Density fractionation reworked: Reduce material and costs     

Patrick Liebmann  Ole Mewes  Georg Guggenberger 《植物养料与土壤学杂志》2023,186(4):383-386

Soil density fractionation is a common tool to separate organic matter of different function and turnover. But it has not been tested so far how much soil material is necessary to obtain reproducible results. A reduction of chemicals like polytungstate would further save valuable resources. Here, we show that soil weight reduction from 25 to 5 g was not significantly affecting fractionation results. Compared to the commonly used 10–25 g, this corresponds to a saving of resources of up to 80%.  相似文献   

Acute Injury Risk and Severity in Indoor Climbing—A Prospective Analysis of 515,337 Indoor Climbing Wall Visits in 5 Years     

Volker R. Schöffl  Georg Hoffmann  Thomas Küpper 《The Forestry Chronicle》2013,24(3):187-194

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Domoic Acid Improves the Competitive Ability of Pseudo-nitzschia delicatissima against the Diatom Skeletonema marinoi     

Emily K. Prince  Friederike Irmer  Georg Pohnert 《Marine drugs》2013,11(7):2398-2412

Because domoic acid, a neurotoxic secondary metabolite produced by marine diatoms in the genus Pseudo-nitzschia, is hypothesized to be part of a high affinity iron uptake system, we investigated whether domoic acid could improve the competitive ability of Pseudo-nitzschia delicatissima, and whether the availability of iron changed the outcome of competition experiments. We found that domoic acid had a slight negative effect on growth of the diatom Skeletonema marinoi when it was grown in monocultures. However, when S. marinoi was cultured with P. delicatissima the presence of domoic acid resulted in a reduction of S. marinoi cells by up to 38% and an increase in P. delicatissima cell numbers by up to 17% under iron replete conditions. Similar effects were not observed in low iron treatments. Domoic acid was not taken up by P. delicatissima cells. Overall, our results indicate that domoic acid can improve the competitive ability of Pseudo-nitzschia spp. and that iron is likely to be involved. This study provides an unusual example of indirect inhibition of competitor growth mediated by a secondary metabolite.  相似文献   

Replication characteristics of swine influenza viruses in precision-cut lung slices reflect the virulence properties of the viruses     

Fandan Meng  Darsaniya Punyadarsaniya  Sabine Uhlenbruck  Isabel Hennig-Pauka  Christel Schwegmann-Wessels  Xiaofeng Ren  Ralf Dürrwald  Georg Herrler 《Veterinary research》2013,44(1):110

Precision-cut lung slices of pigs were infected with five swine influenza A viruses of different subtypes (A/sw/Potsdam/15/1981 H1N1, A/sw/Bad Griesbach/IDT5604/2006 H1N1, A/sw/Bakum/1832/2000 H1N2, A/sw/Damme/IDT5673/2006 H3N2, A/sw/Herford/IDT5932/2007 H3N2). The viruses were able to infect ciliated and mucus-producing cells. The infection of well-differentiated respiratory epithelial cells by swine influenza A viruses was analyzed with respect to the kinetics of virus release into the supernatant. The highest titres were determined for H3N2/2006 and H3N2/2007 viruses. H1N1/1981 and H1N2/2000 viruses replicated somewhat slower than the H3N2 viruses whereas a H1N1 strain from 2006 multiplied at significantly lower titres than the other strains. Regarding their ability to induce a ciliostatic effect, the two H3N2 strains were found to be most virulent. H1N1/1981 and H1N2/2000 were somewhat less virulent with respect to their effect on ciliary activity. The lowest ciliostatic effect was observed with H1N1/2006. In order to investigate whether this finding is associated with a corresponding virulence in the host, pigs were infected experimentally with H3N2/2006, H1N2/2000, H1N1/1981 and H1N1/2006 viruses. The H1N1/2006 virus was significantly less virulent than the other viruses in pigs which was in agreement with the results obtained by the in vitro-studies. These findings offer the possibility to develop an ex vivo-system that is able to assess virulence of swine influenza A viruses.  相似文献   

Physical carbon‐sequestration mechanisms under special consideration of soil wettability     

Jrg Bachmann  Georg Guggenberger  Thomas Baumgartl  Ruth H. Ellerbrock  Emilia Urbanek  Marc‐O. Goebel  Klaus Kaiser  Rainer Horn  Walter R. Fischer 《植物养料与土壤学杂志》2008,171(1):14-26

The protective impact of aggregation on microbial degradation through separation has been described frequently, especially for biotically formed aggregates. However, to date little information exists on the effects of organic‐matter (OM) quantity and OM quality on physical protection, i.e., reduced degradability by microorganisms caused by physical factors. In the present paper, we hypothesize that soil wettability, which is significantly influenced by OM, may act as a key factor for OM stabilization as it controls the microbial accessibility for water, nutrients, and oxygen in three‐phase systems like soil. Based on this hypothesis, the first objective is to evaluate new findings on the organization of organo‐mineral complexes at the nanoscale as one of the processes creating water‐repellent coatings on mineral surfaces. The second objective is to quantify the degree of alteration of coated surfaces with regard to water repellence. We introduce a recently developed trial that combines FTIR spectra with contact‐angle data as the link between chemical composition of OM and the physical wetting behavior of soil particles. In addition to characterizing the wetting properties of OM coatings, we discuss the implications of water‐repellent surfaces for different physical protection mechanisms of OM. For typical minerals, the OM loading on mineral surfaces is patchy, whereas OM forms nanoscaled micro‐aggregates together with metal oxides and hydroxides and with layered clay minerals. Such small aggregates may efficiently stabilize OM against microbial decomposition. However, despite the patchy structure of OM coating, we observed a relation between the chemical composition of OM and wettability. A higher hydrophobicity of the OM appears to stabilize the organic C in soil, either caused by a specific reduced biodegradability of OM or indirectly caused by increased aggregate stability. In partly saturated nonaggregated soil, the specific distribution of the pore water appears to further affect the mineralization of OM as a function of wettability. We conclude that the wettability of OM, quantified by the contact angle, links the chemical structure of OM with a bundle of physical soil properties and that reduced wettability results in the stabilization of OM in soils.  相似文献   

An integrative approach of organic matter stabilization in temperate soils: Linking chemistry,physics, and biology   总被引：1，自引：0，他引：1  

Ingrid Kögel‐Knabner  Klemens Ekschmitt  Heinz Flessa  Georg Guggenberger  Egbert Matzner  Bernd Marschner  Margit von Lützow 《植物养料与土壤学杂志》2008,171(1):5-13

With this topical issue, we present the work of the Priority Program 1090 of the German Research Foundation (“Deutsche Forschungsgemeinschaft DFG”): “Soils as a source and sink for CO₂ – mechanisms and regulation of organic matter stabilisation in soils”. This introduction gives an overview on the sites investigated and the major research approaches, including a glossary of major terms used in the field of soil organic matter research. We point out the advantages of integration of data from a broad field of different soil‐science disciplines and the progress achieved by application and combination of new analytical methods describing the quality and turnover of soil organic matter.  相似文献   

Formation and use of microbial residues after adding sugarcane sucrose to a heated soil devoid of soil organic matter     

Brigitte Engelking  Heiner Flessa  Rainer Georg Joergensen 《Soil biology & biochemistry》2008,40(1):97-105

A 67-day incubation experiment was carried out with a soil initially devoid of any organic matter due to heating, which was amended with sugarcane sucrose (C₄-sucrose with a δ¹³C value of ?10.5‰), inorganic N and an inoculum for recolonisation and subsequently at day 33 with C₃-cellulose (δ¹³C value of ?23.4‰). In this soil, all organic matter is in the microbial biomass or in freshly formed residues, which makes it possible to analyse more clearly the role of microbial residues for decomposition of N-poor substrates. The average δ¹³C value over the whole incubation period was ?10.7‰ in soil total C in the treatments without C₃-cellulose addition. In the CO₂ evolved, the δ¹³C values decreased from ?13.4‰ to ?15.4‰ during incubation. In the microbial biomass, the δ¹³C values increased from ?11.5‰ to ?10.1‰ at days 33 and 38. At day 67, 36% of the C₄-sucrose was left in the treatment without a second amendment. The addition of C₃-cellulose resulted in a further 7% decrease, but 4% of the C₃-cellulose was lost during the second incubation period. Total microbial biomass C declined from 200 μg g^?1 soil at day 5 to 70 μg g^?1 soil at day 67. Fungal ergosterol increased to 1.5 μg g^?1 soil at day 12 and declined more or less linearly to 0.4 μg g^?1 soil at day 67. Bacterial muramic acid declined from a maximum of 35 μg g^?1 soil at day 5 to a constant level of around 16 μg g^?1 soil. Glucosamine showed a peak value at day 12. Galactosamine remained constant throughout the incubation. The fungal C/bacterial C ratio increased more or less linearly from 0.38 at day 5 to 1.1 at day 67 indicating a shift in the microbial community from bacteria to fungi during the incubation. The addition of C₃-cellulose led to a small increase in C₃-derived microbial biomass C, but to a strong increase in C₄-derived microbial biomass C. At days 45 and 67, the addition of N-free C₃-cellulose significantly decreased the C/N ratio of the microbial residues, suggesting that this fraction did not serve as an N-source, but as an energy source.  相似文献   

Nitrogen rhizodeposition in agricultural crops: Methods,estimates and future prospects     

Florian Wichern  Elmar Eberhardt  Jochen Mayer  Rainer Georg Joergensen  Torsten Müller 《Soil biology & biochemistry》2008,40(1):30-48

The objective of the present review was to present the current knowledge on nitrogen (N) rhizodeposition, including techniques for ¹⁵N labelling of agricultural plants, amounts of N rhizodeposition and its fate in soil. Rhizodeposition is the process of release of organic and inorganic compounds from living plant roots. It is often quantified in terms of carbon (C) and less often as N derived from rhizodeposition (NdfR). Rhizodeposition of N can be estimated by labelling plants with ¹⁵N and following its fate in soil. Most methods used for labelling plants with ¹⁵N can only be applied after appearance of the first leaf and only allow pulse or multiple pulse labelling. Only the split-root technique and the application of gaseous ¹⁵N allow continuous labelling. All methods available at present have their flaccidities mostly due to the fact that the application of N is not following its physiological pathway of assimilation or by using artificial conditions. In the studies reviewed, amounts of N rhizodeposits ranged from 4% to 71% of total assimilated plant N. In legumes the median was 16% and in cereals it was 14%. Rhizodeposits were 15–96% of the below-ground plant biomass (BGP). In legumes the median was 73% and in cereal it was 57%. The high variability of these results shows the need for more investigations on N rhizodeposition looking especially on the factors influencing the amounts released in different plant species under field conditions.  相似文献   

Acknowledgements to referees     

Asko Mäki‐Tanila  Georg Erhardt  Ignacy Misztal  Larry Schaeffer  Hnner Simianer  Julius Van Der Werf 《Zeitschrift für Tierzüchtung und Züchtungsbiologie》2008,125(6):431-431

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The benefit of native uniqueness in a local red cattle breed from Northern Germany     

Jonas Schler  Dirk Hinrichs  Georg Thaller 《Zeitschrift für Tierzüchtung und Züchtungsbiologie》2019,136(6):518-525

During last decades, native uniqueness decreased in local livestock breeds due to the introgression of high‐yielding breeds. Recovery of native uniqueness became important because of conservation aspects regarding native genetic diversity and native traits. Thereby the expectation exists, that the relation between native uniqueness and genetic gain is contradictory. The aim of this study was to explore the influence of native uniqueness on performance traits and the total merit index in a local red cattle breed from Northern Germany. Data contained a pedigree file of 178,255 Red Dual‐Purpose cattle, 809 target genotypes and 3,581 reference genotypes from introgressed breeds. Native genetic contributions were tested for correlation with performance traits of milk yield, longevity, foundation, somatic cells, fertility and maternal calving and the total merit index. The study revealed that native uniqueness is favourably related to longevity (0.16), foundation (0.23), and somatic cells (0.08), and the total merit index (0.10). Selection on native uniqueness could probably lead to an increased longevity, udder health and genetic gain of the Red Dual‐Purpose cattle. Moreover, it was shown that the Red Dual‐Purpose cattle was not upgraded through introgression of high‐yielding breeds.  相似文献