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  • 1
    Electronic Resource
    Electronic Resource
    Microbiological processes in soil organic phosphorus transformations in conventional and biological cropping systems (1996)
    Springer
    Biology and fertility of soils 21 (1996), S. 138-148 
    Details
    ISSN: 1432-0789
    Keywords: Organic soil P ; Acid phosphatase activity ; Soil microbial biomass ; Organic C mineralization ; Temporal fluctuations ; Farming systems ; P turnover
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We studied microbiological processes in organic P transformations in soils cultivated with conventional and biological farming systems during the 13th and 14th year of different cropping systems. The treatments included control, biodynamic, bioorganic, and conventional plots and a mineral fertilization treatment. Different P fractions were investigated using a sequential fractionation method. Labile organic P, extracted by 0.5 M NaHCO3, was not affected by the farming systems. However, residual organic P remaining in the soil at the end of the sequential fractionation procedure showed that the biodynamic treatment, in particular, led to a modification of the composition of organic P. Labile organic P, organic P extractable in 0.1 M NaOH, and total residual P all showed temporal fluctuations. As total residual P consists of more than 70% organic P, it can be assumed that residual organic P contributed to these variations. This result indicates that chemically resistant organic P participates in short-term accumulation and mineralization processes. All biological soil parameters tested in this study showed significant temporal fluctuations, mainly attributed to differences in climatic conditions between years, but possibly also related to the growth cycle of the crop. The higher values of the biological soil parameters in the biodynamic and bioorganic treatments were explained by the greater importance of manure and the different plant protection strategies. The level of phosphatase activity and mineralization of organic C indicated a higher turnover of organic substrates, and thus of organic P, in the biodynamic and bioorganic treatments. Biological parameters were shown to be critical for assessing the significance of organic P in the soil P turnover.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00335925
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  • 2
    Electronic Resource
    Electronic Resource
    Microbiological processes in soil organic phosphorus transformations in conventional and biological cropping systems (1996)
    Springer
    Biology and fertility of soils 21 (1996), S. 138-148 
    Details
    ISSN: 1432-0789
    Keywords: Key words Organic soil P ; Acid phosphatase activity ; Soil microbial biomass ; Organic C mineralization ; Temporal fluctuations ; Farming systems ; P turnover
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We studied microbiological processes in organic P transformations in soils cultivated with conventional and biological farming systems during the 13th and 14th year of different cropping systems. The treatments included control, biodynamic, bioorganic, and conventional plots and a mineral fertilization treatment. Different P fractions were investigated using a sequential fractionation method. Labile organic P, extracted by 0.5 M NaHCO3, was not affected by the farming systems. However, residual organic P remaining in the soil at the end of the sequential fractionation procedure showed that the biodynamic treatment, in particular, led to a modification of the composition of organic P. Labile organic P, organic P extractable in 0.1 M NaOH, and total residual P all showed temporal fluctuations. As total residual P consists of more than 70% organic P, it can be assumed that residual organic P contributed to these variations. This result indicates that chemically resistant organic P participates in short-term accumulation and mineralization processes. All biological soil parameters tested in this study showed significant temporal fluctuations, mainly attributed to differences in climatic conditions between years, but possibly also related to the growth cycle of the crop. The higher values of the biological soil parameters in the biodynamic and bioorganic treatments were explained by the greater importance of manure and the different plant protection strategies. The level of phosphatase activity and mineralization of organic C indicated a higher turnover of organic substrates, and thus of organic P, in the biodynamic and bioorganic treatments. Biological parameters were shown to be critical for assessing the significance of organic P in the soil P turnover.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00335925
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  • 3
    Electronic Resource
    Electronic Resource
    Soil phosphorus dynamics in cropping systems managed according to conventional and biological agricultural methods (1993)
    Springer
    Biology and fertility of soils 16 (1993), S. 111-117 
    Details
    ISSN: 1432-0789
    Keywords: Available P ; Isotopic exchange kinetics ; Organic soil P ; Acid phosphatase activity ; Soil microbial biomass ; Farming systems
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of conventional and biological farming systems on soil P dynamics were studied by measuring some microbiological parameters after 13 years of different cropping systems. The treatments included control, biodynamic, bio-organic, and conventional plots and a mineral fertilizer treatment. The farming systems differed mainly in the form and quantity of nutrients applied and in the plant protection strategies. The results of a sequential fractionation procedure showed that irrespective of the form of P applied, neither 0.5 M NaHCO inf3 sup- nor 0.1 M NaOH-extractable organic P, but only the inorganic fractions, were affected. The residual organic P, not extracted by NaHCO3 or NaOH was increased in the biodynamic and bio-organic plots. The soil microbial biomass (ATP content) and the activity of acid phosphatase were also higher in both biologically managed systems. These results were attributed to the higher quantity of organic C and organic P applied in these systems, but also to the absence of or severe reduction in chemical plant protection. The relationship between acid soil phosphatase and residual organic P was interpreted as an indication that this fraction might be involved in short-term transformations. The measurement of the intensity, quantity, and capacity factors of available soil P using the 32P isotopic exchange kinetic method showed that P could not be the factor limiting crop yield in the biological farming systems. The kinetic parameters describing the ability of P ions to leave the soil solid phase, deduced from isotopic exchange, were significantly higher for the biodynamic treatment than for all other treatments. This result, showing a modification of chemical bonds between P ions and the soil matrix, was explained by the higher Ca and organic matter contents in this system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00369411
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  • 4
    Electronic Resource
    Electronic Resource
    Understanding colloidal charge renormalization from surface chemistry: Experiment and theory (1994)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 101 (1994), S. 9924-9936 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: In this paper we report on the charging behavior of latex particles in aqueous suspensions. We use static light scattering and acid–base titrations as complementary techniques to observe both effective and bare particle charges. Acid–base titrations at various ionic strengths provide the pH dependent charging curves. The surface chemical parameters (dissociation constant of the acidic carboxylic groups, total density of ionizable sites and Stern capacitance) are determined from fits of a Stern layer model to the titration data. We find strong evidence that the dissociation of protons is the only specific adsorption process. Effective particle charges are determined by fits of integral equation calculations of the polydisperse static structure factor to the static light scattering data. A generalization of the Poisson–Boltzmann cell model including the dissociation of the acidic surface groups and the autodissociation of water is used to predict effective particle charges from the surface chemical parameters determined by the titration experiments. We find that the light scattering data are best described by a model where a small fraction of the ionizable surface sites are sulfate groups which are completely dissociated at moderate pH. These effective charges are comparable to the predictions by a basic cell model where charge regulation is absent. © 1994 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.467894
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  • 5
    Electronic Resource
    Electronic Resource
    The Rietveld method applied to the quantitative mineralogical and chemical analysis of a ferralitic soil (1998)
    Oxford, UK : Blackwell Science Ltd
    European journal of soil science 49 (1998), S. 0 
    Details
    ISSN: 1365-2389
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The analysis of X-ray diffraction (XRD) patterns by the Rietveld method was tested for characterizing quantitatively the mineralogical composition of a ferralitic soil from southern Mali. Quantitative analysis of two samples from this soil revealed kaolinite and quartz as major components and smaller amounts of haematite, goethite and anatase. Despite a strong overlap of the peaks, precise and reliable cell parameters and Al for Fe substitutions were determined. The quantitative results of the Rietveld refinement were verified by chemical analysis. This comparison revealed a strong influence of sample preparation on the quantitative mineralogical analysis by XRD.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2389.1998.00138.x
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  • 6
    Electronic Resource
    Electronic Resource
    Coating of silica sand with goethite: preparation and analytical identification
    Amsterdam : Elsevier
    Geoderma 58 (1993), S. 43-65 
    Details
    ISSN: 0016-7061
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0016-7061(93)90084-X
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  • 7
    Electronic Resource
    Electronic Resource
    Thermal analysis of synthetic (near-chabazite) zeolites with different Si/Al ratios
    Amsterdam : Elsevier
    Thermochimica Acta 10 (1974), S. 305-311 
    Details
    ISSN: 0040-6031
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0040-6031(74)80027-4
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  • 8
    Electronic Resource
    Electronic Resource
    Flugstaub In Vier Boden Aus Kalk, Dolomit Und Serpentin (Schweizer Jura Und Schweizer Alpen)
    Amsterdam : Elsevier
    Catena 2 (1975), S. 11-22 
    Details
    ISSN: 0341-8162
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Geography , Geosciences
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/S0341-8162(75)80002-6
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  • 9
    Electronic Resource
    Electronic Resource
    Cation transport in natural porous media on laboratory scale: multicomponent effects
    Amsterdam : Elsevier
    Journal of Contaminant Hydrology 16 (1994), S. 319-337 
    Details
    ISSN: 0169-7722
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Geography , Geosciences
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0169-7722(94)90042-6
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  • 10
    Electronic Resource
    Electronic Resource
    Abbau von Quarz mit Brenzkatechin (1966)
    Springer
    Cellular and molecular life sciences 22 (1966), S. 515-516 
    Details
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Fine divided HF-etched quartz was dissolved in a 0.2M solution of pyrocatechol at pH 9.6. Between 17 and 40 °C the dissolution rate (v s ) follows the equation: logv s =0.0295 T-20.87 At 25 °Cv s amounts to 0.8 · 10−12 g cm−2 sec−1. With several phenols the dissolution rate of quartz decreases in the order: pyrocatechol 〉 pyrogallol 〉 2, 3-dihydroxynaphthalene.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01898661
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