ALBERT — All Library Books, journals and Electronic Records Telegrafenberg

1

Electronic Resource

Corrections for interferences in a high-speed automatic thermometric analyzer

Weber, R. ; Blanc, G. ; Peuschel, G. ; [et al.]

Amsterdam : Elsevier

Analytica Chimica Acta 86 (1976), S. 79-85

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ISSN: 0003-2670

Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Topics: Chemistry and Pharmacology

Type of Medium: Electronic Resource

URL: http://linkinghub.elsevier.com/retrieve/pii/S0003-2670(01)83020-8

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2

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A 13C tracer study to identify the origin of dissolved organic carbon in forested mineral soils (2004)

Hagedorn, F. ; Saurer, M. ; Blaser, P.

Oxford, UK : Blackwell Science Ltd

European journal of soil science 55 (2004), S. 0

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ISSN: 1365-2389

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: The relative contributions of sources of carbon in soils, such as throughfall, litter, roots, microbial decay products and stable organic fractions, to dissolved organic C are controversial. To identify the origin of dissolved organic C, we made use of a 4-year experiment where spruce and beech, growing on an acidic loam and on a calcareous sand, were exposed to increased CO2 that was depleted in 13C. We traced the new C inputs from trees into dissolved organic C, into water-extractable organic C, and into several particle-size fractions. In addition, we incubated the labelled soils for 1 year and measured the production of dissolved organic C and CO2 from new and old soil C. In the soil solutions of the topsoil, the dissolved organic C contained only 5–10% new C from the trees. The δ13C values of dissolved organic C resembled those of C pools smaller than 50 µm, which strongly suggests that the major source of dissolved organic C was humified old C. Apparently, throughfall, fresh litter and roots made only minor contributions to dissolved organic C. Water-extractable organic C contained significantly larger fractions of new C than did the natural dissolved organic C (25–30%). The δ13C values of the water-extractable organic C were closely correlated with those of sand fractions, which consisted of little decomposed organic carbon. The different origin of dissolved and water-extractable organic C was also reflected in a significantly larger molar UV absorptivity and a smaller natural 13C abundance of dissolved organic C. This implies that the sampling method strongly influences the characteristics and sources of dissolved organic C. Incubation of soils showed that new soil C was preferentially respired as CO2 and only a small fraction of new C was leached as dissolved organic C. Our results suggest that dissolved organic C is produced during incomplete decomposition of recalcitrant native C in the soils, whereas easily degradable new components are rapidly consumed by microbes and thus make only a minor contribution to the dissolved C fraction.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1046/j.1365-2389.2003.00578.x

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3

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Sorption and transport of metals in preferential flow paths and soil matrix after the addition of wood ash (2001)

Bundt, M. ; Zimmermann, S. ; Blaser, P. ; [et al.]

Oxford, UK : Blackwell Science Ltd

European journal of soil science 52 (2001), S. 0

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ISSN: 1365-2389

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: As a consequence of heterogeneous transport in soils, only a small part of the soil might be responsible for sorbing incoming elements. After staining preferential flow paths in forested Dystric Cambisol with a colour dye, we sampled soil material from the flow paths and from the soil matrix. We measured chemical properties and sorption isotherms of these two flow regions and estimated the significance of preferential flow paths for the transport of solutes leached from wood ash applied at the surface. In the A horizon (0–9 cm depth), the cation exchange capacity of the flow paths was 83.8 mmolc kg−1, while that of the soil matrix was only 74.6 mmolc kg−1. The base saturation was 42% and soil organic matter content was 41% larger in flow paths than in the soil matrix. The sorption capacity for Cu was also larger than in the matrix, whereas the sorption capacity for Sr was similar in both flow regions. The impact of the addition of 8 t wood ash ha−1 on soil chemical properties was restricted mainly to the flow paths in the uppermost 20 cm of the soil; it was negligible in the matrix and at greater depths. Concentrations of exchangeable Ca in the flow paths increased nearly 10-fold during the 6 months following the addition of the wood ash, and those of organically bound Pb by 50%. The opposite effect was found for exchangeable Al. Our results show that only part of the whole soil volume, approximately 50% of 0–20 cm in our study, is involved in transporting and sorbing the elements applied with the wood ash or as tracers. Such differences must be considered when calculating the maximal impact of any addition of fertilizer, wood ash, or liming agent.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1046/j.1365-2389.2001.00405.x

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4

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Carbon sequestration in forest soils: effects of soil type, atmospheric CO2 enrichment, and N deposition (2001)

Hagedorn, F. ; Maurer, S. ; Egli, P. ; [et al.]

Oxford, UK : Blackwell Science Ltd

European journal of soil science 52 (2001), S. 0

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ISSN: 1365-2389

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Soil contains the major part of carbon in terrestrial ecosystems, but the response of this carbon to enriching the atmosphere in CO2 and to increased N deposition is not completely understood. We studied the effects of CO2 concentrations at 370 and 570 μmol CO2 mol−1 air and increased N deposition (7 against 0.7 g N m−2 year−1) on the dynamics of soil organic C in two types of forest soil in model ecosystems with spruce and beech established in large open-top chambers containing an acidic loam and a calcareous sand. The added CO2 was depleted in 13C and thus the net input of new C into soil organic carbon and the mineralization of native C could be quantified.Soil type was the greatest determining factor in carbon dynamics. After 4 years, the net input of new C in the acidic loam (670 ± 30 g C m−2) exceeded that in the calcareous sand (340 ± 40 g C m−2) although the soil produced less biomass. The mineralization of native organic C accounted for 700 ± 90 g C m−2 in the acidic loam and for 2800 ± 170 g C m−2 in the calcareous sand. Unfavourable conditions for mineralization and a greater physico-chemical protection of C by clay and oxides in the acidic loam are probably the main reasons for these differences. The organic C content of the acidic loam was 230 g C m−2 more under the large than under the small N treatment. As suggested by a negligible impact of N inputs on the fraction of new C in the acidic loam, this increase resulted mainly from a suppressed mineralization of native C. In the calcareous sand, N deposition did not influence C concentrations. The impacts of CO2 enrichment on C concentrations were small. In the uppermost 10 cm of the acidic loam, larger CO2 concentrations increased C contents by 50–170 g C m−2. Below 10 cm depth in the acidic loam and at all soil depths in the calcareous sand, CO2 concentrations had no significant impact on soil C concentrations. Up to 40% of the ‘new’ carbon of the acidic loam was found in the coarse sand fraction, which accounted for only 7% of the total soil volume. This suggests that a large part of the CO2-derived ‘new’ C was incorporated into the labile and easily mineralizable pool in the soil.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1046/j.1365-2389.2001.00412.x

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5

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Novel ruthenium-catalyzed synthesis of 1,3-dioxolan-4-ones from α-hydroxy acids and terminal alkynes via enol esters

Neveux, M. ; Seiller, B. ; Hagedorn, F. ; [et al.]

Amsterdam : Elsevier

Journal of Organometallic Chemistry 451 (1993), S. 133-138

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ISSN: 0022-328X

Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002

Topics: Chemistry and Pharmacology

Type of Medium: Electronic Resource

URL: http://linkinghub.elsevier.com/retrieve/pii/0022-328X(93)83017-P

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6

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A review on the potential of improved fallows and green manure in Rwanda (1996)

Drechsel, P. ; Steiner, K. G. ; Hagedorn, F.

Springer

Agroforestry systems 33 (1996), S. 109-136

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ISSN: 1572-9680

Keywords: adoption ; alley cropping ; mineralization ; on-farm research ; organic farming ; planted fallow

Source: Springer Online Journal Archives 1860-2000

Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Abstract Agricultural production in the densely populated highlands of Rwanda is subject to serious soil fertility constraints. As the use of imported mineral fertilizers is beyond the economic means of resource-poor farmers, research and extension efforts of several projects, institutes and organizations concentrated during the last 15 years on the development and promotion of improved fallows with woody and herbaceous legumes, like Tephrosia sp., Cajanus sp., Crotalaria sp., Sesbania sp., Mucuna sp., and Mimosa sp., planted over one or more seasons as pure green manure, in hedgerows (alley cropping), or on fields as seasonal inter- or relay-crop. Green manuring proved to be a risky enterprise, due to highly variable biomass production and residual effects. Yield increments on-farm of up to 74% in the first season and 46% in the second season did not compensate loss of yields and labour investments during green manuring. Even where biomass production was sufficient, residual effects were in most cases unsatisfactory, due to rapid nutrient leaching (N, K) or inappropriate foliage incorporation on-farm. In researcher-managed trials, residual effects were in general somewhat higher, but more than a mere compensation of lost yields was not possible and farmers' adoption of these labour-intensive technologies was rather low. Due to acute land shortage, farmers were reluctant in allocating land to fallows or hedgerows also, with the exception of fields already out of production. Consequently, the concept of improving soil fertility and crop yields with the help of planted fallows or green manure in rotation failed. Woody legumes might have a future on abandoned fields and in wide spaced contour hedges, mainly for the production of firewood and bean stakes. For soil fertility management, the production and availability of farmyard manure and country-own mineral fertilizers, such as travertin and volcanic ashes should be supported. The question is raised as to whether sustainable agricultural development is possible without a credit system for small farmers, reallocating land and creating off-farm employment.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00213645

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7

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Effect of rainfall pattern on nitrogen mineralization and leaching in a green manure experiment in South Rwanda (1997)

Hagedorn, F. ; Steiner, K.G. ; Sekayange, L. ; [et al.]

Springer

Plant and soil 195 (1997), S. 365-375

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ISSN: 1573-5036

Keywords: green manure ; leaching ; N-mineralization ; rainfall pattern ; resin core ; Rwanda

Source: Springer Online Journal Archives 1860-2000

Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition

Notes: Abstract The effects of green manures, sorghum residues and farmyard manure on N dynamics and crop yields were studied during three dry and wet seasons on a Typic Sombriudox in South Rwanda. In addition, a resin core study was conducted within a 4-year green manure field experiment to follow the seasonal pattern of N mineralization and leaching after application of residues from Tephrosia vogelii, Sorghum bicolor, a mixture of both materials, and farmyard manure. During the dry season, topsoil (0–20 cm) mineral N remained constant. At the beginning of the wet season, the rainfall pattern determined N availability. With low rainfall intensities a mineralization flush occurred, doubling topsoil mineral N concentrations within 5 days after wetting. In contrast, under heavy rains at the onset of the rainy season, topsoil mineral N decreased by 50–70% within the first two weeks. The application of organic fertilizers has a strong influence on N availability, but the effects can be negated by heavy rainfall. Incorporation of leaves from Tephrosia vogelii (2.7 t dm ha-1) and farmyard manure (7 t dm ha-1) doubled the mineralization flush after the first rains. During the rest of the wet season, N release by the green manure was small, whereas the farmyard manure was found to mobilize N after a period of N immobilization. Incorporation of sorghum residues had only a small effect, while mixing the straw with green and farmyard manure immobilized N temporarily. Nitrogen leaching, measured by exchange resins at a depth of 20 cm, was increased up to 50% by the incorporation of green and farmyard manure. This points to rapid N translocation of easily mineralizable N. The additional incorporation of sorghum residues reduced N leaching of both materials significantly. Since rainfall is often unpredictable, the synchronization of N released from crop residues with crop N demand may require additional management practices.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1023/A:1004266205502

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8

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Mechanisiertes thermometrisches Analysenverfahren zur Bestimmung von Substanzen in weiten Konzentrationsbereichen (1975)

Peuschel, G. ; Hagedorn, F.

Springer

Fresenius' Zeitschrift für analytische Chemie 277 (1975), S. 177-182

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ISSN: 1618-2650

Keywords: Thermometrie ; mechanisiertes Verfahren für weite Konzentrationsbereiche

Source: Springer Online Journal Archives 1860-2000

Topics: Chemistry and Pharmacology

Description / Table of Contents: Zusammenfassung Ein Verfahren zur Durchführung mechanisierter thermometrischer Analysen wird beschrieben, das sowohl zur kontinuierlichen Untersuchung von Probenströmen als auch zur Bestimmung von Komponenten in Einzelproben eingesetzt werden kann. Im Gegensatz zu den bisher angewandten mechanisierten Analysenmethoden eignet es sich besonders dann, wenn die zu bestimmenden Substanzen in mittleren bis hohen Konzentrationen vorliegen. Damit kann einer Forderung vieler Industriezweige entsprochen werden. Durch die analytische Ausnutzung von Enthalpieänderungen bei z.B. Neutralisations-, Redox- und Fällungsreaktionen sowie bei Verdünnungsvorgängen bieten sich vielfältige Anwendungsmöglichkeiten. Die Streubereiche der Analysenergebnisse sind in der Regel äußerst gering.

Notes: Abstract A procedure for mechanised thermometric analysis is described which can be used for the continuous analysis of sample streams as well as for the determination of components in individual samples. In contrast to thermometric methods of analysis previously used, this new procedure is particularly applicable for substances present in medium to high concentrations, and is therefore suitable for many industrial purposes. The analytical exploitation of enthalpy changes as for example with neutralisation, redox and precipitation reactions as well as with dilution, opens wide application possibilities. The precision of the results is generally very good.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00462232

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