Clay mineralogy effects on sodium fluoride pH of non-allophanic tropical soils

Soil Research ◽  
2004 ◽  
Vol 42 (8) ◽  
pp. 865 ◽  
Author(s):  
M. E. Alves ◽  
A. Lavorenti
Keyword(s):  
Agricultural Soils ◽  
Ammonium Oxalate ◽  
Clay Fraction ◽  
Chemical Properties ◽  
Clay Mineralogy ◽  
Clay Content ◽  
Soil Classification ◽  
Tropical Soils ◽  
Oh Groups ◽  
Soil Weathering

Soil pH measured in 1 m NaF (pHNaF) can be a useful tool for soil classification and to provide better advice on the chemical management of agricultural soils in the tropics. In this study, we verified the effects of clay mineralogy on pHNaF values of non-allophanic soils of São Paulo State, Brazil. Fourteen subsurface soil samples were characterised for chemical properties, clay content, clay mineralogy, and for pHNaF values, which were measured in the whole soil and in both natural and deferrified (dithionite-treated) clay fractions. Regression and correlation analyses showed that both ammonium-oxalate-extractable Al (Alo) and gibbsite contents have positive relationships with both clay and soil pHNaF values. On the other hand, kaolinite is inversely related to the pHNaF measured in the clay and has nonsignificant effect on soil pHNaF. X-ray diffraction patterns of dithionite-treated clays did not show disruption of kaolinite or gibbsite after the treatment with 1 m NaF, suggesting that the displacement of surface OH groups by F– seems to be the main mechanism associated with the pH increase verified in the NaF solution after its contact with the deferrified clay fraction. The smaller influence of hematite on pHNaF seems to be due to its correlation to Alo. Goethite and ammonium-oxalate-extractable Fe (Feo) exert no effect on pHNaF. Finally, the relationships observed in the present study strongly suggest that pHNaF values <10.3 measured in non-allophanic kaolinitic soils with low levels of non-humified organic matter are essentially due to their smaller Alo and gibbsite contents, which agrees with the direct correlation verified between pHNaF and soil weathering degree.

Red soils of different origins from southwest Nigeria: Characteristics, classification, and management considerations

1997 ◽  
Vol 77 (2) ◽  
pp. 295-307 ◽  
Author(s):  
T. A. Okusami ◽  
R. H. Rust ◽  
A. O. Alao
Keyword(s):  
Clay Mineral ◽  
Agricultural Land ◽  
Clay Fraction ◽  
Chemical Properties ◽  
Cropping System ◽  
Clay Content ◽  
Parent Material ◽  
Classification Systems ◽  
Biotite Gneiss ◽  
Variable Charge

Representative profiles of the Owena, Egbeda, Alagba, and Balogun series were studied. The Owena soil is formed in amphibolite whereas Egbeda and Balogun soils are formed in biotite gneiss derived parent materials. The Alagba soil is formed in sandstone parent rock. The main objectives were to characterize the soils and their clay fraction, and to classify and interpret soil properties for agricultural land use. Most soils exhibit 2.5 YR hues in subsurface horizons. A pedon formed in biotite gneiss has the highest dithionite Fe content and Fed/clay ratio. The relationships between clay content and Fed values vary according to parent material origin and, therefore, would have to be interpreted differently for soil weathering processes. Clay coatings were noticeable in some soil horizons of all pedons studied. Soils are generally medium to slightly acid with sandstone-derived soils being the most acid. The clay mineral suite in all soils is dominated by kaolinite with traces of 2:1 and 2:2 clay minerals, goethite, hematite, anatase, maghemite, and rutile. In addition, some soils contain trace amounts of gibbsite. Kandic horizons have been identified in all soils. The low charge properties of the soils reflect the intensely weathered clay mineral suite. The base status is probably influenced by the cropping system and therefore may tend to unnecessarily differentiate highly weathered soils at the order level. The Egbeda and Balogun series were classified as Rhodic Kandiudults, clayey-skeletal, oxidic and Rhodic Kandiudalfs, clayey-skeletal, oxidic, respectively. Others, Owena, and Alagba series, were classified as Typic Kanhaplohumults, clayey, oxidic and Rhodic Kanhaplustults, fine loamy or clayey, oxidic, respectively. In the FAO-Unesco legend, all soils become Rhodic Ferralsols. In addition, the Owena (with its nitic properties) is further classified as niti-rhodic Ferralsol. The two classification systems are at variance for highly weathered (variable charge property) soils and this difference will definitely influence management decisions depending on which system is used at any particular time. Soil attributes favorable for agricultural use include thick sola and favorable structures. Chemical properties suggest minimal fixation of phosphorus. Key words: Dithionite Fe, kandic, oxidic, variable charge, ferralic, exchangeable Al

scholarly journals Remaining phosphorus and sodium fluoride pH in soils with different clay contents and clay mineralogies

2004 ◽  
Vol 39 (3) ◽  
pp. 241-246 ◽  
Author(s):  
Marcelo Eduardo Alves ◽  
Arquimedes Lavorenti
Keyword(s):  
Buffer Capacity ◽  
Ammonium Oxalate ◽  
Clay Mineralogy ◽  
Clay Content ◽  
Response Curves ◽  
Solution Ph ◽  
Ph Values ◽  
Soil Clay ◽  
Soil Clay Content ◽  
Discriminatory Capacity

The remaining phosphorus (Prem) has been used for estimating the phosphorus buffer capacity (PBC) of soils of some Brazilian regions. Furthermore, the remaining phosphorus can also be used for estimating P, S and Zn soil critical levels determined with PBC-sensible extractants and for defining P and S levels to be used not only in P and S adsorption studies but also for the establishment of P and S response curves. The objective of this work was to evaluate the effects of soil clay content and clay mineralogy on Prem and its relationship with pH values measured in saturated NaF solution (pH NaF). Ammonium-oxalate-extractable aluminum exerts the major impacts on both Prem and pH NaF, which, in turn, are less dependent on soil clay content. Although Prem and pH NaF have consistent correlation, the former has a soil-PBC discriminatory capacity much greater than pH NaF.

The forms of potassium and potassium adsorption in some virgin soils from south-western Australia

Soil Research ◽  
1999 ◽  
Vol 37 (4) ◽  
pp. 695 ◽  
Author(s):  
Y. Pal ◽  
R. J. Gilkes ◽  
M. T. F. Wong
Keyword(s):  
Western Australia ◽  
Agricultural Soils ◽  
Clay Mineralogy ◽  
Sorption Isotherms ◽  
Clay Content ◽  
Water Soluble ◽  
X Ray Diffraction ◽  
Exchangeable K ◽  
The North ◽  
Southern District

This investigation was undertaken to determine the potassium (K) status and adsorption behaviour of 227 samples from horizons of 41 representative virgin soil profiles, extending from Geraldton in the north to the Great Southern district of Western Australia. X-ray diffraction analysis of random powder of whole soil indicated that quartz is the dominant mineral and some soils contain significant amounts of feldspars. Clay mineralogy is dominated by kaolinite but minor quantities of illite are present in some soils. Most south-west Australian agricultural soils contain little available K: NaHCO3-extractable K (NaHCO3-K, median value 0·09 cmol K/kg, equivalent to 35 mg K/kg soil), HNO3-extractable K (HNO3-K, median value 0·30 cmol K/kg, equivalent to 117 mg K/kg soil), and total K (XRF determined K, median value, 17 cmol K/kg, equivalent to 6630 mg K/kg soil). The proportion of water-soluble K (H2O-K) ranges from 0 to 3·5% of total K, 0 to 76% of HNO3-K, and 0 to nearly 100% of exchangeable K. Exchangeable K ranges from 0 to 100% (median value 37%) of HNO3-K. These are relatively high proportions of H2O-K and exchangeable K compared with soils from many other parts of the world. The amounts of all forms of K variously increase or decrease downwards in the soil profile depending on both clay content and mineralogy. The commonly assumed increase in K with clay content alone is invalid. The soils mostly have low-to-moderate values of K sorption capacity, ranging from 5% to 67% (median value 14%) of added K (initially 4·1 mM K/L, equivalent to 4·1 cmol K/kg). otassium sorption isotherms conform well to the Freundlich equation. The inability of the Langmuir equation to describe the data may indicate that there are several types of K sorption sites in these soils. The Gapon coefficient KG varied widely from 0·04 to 29·8 (L/mol) ½ [median value 5·4 (L/mol) ½ ].

Acidity control in Latosols under long-term pastures in the Cerrado region, Brazil

Soil Research ◽  
2013 ◽  
Vol 51 (4) ◽  
pp. 253 ◽  
Author(s):  
P. R. S. Vendrame ◽  
O. R. Brito ◽  
E. S. Martins ◽  
C. Quantin ◽  
M. F. Guimarães ◽  
...  
Keyword(s):  
Crop Production ◽  
Clay Fraction ◽  
Clay Mineralogy ◽  
Tropical Soils ◽  
Limiting Factors ◽  
Standard Procedures ◽  
Controlling Parameter ◽  
Exchangeable Al ◽  
The Mean

High acidity and aluminium saturation are among the main limiting factors for crop production in tropical soils. The aim of this work was to measure the acidity of Latosols under pastures in the Brazilian Cerrado and to assess the influence of clay mineralogy as a controlling parameter of soil acidity. Topsoils (n = 73, 0–0.2 m depth) of Latosols developed on different parent materials were sampled in two sub-regions of the Cerrado region. The main chemical characteristics were determined by standard procedures, and kaolinite and gibbsite contents were determined by dissolution with sulfuric acid and thermogravimetric analyses. The exchangeable concentrations of calcium (Ca), magnesium (Mg), and potassium (K) varied considerably among soil samples, with ranges of 0–13.9 cmolc kg–1 (mean ± standard deviation 1.77 ± 1.91 cmolc kg–1) for Ca; 0.2–3.2 cmolc kg–1 (1.13 ± 0.68 cmolc kg–1) for Mg; and 0–1.0 cmolc kg–1 (0.24 ± 0.24 cmolc kg–1) for K. The mean concentration of exchangeable aluminium (Al) was 0.55 ± 0.61 cmolc kg–1 (range 0–2.3 cmolc kg–1). The content of kaolinite (282 ± 96 g kg–1) was higher than of gibbsite (106 ± 77 g kg–1). The amount of exchangeable Al and Al saturation rate varied according to the mineralogy of the clay fraction of the soils. The content of exchangeable Al3+ remained low when gibbsite was the predominant mineral, whereas it increased with kaolinite content. The ratio kaolinite/(kaolinite + gibbsite) could be used as a useful indicator of the sensitivity of soils affected by acidity and Al toxicity.

Forms of K as a function of clay mineralogy and soil development

Clay Minerals ◽  
2006 ◽  
Vol 41 (3) ◽  
pp. 739-749 ◽  
Author(s):  
K. Nabiollahy ◽  
F. Khormali ◽  
K. Bazargan ◽  
SH. Ayoubi
Keyword(s):  
Clay Fraction ◽  
Clay Mineralogy ◽  
Clay Content ◽  
Soil Development ◽  
Water Soluble ◽  
The Other ◽  
Research Station ◽  
Surface Areas ◽  
Regression Slopes ◽  
Diffraction Patterns

AbstractThe relationships between different pools of K, i.e. exchangeable, HN03-extractable, mineral and total, were investigated as a function of clay mineralogy and soil development in soils of Kharkeh Research Station, Kurdestan Province, western Iran. Samples from different horizons often pedons were selected and analysed for clay mineralogy and K fractionation. X-ray diffraction patterns revealed that clay minerals in the soils studied were similar in type, while their abundances were different. The smectite content was significantly greater in Vertisols than in the other soils. The results of K fractionation showed that mineral K and HN03-extractable K (exchangeable and nonexchangeable, respectively) and the clay content of the soils containing lesser illite (10–30%) were significantly different from those with more illite (30–50%). Moreover, the regression slopes between water-soluble and NE4OAc-extractable K were lower in soils with more smectite due mainly to the presence of larger specific surface areas for K sorption in smectitic soils. Based on soil evolution and different forms of K, the soils studied were grouped in two major categories: (1) Vertisols and (2) Entisols, Inceptisols and Mollisols. There were greater contents of all forms of K in Vertisols than in the other soil orders. This was mainly related to the greater clay content and the dominance of smectite in the clay fraction of Vertisols.

Clay mineral associations in melanic soils of South Africa

Soil Research ◽  
2002 ◽  
Vol 40 (1) ◽  
pp. 115 ◽  
Author(s):  
Gertruida M. E. van der Merwe ◽  
Michiel C. Laker ◽  
Christl Bühmann
Keyword(s):  
South African ◽  
Clay Mineral ◽  
Wide Spectrum ◽  
Clay Fraction ◽  
Clay Mineralogy ◽  
Soil Classification ◽  
Large Degree ◽  
Mineral Associations ◽  
Investigative Technique ◽  
African Soil

The melanic horizon is 1 of 5 diagnostic topsoil horizons distinguished in the South African soil classification system. Melanic soils span a wide spectrum, ranging from those that intergrade with a vertic to those that intergrade with a humic horizon. Melanic soils are therefore expected to vary considerably with respect to a variety of physical, chemical, and clay mineralogical properties. The objective of the present study was to determine the clay mineral compositions of melanic horizons from 58 modal profiles and to establish to what extent melanic soil properties are related to clay mineralogy. Special emphasis was placed on the characterisation of the clay fraction in terms of group and species identification. X-ray diffractometry was employed almost exclusively as the investigative technique in mineral identification and quantification. Melanic A horizons showed a large degree of variation with regard to their clay mineral associations. More than half of the soils were dominated by smectite, 30&percnt; by kaolinite, and the rest by an association of about equal proportions of mica, kaolinite, and smectite. Talc and hydroxy-interlayered vermiculite occurred in a number of soils while one horizon was dominated by an illite&sol;smectite interstratification. The smectite component was identified as belonging to either beidellite or vermiculite species, depending on the method employed. About a quarter of the smectitic soils contained montmorillonite as well but not as the dominant swelling phase. mollisols, clay mineralogy, layer charge.

Characteristics and genesis of two strongly weathered soils in Samar, Philippines

Soil Research ◽  
2007 ◽  
Vol 45 (3) ◽  
pp. 153 ◽  
Author(s):  
Ian A. Navarrete ◽  
Victor B. Asio ◽  
Reinhold Jahn ◽  
Kiyoshi Tsutsuki
Keyword(s):  
Clay Fraction ◽  
Chemical Properties ◽  
Morphological Characteristics ◽  
Clay Content ◽  
Parent Material ◽  
Parent Rock ◽  
Soil Taxonomy ◽  
Reference Base ◽  
Weathered Soils ◽  
World Reference Base

Very limited data have been published on the nature of strongly weathered soils in geologically young humid tropical islands. The study evaluated the characteristics and formation of 2 strongly weathered soils in the island of Samar, Philippines, one developed from slate (Bagacay soil) and the other from ultrabasic rock (Salcedo soil). Results revealed that the soils have generally similar morphological characteristics, particularly in terms of colour (2.5 YR-10 R), solum thickness (>5.0 m), and structure (granular to subangular blocky), although the Salcedo soil has much higher clay content than the Bagacay soil. Both soils have similar chemical properties (e.g. acidic, low exchangeable bases) except that the Salcedo soil has lower CEC values but higher exchangeable Na content, resulting in a higher base saturation. They also have high dithionite-extractable Fe contents and very low oxalate/dithionite ratios and are dominated by halloysite, kaolinite, gibbsite, goethite, hematite, and quartz in the clay fraction. Apparently as a result of its more weatherable ultrabasic parent rock and more stable geomorphic surface, the Salcedo soil shows more advanced weathering and soil development than the Bagacay soil. Salcedo soil is classified as Haplic Ferralsol (Dystric, Clayic, Rhodic) in the World Reference Base or very fine, sesquic, isohyperthermic, Rhodic Hapludox in the Soil Taxonomy. Bagacay soil is a Haplic Acrisol (Alumic, Hyperdystric, Clayic, Rhodic) or fine, kaolinitic, isohyperthermic, Typic Paleudult. The Salcedo soil has very high Ni and Cr contents inherited from its ultrabasic parent material. The study reveals that on the geologically young humid tropical island of Samar, the characteristics and genesis of strongly weathered soils are greatly affected by the geochemical characteristic of the parent rock material.

scholarly journals Simulating carbon capture by enhanced weathering with croplands: an overview of key processes highlighting areas of future model development

2017 ◽  
Vol 13 (4) ◽  
pp. 20160868 ◽  
Author(s):  
Lyla L. Taylor ◽  
David J. Beerling ◽  
Shaun Quegan ◽  
Steven A. Banwart
Keyword(s):  
Mathematical Models ◽  
Soil Acidification ◽  
Carbon Capture ◽  
Agricultural Soils ◽  
Model Development ◽  
Ghg Emissions ◽  
Tropical Soils ◽  
Phosphorus Limitation ◽  
Process Models ◽  
Soil Weathering

Enhanced weathering (EW) aims to amplify a natural sink for CO 2 by incorporating powdered silicate rock with high reactive surface area into agricultural soils. The goal is to achieve rapid dissolution of minerals and release of alkalinity with accompanying dissolution of CO 2 into soils and drainage waters. EW could counteract phosphorus limitation and greenhouse gas (GHG) emissions in tropical soils, and soil acidification, a common agricultural problem studied with numerical process models over several decades. Here, we review the processes leading to soil acidification in croplands and how the soil weathering CO 2 sink is represented in models. Mathematical models capturing the dominant processes and human interventions governing cropland soil chemistry and GHG emissions neglect weathering, while most weathering models neglect agricultural processes. We discuss current approaches to modelling EW and highlight several classes of model having the potential to simulate EW in croplands. Finally, we argue for further integration of process knowledge in mathematical models to capture feedbacks affecting both longer-term CO 2 consumption and crop growth and yields.

scholarly journals Spodosols pedogenesis under barreiras formation and sandbank environments in the south of Bahia

2010 ◽  
Vol 34 (3) ◽  
pp. 847-860 ◽  
Author(s):  
Aline Pacobahyba de Oliveira ◽  
João Carlos Ker ◽  
Ivo Ribeiro da Silva ◽  
Maurício Paulo Ferreira Fontes ◽  
Alessandra Pacobahyba de Oliveira ◽  
...  
Keyword(s):  
Ammonium Oxalate ◽  
Clay Fraction ◽  
Chemical Properties ◽  
Sodium Dithionite ◽  
Soil Profiles ◽  
The South ◽  
Acid Attack ◽  
Black And White ◽  
Dark Color ◽  
And Chemical Properties

Morphologically differentiated Spodosols usually occur in the Coastal Plain of the South of Bahia and North of Espírito Santo. They are found in profiles known as "muçungas", i.e. sandy soils that accumulate water. In these areas, two kinds of Spodosols, different from those in the Restinga area, can be found: Spodosols with E albic horizon (white muçunungas) and without this horizon (black muçunungas). Eight soil profiles with spodic characteristics were collected and described in order to evaluate differences in the formation process of Barreiras and Restinga Spodosols in the South of Bahia. The soil profiles were also characterized chemically, physically and mineralogically. Additionally, texture and chemical analysis, Fe and Al extraction by sodium dithionite-citrate-bicarbonate (DBC), acid ammonium oxalate and sodium pyrophosphate, ammonium oxalate extract optic density (DOox), sulphuric acid attack, and X ray difractometry of the clay fraction were performed. In the Spodosols of the Barreiras area, fragipan was found the spodic layers. Cemented B spodic horizon were observed in the white muçunungas, and granular structure and dark color from the surface in the black muçunungas. There was no fragipan or hard spodic horizon in the Restinga Spodosol. This soil is acid, dystrophic and alic, with sandy texture and high clay percentages in the spodic horizons. The CEC, based on H + Al, is predominantly represented by the organic matter. The most representative components of the mineral phase of the clay fraction are kaolinite and possibly vermiculite traces with interlayered hydroxy. Chemical, physical, morphological and mineralogical differences were observed between the Barreiras and Restinga environments. The black and white muçunungas differ in morphologic and chemical properties only.

Clay minerals in the agricultural surface soils in the Central United States

Clay Minerals ◽  
2001 ◽  
Vol 36 (3) ◽  
pp. 277-294 ◽  
Author(s):  
B. Velde
Keyword(s):  
United States ◽  
Clay Minerals ◽  
Agricultural Soils ◽  
Clay Fraction ◽  
Clay Mineralogy ◽  
Parent Material ◽  
X Ray Diffraction ◽  
Charge Site ◽  
X Ray ◽  
Central United States

AbstractA survey of the clay fraction at the surface of 86 loam and silt loam agricultural soils from the Central United States was undertaken to observe the possible influences of climate and parent material (dominantly phyllosilicates in this study) on the clay mineralogy of the upper portions of the soils, for the most part in Mollisol–Alfisol order soils.Decomposed X-ray diffraction spectra show that the most abundant clay minerals are two disordered illite-smectite (I-S) minerals, one with ∼50% smectite layers and another, less abundant, disordered I-S phase with 20% smectite. These minerals usually co-exist in the same samples. The charge site in both of these I-S minerals is both beidellitic and montmorillonitic in the expanding layers. A relatively large proportion of these smectite layers (up to 20%) are of high charge.There seems to be a convergence in mineralogy towards mixed-layer phases formed under a range of mid-Continent climates from a range of phyllosilicate parent materials.

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