A cana-de-açúcar é uma das mais importantes cadeias do agronegócio brasileiro, além do seu elevado destaque no contexto internacional como fonte de energia renovável e sustentável. Com a competitividade que as Usinas vem passando e pelas perspectivas de crescimento, este trabalho teve como hipóteses: i) o preparo profundo em cana-de-açúcar proporciona um maior volume de solo explorado pelas raízes; ii) o trafégo controlado de máquinas aliado ao espaçamento em fileiras duplas irá trazer uma maior população de plantas, traduzindo isso em incrementos de produtividade e redução de custos para o produtor. O objetivo geral, portanto, foi avaliar métodos de preparo do solo e desenvolver o tráfego contrololado na área, propondo assim que o produtor tenha redução nos custos com o manejo da cultura e também aumente a produtividade e longevidade do canavial. Portanto, pode-se concluir que na análise do comprimento de raízes, em todas as profundidades estudadas, o Preparo Profundo obteve comprimento, área e volume de raízes maiores estatisticamente. A Resistência do solo a penetração no tratamento Preparo Profundo, para as profundidades de 20-40 e 40-60 cm foi de 0,29 MPa e 0,45 MPa, respectivamente. Nas avaliações biométricas da parte área, o Preparo Profundo se destacou com um IAF de 7,1. Os custos das operações no momento do plantio foram bem inferiores no Preparo Profundo, sendo 33% e 58% inferiores aos Mínimo duplo e Convencional duplo, respectivamente. A movimentação do solo causada pelo sistema Preparo Profundo no preparo do solo, foi de até 80% inferior ao tratamento Convencional duplo. O tráfego controlado que o Preparo Profundo proporciona, diminui em até 70% o tráfego de máquinas na lavoura; menor consumo de combustível; redução no tempo das operações agrícolas; redução do parque de máquinas; e menor custo operacional. / Sugarcane is one of the most important crops in the Brazilian agribusiness chain, besides its great branch in the international context as a renewable and sustainable energy source. Through the competitiveness that sugar mills experience and through the growth perspectives of the sector, this study focuses the deep soil preparation for sugarcane crop renewal, since it provides a larger soil volume to be explored by the root system. Furthermore, the machinery traffic controlled by a smaller number of soil preparation operations, reduces farmer´s production costs. The general objective was, therefore, evaluate soil preparation methods and develop a controlled traffic system in the area, in order to propose to the farmer a cost reduction in the farm soil management along with yield increase and extension of the longevity of the crop. As a result of the imposed treatments it was possible to conclude that by the root length analysis in all depths of the Deep Soil Preparation, root length, area and volume were greater. Soil resistance to penetration in the Deep Soil Preparation system was much less in relation to the other treatments, assuming values of 0.29 MPa and 0.45 Mpa in the 20-40 and 40-60 cm layers, respectively. The above ground evaluations showed leaf area index of 7.1 for the Deep Soil Preparation, much higher in relation to the other treatments. Operation costs at planting time were much less for the Deep Soil Preparation, 33% and 58% smaller than for the Double Minimum Tillage and Double conventional, respectively. Soil movement caused by Deep Preparation was up to 80% less in relation to the Double conventional. The controlled machinery traffic that the Deep Soil Preparation provides, reduced up to 70% the farming operations, therefore presenting a lower fuel consumption, a reduction of the time used in farming operations, reduction of the machinery park, and a lower operational cost.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The Crop-Livestock System (ILP) refers to an association between two activities in the same area at different periods of the year, that involves annual crops and livestock. This study aimed to: (a) evaluate the dry matter yield and residual dry matter remaining of winter intercrop forage (oat, rye and vetch) under different heights of post-grazing residue, (b) compare the productivity of maize under different crop heights of post-grazing residue and (c) examine the changes in soil properties that may be caused by cattle during the growing season of corn. The experiment was conducted in the city of Mata - RS, on a commercial farm during the agricultural period of 2009/2010 and 2010/2011, in an Ultisol. The experimental design was a randomized block design using four heights of post-grazing residues: conventional grazing (PC), with an area of 500 m2, in which there was no control of movement of animals and tall forage during the grazing; residue height of 0.10 m (M-10), 0.20 m (M- 20), 0.30 m (M-30) and an area not grazed (SP). To meet the proposed objectives, the work was divided into three parts. The first part was performed by evaluating during two periods of each crop year, soil bulk density, microporosity, macroporosity and total porosity at depths of 0.0 to 0.025, 0.025 to 0.05, 0.05-0.10 and 0.10-0.15 m, the rate of water infiltration in soil, soil resistance to penetration, phosphorus, potassium and soil organic matter. When managed correctly, the presence of animals in pasture areas will not negatively effect soil physical and chemical properties. After the grazing cycle, changes in soil physical properties were minimal and did not affect the rate of infiltration of ground water and soil resistance to penetration. The levels of soil organic matter remained in progression for the two years of assessment in both layers evaluated. Values for phosphorus and potassium decreased in every layer over the sample period. In the second part of the study were evaluated agronomic and yield components of maize. The high mass post-grazing residue in 2009/2010 did not affect dry matter yield of corn, but was not repeated in 2010/2011 due to low water availability in the region. The yield components of corn MMG and NGE were negatively influenced by the different heights of residue post-grazing in years of low water availability. The lower heights of post-grazing residue (M-10 and PC) did not provide the optimal intake of straw to the SILP-PD for subsequent crops. In the third part of the work, attributes were evaluated related to pasture (plant height, forage mass and final mass of available forage) and the dynamics of forage production in pasture of oat (Avena strigosa Schreb.), ryegrass (Lolium multiflorum Lam.) and vetch (Vicia villosa L.) managed at different heights of postgrazing residue. The objective of this part was to identify the best height of forage for aerial biomass, the effect of grazing on the mass and the rate of decomposition of winter forages after different heights of forage after grazing. The different heights of residue post-grazing may have limitations in the final mass of forage, and the treatments M-20 and M-30 were ideal for the realization of direct seeding in grazed areas. / A Integração Lavoura-Pecuária (ILP) refere-se a uma associação entre duas atividades em épocas distintas do ano na mesma área, em que se envolvem os cultivos agrícolas e a criação animal. O presente trabalho teve por objetivos: (a) Avaliar a produção de matéria seca e fitomassa remanescente da pastagem consorciada de inverno (aveia preta, azevém e ervilhaca) sob diferentes alturas de massas de forragem póspastejo; (b) Comparar a produtividade da cultura do milho sob diferentes alturas de massas de forragem pós-pastejo e (c) Verificar as alterações nos atributos do solo que os bovinos possam causar no decorrer do ciclo vegetativo do milho. O experimento foi conduzido no município de Mata RS, em propriedade rural, durante os anos agrícolas 2009/2010 e 2010/2011, em um Argissolo Vermelho. O delineamento experimental foi o de blocos ao acaso, utilizando quatro alturas de massa de forragem pós-pastejo: pastejo convencional (PC), com área de 500 m2, em que não se tinha o controle de deslocamento dos animais e altura de massa de forragem durante o pastejo; altura de massa de forragem de 0,10 m (M-10); 0,20 m (M- 20), 0,30 m (M-30) e uma área não pastejada (SP). Para atender aos objetivos propostos, o trabalho foi dividido em três partes. A primeira parte foi realizada avaliando em duas épocas do ano agrícola, a densidade do solo, microporosidade, macroporosidade e porosidade total nas profundidades de 0,0-0,025; 0,025-0,05; 0,05-0,10 e 0,10-0,15 m, bem como a taxa de infiltração de água no solo, resistência mecânica do solo à penetração e teores de fósforo, potássio e matéria orgânica do solo. Quando manejada corretamente a presença dos animais em áreas de pastagem, não ocorrerá interferência negativa nos atributos físicos e químicos do solo. Após o ciclo de pastejo, não houve alterações nos atributos físicos do solo, o que não interferiu na taxa de infiltração de água no solo e resistência mecânica do solo à penetração. Os teores de matéria orgânica do solo mantiveram-se em progressão nos dois anos de avaliação em ambas as camadas avaliadas, o que não ocorreu com os teores de fósforo e potássio, havendo uma diminuição nos teores destes nutrientes em todas as camadas avaliadas. Na segunda parte do estudo, foram realizadas avaliações agronômicas e componentes de produção da cultura do milho. As alturas de massas de forragem pós-pastejo em 2009/2010 não afetaram o rendimento de matéria seca do milho, não se repetindo em 2010/2011, devido à baixa disponibilidade hídrica que ocorreu na região. Os componentes de rendimento da cultura do milho a MMG e o NGE foram influenciados negativamente pelas diferentes alturas de massa de forragem pós-pastejo, no ano de baixa disponibilidade hídrica. As menores alturas de massas de forragem pós-pastejo (M-10 e PC) não fornecem o aporte ideal de palhada para o SILP-PD para culturas subsequentes. Na terceira parte do trabalho, avaliaram-se atributos referentes à pastagem (altura da planta, massa de forragem disponível e massa final da forragem) e à dinâmica de produção de forragem em pastagem de aveia-preta (Avena strigosa Schreb), azevém (Lolium multiflorum Lam) e ervilhaca (Vicia villosa L.) manejada em diferentes alturas de massa de forragem pós-pastejo. O objetivo dessa parte foi identificar qual a melhor altura de massa de forragem para produção de fitomassa aérea, o efeito do pastejo na massa radical e a taxa de decomposição das forrageiras hibernais após diferentes alturas de massa de forragem pós-pastejo. As diferentes alturas de massa de forragem pós-pastejo podem ter limitações na massa final da forragem, sendo que os tratamentos M-20 e M-30 atingem a palhada ideal para realização da semeadura direta nas áreas pastejadas.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / The compaction became one of the main causes for soil degradation in agricultural areas, being directly related to the soil management system adopted. This situation can be observed in the Brazil humid subtropical climate area, by verification of the structural degradation of the soil subsuperficial layer, perceptible, in areas managed under no-till system (NTS), by alterations of soil physical properties, morphologic alterations of roots and perception, occasional, of crop yield reduction. In this sense, this work aimed at to generate knowledge about the residual effect of mechanical interventions for descompaction of soil managed under n0-till, conjugated to the mechanism of soil breaking used in drillers, about physical parameters of the soil, crop yield and force exercised on the agricultural tractor bar. For this, was carried out a study in the municipal district of Coxilha, in the northern area of Rio Grande do Sul, under a long duration experiment of Embrapa - Wheat. This experiment was installed in the year of 2001, in a farming area with eight year-old report under NTS. In that area, annual mechanical interventions were accomplished, by soil plowing and chiseling, previous the implantation of the summer crop. The adopted experimental design was random blocks with subdivided plots, with three repetitions. The treatments were a witness, which was the uninterrupted maintenance of NTS by 16 years and treatments constituted by six periods of time of NTS (7,5; 6,5; 5,5; 4,5; 3,5 and 2,5 years) after chiseling and, the same periods of NTS after plowing. The driller equipped with disks and with knife+disks, for the fertilizer placement in the sowing furrow, constituted the split-plots The results indicated that the mechanical intervention in soil managed under consolidated no-tillage through the soil chiseling or plowing, has potential to mitigate the ephemeral compaction and promote the improvement of soil structure, with a residual effect up to two years and half after the intervention. This residual effectt did not change the parameters of soybean grain yield in the crop year 2008/2009 and the force exercised on the agricultural tractor drawbar, compared to the area managed for 16 years under consolidated no-till. Moreover, the soil breaker mechanism, type knife + disk, which equips the no-till driller, was more effective in changing the evaluated parameters than the residual effect of mechanical intervention of chiseling or plowing the soil managed under comsolidated no-till. In this sense, the use of elements of soil breakers, like knife of deep action, designed to work in the compacted layer by no-till drillers, promoted mitigation of soil compaction in the 7-15 cm layer, by increasing soil macroporosity and reduction of microporosity, bulk density, soil penetration resistance and mechanical force exerted on the farm machinery drawbar, compared with the use of drillers equipped only with discs. / A compactação tornou-se uma das principais causas de degradação do solo em áreas agrícolas, estando diretamente relacionada ao sistema de manejo do solo adotado. Essa situação pode ser observada na região de clima subtropical úmido do Brasil, mediante verificação da degradação estrutural da camada subsuperficial do solo, perceptível, em áreas manejadas sob sistema plantio direto (SPD), por alterações de propriedades físicas do solo, alterações morfológicas de raízes e percepção, ocasional, de redução da produtividade das culturas. Nesse sentido, este trabalho objetivou gerar conhecimento sobre o efeito residual de intervenções mecânicas para descompactação do solo manejado sob sistema plantio direto, conjugadas ao mecanismo de rompimento do solo utilizado na semeadora sobre parâmetros físicos do solo, rendimento de cultura e força exercida na barra de tração de trator agrícola. Para tanto, realizou-se um estudo no município de Coxilha, na região norte do Rio Grande do Sul, sob um experimento de longa duração da Embrapa Trigo. Este experimento foi instalado no ano de 2001, em área de lavoura com histórico de oito anos sob SPD. Nessa área foram realizadas intervenções mecânicas anuais, mediante aração e escarificação do solo, anteriores a implantação da cultura de verão. O delineamento experimental adotado foi blocos ao acaso em parcelas subdivididas, com três repetições. Compõem os tratamentos uma testemunha, representada pela manutenção ininterrupta do SPD por 16 anos e tratamentos constituídos por seis períodos de tempo de condução do SPD (7,5; 6,5; 5,5; 4,5; 3,5 e 2,5 anos) após escarificação e, os mesmo períodos de condução do SPD após aração. A semeadora equipada com discos e com facão+discos, para a colocação do adubo no sulco da semeadura, constituiu as subparcelas. Os resultados obtidos indicaram que a intervenção mecânica em solo manejado sob sistema plantio direto consolidado, mediante a prática de escarificação ou aração do solo, apresenta potencial efêmero para mitigar a compactação e promover a melhoria da estrutura do solo, com efeito residual até dois anos e meio após intervenção. Este efeito residual não promoveu alterações nos parâmetros de rendimento de grãos da cultura da soja na safra agrícola 2008/2009 e força exercida na barra de tração de trator agrícola, comparativamente à área manejada há 16 anos sob sistema plantio direto consolidado. Por outro lado, o mecanismo rompedor de solo, tipo facão+disco, que equipa semeadora para plantio direto, mostrou-se mais efetivo em alterar os parâmetros avaliados do que o efeito residual de intervenção mecânica com aração ou escarificação, em solo manejado sob SPD consolidado. Nesse sentido, o emprego de elementos rompedores de solo, tipo facão de ação profunda, projetado para atuar na camada compactada em semeadoras para plantio direto, promoveu mitigação da compactação do solo na camada de 7 a 15 cm, mediante aumento da macroporosidade do solo e redução da microporosidade, densidade do solo, resistência do solo à penetração mecânica e força exercida na barra de tração de máquina agrícola, em comparação com uso de semeadoras equipadas apenas com discos.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The retention and availability of water in the soil are controlled by soil structure and its temporal variation is associated with the weather and the crops needs. Water also controls the aeration and soil penetration resistance, factors that are directly linked to root growth. The overall objective of this study was to evaluate the effect of management systems and soil compaction levels on soil physical properties to define the conditions that favor the retention, storage and availability of water to plants while maintaining aeration and soil resistance favorable to root growth. To meet these goals an experiment was set up in the experimental station of the Soils Department-UFSM. The area was under fallow and in 2002 year it was incorporated into the crop production under no-tillage. The treatments were: notillage (NT) no-tillage with compaction (NTC), subsoiling (Sub), chiseling (ESC) and conventional tillage (CT). The design was a randomized block design with four replications. Undisturbed soil samples were collected in the soil layers 0.0 to 0.05, 0.05 to 0.10 0.10 0,15; 0.15 to 0.20; 0.20 to 0.30, 0.30 to 0.40 and 0.40 to 0.50 m to determine the bulk density (BD), pore distribution, air permeability (Ka), saturated hydraulic conductivity (Ks) and the water retention curve. For the same layers, soil moisture (UV) was monitored continuously down to the layer of 0.30 m, using an automated TDR. In the other layers readings were taken weekly with a manual TDR. The penetration resistance (Rp) was determined at six points across the plant rows, under eight conditions of soil moisture. The maize parameters evaluated were the emergency, dry mass, root distribution at physiological maturity and yield. The NTC had a higher BD and lower total porosity (Pt) and macropores (Mac) down to 0.40 m depth. The ESC, Sub and the CT reduced the BD and increased Pt. The Ksat and Kl had little influence of the treatments, but showed positive correlation with Pt and negatively with Mac and Ds. The main benefit of tillage is the reduction of its resistance to penetration and improved soil aeration which allows for better root growth. No-tillage did not store more water for plants in relation to conventional tillage, subsoiling and chiseling. Soil compaction increased the water retention in densiest layer, but reduced the plant's ability to exploit the soil, by inhibiting root growth and reduce soil aeration. The compacted soil reached in less time and kept for longer time restrictive values of soil penetration resistance and air permeability. The dry matter production and grain yield of maize was not affected by managements and compaction levels, although some plant growth factors were outside the appropriate range indicated by the least limiting water range. / A retenção e a disponibilidade de água no solo são controladas pela sua estrutura e a sua variação temporal está associada às condições meteorológicas e à necessidade das culturas. A água também controla a aeração e a resistência do solo à penetração, que são fatores diretamente ligados ao crescimento do sistema radicular. O objetivo geral desse estudo foi avaliar o efeito de sistemas de manejo do solo e níveis de compactação sobre as suas propriedades físicas e definir as condições que possam favorecer a retenção, o armazenamento e a disponibilidade de água às plantas, mantendo a aeração e a resistência do solo favorável ao crescimento radicular. Para atender estes objetivos instalou-se um experimento na área experimental do Departamento de Solos da UFSM. A área utilizada estava sob pouso e, a partir de 2002, foi incorporada ao sistema produtivo, sob sistema de plantio direto. Os tratamentos estudados foram: plantio direto (PD); plantio direto com compactação adicional (PDc); escarificação profunda (Sub); escarificação superficial (Esc) e preparo convencional (PC). O delineamento foi em blocos ao acaso com quatro repetições. Amostras de solo com estrutura preservada foram coletadas nas camadas de 0,0 a 0,05; 0,05 a 0,10; 0,10 a 0,15; 0,15 a 0,20; 0,20 a 0,30; 0,30 a 0,40 e 0,40 a 0,50 m, para determinar a densidade (Ds), distribuição de poros, permeabilidade ao ar (Ka), condutividade hidráulica saturada (Ksat) e a curva de retenção de água. Nestas mesmas camadas, a umidade do solo (Uv) foi monitorada continuamente até a camada de 0,30 m, utilizando-se um TDR automatizado. Nas demais camadas as leituras foram feitas semanalmente com um TDR manual. A resistência do solo à penetração (Rp) foi determinada em seis pontos transversalmente às linhas de semeadura, sob oito condições de umidade do solo. Na cultura do milho avaliou-se a emergência, a massa seca, a distribuição radicular na maturação fisiológica e a produtividade. O PDc apresentou maior Ds e menor porosidade total (Pt) e macroporos (Mac) até 0,40 m de profundidade. A Esc, Sub e o PC reduziram a Ds e aumentaram a Pt. A Ksat e a Kl tiveram pouca influência dos tratamentos, mas apresentaram correlação positiva com Pt e Mac e negativa com Ds. O principal beneficio da mobilização do solo é a redução da sua resistência à penetração e a melhoria na aeração do solo, o que permite um melhor crescimento das raízes. O plantio direto não armazenou maior quantidade de água para as plantas em relação ao preparo convencional e a escarificação. A compactação do solo aumentou a retenção de água na camada mais adensada, mas reduziu a capacidade da planta explorar o solo, por dificultar o crescimento radicular e reduzir a aeração do solo. O solo compactado atingiu em menos tempo e manteve por mais tempo valores de resistência à penetração e de permeabilidade ao ar, considerados restritivos. A produção de massa seca e de grãos do milho não foi afetada pelos manejos e níveis de compactação, mesmo que alguns fatores de crescimento da planta estivessem fora da faixa adequada indicada pelo intervalo hídrico ótimo.

Les risques de dégradation physique des sols forestiers sous l'effet de contraintes mécaniques externes liées à la mécanisation des opérations forestières, augmentent considérablement. Les mécanismes et le temps nécessaires à la restauration non assistée de la qualité des sols forestiers tassés restent encore peu étudiés, et leur identification nécessite de coupler les approches physiques, chimiques et biologiques. L'objectif de ce travail était d'étudier l'impact de la circulation d'un porteur forestier sur les conditions de l'enracinement (aération, régime hydrique et pénétrabilité) ainsi que son évolution à court terme. Ce travail s'appuie sur l'observation de deux sites expérimentaux mis en place dans le Nord Est de la France, concernant des sols de morphologie similaire (couche limono-argileuse de 50 cm d'épaisseur reposant sur un substrat argileux) et ayant subi des contraintes identiques. Des paramètres physiques (température et humidité du sol, densité apparente et résistance à la pénétration) et chimiques (composition de l'atmosphère du sol) ont été suivis pendant trois à quatre ans, à des fréquences allant d'un pas de temps quotidien à annuel. Le suivi du climat du sol et de la composition de son atmosphère a mis en évidence une diminution forte des conditions aérobies pendant un à un an et demi après le passage du porteur. Cet effet initial sur l'aération du sol a diminué subitement dès l'apparition de la première période de sécheresse édaphique, probablement grâce à la formation de fissures dans l'horizon de surface du sol tassé. Cependant un effet significatif du traitement sur la composition de l'atmosphère du sol pouvait toujours être observé trois à quatre ans après tassement. Pour suivre l'évolution des propriétés physiques du sol après circulation du porteur, il a été nécessaire d'opérer une normalisation par rapport à l'humidité au moment du prélèvement. Trois ou quatre ans après la circulation du porteur, une différence toujours significative existe entre les propriétés physiques des sols témoins et celles des sols tassés. Cependant une évolution de l'impact du porteur peut être mise en évidence dans la couche de surface (0–10 cm) des deux sites. Ce début de restauration se traduit, sur un des deux sites, par une différence entre traitement qui n'est plus significative quand les sols sont humides mais qui l'est encore quand les sols sont secs. Sur le deuxième site, cette différence a diminué quelle que ce soit l'humidité du sol. Ainsi, le début de régénération de la structure du sol perturbé ne s'accompagne pas d'une disparition de son comportement de prise en masse lors de son desséchement sur un des deux sites. Ce travail a permis de mettre en évidence une évolution des conséquences du porteur en surface du sol tassé qui serait liée à des processus physiques (gonflement –retrait, gel – dégel). Cependant, l'impact sur les conditions de l'enracinement (forte résistance à la pénétration quand les sols sont secs, faible aération quand ils sont humides) reste élevé de même que sur la résilience à long terme du peuplement. / Soil compaction belongs to the major treats to soil quality with no exceptions of forest ecosystems where the frequency and intensity of loads application increase since several decades. The mechanisms and the duration of soil quality recovery following heavy traffic in forests remain poorly documented and their study requires multidisciplinary approaches.The aim of this work was to evaluate the impact of forwarder traffic on the potential constraints to roots growth (aeration, water content, and penetrability) growing in two forest soils sensitive to compaction, and the evolution of these consequences in the short-term. This work is based on two experimental sites, set up in the northeast of France, with soils displaying similar morphologies (50 cm thick silt loam layer laying on a clayey layer) and having being loaded with the same forwarder under similar (wet) soil conditions. Soil climate (temperature and moisture), soil air composition, and soil bulk density and resistance to penetration were investigated continuously, monthly and yearly, respectively. Soil climate and air composition monitoring showed a strong initial decrease in aerobic conditions lasting one to one and a half year. The strong initial impact on soil aeration decreased concurrently with the first soil drought experimented at both sites, probably because of soil cracks formation in the disturbed soil. Yet heavy traffic still affected significantly soil air composition 3 to 4 years after compaction at both sites. To monitor changes in soil physical parameters, we had to standardize measures with regards to soil climatic conditions at the time of sampling. Three to four years after soil compaction, the difference in soil physical properties between treatments was still significant. However, changes in the impact of the forwarder traffic on soil physical characteristics could be stated in the surface layer (0–10 cm) of both sites. This beginning of soil restoration results at one of both sites in a difference between treatments that is no longer significant when soils are wet but that is still significant when the soils are dry. At the second site, the difference is still significant whatever soil moisture conditions but it has decreased since the start of the experiment. Consequently, this beginning of soil structure recovery is not accompanied by a disappearance of the hardsetting behaviour (decrease in hydrostructural stability) of the compacted soil at one site. In this study changes in the consequences of the forwarder traffic were stated in the surface soil layers of both sites, these changes may be due to physical processes (wetting – drying, freezing – thawing). Nevertheless, the impact remains strong on roots growth (high resistance to penetration when dry, poor gas transfer when wet) and on stand resilience to external stresses (drought, storm).

No description available.

Orientador: Paulo Torres Fenner / Banca: Cláudio Angeli Sansígolo / Banca: Sérgio Hugo Benez / Banca: Jorge Roberto Malinovski / Banca: Fernando Seixas / Resumo: Foram avaliados os efeitos causados ao solo pelo tráfego de máquinas florestais de corte e baldeio de madeira, com ênfase à compactação, em floresta de Eucalyptus grandis Hill ex Maiden, de 91 meses de idade, através do comportamento de parâmetros físicos e mecânicos de um Latossolo Vermelho Amarelo, com 480 g.kg-1 de areia total e 430 g.kg-1 de argila. Os tratamentos avaliados foram o trânsito anterior ao experimento, a fase de corte e processamento de madeira, efetuada por colhedora (harvester) sobre esteiras e a fase de extração, por trator transportador autocarregável (forwarder) com rodado de pneus, considerando-se as condições de presença ou ausência de cobertura de galhada. Os parâmetros físicos empregados na avaliação foram: densidade do solo, porosidade total, macroporosidade, microporosidade, água disponível no solo, taxa de infiltração de água, temperatura do solo e estabilidade de agregados a seco. Os parâmetros mecânicos avaliados foram resistência do solo à penetração e ao cisalhamento, densidade máxima do solo, teor de água crítico para compactação e grau de compactação. Também foram avaliadas a área de contato rodado-solo e a pressão de rodados sobre o solo. Adotou-se o delineamento inteiramente casualizado, sendo os resultados obtidos submetidos à análise de variância pelo Statistical Analysis System (SAS), com aplicação do teste Tukey a 5% e 10% de significância. Comparativamente, a densidade do solo, a resistência mecânica ao cisalhamento e a pressão de rodados sobre o solo foram maiores após o tráfego do trator transportador em relação ao conferido pela colhedora de madeira. Os parâmetros porosidade total, macroporosidade, microporosidade, água disponível e estabilidade de agregados a seco foram maiores na fase de corte de madeira do que na fase de baldeio... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: A study of soil compaction was carried out on a Red-Yellow Latosol with 43% of clay and 48% of sand, according to some soil physical and mechanical parameters in a harvester of a 91-month-old Eucalyptus grandis Hill ex-Maiden forest. The aim was to evaluate the influence caused by the traffic of a 100 kWa-tracked harvester followed by a 190 kWa-wheeled-forwarder, over and without slash, in comparison to the soil conditions before the harvesting operations. The physical parameters used were soil dry bulk density, total porosity, air-filled porosity, micro porosity, soil water availability and infiltration rate, temperature and soil mean aggregate sizes. The mechanical parameters were soil penetrometer resistance, shear strength, Proctor test and machine ground pressure. A randomized-block trial with 15 replicates was used, applying Statistical Analysis System (SAS) and Tukey test at 5% and 10% significance levels. Results showed that wheeled-forwarder increased soil dry bulk density, soil shear strength and soil machine pressure in relation to the tracked-harvester. Thus, the parameters total porosity, air-filled porosity, micro porosity, soil water availability and soil mean aggregate sizes were higher on harvesting than on wood hauling. The wheeled-forwarder operating without slash produced a higher soil dry bulk density, temperature and soil compaction degree. Also, this work condition decreased total porosity and air-filled porosity in relation to the same operation accomplished over slash. Micro porosity, water availability, soil infiltration rate, soil penetrometer resistance and the maximum soil dry bulk density were not affected by both machines working on both slash conditions. All the soil mechanized operations evaluated were rated higher than 2 MPa on soil penetrometer resistance parameter, looked like a soil limit to allow the root growing... (Complete abstract, click eletronic address below) / Doutor

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Trees provide numerous benefits crucial to urban environments, yet poor growing conditions often prevent trees from reaching their genetic potential for growth, longevity, and ecosystem function. To overcome these limitations, greater understanding of tree growth in the urban environment is needed. The goal of this research project was therefore to characterize a broad suite of soil characteristics associated with urban tree plantings and evaluate their suitability for modeling physical dimensions and growth rates of urban trees. A series of observational studies and experiments was conducted on urban soils inhabited by two tree species (Zelkova serrata (Thunb.) Mikano and Quercus phellos L.) in Washington, DC and one tree species (Quercus virginiana Mill.) in Jacksonville, FL – two major metropolitan areas of the eastern United States with contrasting climate and soils. Characterization of urban soil attributes within cities revealed low variability for some properties (soil texture, pH, and certain plant nutrients with coefficients of variation (CV) below 0.5), but high variability (CV>1.0) for others (nitrate, ammonium, copper, and zinc). This is dependent on the location. These findings suggest that tree planting site evaluations may not require measurements for all soil properties and that representative sampling may be sufficient to accurately characterize most soil properties within a city. Field assessment of urban tree soils also revealed that conventional measures of soil compaction are difficult to obtain due to obstructions by roots and other foreign objects. To address the critical need for efficient and reliable assessment of soil compaction around urban trees, an experiment was conducted to develop bulk density estimation models for four common soil texture classes using soil strength and soil moisture as predictor variables. These models provided medium (0.42) to high (0.85) coefficients of determination when volumetric water content (VWC) was log transformed, demonstrating that measurements of soil texture, strength, and moisture can provide rapid, reliable assessment of soil compaction. Tree growth modeling focused on three response variables: canopy projection (CP), canopy volume (CV), and peak-increment-area age (PIA). To calculate PIA, tree-ring analysis was used to determine the age at which maximal trunk diameter growth occurred between transplanting and time of sampling. Because Q. virginiana has difficult-to-distinguish growth rings, an intensive tree-ring analysis of cores collected from these trees was conducted. The analysis revealed interseries correlation coefficients of up to 0.66, demonstrating that Q. virginiana can be aged with fairly high confidence in an urban setting. Empirical models developed for all three tree species using the suite of soil and site variables explained 25% – 83% of the observed variability in tree physical dimensions and growth rates. Soil pH was found to be a significant predictor variable for the majority of growth models along with nutrients such as Fe, B, Mn, and Zn, which are also associated with soil alkalinity. Models for PIA possessed the highest coefficient of determination, suggesting that measurements of soil conditions can be used confidently to predict the age at which growth rate subsides in these species. CV and CP were not predicted as well by soil-related variables, presumably because above-ground constraints such as pruning and building encroachment can affect canopy size without necessarily affecting growth rate. Certain prediction models for all three species included predictor variables with counterintuitive influences on tree growth (e.g., negative influences of soil depth on Q. phellos and soil volume on Q. virginiana), suggesting that either these urban trees are responding to these variables in a novel manner or that variables unaccounted for in these models (perhaps related to urbanization or high vehicular traffic) are concomitantly influencing tree growth. / Ph. D.