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  • 11
    Language: English
    In: Geoderma, May, 2014, Vol.219-220, p.125(11)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.geoderma.2013.12.015 Byline: Emmanuel Frossard, Paolo Demaria, Sokrat Sinaj, Michael Scharer Abstract: Controlling phosphate (P) release from agricultural soils to water while maintaining optimal plant growth conditions remain a major challenge for the development of sustainable agricultural systems. To achieve this, it is important to have a proper knowledge of the amount of soil P that can be mobilized by water and of the kinetics of P release. We evaluated the ability of a flow-through reactor in which.sup.33P labeled soils can be inserted and leached continuously with deionized water, to assess P release. The experiment was conducted on five grassland soils presenting a large range in P availability. The availability of P in these soils was further modified by submitting them to 0 to 3 plant growth cycles with Italian ryegrass (Lolium multiflorum) with three levels of P added (0, 20 and 40mgPkgsoil.sup.-1). The P input-output balance, water and oxalate extractable P, the degree of P saturation of the soil and the amount of isotopically exchangeable P (E value) were assessed in all samples. A subset of these soil samples was labeled with.sup.33P, introduced in a flow-through reactor and the release of P and.sup.33P measured over 14days. The cumulated amount of P released after 14days was strongly correlated to the amount of oxalate extractable P, isotopically exchangeable P (E value), and water extractable P. The P release kinetics was modeled with a 2 pools model with each pool following first order kinetics. Plants were able to take up P from both pools. Assuming that the leached P had the same isotopic composition as the pool of soil P it came from it became possible to quantify the amount of isotopically exchangeable remaining in the soil which was called the D value. D decreased during the three first days of the flow-through experiment and then increased linearly with time reaching a maximum after 14days. This maximum remained lower than the oxalate extractable P. Processes contributing to this increase were isotopic exchange and possibly also some organic P mineralization. The D value was strongly linearly correlated to E values measured after different exchange times, but for a given exchange time, the D value was lower than the E value, whereas equality could have been expected. This difference was related to the high rate of.sup.33P export from the soil at the beginning of the flow-through experiment. The D value was also strongly correlated to the oxalate and water extractable P. In conclusion, we suggest that the use of the flow-through reactor yields relevant information on the amount of P that can be leached from a given soil, and that the D value delivers information on the amount of isotopically exchangeable P remaining in the soil and therefore which could still be leached if sufficient time would be given. Article History: Received 24 July 2013; Revised 7 December 2013; Accepted 11 December 2013
    Keywords: Oxalic Acid -- Evaluation ; Oxalic Acid -- Analysis ; Soils -- Analysis ; Phosphates -- Evaluation ; Phosphates -- Analysis ; Oxalates -- Evaluation ; Oxalates -- Analysis
    ISSN: 0016-7061
    Source: Cengage Learning, Inc.
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  • 12
    In: New Phytologist, January 2013, Vol.197(1), pp.186-193
    Description: The objective of this study was to investigate the isotopic composition of oxygen bound to phosphate (δ18O‐PO4) in different phosphorus (P) pools in plant leaves. As a model plant we used soybean (Glycine max cv Toliman) grown in the presence of ample P in hydroponic cultures. The leaf blades were extracted with 0.3 M trichloroacetic acid (TCA) and with 10 M nitric acid. These extractions allowed measurement of the TCA‐soluble reactive P (TCA P) that is rapidly cycled within the cell and the total leaf P. The difference between total leaf P and TCA P yielded the structural P which includes organic P compounds not extractable by TCA. P uptake and its translocation and transformation within the soybean plants lead to an 18O enrichment of TCA P (δ18O‐PO4 between 16.9 and 27.5‰) and structural P (δ18O‐PO4 between 42.6 and 68.0 ‰) compared with 12.4‰ in the phosphate in the nutrient solution. δ18O values of phosphate extracted from soybean leaves grown under optimal conditions are greater than the δ18O‐PO4 values of the provided P source. Furthermore, the δ18O‐PO4 of TCA P seems to be controlled by the δ18O of leaf water and the activity of inorganic pyrophosphatase or other pyrophosphatases.
    Keywords: Acid Phosphatase ; Δo Of Leaf Water ; Δo‐ ; Soybean ; Structural P ; Tca‐Soluble Reactive P P
    ISSN: 0028-646X
    E-ISSN: 1469-8137
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  • 13
    Language: English
    In: Soil Biology and Biochemistry, June, 2012, Vol.49, p.184(9)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.soilbio.2012.01.032 Byline: Monika Welc (a), Else K. Bunemann (a), Andreas Flie[sz]bach (b), Emmanuel Frossard (a), Jan Jansa (a)(c) Abstract: Microbial communities are important components of terrestrial ecosystems. The importance of their diversity and functions for natural systems is well recognized. However, a better understanding of successional changes of microbial communities over long time scales is still required. In this work, the size and composition of microbial communities in soils of a deglaciation chronosequence at the Damma glacier forefield were studied by fatty acid profiling. Soil fatty acid concentrations clearly increased with soil age. The abundances of arbuscular mycorrhizal fungi (AMF), bacteria and other soil fungi, however, were more affected by abiotic soil parameters like carbon content and pH than by soil age. Analysis of ratios of the different microbial groups (AMF, fungi, bacteria) along the soil chronosequence indicated that: i) the ratios of AMF to bacteria and AMF to fungi decreased with soil age; and ii) the ratio of fungi to bacteria remained unchanged along the soil chronosequence. These two pieces of evidence suggest that the evolution of this ecosystem proceeds at an uneven pace over time and that the role of AMF is less important in older, more organic and acidified soils than in mineral soils. In contrast to other studies, no successional replacement of bacteria with fungi in more acidified and organic soil was observed. Author Affiliation: (a) ETH Zurich, Institute of Agricultural Sciences, FMG C 18, Eschikon 33, 8315 Lindau (ZH), Switzerland (b) Research Institute of Organic Agriculture (FiBL), Department of Soil Sciences, Ackerstrasse, 5070 Frick, Switzerland (c) Institute of Microbiology, Academy of Sciences of the Czech Republic, VideAska 1083, Praha 4 - KrA, Czech Republic Article History: Received 10 October 2011; Revised 21 January 2012; Accepted 30 January 2012
    Keywords: Soil Microbiology -- Analysis ; Soil Carbon -- Analysis ; Organic Farming -- Analysis ; Ecosystems -- Analysis ; Bacteria -- Analysis ; Fatty Acids -- Analysis ; Terrestrial Ecosystems -- Analysis ; Fungi -- Analysis
    ISSN: 0038-0717
    Source: Cengage Learning, Inc.
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  • 14
    Language: English
    In: Science of the Total Environment, 15 April 2014, Vol.478, pp.226-234
    Description: This study seeks to identify and specify the components that make up the prospects of U recovery from phosphate rock. A systems approach is taken. The assessment includes i) reviewing past recovery experience and lessons learned; ii) identifying factors that determine recovery; and iii) establishing a contemporary evaluation of U endowments in phosphate rock reserves, as well as the available and recoverable amounts from phosphate rock and phosphoric acid production. We find that in the past, recovery did not fulfill its potential and that the breakup of the Soviet Union worsened then-favorable recovery market conditions in the 1990s. We find that an estimated 5.7 million tU may be recoverable from phosphate rock reserves. In 2010, the recoverable tU from phosphate rock and phosphoric acid production may have been 15,000 tU and 11,000 tU, respectively. This could have filled the world U supply-demand gap for nuclear energy production. The results suggest that the U.S., Morocco, Tunisia, and Russia would be particularly well-suited to recover U, taking infrastructural considerations into account. We demonstrate future research needs, as well as sustainability orientations. We conclude that in order to promote investment and production, it seems necessary to establish long-term contracts at guaranteed prices, ensuring profitability for phosphoric acid producers.
    Keywords: Uranium ; Phosphorus ; Energy Security ; Environmental Pollution ; Food Security ; Resources Conservation ; Environmental Sciences ; Biology ; Public Health
    ISSN: 0048-9697
    E-ISSN: 1879-1026
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  • 15
    Language: English
    In: Soil Biology and Biochemistry, 2015, Vol.85, p.10(11)
    Description: To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.soilbio.2015.02.002 Byline: Michael Gasser, Andreas Hammelehle, Astrid Oberson, Emmanuel Frossard, Jochen Mayer Abstract: Nitrogen (N) rhizodeposition is defined as the release of N from living plant roots into the soil and root turnover. The proportion of N in the soil derived from rhizodeposition (NdfR) is usually determined using.sup.15N labelling of the plant. This isotope approach assumes that i) the enrichment of rhizodeposits is equal to the root enrichment and that ii) the root remains homogeneously enriched over space and iii) over time. The aim of this study was to quantify the bias resulting from a possible violation of the mentioned assumptions and to study the causative factors of bias. We conducted two experiments with single-pulse.sup.15N-urea leaf-labelled red clover (Trifolium pratense L.). In the rhizodeposition experiment, we simultaneously observed the changes in substrate N concentration to obtain the mass-based rhizodeposits and determined the isotope-predicted rhizodeposits using the isotope approach. By comparing isotope-predicted to mass-based rhizodeposits we quantified the bias of the isotope approach for a period of 6 weeks. In the root distribution experiment, we observed the root.sup.15N enrichment over space and time (4 weeks) by sampling roots grown within certain periods relative to the labelling. In both experiments we monitored the.sup.15N distribution between shoots and roots. We observed violations of the three assumptions of the isotope approach. The average root enrichment increased over time in the root distribution experiment, but remained constant in the rhizodeposition experiment. Significant long-term translocation of.sup.15N from shoot to root during the whole experiment (over)-compensated for growth dilution. Spatial root enrichment varied within a factor of 3, peaking in roots grown 2-8 days after labelling (d.a.l.). We observed a significant leakage of 0.5 [+ or -] 0.2% of the applied.sup.15N within the first day after labelling corresponding to an overestimation of first-day rhizodeposits by 1100 [+ or -] 800% which translates to a calculated enrichment of 9 [+ or -] 6 atom%.sup.15N excess for first-day rhizodeposits compared to 0.77 [+ or -] 0.09 atom%.sup.15N excess of the root. The leaked.sup.15N together with ordinary rhizodeposits (rhizodeposits released after the first day of labelling) led to an overestimation of N rhizodeposition by 70 [+ or -] 30% at the end of the six weeks lasting experiment using the isotope approach. The observed.sup.15N distribution in roots and long-term.sup.15N translocation from shoots to roots did not correspond to the expected distribution following classical pulse labelling. Thus, leaf-labelling with.sup.15N-urea should not be considered a pure pulse-labelling method. Author Affiliation: (a) Agroscope, Institute for Sustainability Science ISS, Group of Water Protection and Nutrient Flows, 8046 Zurich, Switzerland (b) Group of Plant Nutrition, Swiss Federal Institute of Technology (ETH), 8092 Zurich, Switzerland Article History: Received 31 October 2014; Revised 9 February 2015; Accepted 9 February 2015
    Keywords: Urea – Analysis
    ISSN: 0038-0717
    Source: Cengage Learning, Inc.
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  • 16
    Language: English
    In: Journal of Cleaner Production, 20 January 2016, Vol.112, pp.2452-2461
    Description: LCA studies reveal emission hotspots along the whole product value chain allowing the researcher to identify opportunities for improvements. Its combination with integrative design offers an opportunity to substantially improve the eco-efficiency. We describe the multi-stakeholder design process that was followed to provide reductions in resource use and emissions from two alternative bread supply chains in France. Case studies of alternative bread were selected because of strong motivation to improve environmental performance and the limited number of actors along the supply chain: farmers are also processors, distributors and retailers. The structured process of integrative design was supported by the use of Life Cycle Assessment (LCA) as an evaluation and information support tool. To avoid any potential burden shifting, environmental impacts were tracked for 13 impact categories. Results of LCA with highlights of processes responsible for the largest share of environmental impacts were disclosed to experts during the collaborative design workshop. Stakeholders included sustainability experts, plant breeders, agronomists and representatives of farmers associations. In the next step, generated improvement scenarios were consulted with farmers on a feedback loop basis. Despite the low acceptance of expert suggestions, the supply of environmental information allowed farmers to find some innovative design solutions. Conservative modelling of approved improvement scenarios revealed 47% potential reduction in the global warming potential in one of the value chains and 40% for aquatic eutrophication potential in the other one. Results of these case studies suggest that in addition to biophysical limitations, some producers may suffer from the lack of innovation, suboptimal management and the lack of access to reliable environmental information. Integrative approaches coupled with systematic, science based assessment tools such as LCA can be effective in overcoming some of these barriers and improving eco-efficiency. More research is needed to understand the social factors driving the life-cycle based eco-innovation on farms.
    Keywords: Integrative Design ; Life Cycle Assessment ; Eco-Design ; Longitudinal Lca ; Alternative Food Supply Chains ; Engineering
    ISSN: 0959-6526
    E-ISSN: 1879-1786
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  • 17
    Language: English
    In: Plant and Soil, 2014, Vol.377(1), pp.439-456
    Description: Aims Phosphorus resources have to be managed sustainably and therefore the recycling of P from waste streams is essential. A thermo-chemical recycling process has been developed to produce a P fertilizer from sewage sludge ash (SSA) but its plant availability is unknown. Methods Two SSA products prepared with either Ca[Cl.sub.2] (SSACa) or Mg[Cl.sub.2] (SSAMg) as chemical reactant during the thermal treatment were mixed with three soils previously labeled with [sup.33]P. Reference treatments with water-soluble P added at equal amounts of total P were included. The transfer of P from SSACa and SSAMg to Lolium multiflorum or P pools of sequentially extracted soil-fertilizer incubations were quantified. Results The shoot P uptake from SSAMg was higher than from SSACa. For SSAMg the relative effectiveness compared to a water-soluble P fertilizer was 88 % on an acidic and 71 % on a neutral soil but only 4 % on an alkaline soil. The proportion of P derived from the fertilizer in the plant and in the first two extraction pools of soil-fertilizer incubations were strongly correlated, suggesting that it is sufficient to conduct an incubation study to obtain robust information on plant P availability. Conclusions We conclude that under acidic to neutral conditions SSAMg presents an appropriate alternative to conventional P fertilizers and the dissolution of P from SSAMg seems to be governed by protons and cations in the soil solution. Keywords Sewage sludge ash * [sup.33]P labeling * Recycling fertilizer * Radioisotopes * Italian ryegrass * Sequential extraction
    Keywords: Sewage sludge ash ; P labeling ; Recycling fertilizer ; Radioisotopes ; Italian ryegrass ; Sequential extraction
    ISSN: 0032-079X
    E-ISSN: 1573-5036
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  • 18
    Language: English
    In: Journal of agricultural and food chemistry, 06 November 2013, Vol.61(44), pp.10409-17
    Description: Organic ligands in soils affect the availability of trace metals such as Zn to plants. This study investigated the effects of two of these ligands, citrate and histidine, on Zn uptake by wheat under hydroponic conditions. Uptake of (65)Zn in the presence of these ligands was compared to uptake in the presence of EDTA at the same free Zn concentration (Zn(2+) ~ 50 nM). In the presence of citrate Zn root uptake was enhanced ~3.5 times and in the presence of histidine, by a factor of ~9, compared to the EDTA treatments. Citrate uptake was slightly reduced in the treatment containing ligands and Zn compared to the treatment containing the same ligand concentration but no Zn. In addition, a higher uptake of Zn than of citrate was observed. This suggests that the enhanced Zn uptake was primarily due to increased supply of Zn(2+) by diffusion and dissociation of Zn-citrate complexes at the root surface. Histidine uptake was much higher than citrate uptake and not influenced by the presence of Zn. As histidine forms stronger complexes with Zn than citrate, the results suggest that the enhancement of Zn uptake in the presence of histidine was in part due to the uptake of undissociated Zn-histidine complexes.
    Keywords: Citric Acid -- Metabolism ; Histidine -- Metabolism ; Triticum -- Metabolism ; Zinc -- Metabolism
    ISSN: 00218561
    E-ISSN: 1520-5118
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  • 19
    Language: English
    In: Applied and environmental microbiology, 01 January 2018, Vol.84(1)
    Description: Soil and plant inoculation with heterotrophic zinc-solubilizing bacteria (ZSB) is considered a promising approach for increasing zinc (Zn) phytoavailability and enhancing crop growth and nutritional quality. Nevertheless, it is necessary to understand the underlying bacterial solubilization processes to predict their repeatability in inoculation strategies. Acidification via gluconic acid production remains the most reported process. In this study, wheat rhizosphere soil serial dilutions were plated on several solid microbiological media supplemented with scarcely soluble Zn oxide (ZnO), and 115 putative Zn-solubilizing isolates were directly detected based on the formation of solubilization halos around the colonies. Eight strains were selected based on their Zn solubilization efficiency and siderophore production capacity. These included one strain of , two of , three strains of , one of , and one strain of In ZnO liquid solubilization assays, the presence of glucose clearly stimulated organic acid production, leading to medium acidification and ZnO solubilization. While solubilization by and was attributed to the accumulated production of six and seven different organic acids, respectively, the other strains solubilized Zn via gluconic, malonic, and oxalic acids exclusively. In contrast, in the absence of glucose, ZnO dissolution resulted from proton extrusion (e.g., via ammonia consumption by strains) and complexation processes (i.e., complexation with glutamic acid in cultures of ). Therefore, while gluconic acid production was described as a major Zn solubilization mechanism in the literature, this study goes beyond and shows that solubilization mechanisms vary among ZSB and are strongly affected by growth conditions. Barriers toward a better understanding of the mechanisms underlying zinc (Zn) solubilization by bacteria include the lack of methodological tools for isolation, discrimination, and identification of such organisms. Our study proposes a direct bacterial isolation procedure, which prevents the need to screen numerous bacterial candidates (for which the ability to solubilize Zn is unknown) for recovering Zn-solubilizing bacteria (ZSB). Moreover, we confirm the potential of matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) as a quick and accurate tool for the identification and discrimination of environmental bacterial isolates. This work also describes various Zn solubilization processes used by wheat rhizosphere bacteria, including proton extrusion and the production of different organic acids among bacterial strains. These processes were also clearly affected by growth conditions (i.e., solid versus liquid cultures and the presence and absence of glucose). Although highlighted mechanisms may have significant effects at the soil-plant interface, these should only be transposed cautiously to real ecological situations.
    Keywords: Maldi-Tof MS ; Biofortification ; Bioremediation ; Metal Solubilization ; Organic Acids ; Proton Extrusion ; Siderophores ; Wheat ; Zinc-Solubilizing Bacteria ; Rhizosphere ; Soil Microbiology ; Bacteria -- Metabolism ; Triticum -- Microbiology ; Zinc -- Metabolism
    ISSN: 00992240
    E-ISSN: 1098-5336
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  • 20
    Language: English
    In: Soil Biology and Biochemistry, December 2015, Vol.91, pp.298-309
    Description: The identification and quantification of different soil organic phosphorus (P) compounds is crucial for a better understanding of soil P dynamics. The aim of this study was to compare two commonly used characterisation methods: P NMR spectroscopy and enzyme addition assays (EAAs). The same 0.25 M NaOH and 0.05 M ethylenediaminetetraacetic acid (EDTA) extracts of ten temperate and tropical topsoils under arable crops or permanent grassland were analysed by each method. Additionally, the substrate specificity of the used enzymes was verified through P NMR analysis of one enzyme-treated soil extract. Finally, the molecular weight distribution of organic P was characterised using gel filtration chromatography. NaOH-EDTA extractable organic P ranged from 7 to 1108 mg P kg soil. Using P NMR spectroscopy, six organic P species in the mono- and diester region plus orthophosphate, pyrophosphate and phosphonates were detected. Deconvolution of P NMR spectra was not possible for two soils due to poor signal to noise ratio. Using EAAs, inositol phosphate-like P was identified as the largest enzyme-labile organic P class in most soils, followed by monoester-like P and DNA-like P. Corresponding classes of organic P determined by P NMR and EAAs were established and concentrations were found to agree well in general. However, repeatability was higher for P NMR spectroscopy than for EAAs. P NMR spectroscopy on an enzyme-treated extract showed that each enzyme acted on the anticipated organic P class, although treatment with phytase caused the appearance of a new and yet unidentified peak in the monoester region. Gel filtration chromatography of alkaline extracts revealed the presence of high-molecular weight organic P (〉5 kDa) which had a 1:1 relationship with enzyme-stable P. For both methods, advantages and drawbacks with respect to required sample pre-treatment, analysis time and cost and the total number of identifiable compounds are discussed. While EAAs are suitable for a quick and coarse characterisation of larger sample numbers, P NMR is more robust and allows a more detailed quantification of P forms.
    Keywords: Organic Phosphorus ; 31p NMR ; Enzyme Additions ; Method Comparison ; High Molecular Weight Compounds ; Agriculture ; Chemistry
    ISSN: 0038-0717
    E-ISSN: 1879-3428
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