Validity of the Centrifuge Method for Determining the Water Retention Properties of Tropical Soils

Reatto, Adriana; Silva, Euzébio Medrado da; Bruand, Ary; Martins, E. S.; Lima, Jorge Enoch Furquim Werneck

doi:10.2136/sssaj2007.0355n

Cited by 87 publications

(49 citation statements)

References 20 publications

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“…Selecionaram-se nove cilindros cujos valores de K SL foram considerados homogêneos e mais próximos da média para serem utilizados na determinação da curva de retenção de água (CRA) do solo. A CRA foi obtida pelo método da centrífuga (Silva & Azevedo, 2002) e a umidade em equilíbrio foi determinada com os potenciais correspondentes a -10, -30, -60, -100, -330, -800, -4.000, -10.000, e -15.198,75 hPa (Reatto et al, 2008). Ao final do processo de dessorção da água, a densidade do solo (D s , em g cm -3 ) foi mensurada pelo método do anel volumétrico, com massa do solo seco obtida na estufa a 105ºC.…”

Section: Methodsunclassified

Qualidade física do solo sob sistemas de integração lavoura-pecuária

Santos

Marchão²,

Silva³

et al. 2011

Pesq. agropec. bras.

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Resumo -O objetivo deste trabalho foi avaliar a qualidade física do solo em sistemas de integração lavoura-pecuária (ILP), em comparação à pastagem contínua e ao cerrado nativo. Durante dois anos (2005 e 2006), amostras de um Latossolo Vermelho argiloso foram coletadas de duas camadas (0-20 e 70-80 cm), em seis áreas cultivadas em diferentes sistemas de rotação de culturas e ILP. Uma área de pastagem contínua e outra de cerrado nativo foram utilizadas como referências. Foram analisados os seguintes atributos físico-hídricos: densidade do solo, umidade de saturação, porosidade total, macroporosidade, microporosidade efetiva, saturação efetiva, condutividade hidráulica saturada de campo e de laboratório, e curva de retenção de água do solo. Todos os sistemas de cultivo provocaram impacto nos atributos físico-hídricos, na camada 0-20 cm. O cultivo contínuo de pastagem proporcionou a melhor qualidade física do solo. Na comparação entre os anos, apenas o sistema preparo convencional do solo mostrou incremento na densidade e redução na porosidade do solo. A pastagem em rotação no sistema ILP, mesmo após quatro anos, não favorece a qualidade física do solo em comparação à pastagem contínua.Termos para indexação: condutividade hidráulica, curva de retenção, porosidade, rotação de culturas, sistema plantio direto. Soil physical quality in integrated crop-livestock systemsAbstract -The objective of this work was to evaluate the physical quality of soil in integrated crop-livestock systems (ICL) in comparison to continuous pasture and native Cerrado. During two years (2005 and 2006), soil samples from a clayed Rhodic Ferralsol were collected from two layers (0-20 and 70-80 cm), in six areas under different crop rotation and ICL. Continuous pasture and native Cerrado were used as reference. The following physical and hydraulic properties were evaluated: bulk density, water saturation, total porosity, macroporosity, effective microporosity, effective saturation, lab and field-saturated hydraulic conductivity, and soil-water retention curve. All the cultivated systems caused impact on the physical and hydraulic properties of the 0-20 cm layer. The continuous pasture provided the best soil physical quality. In the comparison between years, only the soil under conventional tillage had its bulk density increased and its soil porosity decreased. The pasture in the rotation system with ICL, even after four years, does not restore soil physical quality in comparison to continuous pasture.

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Section: Methodsunclassified

Qualidade física do solo sob sistemas de integração lavoura-pecuária

Santos

Marchão²,

Silva³

et al. 2011

Pesq. agropec. bras.

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“…Water mass was determined by weighing the soil sample before and after drying (60°C until constant weight). Soil-water retention properties were also evaluated using the centrifuge method described by Khanzode et al (2002) and modified by Reatto et al (2008) to determine the relationship between soil moisture and soil water potential (ψ soil ).…”

Section: Methodsmentioning

confidence: 99%

Xylem potential- and water content-breakpoints in two wetland forbs: indicators of drought resistance in emergent hydrophytes

Touchette¹,

Frank²

2009

Aquat. Biol.

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Freshwater wetlands commonly occur along the boundaries between terrestrial upland and deep open-water systems, and are consequently prone to dynamic and often highly variable hydrological regimes. Physiological adaptations to drought would be advantageous in emergent vegetation, as wetlands are often susceptible to short periods of water scarcity through seasonal declines in precipitation and/or surface water runoff. This study used 15 l microcosms to examine xylem water potential (ψ xylem )-and tissue water content (θ)-breakpoints in 2 wetland forbs (Justicia americana and Saururus cernuus) to determine how these plants respond to short-term (2 wk) water deficits. Overall, treatment responses by these forbs included reductions in both θ and ψ xylem during the second week of drought, followed by rapid recoveries of θ and ψ xylem within a few days of water repletion. Rapid tissue-water recovery, following extreme water deficits (soil moisture levels < 3%), is beneficial to plants residing in areas prone to intense water fluctuations. Furthermore, while θ and ψ xylem breakpoints in S. cernuus occurred as soil moisture levels fell below 12% (ca. -800 kPa soil water potential), breakpoints for J. americana occurred at considerably lower soil moisture levels (ca. 7 and 10% soil water content for θ and ψ xylem , respectively; or less than -1500 kPa soil water potential). The lower breakpoints observed in J. americana were comparable to values reported for terrestrial grasses, including species adapted to dryer, xeric conditions. Therefore, the results from this study suggest that some wetland forbs are physiologically adapted to environments that undergo rapid changes in water hydrology, including the ability to tolerate short-term water scarcity comparable to dryer upland systems.

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“…An SWRC for the undisturbed soil cores for each site was determined using the centrifugation method (Hitachi CR21G centrifuge; 20°C) [28,29]. Saturated hydraulic conductivity was measured using the constant head method [30].…”

Section: Laboratory Measurementsmentioning

confidence: 99%

Spatial Variability of Soil Parameters of the van Genuchten Model at a Regional Scale

Wang

Shao

Han

et al. 2014

CLEAN Soil Air Water

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Spatial heterogeneity of soil water retention curves (SWRC) plays an important role in modelling the movement of water and solutes in soils. To characterize the spatial variability of SWRC parameters fitted by the van Genuchten (VG) equation, and then identify factors that closely correlated with the VG parameters, we collected undisturbed and disturbed soil samples from the upper 0-5 cm soil layer at 382 sampling sites across the entire Loess Plateau of China ($620 000 km 2 ). We determined the SWRC and six other soil properties as well as nine environmental factors for each site. Results showed that the saturated water content (u s ) and a curve-shape parameter that is related to soil pore size distribution (n) were weakly spatially variable (coefficient of variation (CV) ¼ 15%), and that the residual soil water content (u r ) and a scaling parameter that is related to the inverse of the air entry pressure (a) were moderately (CV ¼ 96%) and strongly variable (CV ¼ 136%), respectively. Semivariograms of ffiffiffiffi u r p and log(a) were best-fitted by an isotropic exponential model, while those of u s and log(n) were fitted by an isotropic spherical model. Fractal analysis indicated that log(a) demonstrated the most short-range variation, while log(n) reflected the importance of long-range variation. Bulk density and the contents of clay, silt, sand and soil organic carbon contributed greatly to the variations in the VG parameters (except a). However, the vegetation, topographic and climatic elements as well as land use also usually explained some of the variation. The VG parameters, at the regional scale, demonstrated different characteristics of spatial variation, which comprehensively reflected the combined effects of processes involving the soil, vegetation, topography and climate as well as effects of land use, which is often determined by human activity.

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Validity of the Centrifuge Method for Determining the Water Retention Properties of Tropical Soils

Cited by 87 publications

References 20 publications

Qualidade física do solo sob sistemas de integração lavoura-pecuária

Qualidade física do solo sob sistemas de integração lavoura-pecuária

Xylem potential- and water content-breakpoints in two wetland forbs: indicators of drought resistance in emergent hydrophytes

Spatial Variability of Soil Parameters of the van Genuchten Model at a Regional Scale

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