Artifacts from manganese reduction in rock samples prepared by focused ion beam (FIB) slicing for X-ray microspectroscopic analysis

Abstract. Manganese (Mn)-rich natural rock coatings, so-called rock varnishes, are discussed controversially regarding their genesis. Biogenic and abiogenic mechanisms, as well as a combination of both, have been proposed to be responsible for the Mn oxidation and deposition process. We conducted scanning transmission X-ray microscopy - near edge X-ray absorption fine structure spectroscopy (STXM-NEXAFS) measurements to examine the abundance and spatial distribution of the different oxidation states of Mn within these nano- to micrometer thick crusts. Such microanalytical measurements of thin and hard rock crusts require sample preparation with minimal contamination risk. Focused ion beam (FIB) slicing, a well-established technique in geosciences, was used in this study to obtain 100–200 nm thin slices of the samples for X-ray transmission spectroscopy. However, even though this preparation is suitable to investigate element distributions and structures in rock samples, we observed that, using standard parameters, modifications of the Mn oxidation states occur in the surfaces of the FIB slices. Based on our results, the preparation technique likely causes the reduction of Mn4+ to Mn2+/3+. We draw attention to this issue, since FIB slicing, SEM imaging, and other preparation and visualization techniques operating in the keV range are well-established in geosciences, but researchers are often unaware of the potential for reduction of Mn and possibly other elements in the samples’ surface layers

Full Color Copying

Electrophotographic powder toners, often called 'electronic ink', typically consist of 90–95% resin (polyester, styrene-acrylic), 5% colorant, 1–3% charge control agent (CCA), and other additives like waxes. CCAs are needed for the correct toner charge. They must overcome the electrostatic influence of the colorants and the other toner ingredients. Both chemical structure and solid-state parameters are responsible for the electrostatic properties of pigments and CCAs. The measurement of the particle surface charge contributes to the understanding of these effects

Entwicklungen begleiten: Neue Bildungsräume zur Verbindung von Theorie und Praxis in einer Vorlesung

Wie kann die aktive und regelmäßige Beteiligung der Studierenden in einer Vorlesung ermöglicht werden? Ein Ansatz ist die Verbindung von Theorie und Praxis, die jedoch insbesondere im traditionellen Format der Vorlesung eine Herausforderung für Lehrende darstellt. E-Learning bietet hier unterschiedliche Möglichkeiten, um die Verknüpfung der beiden Bildungsräume Berufspraxis und Vorlesung zu realisieren. Um diese passgenau für die Disziplin und das Vorlesungsformat auszuwählen und einzusetzen, benötigen Lehrende professionelle Unterstützung. Im vorliegenden Beitrag wird am Beispiel einer Lehrveranstaltung im Fachgebiet Pflanzenbau aufgezeigt, wie ein E-Learning-Vorhaben durch Beratung und Coaching bei der Planung, Umsetzung und Auswertung von Hochschulseite begleitet werden kann. Der Beitrag fokussiert daher zwei Ebenen des E-Learning-Einsatzes: Zum einen die Unterstützung der E-Learning-Implementierung durch ein Lehrcoaching, zum anderen das Zusammenführen verschiedener Lernorte durch digitale Medien in einer Vorlesung. Besonderer Fokus liegt in der Analyse dieser beiden Ebenen auf Entwicklungen, die in Bezug auf die Artefakte, die Lernergebnisse der Studierenden und durch Reflexionen im Coachingprozess stattfanden. (DIPF/Orig.

Comparing the reliability of maize variety data from on-farm trials and experimental stations

Sortenempfehlungen basieren in der Regel auf regionalspezifischen Exaktversuchen. Dabei können die Wechselwirkungen zwischen Sorte und Umwelt sowie zwischen Sorte und Management zu steigenden Problemen bei der Sortenwahl führen. Eine ergänzende Möglichkeit sind daher dezentralisierte Sortenversuche in Landwirtschaftsbetrieben. Für die direkte Sortenwahl bieten diese On-Farm-Versuche eine hohe Praxisrelevanz, da die tatsächlichen Einflussgrößen im Betrieb getreuer abgebildet werden können, als es Exaktversuche vermögen, wenn sie nur an wenigen, zum Teil eingeschränkt repräsentativen Standorten durchgeführt werden. Andererseits ist die Aussagefähigkeit von On-Farm-Versuchen häufig durch Störgrößen und fehlende Feldwiederholungen begrenzt. Anhand von Maissortenversuchen mit sechs verschiedenen Sorten wurden auf vier Brandenburger Landwirtschaftsbetrieben sowie auf zwei Versuchsstationen die Sortenleistung in On-Farm- und Exaktversuchen auf Sandböden geprüft. An jedem Standort wurde die Varianz der Sortenrankings über die Jahre genutzt, um Informationen über die Konsistenz der Sortenleistung an jedem der Standorte zu gewinnen. Für den Trockenmasse-Ertrag zeigten die On-Farm-Versuche sowohl die höchste, als auch die niedrigste Konsistenz der Rankings. Einige Qualitätsparameter, wie die Nichtfaser-Kohlenhydrate (NFC) und der Stärkegehalt, zeigten in den On-Farm-Versuchen eine bessere Konsistenz des Sortenrankings über die Jahre als in beiden Exaktversuchen. Dies legt nahe, dass On-Farm-Versuche das Potenzial haben, die regionale Leistungsprüfung von Sorten zu unterstützen. DOI: 10.5073/JfK.2014.11.03, https://doi.org/10.5073/JfK.2014.11.03While current variety recommendations are based on replicated small-plot trials in a specific region for which the trial is thought to be representative, genotype × envi­ronment interactions, genotype × management interactions, and increasing weather fluctuations make it increasingly difficult to predict which variety will be best in a given environment. An additional approach is therefore to decentralize variety trials and place them on working farms. However, although on-farm trials offer potentially more relevance for direct variety selection on site, they are also likely to be subject to more noise and trial entries can often not be fully replicated. To evaluate the relative merit of on-farm trials vs. fully replicated trials conducted at experimental stations, we tested 6 maize varieties at four farms and at two stations in a region dominated by sandy soils. The variance of variety rankings over the years within each site was used as proxy to evaluate the consistency of variety information gained at each location. For dry matter yield, on-farm trials showed both the highest and the lowest consistency of variety ranking, with the consistency being intermediate at the experimental stations. For some quality parameters, namely non-fibre carbohydrate and starch content, the majority of on-farm trials showed more consistent variety ranking over the years than the more consistent of the two replicated trials. This suggests that in terms of year-on-year reliability of maize yield and quality, on-farm trials may have the potential to complement replicated variety trials. For both types of trials, however, there is also scope for decreasing technical sources of variation. DOI: 10.5073/JfK.2014.11.03, https://doi.org/10.5073/JfK.2014.11.0

Effects of Fertilizers and Manures on Temporal Yield Variability of Winter Rye

The anticipated increases in environmental variability associated with climate change may lead to enhanced abiotic plant stresses (e.g. heat stress, drought stress, etc.) resulting in greater inter‐annual yield fluctuations and higher crop production risk. While there has been increasing attention to adaptation measures, there is little evidence available on how to change agronomic management strategies to maintain stable yields in winter rye production systems in Poland. This study uses rye yields from the unique Skierniewice Long‐term experiment (Poland) to examine for the first‐time the long‐term effects of different nutrient regimes on crop yield stability from 1966 to 2015. Yields from six combinations of mineral fertilizers and lime (CaNPK, NPK,CaPK, CaNK, CaNP, Ca), with and without additional manure, were used to estimate the temporal yield variability of winter rye. A novel statistical approach based on a mixed model approach with REML (restricted maximum likelihood) stability parameter estimation was used. The results showed that the use of additional manure in ‘sub‐optimal’ mineral fertilizer treatments, such as Ca and CaPK (without mineral N), reduced the temporal yield variability of rye. In contrast, additional organic input led to more variable rye yields in already ‘optimal’ treatments including mineral N (CaNPK and NPK), compared to those with no additional manure. Winter rye given CaNPK and NPK, without additional organic manure demonstrated high yield and low temporal yield variability. In contrast, yields of treatments with no mineral N (Ca and CaPK) and no additional manure supply were low and unstable. In addition, it was found that increasing soil organic carbon resulted in larger, more stable yields. These findings highlight the importance of ensuring rye crops receive sufficient fertilizer to maintain crop production levels and yield stability, especially in dry years. They also demonstrate the importance of avoiding the excessive use of organic manures when fertilizer inputs are sufficient to meet crop demand. Overall, the study provides novel insights about how to maintain grain yields and minimize temporal yield variation of rye in arable cropping systems, which will become increasingly important in a changing climate in Poland and in other temperate climate areas. This study also highlights the importance of soil organic carbon for improving the climate resilience of winter rye, while simultaneously meeting the demand for more sustainable management of the soil

Eco-stability of winter rye varieties under site conditions of Brandenburg

Im Mittelpunkt der Untersuchung von Winterroggensorten unter Standortbedingungen Brandenburgs standen die folgenden Fragestellungen: Bieten Hybridroggensorten im Vergleich der Sortentypen neben einer höheren Ertragsfähigkeit auch eine bessere Ökostabilität, vor allem auch unter trockenen Witterungsbedingungen? Welche Unterschiede auf Sortenebene bestehen hinsichtlich der Ökostabilität? Dazu wurden auf Basis von mehrortigen und mehrjährigen Ergebnissen aus Sortenversuchen in Brandenburg und unter Nutzung biostatistischer Parameter verschiedene Roggensorten analysiert. Die Sortenbewertung zur Ökostabilität und Ertragsleistung umfasste neben der deskriptiven Statistik und Varianzanalyse folgende Parameter: Ökovalenz, Ökoregression und Floating Checks. Zusätzlich wurden verschiedene Einflussgrößen auf die Ertragsvariabilität geschätzt und die Sortenreaktion auf unterschiedliche Witterungsbedingungen anhand der klimatischen Wasserbilanz geprüft. Abschließend erfolgte eine kurze Bewertung der verwendeten Parameter und Methoden. Die Ergebnisse der Sortenversuche zeigten, dass die Umwelt (Ort × Jahr) den stärksten Einfluss auf die Ertragsvariabilität hatte. Gegenüber der Umweltwirkung war der Sorteneinfluss geringer. Trotzdem bestanden zwischen den Sorten deutliche Unterschiede hinsichtlich der Leistungsfähigkeit, Ökostabilität und der Reaktion auf differenzierte Umweltbedingungen. Die Hybridroggensorten erwiesen sich im Vergleich der Sortentypen als deutlich ertragsfähiger und tendenziell ökostabiler, vor allem auch unter trockenen Witterungsbedingungen. Die Ergebnisse sind für die Sortenprüfung und -bewertung, die Züchtung und die landwirtschaftliche Praxis gleichermaßen bedeutsam. Sie liefern Informationen zu den umweltabhängig variierenden Eigenschaften der Sorten und bieten Unterstützung für die standortgerechte Sortenempfehlung sowie bestmögliche Sortenwahl durch Entwicklung eines Bewertungsschemas.    The main questions addressed by the present study were: Provide hybrid varieties as compared to other variety types in addition to a higher yield also an improved eco-stability, especially under dry weather conditions? Which differences in eco-stability between varieties of winter rye can be found? To answer the question results from variety trials at multiple environments of Federal State Brandenburg were used and different varieties of winter rye were analyzed according to several bio-statistical parameters. The evaluation of eco-stability and yield capacity included following parameters: Eco-valence, eco-regression and floating checks. Additionally, different impact factors on variability of yield were estimated and the reaction of varieties to different weather conditions was analyzed based on the climatic water balance. Finally a brief review of the used methods and parameters is given. The results of the different tests showed that the yield performance is determined by different environmental factors and by variety. The factor environment (site × year), which includes soil and weather throughout the course of the year, had the strongest influence on the variability of yield. The factor variety was comparatively less influential, but in special environments it can have an important influence on grain yield. There are also considerable differences between varieties with regard to the criteria eco-stability, yield capacity and their response to differentiated environmental conditions. The hybrid varieties compared to other variety types were considerably higher in yield and in tendency more stable in yield, especially also under dry weather conditions. The evaluation results are important for plant breeding as well as for the choice of site-adapted varieties in agricultural practice. They offer information to environment dependent properties of varieties and can support variety selection in breeding and official variety recommendation by using an optimized evaluation scheme.   &nbsp

Yield reduction due to diseases and lodging and impact of input intensity on yield in variety trials in five cereal crops

Breeding of multi-resistant varieties to reduce yield loss due to disease damage and lodging, and reduction of input intensity are of high importance for a more sustainable cereal production. The aim of this study was to evaluate (i) yield reduction caused by diseases and lodging and (ii) impact of input intensity and soil fertility in cereal variety trials grown under two intensities. Intensity 2 was treated with and intensity 1 without fungicides and growth regulators. We applied multiple regression approaches based on mixed linear models. First, we estimated relative yield reduction in intensity 1 compared to intensity 2 as a function of severity scores of diseases and lodging. High yield reductions occurred in winter wheat and winter triticale, moderate in winter rye and winter barley and low in spring barley. The damage potential was highest for yellow rust, followed by brown rust, lodging and Septoria tritici blotch. Medium damage potential was identified for dwarf leaf rust and low for powdery mildew, Septoria nodorum blotch, Rhynchosporium as well as for stem and ear buckling. Second, differences in input intensity did not affect yield in intensity 2 across the range of nitrogen and fungicide application rates while higher yield occurred at higher growth regulator rates and soil fertility. Growth regulator was strongly related with higher yield in winter rye and winter barley, however in spring barley, a negative relation was found. Soil fertility showed the strongest yield impact in all crops

Ertragsdynamik und Risikobewertung von Fruchtfolgen und Bodenbearbeitung im ökologischen Langzeitversuch

Diese Studie vergleicht die Erträge, Ertragsstabilitäten und Produktionsrisiken von Fruchtfolgen mit und ohne Tierhaltung, sowie wendender und reduzierter Bodenbearbeitung aus 24 Jahren von dem ökologischen Langzeitversuch auf dem Gladbacherhof

The effects of cropping sequence, fertilization, and straw management on the yield stability of winter wheat (1986–2017) in the Broadbalk Wheat Experiment, Rothamsted, UK.

The development of resilient cropping systems with high yield stability is becoming increasingly important due to future climatic and agronomic challenges. Consequently, it is essential to be able to evaluate the effects of differing agronomic management practices, such as cropping sequences, and nutrient supply on the stability of crop yields. Long-term experiments are a valuable resource for investigating these effects, providing a sufficient number of years for accurate stability parameter estimation. The objective of the current study was to evaluate the effects of cropping sequence (#1: continuous vs rotational), fertilization (#2: mineral vs organic) and straw management in the case of continuous wheat (#3: removal vs incorporation) on the yield stability of winter wheat; yield risk (the probability of yield falling below a threshold yield level) and inter-annual yield variability were used as stability indicators of the effects. Long-term yield data from the Broadbalk Wheat Experiment (Rothamsted, United Kingdom) were analysed using a mixed model. Overall, the results showed that rotational cropping combined with supply of sufficient nutrients (N, P, and K) from mineral fertilizers, especially mineral N supply, ensured stable wheat yields whilst reducing the yield risk