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  • Articles  (6,711)
  • Articles: DFG German National Licenses  (6,711)
  • Blackwell Science Ltd  (3,508)
  • Cambridge University Press  (3,203)
  • 1995-1999  (6,711)
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  • Articles  (6,711)
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  • 1
    Electronic Resource
    Electronic Resource
    Dynamics of dissolved organic nitrogen and carbon in a Central European Norway spruce ecosystem (1999)
    Oxford, UK : Blackwell Science Ltd
    European journal of soil science 50 (1999), S. 0 
    Details
    ISSN: 1365-2389
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Dissolved organic nitrogen and carbon (DOC) are significant in the C and N cycle in terrestrial ecosystems. Little is known about their dynamics in the field and the factors regulating their concentrations and fluxes. We followed the fluxes and concentrations of the two in a Norway spruce (Picea abies (L.) Karst.) forest ecosystem in Germany from 1995 to 1997 by sampling at fortnightly intervals. Bulk precipitation, throughfall, forest floor percolates from different horizons and soil solutions from different depths were analysed for major ions, dissolved organic N and DOC. The largest fluxes and concentrations were observed in percolates of the Oi layer, which contain amino N and amino sugar N as the major components. The average ratio of dissolved organic C to N in forest floor percolates corresponded to the C/N ratio of the solid phase. Concentrations and fluxes were highly dynamic with time and decreased with depth. The largest fluxes in forest floor percolates occurred when the snow melted. The concentrations and fluxes of dissolved organic N were significantly correlated with DOC, but the correlation was weak, indicating different mechanisms of release and consumption. The dynamics of dissolved organic N and DOC in forest floor percolates were not explained by pH and ionic strength of the soil solution nor by the water flux, despite large variations in these. Furthermore, the release of these fractions from the forest floor was not related to the quality and amount of throughfall. Concentrations of dissolved organic N in forest floor percolates increased with soil temperature, while temperature effects on DOC were less pronounced, but their fluxes from the forest floor were not correlated with temperature. In the growing season concentrations of both dissolved organic N and C in forest floor percolates decreased with increasing intensity of throughfall. Thus, the average throughfall intensity was more important than the amount of percolate in regulating their concentrations in forest floor percolates. Our data emphasize the role of dissolved organic N and DOC in the N and C cycle of forest ecosystems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2389.1999.00267.x
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  • 2
    Electronic Resource
    Electronic Resource
    Modelling particle mobilization and leaching in macroporous soil (1999)
    Oxford, UK : Blackwell Science Ltd
    European journal of soil science 50 (1999), S. 0 
    Details
    ISSN: 1365-2389
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The migration of colloidal particles in the unsaturated zone may enhance leaching of sorbing contaminants to surface waters and groundwaters. This paper describes a simple model of particle leaching and translocation based on the dual-porosity model MACRO. The model includes descriptions of processes such as ‘source-limited’ particle detachment due to the kinetic energy of rain, replenishment of the depleted store of particles up to a maximum value determined by the amount of dispersible clay in the soil, and convective transport of particles in macropores subject to a filter sink term varying as a function of pore water velocity. Estimates of model parameter values are obtained by comparing simulations with measurements of particle concentrations in the discharge from tile drains made in a silty clay soil in southwest Sweden. Calibrated in this way, the model is shown to reproduce satisfactorily the observations. A sensitivity analysis suggests that the critical parameters in the model are those related to particle filtering during vertical transport in soil macropores.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2389.1999.00269.x
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  • 3
    Electronic Resource
    Electronic Resource
    A 13C-NMR study of the interactions of soil organic matter with aluminium and allophane in podzols (1999)
    Oxford, UK : Blackwell Science Ltd
    European journal of soil science 50 (1999), S. 0 
    Details
    ISSN: 1365-2389
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The stabilization of organic matter in soil by interaction with aluminium (Al) or allophane is important in maintaining soil quality, and in retarding the decomposition of soil organic matter. Complexation of Al by soil organic matter may also ameliorate Al toxicity. Here we use 13C-NMR spectroscopy to assess the interaction of soil organic matter with both Al and allophane in two poorly drained podzols containing only trace amounts of iron. The 13C-NMR spectrum of the subsoil of the allophane-rich One Tree Point podzol shows an intense peak at 179 p.p.m., assigned to carbon in carboxylic acids. This peak shifts to 177 p.p.m. after removal of allophane (11% of the soil mass) by treatment with HF. We infer that the carboxyl groups in the organic matter are bonded to structural Al on the surface of allophane spherules. In the non-allophanic Te Kopuru podzol, on the other hand, the organic matter apparently interacts with Al ions in the soil solution. This soil also has more aromatic carbon and fewer carbons in carboxyl and carbohydrate structures than the allophanic sample. There is an indication that allophane stabilizes carbohydrate groups as well as carboxyl groups.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2389.1999.00274.x
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  • 4
    Electronic Resource
    Electronic Resource
    n-Alkanes and free fatty acids in humus and A1 horizons of soils under beech, spruce and grass in the Massif-Central (Mont-Lozère), France (1999)
    Oxford, UK : Blackwell Science Ltd
    European journal of soil science 50 (1999), S. 0 
    Details
    ISSN: 1365-2389
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Soil profiles under beech, spruce and a grassland have been analysed to study the evolution of natural n-alkanes in pollution-free ecosystems. The soils had all developed on granitic bedrock, at an altitude of 1300–1500 m in the region of Mont-Lozère (southern Massif-Central, France). In contrast to the grassland soil, the two forest soils both possessed a well-developed acidic moder humus-type horizon. This could be subdivided as follows: fresh litter (OL), fragmentation (OF) and humification (OH) layers; two litters, one fresh (OL1) and one old (OL2) could actually be distinguished in the beech forest soil. The n-alkane signature of the parent plants was preserved in the top litter. Immediately underneath, in the OF layer(s) the original n-alkane signatures were progressively but rapidly replaced by a common signature composed of n-C27 and n-C25 with larger proportions of the former than of the latter. These two hydrocarbons were most probably produced in situ by fungi. These results appear to illustrate the action of soil microorganisms which metabolize the inherited n-alkanes and produce new compounds of the same family. Unlike the alkanes and the low molecular weight fatty acids ≤ C20 (which increase greatly in the OL2 layer under beech as a result of intense microbial activity), the heavy fatty acids (〉 C20) show no significant change in the organic horizon.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2389.1999.00243.x
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  • 5
    Electronic Resource
    Electronic Resource
    A modified Kjeldahl procedure for determining strongly fixed NH4+-N (1999)
    Oxford, UK : Blackwell Science Ltd
    European journal of soil science 50 (1999), S. 0 
    Details
    ISSN: 1365-2389
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: This paper reports a procedure for determining the content of strongly fixed NH4+ in soil. The procedure consists of a Kjeldahl digestion followed by an acid attack of the residue with a 5 m HF:1 m HCl solution. Distillations after each of the two treatments recover different forms of NH4+. The procedure was tested on fine earth (〈 2 mm) and skeleton (〉 2 mm) fractions of two forest soils developed on sandstone parent material. In both soil fractions we evaluated three different forms of NH4+-N: (i) Kjeldahl, (ii) non-exchangeable and (iii) micaceous. The last is located in the interlayer of mica flakes larger than 50 μm that resist the Kjeldahl digestion and is considered strongly fixed. The total NH4+-N content of a soil is obtained by the summation of the Kjeldahl and the micaceous NH4+-N. In the soils under consideration, the micaceous form prevails in the skeleton because this fraction is richer in micas of sand size (〉 50 μm). Following the proposed procedure, we found that micas (muscovite and biotite) contain about 3000 mg kg–1 of NH4+-N in the interlayer. The presence of micaceous NH4+-N in soil is generally ignored because the skeleton is usually excluded from analyses, and the micas larger than 50 μm cannot be dissolved by the Kjeldahl treatments. The micaceous NH4+ is the least extractable form of NH4+-N, and we infer that it is the least available to plants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2389.1999.00248.x
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  • 6
    Electronic Resource
    Electronic Resource
    Changes to hardsetting properties of soil by addition of metal hydroxides (1999)
    Oxford, UK : Blackwell Science Ltd
    European journal of soil science 50 (1999), S. 0 
    Details
    ISSN: 1365-2389
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Hardsetting of soil comprises two contrasting, unfavourable physical conditions at different water contents, namely extreme hardness when dry and complete slaking when wet. This behaviour was changed by adding small amounts of ferrihydrite and aluminium hydroxide to the soil. The aggregation and its stability in the wet state increased, whereas the tensile strength of the dry soils decreased. Both resulted mainly by making the fine particles less mobile by aggregation. In some cases adding large amounts of Al hydroxide caused a resuspension of soil particles by reversing the charge, resulting in instability when wet and high stability when dry. We postulate that aggregation results from the interaction between negatively charged siliceous surfaces and positively charged oxides. In addition we think that newly formed Si–O–Fe bonds play a role in binding particles together as a result of a positive relation between the amount of ferrihydrite added and the oxalate-soluble Si. We conclude that hardsetting resulting from weak structure is caused by lack of aggregating agents such as metal hydroxides.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2389.1999.00259.x
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  • 7
    Electronic Resource
    Electronic Resource
    Calculation of nitrogen mineralization and leaching in fallow soil using a simple dynamic model (1999)
    Oxford, UK : Blackwell Science Ltd
    European journal of soil science 50 (1999), S. 0 
    Details
    ISSN: 1365-2389
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Simple models describing nitrogen processes are required both to estimate nitrogen mineralization in field conditions and to predict nitrate leaching at large scales. We have evaluated such a model called LIXIM, which allows calculation of nitrogen mineralization and leaching from bare soils, assuming that these are the dominant processes affecting N in bare soil. LIXIM is a layered, functional model, with a 1-day time step. Input data consist of frequent measurements of water and mineral N contents in soil cores, standard meteorological data and simple soil characteristics. The nitrate transport is simulated using the ‘mixing-cells’ approach. The variations in N mineralization with temperature and moisture are accounted for, providing calculation of the ‘normalized time’. An optimization routine is used to estimate the actual evaporation and the N mineralization rates that provide the best fit between observed and simulated values of water and nitrate contents in all measured soil layers.The model was evaluated in two field experiments (on loamy and chalky soils) including treatments, lasting 9–20 months. The water and nitrate contents in soil were satisfactorily simulated in both sites, and all treatments, including a 15N tracer experiment performed in the loamy soil. In the chalky soil, the calculated water balance agreed well with drainage results obtained in lysimeters and independent estimates of evaporation. At both sites, N mineralization was reduced by the incorporation of crop residues (wheat or oilseed rape straw); the amounts of nitrogen immobilized varied between 20 and 35 kg N ha−1. In the treatments without crop residues, the mineralization rate followed first-order kinetics (against normalized time) in the loamy soil, and zero-order kinetics in the chalky soil. In the latter soil, the mineralization kinetics calculated in situ were close to the kinetics measured in laboratory conditions when both were expressed against normalized time.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2389.1999.00264.x
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  • 8
    Electronic Resource
    Electronic Resource
    Modelling changes in cations in the topsoil of an Amazonian Acrisol in response to additions of wood ash (1999)
    Oxford, UK : Blackwell Science Ltd
    European journal of soil science 50 (1999), S. 0 
    Details
    ISSN: 1365-2389
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Predictions of changes in soil solution chemistry and exchangeable cations which occur on ash deposition after slash burning are complex and may be facilitated by the use of chemical models. Multi-ion sorption in the topsoil of an Amazonian Acrisol was studied by sequentially adding small amounts of electrolytes to soil and mixtures of soil and ash in batch experiments. A chemical equilibrium model that included inorganic complexation, multiple cation exchange and sparingly soluble salts (aluminium hydroxide and magnesian calcites) was used to interpret the results. The model predicted well the pH and sorption values in all experiments in which there was no addition of ash. The model suggested that cation exchange was the main process determining concentrations of soil solutions in all cases where neutral salt solutions were added, and that proton buffering was achieved by the dissolution of Al(OH)3 which was followed by Al3+ adsorption. Calculation of ion activity products in solutions from various batch experiments in soil + ash mixtures suggested that magnesian calcites of differing solubility may be in equilibrium with the activities of Mg2+ and Ca2+ in solution. An incongruent dissolution of Mg resulted in less soluble magnesian calcites in the ash. The model estimated satisfactorily the pH and the sorption of ions for all experiments with differing ash additions to the soil. Most of the Ca and significant amounts of Mg added in the ash are expected to remain for a long time in the soil and may determine the Ca and Mg status of the soil solution, primarily controlled by principles of solubility products.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2389.1999.00268.x
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  • 9
    Electronic Resource
    Electronic Resource
    Blocking the release of potassium from clay interlayers by small concentrations of NH4+ and Cs+ (1999)
    Oxford, UK : Blackwell Science Ltd
    European journal of soil science 50 (1999), S. 0 
    Details
    ISSN: 1365-2389
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: To understand the process and the kinetics of potassium release from the clay interlayer in natural and arable soils in more detail, I tested the hypotheses that large, monovalent cations, especially NH4+ and Cs+, can reduce the release rates of K+ which is exchanged by Ca2+, even if these monovalent cations are present in concentrations of only a few μm. Percolation experiments were carried out with different illitic soil materials, some containing vermiculite, with 5 m m CaCl2 at pH 5.8 and 20°C, in some cases for over 7000 h. NH4+ and Cs+ both caused a large decrease in the rate at which K+ was released, Cs+ especially. Suppression began at 5 μm NH4+ Blocking by 20 μm NH4+ was easily reversible: the release rates readily increased when NH4+ was omitted from the exchange solution. Blocking by 2 μm Cs+ was equal to approximately 90% of that at 10 μm Cs+. Larger concentrations of Cs+ than 10 μm did not further reduce release but rather caused a slight increase, probably because of enhanced exchange of K+ by Cs+ without exfoliation of the interlayer space. Blocking by Cs+ was not reversible within 〉 7000 h of percolation by 5 m m CaCl2. The blocking effect was reproduced in several different soil materials using 10 μm Cs+ but was most pronounced in vermiculite-rich samples. As NH4+ is present in most arable soils, at least in concentrations of a few μm, I conclude that the observed effects are of significance in the K dynamics processes in soils, for example near the roots of plants. Further, very small concentrations of Cs+ in exchange solutions containing a large background of Ca2+ appear to be useful for suppressing K+ release from the interlayer in laboratory studies, probably without significantly altering the exchange at outer mineral surfaces.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2389.1999.00272.x
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  • 10
    Electronic Resource
    Electronic Resource
    Charred organic carbon in German chernozemic soils (1999)
    Oxford, UK : Blackwell Science Ltd
    European journal of soil science 50 (1999), S. 0 
    Details
    ISSN: 1365-2389
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Burning vegetation produces partly charred plant material which subsequently could contribute to the highly refractory proportion of soil organic matter. The presence of charred organic carbon (COC) was investigated in 17 horizons originating from nine soils from Germany and the Netherlands using a suite of complementary methods (high-energy ultraviolet photo-oxidation, scanning electron microscopy, solid-state 13C nuclear magnetic resonance, lignin analysis by CuO oxidation). Charred organic carbon could not be detected in the A horizons of an Alisol and a Gleysol, but it contributed up to 45% of the organic carbon and up to about 8 g kg–1 of the soil in a range of grey to black soils (Cambisol, Luvisol, Phaeozem, Chernozem and Greyzem). All these soils have chernozemic soil properties (dark colour, A–C profile, high base saturation, bioturbation). A 10-km colour sequence of four chernozemic soils, which were very similar in chemical and physical properties, showed a strong relation between colour and the content of COC. This suggests that the COC affects mainly soil colour in the sequence studied. Finely divided COC seems to be a major constituent of many chernozemic soils in Germany. These results suggest that besides climate, vegetation and bioturbation, fire has played an important role in the pedogenesis of chernozemic soils.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2389.1999.00236.x
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