A Single-Extraction Method Using Silver-Thiourea for Measuring Exchangeable Cations and Effective Cec in Soils With Variable Charges

Pleysier, J. L.; Juo, A. S. R.

doi:10.1097/00010694-198004000-00002

Cited by 136 publications

(73 citation statements)

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“…Exchangeable cations were determined by the silver thiourea method (Pleysier and Juo, 1980), soil carbon was determined in an automated elemental analyser as described by Pella (1990) and Nelson and Sommers (1996). Particle size analysis was undertaken using the Boyoucos method (Gee and Bauder, 1986).…”

Section: Soil Sampling and Laboratory Methodsmentioning

confidence: 99%

Soils of Amazonia with particular reference to the RAINFOR sites

et al. 2011

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Abstract. The tropical forests of the Amazon Basin occur on a wide variety of different soil types reflecting a rich diversity of geologic origins and geomorphic processes. We here review the existing literature about the main soil groups of Amazonia, describing their genesis, geographical patterns and principal chemical, physical and morphologic characteristics. Original data is also presented, with profiles of exchangeable cations, carbon and particle size fraction illustrated for the principal soil types; also emphasizing the high diversity existing within the main soil groups when possible. Maps of geographic distribution of soils occurring under forest vegetation are also introduced, and to contextualize soils into an evolutionary framework, a scheme of soil development is presented having as its basis a chemical weathering index. We identify a continuum of soil evolution in Amazonia with soil properties varying predictably along this pedogenetic gradient.

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Section: Soil Sampling and Laboratory Methodsmentioning

confidence: 99%

Soils of Amazonia with particular reference to the RAINFOR sites

et al. 2011

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“…The specific surface area was measured following Ethylene Glycol monoethyl Ether method [Cerato and Lutenegger, 2002]. The cation exchange capacity of the clay was determined by Silver Thiourea method [Pleysier and Juo, 1980]. The properties of the bentonite are shown in Table 1.…”

Section: Methodsmentioning

confidence: 99%

Swelling pressure of a divalent‐rich bentonite: Diffuse double‐layer theory revisited

Schanz

Tripathy

2009

Water Resources Research

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[1] Physicochemical forces are responsible for the swelling pressure development in saturated bentonites. In this paper, the swelling pressures of several compacted bentonite specimens for a range of dry density of 1.10-1.73 Mg/m 3 were measured experimentally. The clay used was a divalent-rich Ca-Mg-bentonite with 12% exchangeable Na + ions. The theoretical swelling pressure-dry density relationship for the bentonite was determined from the Gouy-Chapman diffuse double-layer theory. A comparison of experimental and theoretical results showed that the experimental swelling pressures are either smaller or greater than their theoretical counterparts within different dry density ranges. It is shown that for dry density of the clay less than about 1.55 Mg/m 3 , a possible dissociation of ions from the surface of the clay platelets contributed to the diffuse double-layer repulsion. At higher dry densities, the adsorptive forces due to surface and ion hydration dominated the swelling pressures of the clay. A comparison of the modified diffuse double-layer theory equations proposed in the literature to determine the swelling pressures of compacted bentonites and the experimental results for the clay in this study showed that the agreement between the calculated and experimental swelling pressure results is very good for dry densities less than 1.55 Mg/m 3 , whereas at higher dry densities the use of the equations was found to be limited.

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“…Soil pits were situated at representative locations for the dominant soil and 2 http://www.geog.leeds.ac.uk/projects/rainfor/projdocs.html topographic positions, usually located a few metres outside the permanent sample plots in order to reduce potential disturbances. All soil samples were analysed ) and exchangeable Ca, Mg, K, Na and Al were determined by the silver thiourea method (Pleysier and Juo, 1980) as described in detail in ISRI (1995). The sum of bases (SB) was calculated as:…”

Section: Environmental Variablesmentioning

confidence: 99%

Spatial trends in leaf size of Amazonian rainforest trees

et al. 2009

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Abstract. Leaf size influences many aspects of tree function such as rates of transpiration and photosynthesis and, consequently, often varies in a predictable way in response to environmental gradients. The recent development of panAmazonian databases based on permanent botanical plots has now made it possible to assess trends in leaf size across environmental gradients in Amazonia. Previous plot-based studies have shown that the community structure of Amazonian trees breaks down into at least two major ecological gradients corresponding with variations in soil fertility (decreasing from southwest to northeast) and length of the dry season (increasing from northwest to south and east). Here we describe the geographic distribution of leaf size categories based on 121 plots distributed across eight South American countries. We find that the Amazon forest is predominantly populated by tree species and individuals in the mesophyll size class (20.25-182.25 cm 2 ). The geographic distribution of species and individuals with large leaves (>20.25 cm 2 ) is complex but is generally characterized by a higher proportion Correspondence to: A. C. M. Malhado (anaclaudiamalhado@gmail.com) of such trees in the northwest of the region. Spatially corrected regressions reveal weak correlations between the proportion of large-leaved species and metrics of water availability. We also find a significant negative relationship between leaf size and wood density.

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A Single-Extraction Method Using Silver-Thiourea for Measuring Exchangeable Cations and Effective Cec in Soils With Variable Charges

Cited by 136 publications

References 0 publications

Soils of Amazonia with particular reference to the RAINFOR sites

Soils of Amazonia with particular reference to the RAINFOR sites

Swelling pressure of a divalent‐rich bentonite: Diffuse double‐layer theory revisited

Spatial trends in leaf size of Amazonian rainforest trees

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