suction. Field tests were used to evaluate the accuracy of the estimations, and good agreement was observed between measurements and simulations. On simulated scenarios, compacted soils were quite sensitive to the variation of limiting factors for the plants, measured by the least limiting water range. Post-traffic penetration resistance and matric suction measurements did not replace direct volume variation evaluations in the soil compaction diagnosis. A fundamental model of soil strength calculation as a function of the applied stress was proposed, and machinery, tyre and soil parameters can be used to predict the risk of compaction for Brazilian Oxisols.

Irrigation needs to be applied to soils in relatively humid regions such as western Kentucky to supply water for crop uptake to optimize and stabilize yields. Characterization of soil and crop variability at the field scale is needed to apply site specific management and to optimize water application. The objective of this work is to propose a characterization and modeling of soil and crop processes to improve irrigation management. Through an analysis of spatial and temporal behavior of soil and crop variables the variability in the field was identified. Integrative analysis of soil, crop, proximal and remote sensing data was utilized. A set of direct and indirect measurements that included soil texture, electrical conductivity (EC), soil chemical properties (pH, organic matter, N, P, K, Ca, Mg and Zn), NDVI, topographic variables, were measured in a silty loam soil near Princeton, Kentucky. Maps of measured properties were developed using kriging, and cokriging. Different approaches and two cluster methods (FANNY and CLARA) with selected variables were applied to identify management zones. Optimal scenarios were achieved with dividing the entire field into 2 or 3 areas. Spatial variability in the field is strongly influenced by topography and clay content. Using Root Zone Water Quality Model 2.0 (RZWQM), soil water tension was modeled and predicted at different zones based on the previous delineated zones. Soil water tension was measured at three depths (20, 40 and 60 cm) during different seasons (20016 and 2017) under wheat and corn. Temporal variations in soil water were driven mainly by precipitation but the behavior is different among management zones. The zone with higher clay content tends to dry out faster between rainfall events and reveals higher fluctuations in water tension even at greater depth. The other zones are more stable at the lower depth and share more similarities in their cyclic patterns. The model predictions were satisfactory in the surface layer but the accuracy decreased in deeper layers. A study of clay mineralogy was performed to explore field spatial differences based on the map classification. kaolinite, vermiculite, HIV and smectite are among the identified minerals. The clayey area presents higher quantity of some of the clay minerals. All these results show the ability to identify and characterize the field spatial variability, combining easily obtainable data under realistic farm conditions. This information can be utilized to manage resources more effectively through site specific application.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
A retirada da cobertura vegetal original e a implantação de áreas de pastagem e canade- açúcar, com práticas de manejo inadequadas, acarretam modificações nas propriedades químicas, físicas e biológicas dos solos, com limitações na utilização agrícola e susceptibilidade à erosão. Assim, estudos dos processos físicos e químicos são importantes para avaliar as mudanças de origem natural ou antrópica sobre os meios. O estudo teve como objetivos avaliar os atributos químicos e físicos de um Argissolo Vermelho-Amarelo em três microbacias hidrográficas, em áreas de vegetação nativa, pastagem e cana-de-açúcar bem como analisar a ocorrência das áreas de maior escoamento superficial e, consequentemente, maior predisposição ao processo erosivo nas microbacias. A área de estudo compreendeu a microbacia hidrográfica do Córrego da Fazenda Glória, Município de Taquaritinga, Estado de São Paulo. Para a amostragem do solo foi realizada a caracterização do volume superficial, e essas amostras foram coletadas na superfície das vertentes das microbacias e em cada uso/ocupação selecionado. Os resultados obtidos foram avaliados por meio da comparação de médias para o teste de Tukey a 5%. A partir das curvas de nível da carta topográfica e dos pontos levantados com receptor geodésico de navegação com metodologia diferencial foi gerado uma malha de pontos georreferenciados em cada microbacia, para gerar o modelo numérico do terreno a partir da incorporação dos divisores de água e da rede de drenagem. As avaliações dos atributos físicos e químicos dos solos nas microbacias hidrográficas e em diferentes tipos de uso e ocupação demonstraram uma diferença significativa entre as áreas. O manejo do solo alterou os atributos químicos e físicos com impacto nas camadas superficiais do solo. A matéria orgânica foi um dos atributos mais sensíveis...
The removal of original vegetation cover and the deployment of pastures and sugarcane, with inadequate management practices, cause changes in the chemical, physical and biological properties of soils, with limitations on agricultural use and susceptibility to erosion. Thus, studies of physical and chemical processes are important to assess changes of natural development or anthropic on the means. The study was conducted to evaluate the physical and chemical attributes of a Ultisol in three watersheds, in areas of native vegetation, pasture and sugarcane, as well as, analyze the occurrence of the areas of greatest runoff and, consequently, greater predisposition to erosive processes in watersheds. The study area was the Córrego da Fazenda Glória watershed, Municipality of Taquaritinga, State of São Paulo. Soil sampling was performed to characterize the superficial volume, and these samples were collected on the surface of the watersheds and in three different land use selected. The results obtained were evaluated by the comparison of averages for the Tukey test at 5%. From the curves in a topographical map and from points collected with geodetic navigation receiver in a differential methodology was generated a digital elevation method in each watersheds. The assessments of physical and chemical attributes of soils in hydrographic watersheds and different land uses demonstrated a significant difference between the areas. Soil management altered the chemical and physical attributes impact in the soil superficial layers. The organic matter was one of the attributes more sensitive to changes due to agricultural practices. The digital terrain model showed a great potential, considering the scale of study of watersheds; and can help in spatial planning, urban and regional planning and zoning

Soil structure and its associated physical properties are essential soil components. Soil texture and mineralogy are inherent soil properties that influence soil management. This study assessed the implication of tillage, texture and mineralogy on soil sieving, aggregate stability indices and physical fractions of organic matter in soils of Eastern Cape Province of South Africa. An Iris FTLVH – 0200 digital electromagnetic sieve shaker (Filtra Vibraciόn SL Spain), was used to determine settings for sieving efficiency. Mean weight diameter (MWD), water stable aggregate (WSA), state of aggregation (SA), dispersion ratio (DR), water dispersible clay (WDC), clay dispersion ratio (CDR), clay flocculation index (CFI), and potential structural deformation index (PSDI) were aggregate stability indices evaluated to check for sensitivity in evaluating aggregate stability of soils under two tillage systems and physical fractions of carbon and nitrogen in soils of Eastern Cape Province. The T4I3P2 and T4I4P3 settings were sensitive under tillage and T4I1P4, T3I4P3 and T4I4P3 were sensitive under mineralogical considerations for sieving efficiency. The total carbon in soils under conventional tillage (CT) was 17.7 g/kg and in soils under no tillage (NT) it was 15.8 g/kg. The total carbon content in the clay fraction of soils under CT was 24.1 percent higher than the total carbon content in the clay fraction of soils under NT. The total nitrogen content in the clay fraction of soils under CT was 5.4 percent higher than the total nitrogen content in the soils under NT. The total carbon in the sandy loam (SL) textured soils was 17.4 g/kg and in the sandy clay loam (SCL) textured soils it was 17.1 g/kg. The total nitrogen in SL soils was 3.7 g/kg and in SCL soils it was 3.7 g/kg. The clay fraction had higher total carbon than other fractions in Sl and SCL soils. The higher values of nitrogen were observed in the silt fraction for SL soils and clay fraction for SCL soils. The total carbon in the soils dominated with kaolinite was 17.3 g/kg and in quartz dominated soils the value was 16.9 g/kg. The total nitrogen in the soils dominated with kaolinite was 3.7 g/kg and in the soils dominated with quartz the value was 3.7 g/kg. For soils under NT the WDC was 135.8 g/kg and for soils under CT it was 139.7 g/kg. The ASC was 72.5 for soils under NT and 92.0for soils under CT. The DR was 0.9 for soils under NT and 0.8 for soils under CT. The CFI was 0.5 for soils under NT and 0.5 for soils under CT. The CDR was 0.5 for soils under NT and 0.5 for soils under CT. The MWDw was 1.6 mm for soils under NT and 1.4 mm for soils under CT. The MWDd was 4.0 mm for soils under NT and 4.0 for soils under CT. The percent WSA > 0.25 mm was 61.7 percent for soils under NT and 56.2 percent for soils under CT. The PSDI was 55.2 percent for soils under NT and 61.15 percent for soils under CT. The SA was 43.2 percent for soils under NT and 37.89 percent for soils under CT. The WDC was 125.7 g/kg for SCL soils and 151.4 g/kg for SL soils. The CDR was 0.5 for both SCL and SL soils. The DR was 0.9 for SCL soils and 0.8 for SL soils. The CFI was 0.5 for both SCL and SL soils. The ASC was 56.2 g/kg for SCL soils and 115 g/kg for SL soils. The MWDw was 1.5 mm for SCL soils and 1.4 mm for SL soils. The MWDd was 3.6 mm for SCL soils and 3.6 mm for SL soils. The percent WSA > 0.25 mm was 53.0 percent for SCL soils and 62.5 percent for SL soils. The PSDI was 59.2 percent for SCL soils and 59.7 percent for SL soils. The SA was 33.6 percent for SCL soils and 45.2 percent for SL soils. The WDC was 313.3 g/kg for kaolinitic soils and 120.7 g/kg for quartz dominated soils. The CDR was 0.5 for kaolinitic soils and 0.5 for quartz dominated soils. The DR was 0.9 for kaolinitic soils and 0.8 for quartz dominated soils. The CFI was 0.5 for kaolinitic soils and 0.5 for quartz dominated soils. The ASC was 110.0 g/kg for kaolinitic soils and 101.7 g/kg for quartz dominated soils. The WSA > 0.25 mm was 57.3 percent for quartz dominated soils and 68.4 percent for kaolinitic soils. The MWDw was 1.6 mm for quartz dominated soils and 0.8 mm for kaolinitic soils. The MWDd was 3.6 mm for quartz dominated soils and 3.4 mm for kaolinitic soils. The PSDI was 56.3 for quartz dominated soils and 76.0 for kaolinitic soils.

The objectives of this research were to develop and evaluate a field method for in situ measurement of soil properties using visible near-infrared reflectance spectroscopy (Vis-NIRS). A probe with an independent light source for acquiring soil reflectance spectra from soil cores was developed around an existing portable field spectrometer (ASD FieldSpecPro, Boulder, CO, USA; 350-2500 nm). Initial experiments tested the ability of the acquired spectra to predict plant root density, an important property in soil carbon dynamics. Reflectance spectra were acquired from soil containing ryegrass roots (Lolium multiflorum) grown in Allophanic and Fluvial Recent soils in a glasshouse pot trial. Differences in root density were created by differential nitrogen and phosphorus fertilization. Partial least squares regression (PLSR) was used to calibrate spectral data (pre-processed by smoothing and transforming spectra to the first derivative) against laboratory-measured root density data (wet-sieve technique). The calibration model successfully predicted root densities (r2 = 0.85, RPD = 2.63, RMSECV = 0.47 mg cm-3) observed in the pots to a moderate level of accuracy. This soil reflectance probe was then tested using a soil coring system to acquire reflectance spectra from two soils under pasture (0-60 mm soil depths) that had contrasting root densities. The PLSR calibration models for predicting root density were more accurate when soil samples from the two soils were separated rather than grouped. A more accurate prediction was found in Allophanic soils (r2 = 0.83, RPD = 2.44, RMSECV = 1.96 mg g-1) than in Fluvial Recent soils (r2 = 0.75, RPD = 1.98, RMSECV = 5.11 mg g-1). The Vis-NIRS technique was then modified slightly to work on a soil corer that could be used to measure root contents from deeper soil profiles (15- 600 mm depth) in arable land (90-day-old maize crop grown in Fluvial Recent soils). PLSR calibration models were constructed to predict the full range of maize root densities (r2 = 0.83, RPD = 2.42, RMSECV = 1.21 mg cm-3) and also soil carbon (C) and nitrogen (N) concentrations that had been determined in the laboratory (LECO FP- 2000 CNS Analyser; Leco Corp., St Joseph, MI, USA). Further studies concentrated on improving the Vis-NIRS technique for prediction of total C and N concentrations in differing soil types within different soil orders in the field. The soil coring method used in the maize studies was evaluated in permanent and recent pastoral soils (Pumice, Allophanic and Tephric Recent in the Taupo-Rotorua Volcanic Zone, North Island) with a wide range of soil organic matter contents resulting from different times (1-5 years) since conversion from forest soils. Without any sample preparation, other than the soil surface left after coring, it was possible to predict soil C and N concentrations with moderate success (C prediction r2 = 0.75, RMSEP = 1.23%, RPD = 1.97; N prediction r2 = 0.80, RMSEP = 0.10%, RPD = 2.15) using a technique of acquiring soil reflectance spectra from the horizontal cross-section of a soil core (H method). The soil probe was then modified to acquire spectra from the curved vertical wall of a soil core (V method), allowing the spectrometer’s field of view to increase to record the reflectance features of the whole soil sample taken for laboratory analysis. Improved predictions of soil C and N concentrations were achieved with the V method of spectral acquisition (C prediction r2 = 0.97, RMSECV = 0.21%, RPD = 5.80; N prediction r2 = 0.96, RMSECV = 0.02%, RPD = 5.17) compared to the H method (C prediction r2 = 0.95, RMSECV = 0.27%, RPD = 4.45; N prediction r2 = 0.94, RMSECV = 0.03%, RPD = 4.25). The V method was tested for temporal robustness by assessing its ability to predict soil C and N concentrations of Fluvial Recent soils under permanent pasture in different seasons. When principal component analysis (PCA) was used to ensure that the spectral dimensions (which were responsive to water content) of the data set used for developing the PLSR calibration model embraced those of the “unknown” soil samples, it was possible to predict soil C and N concentrations in “unknown” samples of widely different water contents (in May and November), with a high level of accuracy (C prediction r2 = 0.97, RMSEP = 0.36%, RPD = 3.43; N prediction r2 = 0.95, RMSEP = 0.03%, RPD = 3.44). This study indicates that Vis-NIRS has considerable potential for rapid in situ assessment of soil C, N and root density. The results demonstrate that field root densities in pastoral and arable soil can be predicted independently from total soil C, which will allow researchers to predict C sequestration from root production. The recommended “V” technique can be used to assess spatial and temporal variability of soil carbon and nitrogen within soil profiles and across the landscape. It can also be used to assess the rate of C sequestration and organic matter synthesis via root density prediction. It reduces the time, labour and cost of conventional soil analysis and root density measurement.

Orientadores: Zigomar Menezes de Souza, Reginaldo Barboza da Silva
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agrícola
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Resumo: O sistema de produção da cana crua, sem queima da palha e com frequente uso da mecanização agrícola promove o tráfego intenso sobre o solo, resultando na sua compactação. O sistema de manejo com controle de tráfego agrícola representa uma alternativa viável para o setor agrícola, pois separa as zonas de tráfego e não tráfego, concentrando a passagem de pneus em linhas permanentes, diminuindo a influência da compactação sobre a cultura. O objetivo deste trabalho foi comparar os sistemas de manejo com e sem controle de tráfego agrícola em relação à qualidade física de um Latossolo Vermelho, indicada por meio da análise de atributos físicos e mecânicos do solo, e seu efeito na cana-de-açúcar colhida mecanicamente e sem queima. A pesquisa foi desenvolvida em lavoura comercial com os manejos: ausência de controle de tráfego (T); controle de tráfego com ajuste da bitola do trator e transbordos para 3,0 m (CT1); e controle de tráfego com ajuste da bitola e piloto automático. Os atributos do solo avaliados foram: densidade, porosidade, resistência à penetração, conteúdo de água, estabilidade de agregados, teor de carbono e curva de retenção de água do solo. O solo foi amostrado nas linhas de plantio e do rodado e no canteiro, nas camadas 0,00-0,10; 0,10-0,20 e 0,20-0,30 m. A qualidade física do solo foi avaliada por meio do intervalo hídrico ótimo. A estrutura do solo foi avaliada por meio de análise de imagens digitalizadas de monólitos de solo, quantificando a forma e tamanho dos poros. Foram coletadas amostras indeformadas para análise da capacidade de suporte de carga do solo. A cana foi colhida mecanicamente e a produtividade medida por meio de balança específica para transbordo. Amostras de colmo foram coletadas em cada parcela para determinação das variáveis tecnológicas. As raízes foram coletadas em monólitos, separadas do solo por peneiramento. Densidade, porosidade e resistência do solo a penetração demonstraram diferenças entre os sistemas de manejo, com melhores condições físicas nos manejos com controle de tráfego na linha da soqueira e no canteiro. Os índices de agregação e o teor de carbono do solo não diferiram entre os manejos. Foram observadas alterações na retenção de água do solo entre tratamentos. O intervalo hídrico ótimo foi maior no canteiro e linha de plantio nos manejos com controle de tráfego. Predomínio de poros arredondados e complexos indicaram maior porosidade e menor compactação no manejo com controle de tráfego na linha de plantio. A testemunha apresentou maior pressão de pre- consolidação na linha de plantio, enquanto o manejo com controle de tráfego apresentou maior capacidade de suporte de carga na linha do rodado. Os manejos com controle de tráfego apresentaram maior produtividade e rendimento de açúcar. As variáveis tecnológicas não diferiram entre os manejos. O manejo com controle de tráfego apresentou maior massa seca, superfície e volume radicular. Os manejos com controle de tráfego proporcionaram compactação na linha do rodado e preservaram a qualidade física do solo na região da soqueira, resultando no maior desenvolvimento do sistema radicular, com aumento de 18% na produtividade e 20% no rendimento de açúcar
Abstract: The sugarcane production system without straw burning and with frequent use of agricultural mechanization promotes the excessive traffic on the soil, resulting in their compaction. The management with controlled traffic farming is a viable alternative for the agricultural sector, because it separates the areas of traffic and no-traffic, focusing on the passage of tires in permanent lines, reducing the influence of compaction on the crop. The objective this work was to compare the management systems with and without controlled traffic farming in relation to soil physical quality, indicated by the analysis of attributes physical and mechanical soil and its effects on sugarcane harvested mechanically and without burning. The research was developed in a commercial farm with the managements: non-controlled traffic (T); controlled traffic with adjustment of the tractor and trailer gauge to 3.0 m (CT1), and controlled traffic with adjustment of the gauges and autopilot (CT2). The soil attributes evaluated were: bulk density, porosity, penetration resistance, water content, aggregate stability, carbon content and soil water retention curve. Soil samples were collected in plant and wheel rows and in the seedbed, in the layers 0.00 to 0.10; 0.10 to 0.20 and 0.20 to 0.30 m. The soil physical quality was evaluated using the least limiting water range. The soil structure was evaluated by digitized images analysis of soil monoliths, quantifying shape and size of the pores. Undisturbed samples were collected for analysis of soil load carrying capacity. The sugarcane was mechanically harvested and the productivity was measured by weighing the sugarcane trailer. Sugarcane stalks were collected from each plot to determine the technological variables. The roots were collected in monoliths, separated from the soil by sieving. Bulk density, porosity and penetration resistance showed differences among management systems, with better physical conditions in the managements with controlled traffic in the plant row and seedbed. The aggregation indices and carbon content didn't differ between managements. There were changes in soil water retention curve between treatments. The least limiting water range was higher in the seedbed and plant row in the controlled traffic. Predominance of rounded and complexes pores showed higher porosity and lower compaction in the controlled traffic in the plant row. The management with non-controlled traffic had a higher soil preconsolidation pressure in the plant row, while the management of controlled traffic had a higher load carrying capacity in the wheel row. The management of controlled traffic had a higher cane productivity and sugar yield. The technological variables didn't differ between managements. The handling with controlled traffic had higher dry mass, surface and volume of roots. The management with controlled traffic promoted soil compaction in wheel row and preserved the soil physical quality in the plant row, resulting in greater root development, with 18% increase in productivity and 20% on yield of sugar
Doutorado
Engenharia de Água e Solo
Doutor em Engenharia Agrícola

In 1991, a project was initiated at Quinn and Ormstown, two sites with soils representative of Quebec's present-day agriculture. Three field management techniques were studied related to their possible impact on the soils: tillage, rotation, and N fertilization. The three treatments were randomly assigned in two blocks of a split-split-plot design. The main treatment, tillage, had two levels, conventional tillage (CT) and no-till (NT). The sub-treatment was represented by five 4-year rotations, starting from 1991 as follows: CCCC (continuous corn), CSAC (corn-soybean-alfalfa-corn), CSCS (corn-soybean-corn-soybean), SCSC (soybean-corn-soybean-corn) and SSSS (soybean monocrop). The third factor was N fertilization, at three different rates: 0, 90, and 180 kg/ha, excepting the continuous soybeans which received lower rates of, respectively, 0, 20 and 40 kg N/ha. Soil sampling was performed in 1994, during the last year of the 4-year rotations, at two different moments over the growing season, June and August, for all analysed soil properties, except aggregate stability and organic matter for which samples were taken only in September. (Abstract shortened by UMI.)

Nos últimos anos, novas estratégias têm sido desenvolvidas na obtenção de incrementos da produtividade agrícola associados à manutenção da qualidade do solo. No entanto, as terras agrícolas vêm perdendo a sua qualidade física decorrente dos processos de compactação a que estão sendo expostas. A compactação do solo, destaca-se a nível mundial como um dos principais responsáveis pela redução da produtividade das culturas. Pesquisas têm descrito o processo de compressão de solos formados sob a influência de clima temperado, bem como modelos que relacionam esse processo com os atributos intrínsecos dos solos. A informação disponível também demonstra que o processo de compactação depende do sistema de manejo de solo adotado. Entretanto, existe a necessidade de desenvolver estudos que permitam uma melhor compreensão do processo de compactação de solos desenvolvidos sob clima tropical. Nesse sentido, este trabalho testou a hipótese de que o processo de compactação e os indicadores derivados da curva de compressão de solos tropicais são influenciados diferenciadamente pelo sistema de manejo aplicado, devido às alterações que o mesmo induz nas propriedades físicas do solo. O objetivo geral deste estudo foi avaliar quantitativamente o processo de compactação e os indicadores “índice de compressão” e “pressão de preconsolidação” de solos submetidos a diferentes intensidades de tráfego em um pomar de laranja e diferentes intensidades de pisoteio animal em uma pastagem irrigada e obter, se possível, relações que permitam estimar esses indicadores a partir de propriedades do solo facilmente mensuráveis. Os objetivos específicos foram: i) determinar a influência de diferentes intensidades de tráfego no processo de compactação e nos parâmetros índice de compressão e pressão de preconsolidação de um Latossolo Vermelho Amarelo sob pomar de laranja e, a partir desses indicadores, avaliar a heterogeneidade da compactação; ii) avaliar a influência do pisoteio animal na compressibilidade de um Argissolo Vermelho submetido aos sistemas de pastejo rotacionado intensivo: irrigado e não irrigado; e iii) obter funções que permitam estimar a capacidade de suporte de carga do solo a partir de uma propriedade facilmente mensurável e de extrema importância para o crescimento de plantas: a resistência do solo à penetração. Os resultados referentes ao primeiro objetivo indicaram que o processo de compactação foi influenciado pela intensidade de tráfego, visto que os valores de pressão de preconsolidação diferiram nas posições de amostragem entre rodado, rodado e projeção da copa em relação à linha de cultivo. A pressão de preconsolidação resultou ser um indicador mais sensível que o índice de compressão na avaliação da heterogeneidade da compactação em áreas citrícolas. Os resultados obtidos no segundo objetivo revelaram diferenças na compressibilidade do solo, refletindo-se nas curvas de compressão uniaxial dos sistemas de pastejo rotacionado intensivo irrigado e não irrigado. Os sucessivos ciclos de pastejo induziram aumento da pressão de preconsolidação do solo nos dois sistemas de pastejo, sendo significativamente superior no sistema de pastejo rotacionado intensivo irrigado. No que se refere ao terceiro objetivo, foi determinada uma relação significativa, positiva e linear entre a pressão de preconsolidação e a resistência do solo à penetração medida no laboratório e no campo. Estes resultados possibilitam afirmar que a capacidade de suporte de carga do solo pode ser estimada a partir de uma propriedade física facilmente mensurável como a resistência do solo à penetração avaliada no campo.
In the last years new strategies have been developed to obtain increment of the agricultural productivity maintaining the soil quality. However, the agricultural lands quality is decreasing as a consequence of the soil compaction process. Soil compaction is considered as one of the main factors responsible for the reduction of the cultures productivity. Researches related to soils formed under the influence of temperate climate have described the process of soil compression, and developed models that relate this process with the soil intrinsic attributes. Studies have also shown that the soil compression process depends on the soil management practices. However, it is still necessary to develop studies that allow a better understanding the compaction process of soils developed under tropical climate. In this context, this research tested the hypothesis that the soil compaction process is influenced differently by the management practices, due to the alterations that induce on the soil physical properties. The general objective of this study was to evaluate quantitatively the compaction process, and the indicators “compression index” and “preconsolidation pressure” of soils submitted to different traffic intensities in an orchard, and different animal trampling intensities in an irrigated short duration grazing system, and to obtain relationships that allow to estimate these indicators using easily measurable soil attributes. The specific objectives were: i) to determinate the influence of different traffic intensities in the soil compaction process, and in the compression index and preconsolidation pressure of an Haplustox under an orange orchard, and to use these indicators to evaluate the soil compaction heterogeneity; ii) to evaluate the influence of the animal trampling on the soil compressibility of an Hapludalf submitted to two rotation short-duration grazing systems: not irrigated and irrigated; and iii) to obtain functions that allow to estimate the load support capacity using an easily measurable and very important soil property for plant growth; i.e. the soil resistance to penetration. The results related to the first objective indicated that the compaction process was influenced by the traffic intensity, since that the preconsolidation pressure values were different between the sampling positions; i.e., between wheel track, wheel track, canopy projection, and row. The preconsolidation pressure demonstrated to be a more sensitive indicator than the compression index in the evaluation of the soil compaction heterogeneity in an orange orchards. The results related to the second objective have indicated differences in the soil compressibility, which in turn were expressed in the soil compression curves of the irrigated and not irrigated rotation short-duration grazing systems. The successive grazing cycles have induced increases of the soil preconsolidation pressure values of the two grazing systems, being significantly greater in the irrigated rotation short-duration grazing system. The results related to the third objective have demonstrated the existence of a significant, positive and linear relationship between the preconsolidation pressure values and the soil mechanical resistance that were measured in the laboratory and in the field. These results make possible to state that the soil load support capacity can be estimated using an easily measurable soil property; i.e. the soil resistance to penetration.

A compactação do solo é comumente observada em lavouras em que foi adotado o sistema de plantio direto. Sua origem está relacionada ao acúmulo do efeito das pressões produzidas pelo trânsito de máquinas agrícolas e/ou de animais. A compactação do solo impõe restrições ao desenvolvimento das culturas e compromete seu potencial produtivo, basicamente por reduzir a disponibilidade de água às plantas, por dificultar as trocas gasosas e o suprimento de oxigênio às raízes e por reduzir o volume de solo explorado pelas raízes em função da elevada impedância mecânica. Este trabalho foi realizado na área experimental da Universidade Tecnológica Federal do Paraná (UTFPR), Campus Dois Vizinhos. Os objetivos do estudo foram avaliar as alterações nas propriedades físicas do solo e os efeitos sobre a produtividade da cultura do trigo em um Nitossolo Vermelho distroférrico submetido a três níveis iniciais de compactação. O delineamento experimental foi o de blocos ao acaso com três repetições com parcelas subdivididas. Os níveis de compactação do solo utilizados foram distribuídos nas parcelas principais sendo caracterizados como: plantio direto contínuo (PDC); plantio direto escarificado (PDE); plantio direto com compactação adicional (PDA). Nas subparcelas aplicaram-se quatro sistemas de manejo: PD + escarificacão antecedendo a implantação da cultura de verão; cultivo de guandu-anão (Cajanus cajan L.) no outono; cultivo de nabo forrageiro (Raphanus sativus L.) no outono; e plantio direto contínuo. A escarificação reduziu a densidade do solo na profundidade de 0,05 – 0,10 m, em relação aos níveis de compactação PDC e PDA, mas não incrementou o rendimento. O sistema de manejo do solo utilizando a escarificação promoveu alterações significativas nas propriedades físicas do solo, porosidade total e resistência à penetração e aumentou o número de grãos por espigueta. A produtividade do trigo não foi sensível às variações de resistência à penetração, densidade e porosidade do solo resultantes de diferentes níveis de compactação iniciais do solo e dos sistemas de manejo de recuperação do solo.
Soil compaction is usually observed in soil cultivated at no-tillage system. Soil compaction is caused by accumulation of pressure exerted by machines and animal that travels on the soil. Soil compacted affect the crops development and yield, mainly because decrease the water disponibility, reduce the soil aeration and restrict root growth because increase the soil resistance to penetration. This study was performed at the experimental area of Federal Technological University of Paraná (UTFPR), Campus Dois Vizinhos, State of Paraná, Brazil. The present study was carried out with the objective of evaluating the change in soil physical properties and a Wheat grain yield in an Oxisol (Nitossolo Vermelho distroférrico, Brazilian Soil Classification System) submited to three initials compaction levels. The experimental design was a two-factors split-plot arranged in complete random blocks, with three repetitions. The main plots had three compaction levels: continuous no-tillage (PDC); no tillage with chiseling (PDE); no tillage with additional compaction (PDA). The subplots had the soil management systems: chiseling every two years; oil seed radish (Raphanus sativus L.) cultivated every two years, in the Fall; pigeon pea (Cajanus cajan L.) cultivated every two years, in the Fall; and a control treatment without green manure and chiseling. The results showed that the chiseling reduced bulk density at depth 0,05 – 0,10 m, compared with levels continuous no-tillage and additional compaction, but, did not enhance performance the wheat. The soil chiseling or cover crops cultive showed effects on the physics soil properties evaluated, total porosity and resistance to penetration and increased the number of grains per spikelet The wheat yield wasn’t sensitive to changes on physics soil properties observed in the soil with different initial levels compaction and soil management systems.

Naturally occurring radioactive isotopes of 210Pb and 7Be in the atmosphere, plant material and soil have been used to investigate the transport and removal of atmospheric aerosols from the atmosphere by precipitation and turbulent deposition to natural surfaces. Concentrations of 210Pb and 7Be contained in aerosols in surface air were measured using a high volume sampler at the King’s Buildings site of the University of Edinburgh (55.9°N, 03.2°W) over a 12 month period (July 2002-June 2003). The log-normally distributed concentrations of 210Pb, with a median of 0.141 mBq m−3 over the monitoring period, indicated a surface source and dispersion by wind. The concentrations were largest in air with trajectories over terrestrial surfaces, consistent with soil as the source, and smallest in air with marine trajectories and also air masses subject to precipitation, the main removal process for aerosol bound 210Pb. Concentrations of 7Be were largest during spring which is consistent with a stratospheric origin and, like 210Pb, concentrations were smaller in air masses subject to precipitation. Measurements of 210Pb and 7Be in tree foliage, precipitation and throughfall water beneath tree canopies were used to investigate the transport pathway of these isotopes from the atmosphere to soil. The measurements showed that the 210Pb aerosols attach and bind effectively to foliar surfaces, so that deposition to soil relies mainly on leaf fall. In open parkland trees, the distribution of the falling leaves determines the deposition of the 210Pb. Foliar surfaces effectively filter 7Be from precipitation as it passes through the woodland canopy. Studies of soil inventories of 210Pb beneath woodland and grassland, undisturbed for several half-lives of the isotope, were used to deduce annual average fluxes, wet deposition, cloud droplet deposition and dry deposition of aerosols onto these surfaces. The measurements showed dry deposition velocities of 210Pb containing aerosols of 7.4 +/- 1.8 mm s−1 on mature mixed deciduous woodland, and 2.6 +/- 1.3 mm s−1 on grassland, substantially larger than current theoretical values but consistent with much recent work by a range of methods.

A região amazônica possui extensas áreas que foram desmatadas e convertidas em sistemas de pastagens. A falta de técnicas na implantação e no manejo destes sistemas resultou em inúmeras áreas de pastagens degradadas. A condução de experimentos de campo visando a reversão deste quadro está sendo avaliada no presente estudo. A área em estudo está localizada na Fazenda Nova Vida, município de Ariquemes, Estado de Rondônia/RO. O solo da fazenda foi classificado como Latossolo Vermelho Amarelo. Os tratamentos utilizados consistiram em dois sistemas de plantio direto (arroz e soja), aplicação de herbicida no controle de invasoras, operação de gradagem e a pastagem controle. O Intervalo Hídrico Ótimo (IHO), a densidade do solo, resistência à penetração, macroporosidade, microporosidade, porosidade total e permeabilidade do solo ao ar foram determinadas. Não foi verificada diferença significativa entre os tratamentos utilizados. O solo estudado não apresentou restrições físicas ao crescimento de plantas. As variações na estrutura do solo são melhor avaliadas quando os fatores que afetam diretamente o crescimento de plantas são integrados em um único parâmetro. As propriedades físicas determinadas foram menos sensíveis que o IHO às alterações provocadas pelos sistemas de manejo. O IHO possui um grande potencial como índice de qualidade física do solo na avaliação de experimentos que visam a recuperação de pastagens degradadas, pois integra em um único parâmetro os fatores diretamente relacionados ao crescimento de plantas.
The Brazilian Amazon region has extensive areas that had been deforested and converted into pasture systems. The absence of adequate techniques in implementation and management of these pastures resulted in pasture degradation in several areas. Field experiments with objective of reverting the degradation process are being evaluated in this study. The field site was located at the Nova Vida farm, Ariquemes county, Rondonia State, Brazil. The soil at the farm was classified as “Latossolo Vermelho Amarelo” in agreement with Brazilian classification system. The treatments consisted of two no-tillage systems (rice and soybeans), weed control using herbicides, harrowing and control pasture. The Least Limiting Water Range (LLWR), soil bulk density, soil penetration resistance, macroporosity, microporosity, total porosity and soil air permeability were also evaluated. There was no significant difference between treatments under evaluation. The soil estudied did not show physical restrictions to plants growth. Soil structure variations are better evaluated when the factors that affect directly plant growth are integrated in a single parameter. The soil physical properties evaluated were less sensitive than the LLWR to alterations caused by the management systems. The LLWR has a great potential as a soil physical quality index in the evaluation of experiments designed to recover degraded pastures because it integrates in a single parameter the factors directly related to plant growth.

The impacts of El Nino Southern Oscillation (ENSO) on precipitation, reference evapotranspiration, and vegetation in a three-state region of central Mexico were investigated using daily weather data from 20 weather stations for the years 1970 through 1990, which included 5 El Nino years, 5 La Nina years, and 11 Neutral years. In addition, two years, 1997 (El Nino), and 1998 (La Nina) of 10-day NDVI composites were analyzed during the growing season (May-Oct) along with precipitation and reference evapotranspiration (ETo) over central Mexico. Regional precipitation trends were analyzed using the normalized rainfall departures. The interannual variation of vegetation cover was analyzed using the NDVI on 10-day and monthly bases. The Food and Agricultural Organization (FAO) Penman-Monteith method was used to calculate ETo. The dynamics of the soil water balance in central Mexico was evaluated according to the method proposed by Thornthwaite and Mather. Analyses indicate that driest conditions occurred within the northern part of the region and during neutral ENSO years. Rainfall amounts during El Nino and Neutral years were not statistically different however, La Nina years were about 30% wetter than N and EN years (0.05 level). The correlation coefficient between NDVI and precipitation was 0.79 in 1997, and 0.52 in 1998, in June and July, respectively. Negative correlation was found between NDVI and reference evapotranspiration during the rainy months of July and August. The spatio-temporal variability of NDVI showed that there was significant statistical difference in NDVI between regions, but not between years. Regional soil water balance determinations indicated that conditions were most favorable in the Southern part of the region for crop growth during La Nina years. In general, soil water deficits were reduced by about 50% during the growing season compared to the annual soil water deficits.

Orientador: Carolina Fernandes
Banca: Ricardo Augusto Martins Cordeiro
Banca: José Eduardo Corá
Resumo: O preparo do solo é uma operação de alto custo na reforma do canavial, portanto medidas para a redução desse custo são desejáveis, desde que propiciem boas condições físicas para o desenvolvimento das plantas. O objetivo deste trabalho foi avaliar os atributos físicos de Latossolo Vermelho e de Argissolo Amarelo após o preparo do solo e após o plantio da cana-de-açúcar. O delineamento experimental foi em parcelas grandes e uniformes com dois tratamentos e dez repetições. Os tratamentos consistiram no preparo do solo para plantio da cana-de-açúcar: escarificação na linha de plantio e escarificação em área total. Após o preparo do solo e após o plantio, foram coletadas amostras indeformadas de solo em cada parcela experimental, em quatro camadas: 0,00-0,10; 0,10-0,20; 0,20-0,40 e 0,40-0,60 m em dois locais de amostragem, na linha e na entrelinha de plantio. Foi avaliada a resistência à penetração, a densidade do solo, a porosidade total, a macroporosidade e a microporosidade. Os resultados indicaram que o Latossolo Vermelho foi mais susceptível que o Argissolo Amarelo às alterações nos atributos físicos do solo após as operações de plantio da cana-deaçúcar até a camada de 0,40 m. Para o Latossolo Vermelho, após as operações de plantio da cana-de-açúcar foi verificado redução nos valores dos atributos físicos do solo na camada superficial. Para o Argissolo Amarelo, as operações de plantio da cana-de-açúcar não influenciaram nos valores dos atributos físicos. A escarificação do s... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The soil tillage demands a high cost operation to repair the canebrake. So, it is necessary some activities to reduce these costs to get good physical conditions for plant development. The aim of this study was to evaluate the physical attributes of Oxisol and Ultisol, after the soil have been prepared and after sugar cane plantation. The experimental approach was in big and uniforms parcels with two treatments and ten repetitions. The treatment was made in the prepare of soil and in the cane plantation: chiselling in the planting line and in total area. After the soil has been prepared, also after planting sugar cane, some undeformed samples of soil was collected in each experimental parcel, in four layers: 0,00-0,10; 0,10-0,20; 0,20-0,40 and 0,40-0,60 m in two different place, in the line and between line of planting area. It was also evaluated the resistance and penetration, soil density, total porosity, macro and micro porosity. The results indicates that Oxisol was more susceptible than Ultisol to alterations in the soil physical attributes after operations in cane plantation until the layer 0,40 m. For the Oxisol, after the plantation of sugar cane, was verified some reduction of values in soil physical attributes in the superficial layer. For Ultisol, the operations in the planted area of sugar cane did not influence in these attributes values. The chiselling of soil was done just in the planting line of sugar cane, it indicates that the chiselling is more recommended ... (Complete abstract click electronic access below)
Mestre

O Estado do Rio Grande do Sul é responsável por 90% da produção nacional de uvas, sobretudo para a elaboração de vinhos finos. O município de Encruzilhada do Sul apresenta potencial edafoclimático ideal para a produção de uvas que abastecem grandes vinícolas da Serra Gaúcha. Entretanto o uso indiscriminado do solo pode resultar em uma degradação do solo. Este trabalho foi dividido em três estudos, que tiveram como objetivo Identificar as classes de solos ocorrentes no vinhedo, de acordo com a descrição morfológica e análise dos atributos químicos e físicos dos horizontes superficiais e subsuperficiais; Avaliar o efeito do manejo na qualidade química do solo de um vinhedo comercial, em áreas com 4, 9 e 16 anos de manejo após o plantio de videira da variedade Vitis vinifera L. cv. Pinot Noir para a elaboração de espumantes; Avaliar o efeito do tráfego de máquinas agrícolas na qualidade física do solo de um vinhedo comercial com diferentes anos de condução após o plantio das mudas. Foram realizados análises de perfis de 8 trincheiras em campo e com análises laboratoriais. Foi realizado o estudo dos atributos químicos e físicos do solo utilizados como indicadores de qualidade do solo, para avaliar o efeito do manejo do vinhedo com 4, 9 e 16 anos de condução após o plantio das mudas. Para análise da qualidade química do solo foram coletadas amostras indeformadas do solo nas profundidades de 0-10, 10-20, 20-30, 30-40, 40-50 e 50-60 cm, em três repetições. Os atributos físicos do solo foram analisados nas mesmas áreas e profundidades, que foram coletadas no local de trafego do rodado (R), entre rodados (ER) e linha de plantio (LP). 80% da propriedade é constituída por Argissolos diversificados, além de Cambissolos, estes ideais para a cultura da videira. Além desses solos, foi identificado na propriedade a presença de Gleissolo, que não são recomendados para o cultivo devido ao seu caráter hidromórfico. Pode-se observar uma redução na acidez do solo e incremento da fertilidade devido ao histórico de cultivo do vinhedo. Para a análise dos indicadores de qualidade física do solo, foram coletadas amostras do solo nas mesmas profundidades, em três locais na entrelinha: entre rodados, rodados e linha de plantio. A área com 16 anos de condução após o plantio apresentou maior efeito do uso de máquinas no vinhedo, sobretudo na posição de tráfego dos rodados do trator, afetando seriamente a qualidade física devido à compactação e baixa infiltração de água no solo.
The State of Rio Grande do Sul is responsible for 90% of the national production of grapes, mainly for the elaboration of fine wines. The municipality of Encruzilhada do Sul presents ideal edafoclimatic potential for the production of grapes that supply large wineries in the Serra Gaúcha. However the indiscriminate use of the soil can result in a degradation of the soil. This work was divided into three studies, which aimed to identify the soil classes occurring in the vineyard, according to the morphological description and analysis of the chemical and physical attributes of the superficial and subsurface horizons; To evaluate the effect of the management on the chemical quality of the soil of a commercial vineyard in areas with 4, 9 and 16 years of management after planting Vitis vinifera L. cv. Pinot Noir for the preparation of sparkling wines; To evaluate the effect of the traffic of agricultural machines on the physical quality of the soil of a commercial vineyard with different years of driving after planting the seedlings. Analyzes of profiles of 8 trenches were carried out in the field and with laboratory analyzes. The study of soil chemical and physical attributes used as soil quality indicators was carried out to evaluate the effect of vineyard management at 4, 9 and 16 years of age after planting the seedlings. For the analysis of soil chemical quality, undisturbed soil samples were collected at depths of 0-10, 10-20, 20-30, 30-40, 40-50 and 50-60 cm in three replicates. The physical attributes of the soil were analyzed in the same areas and depths, which were collected in the traffic site of the wheel tracks of the tractor (WT), between the wheel tracks (BWT), and in the area under the line projection of the canopy (CLP). 80% of the property consists of diversified Argissolos, in addition to Cambisols, these are ideal for vine growing. In addition to these soils, the presence of Gleissolo was identified in the property, which are not recommended for cultivation due to its hydromorphic character. A reduction in soil acidity and an increase in fertility can be observed due to the vineyard's cultivation history. For the analysis of soil physical quality indicators, soil samples were collected at the same depths, at three sites in the interline: between rounds, rounds and planting line. The area with 16 years of driving after planting showed a greater effect of the use of machines in the vineyard, especially in the traffic position of tractor wheels, seriously affecting the physical quality due to compaction and low infiltration of water in the soil.

Orientadora: Teresa Cristina Tarlé Pissarra
Banca: Renato Farias do Valle Junior
Banca: Sérgio Campos
Banca: José Frederico Centurion
Banca: João Antonio Galbiatti
Resumo: A retirada da cobertura vegetal original e a implantação de áreas de pastagem e canade- açúcar, com práticas de manejo inadequadas, acarretam modificações nas propriedades químicas, físicas e biológicas dos solos, com limitações na utilização agrícola e susceptibilidade à erosão. Assim, estudos dos processos físicos e químicos são importantes para avaliar as mudanças de origem natural ou antrópica sobre os meios. O estudo teve como objetivos avaliar os atributos químicos e físicos de um Argissolo Vermelho-Amarelo em três microbacias hidrográficas, em áreas de vegetação nativa, pastagem e cana-de-açúcar bem como analisar a ocorrência das áreas de maior escoamento superficial e, consequentemente, maior predisposição ao processo erosivo nas microbacias. A área de estudo compreendeu a microbacia hidrográfica do Córrego da Fazenda Glória, Município de Taquaritinga, Estado de São Paulo. Para a amostragem do solo foi realizada a caracterização do volume superficial, e essas amostras foram coletadas na superfície das vertentes das microbacias e em cada uso/ocupação selecionado. Os resultados obtidos foram avaliados por meio da comparação de médias para o teste de Tukey a 5%. A partir das curvas de nível da carta topográfica e dos pontos levantados com receptor geodésico de navegação com metodologia diferencial foi gerado uma malha de pontos georreferenciados em cada microbacia, para gerar o modelo numérico do terreno a partir da incorporação dos divisores de água e da rede de drenagem. As avaliações dos atributos físicos e químicos dos solos nas microbacias hidrográficas e em diferentes tipos de uso e ocupação demonstraram uma diferença significativa entre as áreas. O manejo do solo alterou os atributos químicos e físicos com impacto nas camadas superficiais do solo. A matéria orgânica foi um dos atributos mais sensíveis... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The removal of original vegetation cover and the deployment of pastures and sugarcane, with inadequate management practices, cause changes in the chemical, physical and biological properties of soils, with limitations on agricultural use and susceptibility to erosion. Thus, studies of physical and chemical processes are important to assess changes of natural development or anthropic on the means. The study was conducted to evaluate the physical and chemical attributes of a Ultisol in three watersheds, in areas of native vegetation, pasture and sugarcane, as well as, analyze the occurrence of the areas of greatest runoff and, consequently, greater predisposition to erosive processes in watersheds. The study area was the Córrego da Fazenda Glória watershed, Municipality of Taquaritinga, State of São Paulo. Soil sampling was performed to characterize the superficial volume, and these samples were collected on the surface of the watersheds and in three different land use selected. The results obtained were evaluated by the comparison of averages for the Tukey test at 5%. From the curves in a topographical map and from points collected with geodetic navigation receiver in a differential methodology was generated a digital elevation method in each watersheds. The assessments of physical and chemical attributes of soils in hydrographic watersheds and different land uses demonstrated a significant difference between the areas. Soil management altered the chemical and physical attributes impact in the soil superficial layers. The organic matter was one of the attributes more sensitive to changes due to agricultural practices. The digital terrain model showed a great potential, considering the scale of study of watersheds; and can help in spatial planning, urban and regional planning and zoning
Doutor

Estudos mostram que ocorre uma compactação superficial após alguns anos de utilização do sistema plantio direto (SPD), podendo interferir no desenvolvimento das plantas. A escarificação tem sido utilizada para amenizar os efeitos da compactação sob SPD, porém há evidências de que seus efeitos são de curta duração. O objetivo deste trabalho foi avaliar o comportamento de alguns parâmetros físicos após a escarificação em curto prazo (um ano) nas seguintes profundidades: 0,0-0,10 m; 0,10-0,20 m; 0,20-0,30 m; 0,30-0,40 m. A densidade do solo (Ds) e o grau de compactação (Gc) foram analisados em área de plantio direto por 16 anos (PD), imediatamente após a escarificação (ESC), seis meses (ESC6M) e um ano após a escarificação (ESC12M). Nas camadas superiores a densidade do solo apresentou variação semelhante, com redução significativa em ESC e um aumento expressivo em ESC6M, sendo que a Ds retornou aos valores registrados antes da mobilização em ESC12M. Nos períodos ESC, ESC6M e ESC12M foi observado um aumento da Ds na camada 0,30-0,40 m em comparação com o PD. A escarificação provocou redução do grau de compactação nas camadas 0,0-0,10 m e 0,10-0,20 m, com o Gc retornando aos valores originais um ano após a escarificação. Os maiores valores de Gc foram observados seis meses após a escarificação, porém o solo apresentou grande recuperação visto que em ESC12M o grau de compactação apresentou tendência de retorno aos valores originais em todas as profundidades, possivelmente devido à alta resiliência do solo. Os efeitos da escarificação avaliados pela Ds e Gc apresentaram duração inferior a um ano, sugerindo que neste solo não é necessária esta operação.
Studies show that a surface compaction occurs after some years adoption of no-tillage (NT), which may interfere in plant development. Chiseling has been used to alleviate the effects of soil compaction under NT, but studies show that this operation has short-term effects. The aim of this study was to evaluate the behavior of some physical parameters after chiseling in shortterm (one year) in the following depths: 0.0 to 0.10 m, 0.10-0.20 m, 0.20-0, 30 m, 0.30 to 0.40 m. Soil bulk density (BD) and the degree of compactness (DC) were analyzed in long-term (16 years) no-tillage (NT), chiseling of the long-term no-tillage (CHI), six months (CHI6M) and one year after chiseling (CHI12M). In top layers bulk density showed similar variation, with significant reduction in CHI and a marked increase in CHI6M, returning to the values recorded before mobilization in CHI12M. In periods CHI, CHI6M and CHI12M was an increase in the BD 0.30-0.40 m layer in comparison with NT. Chiseling caused a reduction the degree of compaction in the layers 0.0-0.10 m and 0.10-0.20 m, with DC returning to the original values one year after chiseling. The greatest DC values were observed six months after chiseling, nevertheless the soil showed great recovery whereas in CHI12M the degree of compactness tended to return to the original values in all layers, possibly due the high soil resilience. The duration of chiseling effects measured by BD and DC was less than one year, suggesting in this soil is not necessary this operation.

O presente trabalho teve por objetivo estudar o tempo necessário para que o fluxo da água no solo sob condições de saturação atinja o equilíbrio dinâmico, medindose a condutividade hidráulica saturada (K0) do solo. A condição de equilíbrio dinâmico é a etapa que antecede a aplicação do íon no solo em estudos de eluição de solutos. Utilizaram-se amostras deformadas de três solos com diferentes granulometrias: muito argilosa, média e arenosa, coletadas em área experimental da ESALQ/USP. As amostras foram acondicionadas em colunas de PVC, e utilizou-se água destilada e deaerada para saturação e posterior escoamento nas colunas, conforme a montagem experimental do permeâmetro de carga constante. Os resultados demonstraram que para as amostras dos solos muito argiloso e médio, o equilíbrio foi atingido após 15 dias de drenagem e para o arenoso essa condição só foi verificada após 27 dias, sendo a variabilidade de K0 maior nos primeiros seis dias de ensaio. Concluindo-se, portanto pela inadequação da utilização de um tempo fixo para a adição dos solutos.
The purpose of this work is to study the time for the water flow in soil under saturation to reach the steady-state, by measuring the saturated hydraulic conductivity (K0) of soil. The steady-state is the stage that precedes the application of the ion solution in the soil sample in solute elution studies. Disturbed soil samples with different granulometries were used: very clayey, clay-sandy and sandy soil, collected in experimental area of the ESALQ/USP. The samples were conditioned in PVC columns, and distilled and deaerated water were used for saturation and subsequent drainage in the columns, the test is in accordance with the experimental assembly of constant head permeameter. The data demonstrated that for very clayey and clay-sandy samples, the steady-state was reached after 15 days and for sandy soil this condition was verified after 27 days, being the variability of K0 bigger in the first six days of the test. Therefore it was concluded that is inadequate to use a fixed time for the addition of solutes in soil.

Sendo a condutividade hidráulica do solo um parâmetro que traduz a facilidade com que a água se movimenta ao longo do perfil de solo, sua determinação, principalmente no campo, torna-se imprescindível, visto que o movimento da água no solo está diretamente relacionado à produção das culturas agrícolas. Com isso, a aplicação de um método confiável que quantifique a condutividade hidráulica versus umidade, a função ( ) q K , certamente contribuirá muito para uma correta avaliação dos resultados, principalmente tendo em conta a grande variabilidade dessa função devido à variabilidade natural das características do solo. Neste trabalho, testou-se o método do perfil instantâneo com o objetivo de avaliar a função ( ) q K com e sem a suposição de gradiente unitário e também o seu comportamento com relação aos os horizontes pedológicos do solo. A determinação da função foi feita usando tensiômetros com manômetros de mercúrio instalados às profundidades de 0,1; 0,2; 0,3; 0,4; 0,5; 0,6; 0,7; 0,8; 0,9; 1,0; 1,1 e 1,2 m e curvas de retenção determinadas para as mesmas profundidades, num Latossolo Vermelho Distrófico argissólico A moderado textura média, localizado no campo experimental da Escola Superior de Agricultura "Luiz de Queiroz", Universidade de São Paulo. A análise dos resultados foi feita pelo teste F de análise de variância, a fim de testar o paralelismo, a igualdade dos interceptos e a coincidência entre as retas lnK versus q, considerando e não considerando a suposição do gradiente unitário. Além disso, foram feitos também testes de similaridade da função ( ) q K de cada profundidade do solo pelo índice de concordância de Willmott (1981). Com base na análise dos resultados pode-se dizer que, com os procedimentos utilizados de delimitação da área para inundação e redistribuição da água, podem ser empregados modelos simples que consideram unitário o gradiente de potencial total e que, pela comparação feita entre as profundidades, a separação do perfil do solo em horizontes pedológicos parece seguir a separação em camadas com funções ( ) q K semelhantes, apenas a partir da profundidade 0,6 m.
The soil hydraulic conductivity is a parameter that quantifies the ability of the soil to conduct water along the soil profile. Hence its field determination is indispensable, since soil water movement is directly related to the field crop productions. Thus, the use of an adequate method that assesses the hydraulic conductivity as a function of soil-water content, the ( ) q K function, certainly will very contribute to a proper evaluation of results, mainly if it is considered the great variability of this function as a result of the natural variability of the soil characteristics. In this work, the instantaneous profile method was tested with the objective to evaluate a) the ( ) q K function taking and not taking into consideration the assumption of unit gradient and b) the behaviour of the ( ) q K function with respect to the pedological horizons of the soil. The determination of the function was made using mercury manometer tensiometers installed at the depths of 0.1; 0.2; 0.3; 0.4; 0.5; 0.6; 0.7; 0.8; 0.9; 1.0; 1.1 and 1.2 m and soil water retention curves determined for the same depths, in an Oxisol, located at experimental fields of Escola Superior de Agricultura Luiz de Queiroz, University de São Paulo, in Piracicaba (SP), Brasil (22 o 42’ 43,3’’ W and 47 o 37’ 10,4’’ S). The result analysis was made using an F-test in order to verify the paralelism, the intercept equality and the coincidence of the lnK versus q straight lines, taking and not taking account of the assumption of unit hydraulic gradient. Basides, similarity tests of the ( ) q K function were also made by the Willmott (1981) index. From the analysis of results, it could be concluded that, with the procedures used to delimit the experimental plots in this experiment to water the soil profile and to follow the water redistribuition, the unit gradient approches seem to be adequate to assess the field ( ) q K function and also that the pedological horizons seem to follow the layers of similar ( ) q K function, for depths greater than 0.6 m.

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As modificações causadas por atividades antrópicas como o tráfego de máquinas afetam diretamente a estrutura do solo, por isto, a importância de avaliar a compactação do solo devido ao tráfego agrícola, assim como a magnitude dos impactos do rodado sobre a qualidade física dos solos. O trabalho teve por objetivo avaliar a influência do teor de agua na avaliação de resistência mecânica a penetração do solo medida através do índice de cone (IC), a ocorrência e distribuição da compactação ao longo do perfil do solo causada pelo trafego agrícola, assim como os consequentes reflexos nos atributos físicos do solo. O experimento foi realizado na Fazenda Lageado da UNESP/FCA, Botucatu/SP, sendo selecionadas duas classes de solo, o Nitossolo Vermelho distroférrico (NVd) de textura argilosa, com 50 % de teor de argila e o Latossolo Vermelho (LV) de textura média, com 25 % de teor de argila. O delineamento experimental foi casualizado, com os seguintes tratamentos de compactação: T0 = 0; T1 = 1; T2 = 2; T3 = 3; T4=5 e T5 = 10 passadas consecutivas de um trator agrícola. Utilizou-se um penetrômetro hidráulicoeletrônico para a amostragem da resistência mecânica do solo a penetração nas camadas de 0 a 0,10; 0,10 a 0,20; 0,20 a 0,30; 0,30 a 0,40m em 4 condições de teor de água, que variou de 17,1 a 24,5% para o NVd e de 10,0 a 17,8% para o LV. Também foram determinados os seguintes atributos: recalque do solo, infiltração de água no solo...
The changes caused by human activities such as machinery traffic directly affect soil structure, therefore, the importance of assessing soil compaction due to agricultural traffic, as well as the magnitude of the impact of the wheelset on the physical quality of the soil. The study aimed to evaluate the influence of water content in soil penetration resistance evaluation measured by the soil Cone Index (CI), the occurrence and distribution of compression along the soil profile, caused by agricultural traffic, as well as the resulting consequences on soil physical properties. The experiment area was at Lageado Experimental Farm, UNESP/FCA, Botucatu/São Paulo, two different soil type was used, Nitossolo Vermelho distroférrico (NVd) clayey, 50% clay content and Latossolo Vermelho (LV) of medium texture, 25% clay content. Was used an randomized experimental design with the following compaction treatments: T0 = 0; T1 = 1; T2 = 2; T3 = 3; T4= 5 and T5 = 10 consecutive passes of an tractor. An hydraulic-electronic penetrometer was used to measure the soil resistance at 0-0.10; 0.10-0.20; 0.20-0.30 and 0.30-0.40 m in 4 different water content ranging from 17.1 to 24.5% for NVD and 10 to 17.8% for LV. It was also determined the following attributes: soil repression, water infiltration into the soil, bulk density and porosity. The major soil penetration resistance values were detected near the ground shrinkage limit and the treatment with increased intensity agricultural traffic, already in high moisture soil conditions, the soil penetration resistance values were reduced being considered not hindering the growth of roots. The clay soil proved to be the most sensitive to the effect of water content in soil compaction evaluation, the greater variation among samples collected with water content between field capacity (FC) and permanent wilting point (PWP) ...

Orientador: Kleber Pereira Lanças
Banca: Maria Helena Moraes
Banca: Marlene Cristina Alves
Resumo: As modificações causadas por atividades antrópicas como o tráfego de máquinas afetam diretamente a estrutura do solo, por isto, a importância de avaliar a compactação do solo devido ao tráfego agrícola, assim como a magnitude dos impactos do rodado sobre a qualidade física dos solos. O trabalho teve por objetivo avaliar a influência do teor de agua na avaliação de resistência mecânica a penetração do solo medida através do índice de cone (IC), a ocorrência e distribuição da compactação ao longo do perfil do solo causada pelo trafego agrícola, assim como os consequentes reflexos nos atributos físicos do solo. O experimento foi realizado na Fazenda Lageado da UNESP/FCA, Botucatu/SP, sendo selecionadas duas classes de solo, o Nitossolo Vermelho distroférrico (NVd) de textura argilosa, com 50 % de teor de argila e o Latossolo Vermelho (LV) de textura média, com 25 % de teor de argila. O delineamento experimental foi casualizado, com os seguintes tratamentos de compactação: T0 = 0; T1 = 1; T2 = 2; T3 = 3; T4=5 e T5 = 10 passadas consecutivas de um trator agrícola. Utilizou-se um penetrômetro hidráulicoeletrônico para a amostragem da resistência mecânica do solo a penetração nas camadas de 0 a 0,10; 0,10 a 0,20; 0,20 a 0,30; 0,30 a 0,40m em 4 condições de teor de água, que variou de 17,1 a 24,5% para o NVd e de 10,0 a 17,8% para o LV. Também foram determinados os seguintes atributos: recalque do solo, infiltração de água no solo...
Abstract: The changes caused by human activities such as machinery traffic directly affect soil structure, therefore, the importance of assessing soil compaction due to agricultural traffic, as well as the magnitude of the impact of the wheelset on the physical quality of the soil. The study aimed to evaluate the influence of water content in soil penetration resistance evaluation measured by the soil Cone Index (CI), the occurrence and distribution of compression along the soil profile, caused by agricultural traffic, as well as the resulting consequences on soil physical properties. The experiment area was at Lageado Experimental Farm, UNESP/FCA, Botucatu/São Paulo, two different soil type was used, Nitossolo Vermelho distroférrico (NVd) clayey, 50% clay content and Latossolo Vermelho (LV) of medium texture, 25% clay content. Was used an randomized experimental design with the following compaction treatments: T0 = 0; T1 = 1; T2 = 2; T3 = 3; T4= 5 and T5 = 10 consecutive passes of an tractor. An hydraulic-electronic penetrometer was used to measure the soil resistance at 0-0.10; 0.10-0.20; 0.20-0.30 and 0.30-0.40 m in 4 different water content ranging from 17.1 to 24.5% for NVD and 10 to 17.8% for LV. It was also determined the following attributes: soil repression, water infiltration into the soil, bulk density and porosity. The major soil penetration resistance values were detected near the ground shrinkage limit and the treatment with increased intensity agricultural traffic, already in high moisture soil conditions, the soil penetration resistance values were reduced being considered not hindering the growth of roots. The clay soil proved to be the most sensitive to the effect of water content in soil compaction evaluation, the greater variation among samples collected with water content between field capacity (FC) and permanent wilting point (PWP) ...
Mestre

In order to better model the climate system, land-surface models are continuously being improved. Several studies using the Biosphere-Atmosphere Transfer Scheme (BATS) are presented. One study compares simulations with the new ten-layer soil model (TLSM) and the previous BATS soil model at global and regional scales. TLSM tends to have much higher bare soil evaporation than the previous soil model. Soil in regions with high precipitation became wetter, while soil in regions with less precipitation became much drier. Potential errors in TLSM included underpredicted runoff and high-latitude transpiration. Corrections for these errors were incorporated and tested at six points. Surface runoff is increased by extracting water from the upper three TLSM layers rather than only the top layer. Bare soil evaporation is limited to the water present in the surface soil layer. A diurnal temporal error in the downward longwave radiation forcing data did not appear to significantly affect simulated long-term or large-scale averages. However, the assumption of uniform hourly distribution of 6-hour total precipitation did impact the partitioning of precipitation into evaporation, transpiration and runoff. A new method for modeling vertical water flow in heterogeneous porous media using the water-content based form of Richards equation is described, then used with BATS/TLSM to simulate the boreal forest energy and water exchanges at a black spruce site, where a thick moss layer covers a peat/loam soil, and at an aspen site with a homogenous clay soil. The moss is treated as a type of porous media, so its unique hydraulic and thermal properties can be modeled directly. Simulated net radiation is very similar to that observed over the summer months at both sites, but latent heat is greatly overestimated and simulated sensible heat fluxes are not well correlated with the observations. Observed soil temperature profiles and soil water content profiles are well captured at the black spruce site, as is the ability of moss to keep the underlying soil layers moist and cool. Despite the successful modifications made to TLSM during this study, the overestimation of evaporation remains a problem that should be addressed before widespread use of this model occurs.