Stabilization mechanisms of organic matter in four temperate soils: Development and application of a conceptual model

Based on recent findings in the literature, we developed a process‐oriented conceptual model that integrates all three process groups of organic matter (OM) stabilization in soils namely (1) selective preservation of recalcitrant compounds, (2) spatial inaccessibility to decomposer organisms, and (3) interactions of OM with minerals and metal ions. The model concept relates the diverse stabilization mechanisms to active, intermediate, and passive pools. The formation of the passive pool is regarded as hierarchical structured co‐action of various processes that are active under specific pedogenetic conditions. To evaluate the model, we used data of pool sizes and turnover times of soil OM fractions from horizons of two acid forest and two agricultural soils. Selective preservation of recalcitrant compounds is relevant in the active pool and particularly in soil horizons with high C contents. Biogenic aggregation preserves OM in the intermediate pool and is limited to topsoil horizons. Spatial inaccessibility due to the occlusion of OM in clay microstructures and due to the formation of hydrophobic surfaces stabilizes OM in the passive pool. If present, charcoal contributes to the passive pool mainly in topsoil horizons. The importance of organo‐mineral interactions for OM stabilization in the passive pool is well‐known and increases with soil depth. Hydrophobicity is particularly relevant in acid soils and in soils with considerable inputs of charcoal. We conclude that the stabilization potentials of soils are site‐ and horizon‐specific. Furthermore, management affects key stabilization mechanisms. Tillage increases the importance of organo‐mineral interactions for OM stabilization, and in Ap horizons with high microbial activity and C turnover, organo‐mineral interactions can contribute to OM stabilization in the intermediate pool. The application of our model showed that we need a better understanding of processes causing spatial inaccessibility of OM to decomposers in the passive pool.     

Chlamydophila psittaci infections in humans during an outbreak of psittacosis from poultry in Germany

In 2005, an outbreak of severe respiratory disease in a mixed poultry flock that was infected with Chlamydophila (C.) psittaci led to dissemination of the infection to at least 100 small poultry farms in 11 districts of Central Germany. At the same time, a total of 24 persons in contact with poultry from one of the flocks reported flu-like symptoms to their physician, thus suggesting zoonotic transmission. Within 3 weeks, seven individuals had to be hospitalized, with three of them requiring intensive care. Analysis of ompA sequences from chlamydial isolates and directly from clinical samples revealed the presence of both genotype A and E/B of C. psittaci at the source of the outbreak and in contact flocks. Genotype A was also detected in the three severely ill patients. The findings of the present study demonstrate the high zoonotic potential of avian chlamydiae. To ensure speedy eradication of psittacosis in poultry flocks and effective treatment of infected humans, fast, sensitive and species-specific detection of the causative agent is essential, as well as close collaboration between regional public health services, attending physicians and the diagnostic laboratories involved.     

Successful rearing of whiteleg shrimp Litopenaeus vannamei larvae fed a desiccation‐tolerant nematode to replace Artemia

The nematode Panagrolaimus sp. was tested as live feed to replace Artemia nauplii during first larval stages of whiteleg shrimp Litopenaeus vannamei. In Trial 1, shrimp larvae were fed one of four diets from Zoea 2 to Postlarva 1 (PL1): (A) Artemia nauplii, control treatment; (NC) nematodes enriched in docosahexaenoic acid (DHA) provided by the dinoflagellate Crypthecodinium cohnii; (N) non‐enriched nematodes; and (Algae) a mixture of microalgae supplemented in C. cohnii cells. In Trial 2, shrimp were fed (A), (NC) and a different treatment (NS) with nematodes enriched in polyunsaturated fatty acids (PUFAs) provided by the commercial product S.presso^®, until Postlarva 6 (PL6). Mysis 1 larvae fed nematodes of the three dietary treatments were 300 μm longer (3.2 ± 0.3 mm) than control larvae. At PL1, control shrimp were 300 μm longer (4.5 ± 0.3 mm) than those fed DHA‐enriched or PUFAs‐enriched nematodes. No differences were observed in length and survival at PL6 between control larvae and those fed DHA‐enriched nematodes (5.1 ± 0.5 mm; 33.1%–44.4%). Shrimp fed microalgae showed a delay in development at PL1. This work is the first demonstration of Panagrolaimus sp. suitability as a complete substitute for Artemia in rearing shrimp from Zoea 2 to PL6.     

Influence of Age on Surfactant Isolated from Healthy Horses Maintained on Pasture

Background: Surfactant alterations are described in horses after exercise, anesthesia, and prolonged transport, in horses with recurrent airway obstruction, and in neonatal foals. The effect of horse age or bronchoalveolar lavage fluid (BALF) sample characteristics on surfactant is unknown.
Objectives: To evaluate surfactant phospholipid composition and function in healthy horses, and to investigate the influence of age and BALF sample characteristics on surfactant.
Animals: Seventeen healthy horses 6–25 years of age maintained on pasture year-round.
Methods: BALF was collected by standard procedures and was assessed for recovery volume, nucleated cell count (NCC), and cytology. Cell-free BALF was separated into crude surfactant pellet (CSP) and surfactant supernatant (Supe) by ultracentrifugation. Phospholipid and protein content were determined from both fractions. CSP phospholipid composition was analyzed by high-performance liquid chromatography with an evaporative light scatter detector. Surface tension of CSP was evaluated with a pulsating bubble surfactometer. Regression analysis was used to evaluate associations between age, BALF sample characteristics, and surfactant variables.
Results: Results and conclusions were derived from 15 horses. Increasing age was associated with decreased phospholipid content in CSP but not Supe. Age did not affect protein content of CSP or Supe, or surfactant phospholipid composition or function. Age-related surfactant changes were unaffected by BALF recovery percentage, NCC, and cytological profile.
Conclusions and Clinical Importance: Older horses have decreased surfactant phospholipid content, which might be because of age-related pulmonary changes. Surfactant composition is unaffected by BALF sample characteristics at a BALF recovery percentage of at least 50%.     

Prediction of model pools for a long‐term experiment using near‐infrared spectroscopy

Fourty‐one soil samples from the “Eternal Rye” long‐term experiment in Halle, Germany, were used to test the usefulness of near‐infrared spectroscopy (NIRS) to differentiate between C derived from C₃ and C₄ plants by using the isotopic signature (δ¹³C) and to predict the pools considered in the Rothamsted Carbon (RothC) model, i.e., decomposable plant material, resistant plant material, microbial biomass, humified organic matter, and inert organic matter. All samples were scanned in the visible‐light and near‐infrared region (400–2500 nm). Cross‐validation equations were developed using the whole spectrum (first to third derivative) and a modified partial least‐square regression method. δ¹³C values and all pools of the RothC model were successfully predicted by NIRS as reflected by RSC values (ratio between standard deviation of the laboratory results and standard error of cross‐validation) ranging from 3.2 to 3.4. Correlations analysis indicated that organic C can be excluded as basis for the successful predictions by NIRS in most cases, i.e., 11 out of 16.     

Influence of the distillation step on the ratios of stable isotopes of ethanol in cherry brandies

Isotope ratio mass spectrometry and site-specific natural isotope fractionation-nuclear magnetic resonance were applied to determine the overall carbon isotope ratio (delta13C) and the hydrogen isotope ratios [(D/H)I and (D/H)II] of ethanol, respectively. Ethanol was obtained by distillation of fermented cherry mash from a pot still commonly used in fruit brandy production. Analyses of distillate fractions revealed that the distillation proceeds with a fractionation of ethanol isotopologues. The inverse vapor pressure isotope effect (VPIE) observed for the carbon isotopologues is in accordance with the data reported for distillation of ethanol in spinning band columns. In contrast, the inverse VPIE for hydrogen isotopologues of ethanol observed in spinning band columns could not be confirmed. To investigate whether the observed isotope fractionations might influence the applicability of stable isotope analysis for quality and authenticity assessment of fruit brandies, the collected distillate fractions were recombined to cuts, as is common practice in commercial fruit brandy production. Taking into consideration the limits of repeatability of the method, it could be demonstrated that the isotope fractionations observed do not impair the applicability of stable isotope analysis of the carbon and hydrogen isotopes of ethanol for the authenticity assessment of cherry brandies if the cuts are placed in accordance with common distillers' practice.     

Adoption of precision agriculture technologies by German crop farmers

In recent years, precision farming has been receiving more attention from researchers. Precision farming, which provides a holistic system approach, helps farmers to manage the spatial and temporal crop and soil variability within a field in order to increase profitability, optimize yield and quality, and reduce costs. There has been considerable research in farmers’ adoption of precision agriculture technologies. However, most recent studies have considered only a few aspects, whereas in this study a wide range of farm characteristics and farmer demographics are tested to gain insight into the relevant aspects of adoption of precision farming in German crop farming. The results of a logistic regression analysis show that predictors with positive influence on the adoption of precision farming are agricultural contractor services such as an additional farming business, having under 5 years’ experience in crop farming, having between 16 and 20 years’ experience in crop farming, and having more than 500 ha of arable land. However, having a farm of less than 100 ha and producing barley are factors that exert a negative influence on the adoption of precision farming. The results of this study provide manifold starting points for the further proliferation of precision agriculture technologies and future research directions.