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1.
Plants (Basel) ; 12(21)2023 Nov 03.
Artigo em Inglês | MEDLINE | ID: mdl-37960118

RESUMO

Soil management systems can directly interfere with crop yield via changes in the soil's physical and hydraulic properties. However, short- to medium-term experiments of conduction do not always demonstrate the modifications of the management systems in these properties. Thus, the aim of this study was to evaluate the physical properties of the soil in a long-term management system and to relate it to the storage and availability of water to plants, verifying its effect on soybean yield. The experiment was conducted in randomized blocks in a split-plot scheme with four replications. Plots were composed by soil management (conventional tillage and no-tillage), and subplots represented three soil depths (0.0-0.1, 0.1-0.2, and 0.2-0.4 m). The soil's physical and hydraulic properties, root development, and soybean yield were evaluated. The no-tillage system not only presented higher bulk density and soil resistance to compaction up to a depth of 0.2 m but also greater root development. This management also did not affect the process of water infiltration in the soil and presented an increase in soybean grain yield by 6.5%. The long-term no-tillage system (33 years) offers less risk of water stress to soybean plants; it contributes to greater grain yield of this crop when compared to the conventional tillage system.

2.
Plants (Basel) ; 11(19)2022 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-36235523

RESUMO

No-tillage cover crops contribute to better soil quality, being able to replace mechanized tillage management. This observation can only be made after several years of adopting conservationist practices and through research on soil-plant relationships. The objective of the research was to verify the relationship between the production components, physiological, root development, and physical-hydric properties of the soil in the yield of soybean grown in succession to different cover crops or with soil chiseling. The experiment was carried out in a randomized block design with four replications, comparing the cultivation of sunn hemp (Crotalaria juncea) and millet (Penninsetum glaucum L.) as cover crops and a treatment with soil chiseling. The evaluations were carried out during soybean (Glycine max L.) cultivation in the 2019/20 summer crop, that is, after 17 years of experimenting started in 2003. Rotation with sunn hemp increased soybean yield by 6% and 10%, compared with millet rotation and soil chiseling. The species used in crop rotation in a long-term no-tillage system interfere with the physical and water characteristics of the soil, affecting the physiological responses and soybean yield. The rotation with sunn hemp offers greater water stability to the plants and provides greater soybean yield in succession. Future research that better addresses year-to-year variation, architecture, and continuity of pores provided by crop rotation, and evaluations of gas exchange, fluorescence, and activities of stress enzymes in soybean plants may contribute to a better understanding of soil-plant relationships in long-term no-till.

3.
PeerJ ; 10: e13526, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35669963

RESUMO

Benggang with steep collapsing walls is one of the worst soil erosion problems in South China. The collapse of walls is the most critical process in Benggang development. This is mainly due to the soil water properties. The soil water characteristic curve (SWCC) is a key indicator for analyzing soil moisture, but the SWCC and its mechanism of influence in collapsing walls remain obscure. A pressure plate meter was used for drying experiments to research the SWCCs of undisturbed soils of five layers (from top to bottom: red soil layer, transition layer I, sand soil layer, transition layer II and detrital layer) of two typical collapsing walls. The van Genuchten (VG) model can be fitted to the SWCCs for different layers (NSE ≥ 0.90). With increasing soil depth, the parameters a and θ s first decreased and then increased, the parameters n first increased and then decreased, θ r declined as the soil depth increased. These findings illustrate that soil water holding capacity decreases with increasing soil depth. The bottom of the soil is weak in water retention and water can easily reach saturation, resulting in a decline in soil stability, thus promoting soil collapse and finally inducing upper soil collapse. Furthermore, gravel content and particle morphology are factors that should not be neglected for SWCCs. The results of this study provide a theoretical basis for understanding the process of wall collapse in Benggang landforms in South China.


Assuntos
Solo , Água , Água/análise , Dióxido de Silício , China
4.
MethodsX ; 8: 101566, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-35004200

RESUMO

Soil processes have a major impact on agroecosystems, controlling water and nutrient cycling, regulating plant growth and losses to the wider environment. Process-based agroecosystem simulation models generally encompass detailed descriptions of the soil, including a wide number of parameters that can be daunting to users with a limited soil science background. In this work we review and present an abridged description of the models used to simulate soil processes in the APSIM (Agricultural Production Systems sIMulator) framework. Such a resource is needed because this information is currently spread over multiple publications and some elements have become outdated. We list and briefly describe the parameters, and establish a protocol with guidelines, for building a soil description for APSIM. This protocol will promote consistency, enhancing the quality of the science done employing APSIM, and provide an easier pathway for new users. This compilation should also be of relevance to users of other models that require detailed soil information.•This paper presents a brief description of the models for simulating soil processes in the APSIM model.•The method stablishes guidelines to define the parameters for building a soil description for APSIM.

5.
Biosci. j. (Online) ; 36(6): 1961-1974, 01-11-2020. ilus, tab, graf
Artigo em Inglês | LILACS | ID: biblio-1147962

RESUMO

Studying particle size distribution is important to understand soil structure and formation processes. This research aimed to assess the fractal dimension of soil texture in Indian Dark Earth (IDE) areas in southern Amazonas state under different land uses, as follows: two areas in the municipality of Apuí, one growing cocoa and the other coffee; a grassland area in the municipality of Manicoré; and a forest area in the municipality of Novo Aripuanã. A sampling grid containing 88 collection points (intersecting points on the grid) was established in each area, measuring 80 x 42 m for the cocoa and coffee-growing sites, and 80 x 56 m and 60 x 42 m for the grassland and forest areas, respectively. Soil samples were collected in soil core and as clumps at a depth of 0.0-0.20m to determine the structural physical properties and texture of the soil. The following physical attributes were assessed: texture (PSD), bulk density (BD), macroporosity (Macro), microporosity (Micro), total porosity (TP) and aggregate stability (GMD and WMD). The fractal dimension (D) of the soil texture was determined, followed by analysis of variance and comparison of the means using Tukey's test (p≤0.05). Pearson's correlation was applied to assess the correlation between variables. There was a significant difference between the IDEs studied, with a higher D value in the cocoa-growing area in relation to the other sites. Additionally, the larger the clay fraction, the higher the D value. Fractal dimension (D) showed a positive correlation with sand, clay, BD, Macro, GMD and WMD, and a negative correlation with silt, micro, TP. Based on the D values obtained, the ADE cultivated with cocoa showed superior quality in relation to the other areas studied.KEYWORDS: Fractal dimension. Soil physics. Soil use. INTRODUCTION Applications of fractal geometry in soil science have shown that soil exhibits fractal characteristics, being a porous medium having different particle compositions, with irregular shape and self-similar structure (TYLER; WHEATCRAFT, 1989; KRAVCHENKO; ZHANG, 1998). Fractal geometry, proposed and established by Mandelbrot (1982), is a method for describing systems with non-characteristic scales and self-similarity. In recent years, this theory has been used to quantitatively describe the particle size distribution of soil, attracting the interest of pedologists worldwide (DENG et al., 2017). Particle size distribution is one of the most important physical characteristics of soil because of its significant influence on water flow and soil erosion (XU; LI; LI, 2013). In this respect, broad and precise knowledge of particle size distribution is vital to understanding soil structures and formation, since it is closely related to soil erosion, organic matter content and moisture content (DU et al., 2017). Deng et al. (2017) studied the fractal features of soil particle size distribution and found an association between fractal dimensions and the physical and chemical properties of the soil analyzed, indicating that the lower the fractal dimension, the worse the soil physical and chemical properties. Recently, the fractal method was applied to estimate soil structure and proved to be an efficient tool in analyzing soil Received: 01/04/2019 Accepted: 30/01/2020


Estudar a distribuição do tamanho das partículas é importante para entender a estrutura do solo e os processos de formação. Esta pesquisa teve como objetivo avaliar a dimensão fractal da textura do solo em áreas de Terra Preta de Índio (TPI) no sul do Estado do Amazonas sob diferentes usos da terra: duas áreas no município de Apuí, uma com cultivo de cacau e outra de café; uma área de pastagem no município de Manicoré; e uma área florestal no município de Novo Aripuanã. Uma malha de amostragem contendo 88 pontos de coleta (pontos de interseção na grade) foi estabelecida em cada área, medindo 80 x 42 m para as áreas de cacau e café, e 80 x 56 m e 60 x 42 m para as áreas de pastagem e floresta, respectivamente. Amostras de solo foram coletadas em torrões a uma profundidade de 0,0-0,20 m para determinar as propriedades físicas estruturais e a textura do solo. Os seguintes atributos físicos foram avaliados: textura, densidade do solo (DS), macroporosidade (Macro), microporosidade (Micro), porosidade total (PT) e estabilidade de agregados (DMG e DMP). Determinou-se a dimensão fractal da textura do solo (D), seguida da análise de variância e comparação das médias pelo teste de Tukey (p≤0,05). A correlação de Pearson foi aplicada para avaliar a correlação entre as variáveis. Houve uma diferença significativa entre as TPIs estudadas, com um maior valor D na área de cultivo de cacau em relação aos outros locais. Além disso, quanto maior a fração argila, maior o valor de D. A dimensão fractal (D) apresentou correlação positiva com areia, argila, DS, Macro, DMG e DMP, e correlação negativa com silte, micro, PT. Com base nos valores de D obtidos, as TPIs cultivadas com cacau apresentaram qualidade superior em relação às demais áreas estudadas.PALAVRAS-CHAVES: Dimensão Fractal. Física do solo. Uso do solo. REFERENCES ALVARENGA, R. C.; FERNANDES, B.; SILVA, T. C. A.; RESENDE, M. Estabilidade de agregados de um Latossolo Roxo sob diferentes métodos de preparo do solo e de manejo da palha do milho. Revista Brasileira de Ciência do Solo, Viçosa, v. 10, n. 2, p. 273-277, 1986.


Assuntos
Fractais , Ciências do Solo
6.
Glob Chang Biol ; 25(6): 1895-1904, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-30900360

RESUMO

Although only representing 0.05% of global freshwater, or 0.001% of all global water, soil water supports all terrestrial biological life. Soil moisture behaviour in most models is constrained by hydraulic parameters that do not change. Here we argue that biological feedbacks from plants, macro-fauna and the microbiome influence soil structure, and thus the soil hydraulic parameters and the soil water content signals we observe. Incorporating biological feedbacks into soil hydrological models is therefore important for understanding environmental change and its impacts on ecosystems. We anticipate that environmental change will accelerate and modify soil hydraulic function. Increasingly, we understand the vital role that soil moisture exerts on the carbon cycle and other environmental threats such as heatwaves, droughts and floods, wildfires, regional precipitation patterns, disease regulation and infrastructure stability, in addition to agricultural production. Biological feedbacks may result in changes to soil hydraulic function that could be irreversible, resulting in alternative stable states (ASS) of soil moisture. To explore this, we need models that consider all the major feedbacks between soil properties and soil-plant-faunal-microbial-atmospheric processes, which is something we currently do not have. Therefore, a new direction is required to incorporate a dynamic description of soil structure and hydraulic property evolution into soil-plant-atmosphere, or land surface, models that consider feedbacks from land use and climate drivers of change, so as to better model ecosystem dynamics.


Assuntos
Retroalimentação , Água Subterrânea , Plantas/metabolismo , Solo/química , Ciclo do Carbono , Clima , Secas , Ecossistema , Meio Ambiente , Hidrologia
7.
Proc Natl Acad Sci U S A ; 115(39): 9791-9796, 2018 09 25.
Artigo em Inglês | MEDLINE | ID: mdl-30209211

RESUMO

Bacterial cell-to-cell interactions are in the core of evolutionary and ecological processes in soil and other environments. Under most conditions, natural soils are unsaturated where the fragmented aqueous habitats and thin liquid films confine bacterial cells within small volumes and close proximity for prolonged periods. We report effects of a range of hydration conditions on bacterial cell-level interactions that are marked by plasmid transfer between donor and recipient cells within populations of the soil bacterium Pseudomonas putida Using hydration-controlled sand microcosms, we demonstrate that the frequency of cell-to-cell contacts under prescribed hydration increases with lowering water potential values (i.e., under drier conditions where the aqueous phase shrinks and fragments). These observations were supported using a mechanistic individual-based model for linking macroscopic soil water potential to microscopic distribution of liquid phase and explicit bacterial cell interactions in a simplified porous medium. Model results are in good agreement with observations and inspire confidence in the underlying mechanisms. The study highlights important physical factors that control short-range bacterial cell interactions in soil and on surfaces, specifically, the central role of the aqueous phase in mediating bacterial interactions and conditions that promote genetic information transfer in support of soil microbial diversity.


Assuntos
Microbiologia do Solo , Bactérias/metabolismo , Fenômenos Fisiológicos Bacterianos , Conjugação Genética , Modelos Teóricos , Pseudomonas putida/metabolismo , Pseudomonas putida/fisiologia , Água
8.
FEMS Microbiol Rev ; 41(5): 599-623, 2017 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-28961933

RESUMO

Soil, the living terrestrial skin of the Earth, plays a central role in supporting life and is home to an unimaginable diversity of microorganisms. This review explores key drivers for microbial life in soils under different climates and land-use practices at scales ranging from soil pores to landscapes. We delineate special features of soil as a microbial habitat (focusing on bacteria) and the consequences for microbial communities. This review covers recent modeling advances that link soil physical processes with microbial life (termed biophysical processes). Readers are introduced to concepts governing water organization in soil pores and associated transport properties and microbial dispersion ranges often determined by the spatial organization of a highly dynamic soil aqueous phase. The narrow hydrological windows of wetting and aqueous phase connectedness are crucial for resource distribution and longer range transport of microorganisms. Feedbacks between microbial activity and their immediate environment are responsible for emergence and stabilization of soil structure-the scaffolding for soil ecological functioning. We synthesize insights from historical and contemporary studies to provide an outlook for the challenges and opportunities for developing a quantitative ecological framework to delineate and predict the microbial component of soil functioning.


Assuntos
Biodiversidade , Fenômenos Biofísicos , Microbiota/fisiologia , Microbiologia do Solo , Ecossistema
9.
MethodsX ; 4: 134-142, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28337415

RESUMO

The saturated hydraulic conductivity (Ks ) is a key characteristic of porous media, describing the rate of water flow through saturated porous media. It is an indispensable parameter in a broad range of simulation models that quantify saturated and/or unsaturated water flow. The constant-head permeameter test is a common laboratory method to determine Ks on undisturbed soil samples collected from the field. In this paper we show that the application of this conventional method may result in a biased Ks in the case of highly permeable media, such as the top layer of Sphagnum peat and gravel. Tubes in the conventional permeameter, that collect water under the sample, introduce a hydraulic head-dependent resistance for highly permeable media and result in an underestimation of Ks . We present a simple and low-budget alternative of the constant-head permeameter test that overcomes the disadvantages of conventional permeameters. The new method was successfully tested on intact highly permeable peatmoss collected from a northern peatland. •Conventional constant-head permeameters underestimate Ks of highly permeable media due to flow resistance in tubing systems•We developed the low-resistance permeameter to overcome this disadvantage.•Testing of the low-resistance permeameter demonstrated no systematic bias and successful application for highly permeable media.

10.
Ecol Lett ; 19(9): 1140-9, 2016 09.
Artigo em Inglês | MEDLINE | ID: mdl-27459206

RESUMO

Plant diversity loss impairs ecosystem functioning, including important effects on soil. Most studies that have explored plant diversity effects belowground, however, have largely focused on biological processes. As such, our understanding of how plant diversity impacts the soil physical environment remains limited, despite the fundamental role soil physical structure plays in ensuring soil function and ecosystem service provision. Here, in both a glasshouse and a long-term field study, we show that high plant diversity in grassland systems increases soil aggregate stability, a vital structural property of soil, and that root traits play a major role in determining diversity effects. We also reveal that the presence of particular plant species within mixed communities affects an even wider range of soil physical processes, including hydrology and soil strength regimes. Our results indicate that alongside well-documented effects on ecosystem functioning, plant diversity and root traits also benefit essential soil physical properties.


Assuntos
Biodiversidade , Pradaria , Fenômenos Fisiológicos Vegetais , Raízes de Plantas/fisiologia , Solo/química , Alemanha
11.
Biosci. j. (Online) ; 28(3): 338-345, may/june 2012. tab, graf
Artigo em Português | LILACS | ID: biblio-912598

RESUMO

Neste estudo foi verificada a adequação de uso do índice S no diagnóstico da qualidade estrutural de um Latossolo Vermelho distrófico de cerrado cultivado com cafeeiro sob sistema de manejo que adota a aplicação de altas doses de gesso na linha da cultura, cultivo e manejo mecanizado de braquiária na entrelinha da cultura, além de preparo do sulco de plantio até 60 cm de profundidade, dentre outras técnicas de manejo intensivo. O índice S foi correlacionado à densidade e à porosidade do solo nas profundidades de 5, 20, 40 e 80 cm, na linha do cafeeiro, e 5, 10, 20, 40, 65 cm na entrelinha do cafeeiro. Para a determinação do índice S nas diferentes profundidades e locais de amostragem foram construídas curvas de retenção de água, sendo utilizadas amostras com estrutura preservada. Os valores deste atributo físico foram superiores a 0,045 indicando ótima qualidade física do solo sob o sistema de manejo adotado. Houve boa correlação entre o índice S com os atributos físicos analisados, mostrando ser esta uma boa ferramenta a ser utilizada no diagnóstico da qualidade estrutural do solo.


In this study we verified the adequacy of use of the Dexter S index in the diagnosis of structural quality of a Cerrado Oxisol cultivated with coffee in management system that adopts the application of high doses of gypsum in row culture, mechanized cultivation and management of Brachiaria in the interrows, and preparation of the furrow 60 cm deep, among other techniques of intensive management. The S was correlated with the density and porosity of the soil at depths of 5, 20, 40 and 80 cm along the row of coffee, and 5, 10, 20, 40, 65 cm between rows of coffee. For the determination of the S at different depths and sampling sites were built water retention curves, using samples with structure preserved. The values of this physical attribute were greater than 0.045 indicating good soil physical quality under the management system adopted. There was good correlation between the S with the physical attributes analyzed, showing that this is a good tool to use in the diagnosis of structural soil quality.


Assuntos
Qualidade do Solo , Características do Solo , Conservação de Terras , Produção Agrícola
12.
Ciênc. rural ; 41(12): 2096-2100, Dec. 2011. ilus, tab
Artigo em Inglês | LILACS | ID: lil-608076

RESUMO

Soil clay content is an important soil attribute and has been used to classification of phosphorus status in the soil in order to determinate the needing of phosphorus amounts to be applied to crops production. The aim of this research was to adjust the method for soil clay content determination, adopted by the laboratories of Southern Brazil (ROLAS-RS/SC), for soil clay content evaluation in Rondônia soils. The study was conducted using 50 soil samples from Rondônia State with wide range clay content. It was tested shaking periods (1.5, 2.0 and 2.5h) associated with periods for soil particles decantation (1.5 and 2.0h) to correlate with the standard method for soil texture testing, known as the pipette method. Clay content determined through this method was significantly correlated with pipette method. The better treatment was the combination of 2.0h of shaking and 1.5h of decantation, resulted in total period of 3.5h, which reduced the period to determine the soil clay content without loss of accuracy.


O teor de argila é um importante atributo de solo e é utilizado na determinação de faixas de teores de fósforo para fins de recomendação de adubação. O objetivo deste trabalho foi ajustar o método de determinação de argila utilizado pelos laboratórios da ROLAS-RS/SC para avaliar os teores de argila dos solos de Rondônia. O estudo foi conduzido com 50 amostras de solos do Estado de Rondônia, com diferentes teores de argila. O teor de argila foi determinado utilizando-se o método da ROLAS-RS/SC, com diferentes períodos de agitação (1,5; 2,0 e 2,5h) e de decantação das partículas do solo (1,5 e 2,0h) e o método da pipeta, considerado padrão para essa determinação. Os teores de argila determinados nas combinações de períodos de agitação e de decantação se correlacionaram significativamente com os teores determinados pelo método da pipeta. O melhor tratamento foi a combinação de 2,0h de agitação e 1,5h de decantação, resultando em tempo total de 3,5h, que reduz o tempo para determinação do teor de argila do solo sem perda significativa da eficiência.

13.
An. acad. bras. ciênc ; 83(3): 1097-1108, Sept. 2011. ilus, graf, tab
Artigo em Inglês | LILACS | ID: lil-595547

RESUMO

Wetting and drying (W-D) cycles can induce important elemental migrations in soils. The main purpose of this work was to study the possible existence of soil chemical elemental migrations in samples submitted to repeated W-D cycles during evaluations of soil water retention curve (SWRC). The experimental measurements were carried out by Atomic Absorption Spectrometry (AAS) for Ca2+, Mg2+ and K+ on samples of three different Brazilian tropical soils (Geric Ferralsol, Eutric Nitosol and Rhodic Ferralsol). Results demonstrate an increase in the electrical conductivity of the water extracted from the samples and significant losses of Ca2+, Mg2+ and K+ during the applications of up to nine W-D cycles. It was also observed differences in SWRC for all soils when samples submitted to the application of several W-D cycles were compared with samples not submitted to it. These differences occurred at the region of both structural and textural pores. A possible explanation for these results could be the soil chemical migration during the sequences of W-D cycles, which can affect the soil structure development.


Os ciclos de umedecimento e secamento (U-S) podem induzir importantes migrações de elementos químicos no solo. O objetivo principal deste trabalho foi estudar a possível existência de migração de elementos químicos em amostras de solos submetidas a repetidos ciclos de U-S durante a avaliação da curva de retenção de água do solo. As determinações de Ca2+,Mg2+ e K+ foram obtidas por Espectrometria de Absorção Atômica em três diferentes solos tropicais do Brasil (Latossolo Vermelho-Amarelo, Nitossolo Vermelho e Latossolo Vermelho). Os resultados demonstram um aumento da condutividade elétrica da água extraída das amostras de solo e perda significativa de Ca2+, Mg2+ e K+ após a aplicação de nove ciclos de U-S. Diferenças nas curvas de retenção foram também observadas para todos os solos quando as amostras submetidas aos ciclos de U-S foram comparadas com as amostras não submetidas. Essas diferenças ocorreram tanto na região estrutural quanto textural dos poros do solo. Uma possível explicação para esses resultados pode ser a migração de elementos químicos do solo durante as sequências de ciclos de U-S, os quais podem afetar o desenvolvimento da estrutura do solo.


Assuntos
Cálcio/análise , Magnésio/análise , Potássio/análise , Solo/química , Espectrofotometria Atômica , Movimentos da Água
14.
Ciênc. rural ; 39(1): 74-81, Jan.-Feb. 2009. graf, tab
Artigo em Português | LILACS | ID: lil-502637

RESUMO

Os objetivos deste trabalho foram determinar e modelar o escoamento superficial para solos com diferentes características físicas a partir de diferentes intensidades de chuva. Foram realizadas chuvas simuladas em diferentes solos, no Uruguai. Chuvas artificiais com intensidades de 30, 60 e 120mm h-1 foram aplicadas utilizando-se um simulador estacionário de bicos múltiplos e oscilantes. Em cada solo foram determinados o tempo de início e a taxa de escoamento superficial, além da chuva (quantidade, duração e intensidade), declividade do terreno, matéria seca na superfície e cobertura do solo, densidade (do solo e de partícula), porosidade do solo (macro, micro e total), textura (argila, silte e areia), umidade inicial e saturação do solo. Foi utilizado o modelo modificado de Smith para estimativa do escoamento superficial. As perdas acumuladas por escoamento superficial foram de 64, 32, 30 e 15 por cento do total aplicado para Vertissolo 1, Chernossolo, Argissolo e Vertissolo 2, respectivamente. Há uma relação inversa entre o tempo de início do escoamento e a taxa constante de escoamento superficial, independentemente das condições da superfície do solo e da chuva. Isso está associado à intensidade da chuva, pois quanto mais esta aumentar, menor é o tempo de início do escoamento e maior é a taxa constante de escoamento superficial. O modelo modificado de Smith estima melhor o escoamento superficial sob condições de elevada umidade do solo.


The objective of this research was to determinate and modeling the runoff for different soils classes based on different simulated rainfall intensities (30, 60 and 120mm h-1) in different soils in Uruguay. A portable rainfall simulator with multiple nozzles was used to simulate different rainfall intensities. On each soil was measured the initial time and rate of runoff, rainfall (total, duration and intensities), direction of slope, crop residue and cover percentage, soil densities (bulk and particle), soil porosity (bulk, macro and micro), textural fractions (clay, silt and sand), initial and saturated soil moisture. The runoff was estimated with Smith's modified model. The accumulate runoff losses were 64, 32, 30 e 15 percent from the total rainfall, for Vertissolo 1, Chernossolo, Argissolo e Vertissolo 2, respectively. The relationship between initial runoff and the runoff rate was inversively, independently of the soil surface and rainfall conditions. Increasing rainfall intensity decreases the initial runoff time and increase runoff rate. Smith's modified model provides a better runoff estimated in soils with high soil moisture content.

15.
Acta amaz ; 32(3)2002.
Artigo em Português | LILACS-Express | LILACS, VETINDEX | ID: biblio-1454900

RESUMO

Soil physical variables were investigated in forest plots submitted to selective logging in Central Amazonia. After logging, soil samples were collected to obtain soil water retention curves and measure: available soil water to the plants, soil density, and total porosity. Temperature measurements were carried out for 13 months, considering six treatments: control, center of the gaps, edge of the gaps, edge of the remaining forest, remaining forest and tractor tracks. Hydraulic conductivity measurements on saturated soil were conducted both on the control forest as well as on the logged plots, with no treatment distinction. The soil showed a low available water storage capacity: only 11 to 18% can be available to the plants, up to 1 meter depth. The temperature of the soil upper layers was influenced by logging, i. e., through the opening of the gaps, light reaches the soil more intensely in the center and edge of gaps, increasing temperatures in relation to the control and the remaining forest.


Variáveis físicas do solo foram investigadas em parcelas de floresta de terra firme submetidas à extração seletiva de madeira na Amazônia central. Foram obtidas curvas de retenção de água no solo, juntamente com medidas de água disponível no solo às plantas, densidade do solo e porosidade total. Medidas de temperatura do solo foram realizadas por mais de 13 meses, considerando seis tratamentos: controle, centro da clareira, borda da clareira, borda da floresta remanescente, floresta remanescente e trilha do trator. Medidas de condutividade hidráulica de solo saturado foram feitas na floresta e em clareiras, sem distinguir os tratamentos. O solo revelou baixa capacidade de armazenar água disponível: apenas 11 a 18% da água pode estar disponível às plantas, num perfil de 1 m de profundidade. A temperatura das camadas superiores do solo foi influenciada pela extração seletiva de madeira: nas clareiras abertas, a luz chega com mais intensidade no solo, proporcionando temperaturas mais elevadas no centro e nas bordas das clareiras do que no controle e na floresta remanescente.

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