Nitrogen transformations and its underlying microbial communities in differently managed soils under future projected rainfall variability

Soil microbial communities play a fundamental role in maintaining a broad range of soil functions and ecosystem services. Especially nutrient provisioning to cultivated crops are of prime interest in agricultural contexts in order to maintain the production of food, fibre and fuel for the ever increasing human population. Since Nitrogen (N) is the most limiting nutrient in agroecosystem and it’s cycling and availability is highly dependent on microbial driven processes, we investigated the impact of farming systems on related ecosystem processes and herein involved soil microbial communities. Considering global climate change, also the potential to withstand rainfall variability was assessed

Determination of greenhouse gas sources and sinks in Swiss arable soils under organic and non-organic management

Agricultural practices contribute considerably to emissions of greenhouse gases (GHG). Knowledge on the impact of organic (ORG) compared to non-organic (NON-ORG) farming on soil-derived nitrous oxide (N2O) and methane (CH4) emissions is still limited. We conducted a literature search on measured soil GHG fluxes under ORG and NON-ORG from farming system comparisons and performed a meta-analysis. Based on 12 studies covering annual measurements, it appeared that area-scaled N2O emissions are with 14% significantly lower under ORG. However, yield-scaled N2O emissions are only 9% higher for ORG. Emissions from NON-ORG soils seemed to be influenced mainly by total N inputs, whereas for ORG other soil characteristics seemed to be more important because N2O from organic N fertilisers emits decoupled from the inputs. Furthermore, we observed a 12% higher CH4 uptake for arable soils under ORG

Soil-derived greenhouse gas emissions as influenced by farming management

Agricultural practices contribute considerably to emissions of greenhouse gases. So far, knowledge on the impact of organic compared to non-organic farming on soil-derived nitrous oxide (N2O) and methane (CH4) emissions is rather limited. Meta-studies studies show, that organically managed soils emit less N2O and take up more CH4 than those under non-organic management. This in contrast of that what has been found in the laboratory with soil material from the DOK trial

EHEC – kein spezifisches Problem nachhaltiger Landwirtschaft - [EHEC – A problem not specific to sustainable agriculture] [La EHEC – no es un problema específico de la agricultura sostenible] - [EHEC – Non è un problema specifi-co dell’agricoltura biologica] - [ECEH n’est pas un problème dû à l’agriculture durable] - [EHEC – nem speciálisan a fenntartható mezőgazdaság gondja] - [ECEH n’est pas un problème dû à l’agriculture durable]

DEUTSCH Über den EHEC-Erreger, der in Deutschland zu über dreissig tragischen Todesfällen geführt hat, ist viel spekuliert worden. Unterdessen konnten die Verbreitungswege nahezu aufgeklärt werden, während die Entstehung des Krankheitserregers noch weitgehend unklar ist. Im Zusammenhang mit dem EHEC-Ausbruch wurde auch die Frage erörtert, ob bestimmte Landwirtschaftsmethoden (zum Beispiel gemischte Betriebe mit Tierhaltung und Pflanzenbau oder die organische Düngung von Gemüse) oder ob gewisse Hygienisierungsmethoden für frische, konsumfähige Produkte(wie zum Beispiel die Verwendung von schonenden, weniger Rückstände verursachenden organischen Säuren) das Risiko erhöhen könnten. Diese Dokumentation geht nicht auf die aktuellen Fälle von EHEC in Norddeutschland ein, sondern liefert an diesem Beispiel Hintergrundinformationen zur Frage, wie nachhaltige, in Kreisläufen arbeitende Landwirtschaftsmethoden mit vom Tier auf den Menschen übertragbare Krankheitserreger (Zoonosen) umgehen. ENGLISH There has been much speculation about the pathogenic EHEC bacterial strain that has tragically claimed the lives of more than 30 people so far in Germany. Meanwhile, the transmission pathways have for the most part been identified. The origin of the pathogen, however, is largely unclear. In the context of the EHEC outbreak there have been debates as to whether certain agriculturalmethods (e.g. mixed holdings including both livestock and crop production, or the use of organic fertilizers for vegetable production) or certain sanitization methods for fresh consumable products (such as the use of organic acids, a mild treatment that leaves fewer residues) may increase the risk of infection. This document does not address the current epidemiological situation of the outbreak in northern Germany. Its purpose is rather to provide background information on the question of how sustainable agricultural methods based on nutrient cycling deal with pathogens that can be transmitted from animals to humans (zoonoses). CASTELLANO Mucho se ha especulado sobre la bacteria patógena Escherichia coli enterohemorrágica (ECEH), que ha ocasionado más de treinta muertes trágicas en Alemania. Hasta ahora casi se ha podido esclarecer la via de su propagación, mientras que sigue estando poco claro como ha aparecido el agente patógeno. Con el brote de la ECEH se ha cuestionado si determinadas prácticas agrícolas (por ejemplo, mantener explotaciones mixtas con ganado y cultivos, o la fertilización orgánica de los vegetales) o si los métodos de higiene para productos frescos, listos para el consumo (como por ejemplo, el uso de ácidos orgánicos menos agresivos y con menor riesgo de dejar residudos), pudieran incrementar los riesgos. Esta documento no se refiere sólo a los casos actuales de ECEH en el norte de Alemania, sino que proporciona, información básica de fondo, aprovechando este ejemplo, sobre como los métodos de producción agraria de ciclos cerrados con animales evitan forma sostenible que los patógenos generadores de enfermedades contagiosas (zoonosis) trasmisibles al ser humano. ITALIANO A proposito dell’insorgenza di EHEC è stata sollevata la questione se determinati metodi agricoli (per esempio aziende miste con allevamento di animali e produzione vegetale o la concimazione organica di ortaggi) oppure se determinati metodi di igienizzazione per pro-dotti freschi adatti al consumo (come per esempio l’impiego di acidi organici che provocano meno residui) possano aumentare i rischi. La presente documentazione non entra nei particolari degli attuali casi di EHEC nella Ger-mania settentrionale bensì fornisce informazioni d’approfondimento su come i me-todi agri-coli sostenibili basati sui cicli degli elementi nutritivi trattano la questione degli agenti pato-geni trasmissibili dagli animali all’uomo (zoonosi). HUNGARIAN Sok a spekuláció az EHEC kórokozót illetően, amely Németországban harmincnál is több tragikus halálesethez vezetett. Időközben a terjedés útját már csaknem teljesen felderítették, míg a kórokozó létrejöttéről még szinte semmit sem tudunk. Az EHEC fertőzés kitörése kapcsán az a kérdés is felmerült, hogy bizonyos mezőgazdasági módszerek (pl. a vegyes üzemek, melyek egyaránt foglalkoznak növénytermesztéssel és állattenyésztéssel, vagy a zöldségek szerves trágyázása), ill. a friss, fogyasztásra kész termékek egyes fertőtlenítési módszerei (így pl. a kímélőbb, kevesebb hulladékot eredményező szerves savak alkalmazása) nem növelhetik-e a kockázatot. A jelen tanulmány nem a Németország északi részén kialakult aktuális EHEC esetekkel foglalkozik, hanem háttér-információval szolgál arról, hogy a körforgásos működésű, fenntartható mezőgazdasági módszerek milyen kapcsolatban lehetnek az állatról emberre terjedő betegségekkel, az ún. zoonózisokkal. FRANCAIS ECEH n’est pas un problème dû à l’agriculture durabl

Optical and Radar Characterization of a Short-Lived Auroral Event at High Latitude

Observations of optical emission intensities and incoherent scatter radar returns in the magnetic zenith were compared in a study carried out at Sondre Stromfjord (Λ = 76.1°) in Greenland. The results were used to test the consistency of a theoretical model of ion chemistry and optical emissions in aurora and to explore the accuracy of relations between optical measurements and the average energy of the incident electrons. The incident primary electron spectrum and its temporal variation were inferred from zenith electron density profiles from the radar. The inferred primary energy spectrum at the peak intensity of the event approximated a Maxwellian distribution of characteristic energy 1.3 keV accelerated by an energy increment between 2 and 5 keV. Average energies inferred from the radar electron density profiles, from the N2 + rotational temperature and the I(6300)/I(4278) ratio were in good agreement. The variation of the I(8446)/I(4278) ratio was studied and was found to be promising as an index of average incident electron energy. An empirical relation between this ratio and average energy was derived from the data. The observed values of I(4278) exceeded the theoretical values derived from the ionization rate profiles deduced from the radar data by a factor near 2.0. Observed electron density profiles and theoretical profiles calculated from optical data were in good agreement provided that the optically inferred ion production rates were reduced by the same factor of 2. This discrepancy is probably the cumulative result of small errors in instrument calibrations, viewing geometry, recombination coefficients and the excitation and ionization cross sections used in the model

Temperature and Field Dependence of the Mobility in Liquid-Crystalline Conjugated Polymer Films

The transport properties of organic light-emitting diodes in which the emissive layer is composed of conjugated polymers in the liquid-crystalline phase have been investigated. We have performed simulations of the current transient response to an illumination pulse via the Monte Carlo approach, and from the transit times we have extracted the mobility of the charge carriers as a function of both the electric field and the temperature. The transport properties of such films are different from their disordered counterparts, with charge carrier mobilities exhibiting only a weak dependence on both the electric field and temperature. We show that for spatially ordered polymer films, this weak dependence arises for thermal energy being comparable to the energetic disorder, due to the combined effect of the electrostatic and thermal energies. The inclusion of spatial disorder, on the other hand, does not alter the qualitative behaviour of the mobility, but results in decreasing its absolute value.Comment: 9 pages, 8 figures, submitted to Phys. Rev.

The Roles of Vertical Advection and Eddy Diffusion in the Equatorial Mesospheric Semi-Annual Oscillation (MSAO)

Observations of the mesospheric semi-annual oscillation (MSAO) in the equatorial region have been reported dating back several decades. Seasonal variations in both species densities and airglow emissions are well documented. The extensive observations available offer an excellent case study for comparison with model simulations. A broad range of MSAO measurements is summarised with emphasis on the 80-100 km region. The objective here is not to address directly the complicated driving forces of the MSAO, but rather to employ a combination of observations and model simulations to estimate the limits of some of the underlying dynamical processes. Photochemical model simulations are included for near-equinox and near-solstice conditions, the two times with notable differences in the observed MSAO parameters. Diurnal tides are incorporated in the model to facilitate comparisons of observations made at different local times. The roles of water vapour as the driver species and ozone as the response species are examined to test for consistency between the model results and observations. The simulations suggest the interactions between vertical eddy diffusion and background vertical advection play a significant role in the MSAO phenomenon. Further, the simulations imply there are rigid limits on vertical advection rates and eddy diffusion rates. For August at the Equator, 90 km altitude, the derived eddy diffusion rate is approximately 1 x 106 cm2 s-1 and the vertical advection is upwards at 0.8 cm s-1. For April the corresponding values are 4 x 105 cm2 s-1 and 0.1 cm s-1. These results from the current 1-D model simulations will need to be verified by a full 3-D simulation. Exactly how vertical advection and eddy diffusion are related to gravity wave momentum as discussed by Dunkerton (1982) three decades ago remains to be addressed

Assessment of multiple stable isotopes for tracking regional and organic authenticity of plant products in Hesse, Germany

As demand for regional and organically produced foodstuff has increased in Europe, the need has arisen to verify the products’ origin and production method. For food authenticity tracking (production method and origin), we examined 286 samples of wheat (Triticum aestivum), potatoes (Solanum tuberosum), and apples (Malus domestica) from different regions in Germany for their stable isotope compositions of oxygen, hydrogen, carbon, nitrogen and sulphur. Single-variate authentication methods were used. Suitable isotope tracers to determine wheat's regional origin were δ 18O and δ 34S. δ 13C helped to distinguish between organic and conventional wheat samples. For the separation of the production regions of potatoes, several isotope tracers were suitable (e.g. δ 18O, δ 2H, δ 15N, δ 13C and δ 34S isotopes in potato protein), but only protein δ 15N was suitable to differentiate between organic and conventional potato samples. For the apple samples, 2H and 18O isotopes helped to identify production regions, but no significant statistical differences could be found between organically and conventionally farmed apples. For food authenticity tracking, our study showed the need to take the various isotopes into account. There is an urgent need for a broad reference database if isotope measurements are to become a main tool for determining product's origin

Compared to conventional, ecological intensive management promotes beneficial proteolytic soil microbial communities for agro-ecosystem functioning under climate change-induced rain regimes

Projected climate change and rainfall variability will affect soil microbial communities, biogeochemical cycling and agriculture. Nitrogen (N) is the most limiting nutrient in agroecosystems and its cycling and availability is highly dependent on microbial driven processes. In agroecosystems, hydrolysis of organic nitrogen (N) is an important step in controlling soil N availability. We analyzed the effect of management (ecological intensive vs. conventional intensive) on N-cycling processes and involved microbial communities under climate change-induced rain regimes. Terrestrial model ecosystems originating from agroecosystems across Europe were subjected to four different rain regimes for 263 days. Using structural equation modelling we identified direct impacts of rain regimes on N-cycling processes, whereas N-related microbial communities were more resistant. In addition to rain regimes, management indirectly affected N-cycling processes via modifications of N-related microbial community composition. Ecological intensive management promoted a beneficial N-related microbial community composition involved in N-cycling processes under climate change-induced rain regimes. Exploratory analyses identified phosphorus-associated litter properties as possible drivers for the observed management effects on N-related microbial community composition. This work provides novel insights into mechanisms controlling agro-ecosystem functioning under climate change

OSIRIS: A Decade of Scattered Light

Into year 11 of a 2-yr mission, OSIRIS is redefining how limb-scattered sunlight can be used to probe the atmosphere, even into the upper troposphere