ABSTRACT: Knowledge of the hydraulic properties of the soil is of crucial importance to an understanding of the interactions between vegetation, soil and water. There is little information available about the hydraulic properties of Podzol soils found in tropical regions. The aim of this study was to present the soil morphology and hydraulic properties of a toposequence situated in a permanent plot at the Ilha do Cardoso State Park (Cananéia, SP, Brazil). Ultradetailed soil maps were used to define a toposequence inside the permanent plot. Five profiles, representing the main types of soil, were opened along the toposequence, in which Podzols are dominant. The levels of bulk density, sand content, porosity and permeability in these soils were all high. Consequently, these soils have a high level of hydraulic conductivity with low water retention. This behavior undergoes an alteration in the Bh and Bs horizons due to the accumulation of organic and metallic compounds and a changing structure that modifies the pore distribution. Furthermore, the characterization of the hydro-physical functioning of soils in natural environments is an important source of encouragement to further investigative study of soil water dynamics and its relationship to the native vegetation.

Abstract Erosion generates large amounts of sediment, which may be deposited at the site of origin, on the slope of a hill, or along waterways. The transportability of each type of sediment by runoff and its potential for subsequent deposition largely depends on its morphological features and particle size distribution. The aim of this study is to describe and characterize the morphology and micromorphology of sediments deposited in a reforested area and to understand the dynamics of the transport process. In order to understand the sedimentation processes, the following analyses were performed: particle size distribution, with and without the use of a dispersant solution; statistical analysis of the sand fraction using Folk and Ward parameters; sediment and soil micromorphology; and two-dimensional distribution and geometry of soil horizons and sediments. The sedimentation occurred in a localized and discontinuous manner and in the lowest parts of the landscape. The sediments were generated by low intensity erosive events producing well-sorted sediments and the clay in these deposits was transported mainly in the form of silt-sized clay aggregates. Microscopic analysis of the sediments was important for clarifying the genesis and transport dynamics of the sedimentary deposits.

ABSTRACT Studies of soil porosity through image analysis are important to an understanding of how the soil functions. However, the lack of a simplified methodology for the quantification of the shape, number, and size of soil pores has limited the use of information extracted from images. The present work proposes a software program for the quantification and characterization of soil porosity from data derived from 2-D images. The user-friendly software was developed in C++ and allows for the classification of pores in terms of size, shape, and combinations of size and shape. Using raw data generated by image analysis systems, the software calculates the following parameters for the characterization of soil porosity: total area of pore (Tap), number of pores, pore shape, pore shape and pore area, and pore shape and equivalent pore diameter (EqDiam). In this paper, the input file with the raw soil porosity data was generated using the Noesis Visilog 5.4 image analysis system; however other image analysis programs can be used, in which case, the input file requires a standard format to permit processing by this software. The software also shows the descriptive statistics (mean, standard deviation, variance, and the coefficient of variation) of the parameters considering the total number of images evaluated. The results show that the software is a complementary tool to any analysis of soil porosity, allowing for a precise and quick analysis.

ABSTRACT: Knowledge of soils in the Amazon rainforest is becoming increasingly essential due to dynamics adopted by farmers that substitute forest for pastures, together with growing pressure from diverse segments of society towards adoption of sustainable production systems. The objective of this study was to characterize the soils along two toposequences, one under forest (F) and the other under pasture (P), and to verify how the change in land use influences soil attributes, evaluating their inclusion in the Brazilian Soil Classification System (SiBCS). The soils were sampled in pits located at the summit, backslope and footslope positions for morphological, chemical, physical, and clay mineralogy analysis. The results show that the soils are chemically poor and predominately kaolinitic. Sandy and loamy sand soils are in the surface horizons, with an increase in clay content with depth. The highest values of bulk density and lowest values of macroporosity were observed in the Bt horizons due to the change from a granular structure in the surface to an angular and subangular blocky structure in these horizons. The morphological properties observed in the field are strongly influenced by the annual soil water dynamics, the parent material, and the landscape, representing diagnostic characteristics that influenced classification of the soils, such as aquic with episaturation (epirredóxico), saprolitic, and gravelly. These diagnostic characteristics in the Argissolo Amarelo (Hapludults) are important morphological properties that have not been highlighted by the current edition of the SiBCS.

O manejo agrícola influencia a estrutura do solo, modificando os atributos físicos e o comportamento hídrico do solo. O objetivo deste trabalho foi avaliar os efeitos da semeadura direta (SD) e do preparo convencional (PC) sobre a estrutura do solo, por meio de atributos físicos e da distribuição dos poros, utilizando imagens digitais 2-D. O estudo foi realizado em um Latossolo Vermelho distroférrico com delineamento de blocos casualizados. A densidade do solo, macroporosidade, diâmetro médio ponderado (DMP), condutividade hidráulica do solo saturado (Kfs) e análise de imagens digitais 2-D (resolução de 156,25 μm2) foram avaliadas nas profundidades de 0-0,20 e 0,20-0,40 m. Os manejos não diferiram para a densidade e macroporosidade do solo. A SD revelou maior DMP e Kfs em relação ao PC. O PC apresentou maior área total de poros na profundidade de 0-0,20 m em relação ao SD, ocorrendo o inverso na profundidade de 0,20-0,40 m. A SD apresentou maior quantidade de poros complexos de tamanho grande (>0,156 mm2) na camada de 0,20-0,40 m em relação ao PC, que evidenciou predomínio de poros arredondados. A SD demonstrou melhorias na estrutura do solo em relação ao PC, com maior estabilidade dos agregados, condutividade hidráulica e área total de poros, contribuindo para a conservação do solo e da água em sistemas produtivos.

Agricultural management affects soil structure, modifying soil physical properties and soil water movement. The objective of this study was to evaluate the effects of no-tillage (NT) and conventional tillage (CT) on soil structure through physical properties and pore distribution in 2-D digital images. The study was conducted in an Oxisol with a randomized block design. Soil bulk density, soil macroporosity, mean weighted diameter (MWD), saturated hydraulic conductivity (SHC), and analysis of 2-D digital images (156.25 μm2 resolution) were evaluated at the depths of 0-0.20 and 0.20-0.40 m. Management systems did not differ for soil bulk density and soil macroporosity. The NT showed higher MWD and SHC compared to CT. The CT had a greater total pore area at the 0-0.20 m depth in relation to NT, with the opposite occurring at the 0.20-0.40 m depth. The NT had a greater number of complex pores of large size (>0.156 mm2) at the depth of 0.20-0.40 m in relation to the CT, which showed a predominance of rounded pores. The NT showed improvements in soil structure in relation to the CT, with greater aggregate stability, hydraulic conductivity, and total pore area, contributing to soil and water conservation in production systems.

Na avaliação da qualidade do solo para uso agrícola, a estrutura é um dos seus atributos mais importantes, sendo não somente influenciada pelo clima, pela atividade biológica e pelas práticas de manejo, como também por forças de natureza mecânica e físico-químicas atuantes no solo. O objetivo deste trabalho foi avaliar a influência do manejo agrícola convencional na estrutura e microestrutura de um Latossolo Vermelho distroférrico típico de área experimental cultivada com milho. A morfologia do solo foi descrita conforme o método do perfil cultural, identificando-se as diferentes Unidades Morfologicamente Homogêneas (UMHs). Para fins de comparação, também foi descrito um perfil em área sem uso agrícola e sob revegetação natural referida por parcela Memória. Foram extraídas amostras indeformadas das principais UMHs visando a confecção de lâminas delgadas e blocos de solo destinados às análises micromorfológicas e micromorfométricas. Os resultados revelaram a ocorrência de estruturas dos tipos livre (L), fragmentada (F) e contínua (C) em ambos perfis avaliados. No perfil da parcela Memória, as estruturas fragmentadas são as dos subtipos Fptμ∆+tf e Fmt∆μ, cuja micromorfologia mostrou uma distribuição relativa enáulica-porfírica (porosa), com grande atividade biológica evidenciada pela presença de cavidades e canais. Mais abaixo, entre 0,20 e 0,35 m, o volume de solo é contínuo do subtipo C∆μ, apresentando microestrutura em blocos subangulares e matriz com distribuição relativa enáulica-porfírica, porém mais compacta e com coalescência de agregados e menor incidência de atividade biológica. O estudo micromorfométrico do solo da parcela Memória revelou predomínio de poros complexos nas unidades NAM (15,03 %), Fmt∆μ (11,72 %) e Fptμ∆+tf (7,73 %) e de poros arredondados na unidade C∆μ (8,21 %). No solo sob manejo agrícola, observaram-se estruturas fragmentadas similares às da parcela Memória entre 0,02 e 0,20 m seguidas de um volume contínua compacta (C∆μ), sem porosidade visível a olho nu e com pouquíssimas raízes. Nas UMHs sob manejo convencional, observou-se redução da porosidade de empilhamento (40 %), principalmente nas unidades contínuas (C), com surgimento de formas fissuradas e menor evidencia de atividade biológica. Concluindo, as análises morfológicas e micromorfológica dos perfis de solo estudados forneceram informações complementares acerca da qualidade estrutural do solo, em especial quanto às alterações dos tipos de poros decorrentes de estresse mecânico sofrido pelo solo.

In evaluation of soil quality for agricultural use, soil structure is one of the most important properties, which is influenced not only by climate, biological activity, and management practices but also by mechanical and physico-chemical forces acting in the soil. The purpose of this study was to evaluate the influence of conventional agricultural management on the structure and microstructure of a Latossolo Vermelho distroférrico típico (Rhodic Hapludox) in an experimental area planted to maize. Soil morphology was described using the crop profile method by identifying the distinct structural volumes called Morphologically Homogeneous Units (MHUs). For comparison, we also described a profile in an adjacent area without agricultural use and under natural regrowth referred to as Memory. We took undisturbed samples from the main MHUs so as to form thin sections and blocks of soil for micromorphological and micromorphometrical analyses. Results from the application of the crop profile method showed the occurrence of the following structural types: loose (L), fragmented (F) and continuous (C) in both profiles analyzed. In the Memory soil profile, the fragmented structures were classified as Fptμ∆+tf and Fmt∆μ, whose micromorphology shows an enaulic-porphyric (porous) relative distribution with a great deal of biological activity as indicated by the presence of vughs and channels. Lower down, from 0.20 to 0.35 m, there was a continuous soil volume (sub-type C∆μ), with a subangular block microstructure and an enaulic-porphyric relative distribution, though in this case more compact and with aggregate coalescence and less biological activity. The micromorphometrical study of the soil of the Memory Plot showed the predominance of complex pores in NAM (15.03 %), Fmt∆μ (11.72 %), and Fptμ∆+tf (7.73 %), and rounded pores in C∆μ (8.21 %). In the soil under conventional agricultural management, we observed fragmented structures similar to the Memory Plot from 0.02 to 0.20 m, followed by a volume with a compact continuous structure (C∆μ), without visible porosity and with few roots. In the MHUs under conventional management, reduction in the packing pores (40 %) was observed, mainly in the continuous units (C). The microstructure had well-defined blocks, with the occurrence of planar pores and less evidence of biological activity. In conclusion, the morphological and micromorphological analyses of the soil profiles studied offered complementary information regarding soil structural quality, especially concerning the changes in pore types as result of mechanical stress undergone by the soil.

O conceito de qualidade do solo é muito discutido atualmente em razão das relações do solo com o meio ambiente (solo-planta-atmosfera) e das práticas intervencionistas do homem. Esse conceito relaciona a qualidade com a produtividade agrícola, mas sua avaliação em um contexto agronômico pode ser diferente em ecossistema natural. Este estudo teve como objetivo avaliar os índices de qualidade física do solo, o índice S, a capacidade de aeração do solo (ACt/Pt) e a capacidade de armazenamento de água do solo (CC/Pt) da parcela permanente localizada na Estação Experimental de Caetetus em Galia, São Paulo, Brasil, sob Floresta Estacional Semidecidual e compará-los com valores de referência de índices de qualidade física do solo encontrados na literatura. Para tanto, curvas de retenção de água foram utilizadas para o cálculo desses índices. Os valores do índice S encontrados foram superiores ao limite proposto de qualidade física do solo (0,035). Os horizontes A e E apresentaram os valores mais altos, pois sua textura arenosa refletiu em elevada inclinação da curva de retenção. Os horizontes B evidenciaram os menores valores de S, pois seu adensamento natural refletiu curvas de retenção com menor inclinação. Os valores de ACt/Pt e CC/Pt foram maiores e menores que os valores definidos como ideais. Os índices de qualidade física do solo, o índice S, a capacidade de aeração do solo (ACt/Pt) e a capacidade de armazenamento de água do solo (CC/Pt) sob vegetação natural podem representar valores de referência para solos com características semelhantes que sofrem alguma atividade ou influência antrópica. Todos os índices avaliados foram eficientes para diferenciar os efeitos dos horizontes no funcionamento físico-hídrico natural dos solos estudados.

The concept of soil quality is currently the subject of great discussion due to the interaction of soil with the environment (soil-plant-atmosphere) and practices of human intervention. However, concepts of soil quality relate quality to agricultural productivity, but assessment of soil quality in an agronomic context may be different from its assessment in natural areas. The aim of this study was to assess physical quality indices, the S index, soil aeration capacity (ACt/Pt), and water storage capacity (FC/Pt) of the soil from a permanent plot in the Caetetus Ecological Reserve (Galia, São Paulo, Brazil) under a seasonal semideciduous forest and compare them with the reference values for soil physical quality found in the literature. Water retention curves were used for that purpose. The S values found were higher than the proposed limit for soil physical quality (0.035). The A and E horizons showed the highest values because their sandy texture leads to a high slope of the water retention curve. The B horizons showed the lowest S values because their natural density leads to a lower slope of the water retention curve. The values found for ACt/Pt and FC/Pt were higher and lower than the idealized limits. The values obtained from these indices under natural vegetation can provide reference values for soils with similar properties that undergo changes due to anthropic activities. All the indices evaluated were effective in differentiating the effects of soil horizons in the natural hydro-physical functioning of the soils under study.

A dispersão da amostra de solo é uma etapa fundamental da análise granulométrica, sendo realizada mediante o uso de dispersantes químicos e agitação mecânica. O objetivo deste trabalho foi avaliar a eficiência de mesa agitadora reciprocante de baixa rotação na dispersão mecânica de amostras de solos de diferentes classes texturais. Foram realizadas análises granulométricas em 61 amostras com quatro repetições, empregando o método da pipeta para determinação da fração argila e tamisagem para determinação das frações areia grossa, areia fina e areia total, sendo o silte determinado por diferença. Na avaliação de desempenho, os resultados obtidos com uso da mesa agitadora reciprocante (MAR) foram comparados com dados disponíveis para as mesmas amostras oriundos de relatórios do Ensaio de Proficiência IAC para Laboratórios de Análises de Solos - Prolab/IAC. Análises de acurácia foram realizadas com base nos valores dos intervalos de confiança definidos para cada fração granulométrica componente de cada amostra ensaiada. Indicadores gráficos também foram utilizados na comparação de dados, por meio de dispersão e ajuste linear. A estatística descritiva indicou preponderância de baixa variabilidade em mais de 90 % dos resultados obtidos para as amostras de texturas arenosa, média e argilosa e em 68 % dos obtidos para as amostras de textura muito argilosa, indicando boa repetibilidade dos resultados obtidos com a MAR. Média variabilidade foi mais frequentemente associada à fração silte, seguida da fração areia fina. Os resultados das análises de sensibilidade indicam acurácia de 100 % nas três frações granulométricas - areia total, silte e argila - para todas as amostras analisadas pertencentes às classes texturais muito argilosa, argilosa e média. Para as nove amostras de textura arenosa, a acurácia média foi de 85,2 %, e os maiores desvios ocorreram em relação à fração silte. Nas aproximações lineares, coeficientes de correlação igual (silte) ou superiores (areia total e argila) a 0,93, bem como diferenças menores do que 0,16 entre os coeficientes angulares das retas e o valor unitário, indicam alta correlação entre os resultados de referência (Prolab/IAC) e os obtidos nos ensaios com a MAR. Conclui-se pelo desempenho satisfatório da mesa agitadora reciprocante de baixa rotação para dispersão mecânica de amostras de solo de diferentes classes texturais para fins de análise granulométrica, permitindo recomendar o uso alternativo do equipamento quando se emprega agitação lenta. As vantagens do uso do equipamento nacional incluem o baixo custo, a possibilidade de análise simultânea de grande número de amostras e o uso de frascos comuns, de vidro ou de plástico, baratos e de fácil reposição.

The dispersion of the samples in soil particle-size analysis is a fundamental step, which is commonly achieved with a combination of chemical agents and mechanical agitation. The purpose of this study was to evaluate the efficiency of a low-speed reciprocal shaker for the mechanical dispersion of soil samples of different textural classes. The particle size of 61 soil samples was analyzed in four replications, using the pipette method to determine the clay fraction and sieving to determine coarse, fine and total sand fractions. The silt content was obtained by difference. To evaluate the performance, the results of the reciprocal shaker (RSh) were compared with data of the same soil samples available in reports of the Proficiency testing for Soil Analysis Laboratories of the Agronomic Institute of Campinas (Prolab/IAC). The accuracy was analyzed based on the maximum and minimum values defining the confidence intervals for the particle-size fractions of each soil sample. Graphical indicators were also used for data comparison, based on dispersion and linear adjustment. The descriptive statistics indicated predominantly low variability in more than 90 % of the results for sand, medium-textured and clay samples, and for 68 % of the results for heavy clay samples, indicating satisfactory repeatability of measurements with the RSh. Medium variability was frequently associated with silt, followed by the fine sand fraction. The sensitivity analyses indicated an accuracy of 100 % for the three main separates (total sand, silt and clay), in all 52 samples of the textural classes heavy clay, clay and medium. For the nine sand soil samples, the average accuracy was 85.2 %; highest deviations were observed for the silt fraction. In relation to the linear adjustments, the correlation coefficients of 0.93 (silt) or > 0.93 (total sand and clay), as well as the differences between the angular coefficients and the unit < 0.16, indicated a high correlation between the reference data (Prolab/IAC) and results obtained with the RSh. In conclusion, the mechanical dispersion by the reciprocal shaker of soil samples of different textural classes was satisfactory. The results allowed recommending the use of the equipment at low agitation for particle size- analysis. The advantages of this Brazilian apparatus are its low cost, the possibility to simultaneously analyze a great number of samples using ordinary, easily replaceable glass or plastic bottles.

O manejo agrícola interfere nas condições físicas, químicas e biológicas do solo, na capacidade produtiva do sistema agrícola e na susceptibilidade do solo ao processo erosivo, não raramente acentuando-a. Objetivou-se, neste estudo, estudar a influência de dois sistemas de manejo sobre a qualidade física de um Latossolo Vermelho Distroférrico típico da região de Campinas, SP, bem como seus efeitos tanto no desenvolvimento e produtividade da cultura do milho, quanto no controle das perdas de terra e de nutrientes por erosão. Foram comparados dois sistemas de manejo, sistema plantio direto (SPD) e sistema convencional com grade aradora (SC), aplicando-os em parcelas experimentais dotadas com sistemas coletores de enxurrada para avaliação das perdas de terra e de nutrientes por erosão. Também foram analisados atributos físicos e químicos do solo, bem como dados biométricos e de produtividade da cultura do milho. Os resultados evidenciam que o manejo agrícola influenciou a qualidade do solo, sendo que os indicadores físicos foram melhores no sistema convencional. No entanto, os indicadores biométricos, em especial altura de plantas, foram superiores no sistema plantio direto. Também houve influência do manejo sobre o controle da erosão, ocorrendo maiores perdas de solo e de nutrientes, em particular, de fósforo e de matéria orgânica nas parcelas sob SC.

Agricultural management influences the physical, chemical and biological conditions of the soil, affecting soil quality, the productivity capacity of the agricultural system and its vulnerability to erosion process, frequently increasing it. The purpose of this work was to study the influence of two agricultural management systems on physical soil quality of a Rhodic Hapludox occurring in Campinas, State of São Paulo, and their effects not only on corn crop development and yield, but also on soil and nutrient loss by erosion. Two management systems were compared, named direct drilling system (DDS) and conventional system (CS), by applying them in experimental plots having runoff collectors to assess soil and nutrient losses by erosion. Soil physical and chemical attributes were also analyzed, as well as biometrical and yield data of the corn crop. The results indicate that agricultural management has differently influenced soil quality, and that soil physical indicators were better under the conventional system (CS). However, biometrical indicators, especially plant height, were superior under direct drilling system (DDS). There was also influence of agricultural management on erosion control, occurring greater soil losses and particularly larger phosphorous and organic matter losses from plots under conventional system (CS).

O efeito do cultivo do mamoeiro em ambiente protegido foi estudado em três condições: sem cobertura e em dois telados construídos com tela de propileno branca, com malhas de 2 x 2 mm e 2 x 1 mm. Nessa área foram feitas avaliações na cultivar Baixinho de Santa Amália, contando-se o número de plantas com sintomas de ataque recente, para o ácaro branco Polyphagotarsonemus latus, com sintomas e presença de ácaros, para o ácaro rajado Tetranychus urticae e com presença de adultos ou ninfas nas folhas, no caso das moscas-brancas Trialeurodes sp., Bemisia tabaci biótipo B e uma terceira espécie não identificada. Para moscas-brancas, também foram realizadas contagens de ninfas e exúvias em laboratório. O cultivo em ambiente protegido favoreceu a sobrevivência e o desenvolvimento populacional das espécies estudadas, sendo que algumas possíveis causas são discutidas no texto. Considerando-se que o cultivo protegido pode ser uma boa alternativa para o controle de viroses, como o mosaico do mamoeiro, problema limitante para a cultura, estratégias de manejo de pragas nesses ambientes devem ser desenvolvidas, para viabilizar o seu uso.

It was measured the effect of cultivating papaya cultivar "Baixinho de Santa Amália" in a protected environment and in three situations: without shade, and under screen shades of white polyethylene mesh sizes 2 x 2 mm or 2 x 1 mm. It was registered the number of plants with symptoms of recent attacks of the broad mite (Polyphagotarsonemus latus), symptoms and presence of the two-spotted spider mite (Tetranychus urticae) and the presence on leaves of adults or nymphs of whiteflies (Trialeurodes sp., Bemisia tabaci biotype B and a third unidentified species). Whitefly nymph and exuviae numbers were also counted in the laboratory. Cultivation in a protected environment favored the survival and development of the species under study, and some possible reasons for these are discussed along the text. Since cultivating papaya in protected environment can be a good alternative for "papaya ringspot virus" control, which is a restrictive factor for the crop, the development of strategies to control the pests in this condition is necessary for correct recommendation of such measure.