Nmin−Gehalt im Boden,mineralische N-Düngung und N-Entzug von Winterweizen im Internationalen Organischen Stickstoffdauerdüngungsversuch (IOSDV) Berlin-Dahlem

N_mim content in the soil, N-fertilization and N uptake of winter wheat in the international organic nitrogen long-term fertilization experiment (IOSDV) Berlin-Dahlem During the 9th and 10th year of the long-term IOSDV field experiment micro plots were put in three treatments. Labelled¹⁵ N (160 resp. 110 kg/ha N as ammonium sulfate) was fertilized to winter wheat subdivided into three portions. N_min in soil was determined five times during the season, plant biomass was harvested at different growth stages and N uptake was calculated. Using the¹⁵ N-technique permitted a discrimination between fertilizer-N and soil-N. Preferential uptake of fertilizer-N by the wheat crop but also immobilisation in soil were observed until June. Subsequently the immobilized N was remineralized and assimilated by wheat. But the native N_min of soil was minimaly utilized during the initial growth of wheat. Therefore the absolute amount of soluble N temporarily increased caused by a mineralisation of the organic matter.     

Usage of feeding yeast "Fermosin" grown on mineral oil distillate in animal nutrition. 2. Digestibility of the nutrients of Fermosin feeding yeast on broilers (chickens) and fattening pigs]

The digestibility of the nutrients of Fermosin was tested on pigs and the following values were ascertained: organic matter=86%, crude protein=89% and N-free extractives=83%. The net energy ascertained on the basis of the content of nutrients and the digestibility of the nutrients of Fermosin amounts to 617 energetic feed units for pigs/kg dry matter. The true digestibility of the amino acids of Fermosin was determined on pigs and chicken. For lysin the true digestibility was ascertained as 95% (pigs) and 73% (Broilers). Due to the different digestion abilities of the two animal species, corresponding differences in the digestibility of the other amino acids were found as well.     

Brain lesions in mallard ducklings from parents fed methylmercury.

Methylmercury dicyandiamide was fed to mallard ducks at 3 ppm mercury. Mercury accumulated in the eggs to an average of 7.18 and 5.46 ppm on a wet-weight basis in 2 successive years. Mercury in the eggs is believed to have caused brain lesions in the hatched ducklings. Lesions included demyelination, neuron shrink-age, necrosis, and hemorrhage in the meninges overlying the cerebellum. Brains of dead ducklings contained an average of 6.17 and 5.19 ppm mercury on a wet-weight basis in 2 successive years.     

A nodular granulomatous posthitis caused by Halicephalobus sp. in a horse

This report describes a case of nodular posthitis caused by Halicephalobus gingivalis in a 24-year-old warmblood horse. Macroscopic examination revealed a multinodular, partially ulcerated mass on the external lamina of the prepuce. Nematode migration from unfixed biopsy material in phosphate-buffered saline revealed adult nematodes with the typical morphological features of H. gingivalis: distinctive rhabditiform oesophagus with corpus, isthmus and bulb and the dorsoflexed ovary. The main histopathological features consisted of submucosal confluent granulomatous foci containing cross- and tangential sections of larval and adult nematodes surrounded by cellular debris, epitheloid macrophages, multinucleated giant cells, lymphocytes and plasma cells. Therapy including oral administration of moxidectin and local application of an ointment containing prednisolone and moxidectin was initiated but clinical response was poor. Five months later, the nodular mass was still present and histologically, the same lesions with numerous intact nematodes were identified. In the present case, a localized infection with granuloma formation in the area of the prepuce was observed. Clinically, it cannot be distinguished from other nematode infections or even from a squamous cell carcinoma. An accurate clinical examination followed by histopathological and parasitological examinations was necessary to establish the final diagnosis. This case is unusual in that the lesions were locally very extensive (10 cm), but they remained confined to the preputium and the nematodes did not spread haematogenously to other internal organs.     

Potentiation of the Cytotoxic Activity of Copper by Polyphosphate on Biofilm-Producing Bacteria: A Bioinspired Approach

Adhesion and accumulation of organic molecules represent an ecologically and economically massive problem. Adhesion of organic molecules is followed by microorganisms, unicellular organisms and plants together with their secreted soluble and structure-associated byproducts, which damage unprotected surfaces of submerged marine structures, including ship hulls and heat exchangers of power plants. This is termed biofouling. The search for less toxic anti-biofilm strategies has intensified since the ban of efficient and cost-effective anti-fouling paints, enriched with the organotin compound tributyltin, not least because of our finding of the ubiquitous toxic/pro-apoptotic effects displayed by this compound [1]. Our proposed bio-inspired approach for controlling, suppressing and interfluencing the dynamic biofouling complex uses copper as one component in an alternative anti-fouling system. In order to avoid and overcome the potential resistance against copper acquired by microorganisms we are using the biopolymer polyphosphate (polyP) as a further component. Prior to being functionally active, polyP has to be hydrolyzed to ortho-phosphate which in turn can bind to copper and export the toxic compound out of the cell. It is shown here that inhibition of the hydrolysis of polyP by the bisphosphonate DMDP strongly increases the toxic effect of copper towards the biofilm-producing Streptococcus mutans in a synergistic manner. This bisphosphonate not only increases the copper-caused inhibition of cell growth but also of biofilm production by the bacteria. The defensin-related ASABF, a marine toxin produced by the sponge Suberites domuncula, caused only an additive inhibitory effect in combination with copper. We conclude that the new strategy, described here, has a superior anti-biofilm potential and can be considered as a novel principle for developing bio-inspired antifouling compounds, or cocktails of different compounds, in the future.     

Isotopologue ratios of N2O emitted from microcosms with NH4 fertilized arable soils under conditions favoring nitrification

Soils represent the major source of the atmospheric greenhouse gas nitrous oxide (N₂O) and there is a need to better constrain the total global flux and the relative contribution of the microbial source processes. The aim of our study was to determine variability and control of the isotopic fingerprint of N₂O fluxes following NH₄⁺-fertilization and dominated by nitrification. We conducted a microcosm study with three arable soils fertilized with 0–140 mg NH₄⁺–N kg⁻¹. Fractions of N₂O derived from nitrification and denitrification were determined in parallel experiments using the ¹⁵N tracer and acetylene inhibition techniques or by comparison with unfertilized treatments. Soils were incubated for 3–10 days at low moisture (30–55% water-filled pore space) in order to establish conditions favoring nitrification. Dual isotope and isotopomer ratios of emitted N₂O were determined by mass spectrometric analysis of δ¹⁸O, average δ¹⁵N (δ¹⁵N^bulk) and ¹⁵N site preference (SP = difference in δ¹⁵N between the central and peripheral N positions of the asymmetric N₂O molecule). N₂O originated mainly from nitrification (>80%) in all treatments and the proportion of NH₄⁺ nitrified that was lost as N₂O ranged between 0.07 and 0.45%. δ¹⁸O and SP of N₂O fluxes ranged from 15 to 28.4‰ and from 13.9 to 29.8‰, respectively. These ranges overlapped with isotopic signatures of N₂O from denitrification reported previously. There was a negative correlation between SP and δ¹⁸O which is opposite to reported trends in N₂O from denitrification. Variation of average ¹⁵N signatures of N₂O (δ¹⁵N^bulk) did not supply process information, apparently because a strong shift in precursor signatures masked process-specific effects on δ¹⁵N^bulk. Maximum SP of total N₂O fluxes and of nitrification fluxes was close to reported SP of N₂O from NH₄⁺ or NH₂OH conversion by autotrophic nitrifiers, suggesting that SP close to 30‰ is typical for autotrophic nitrification in soils following NH₄⁺-fertilization. The results suggest that the δ¹⁸O/SP fingerprint of N₂O might be used as a new indicator of the dominant source process of N₂O fluxes in soils.     

Decomposition of maize residues after manipulation of colonization and its contribution to the soil microbial biomass

A 28-day incubation experiment at 12°C was carried out on the decomposition of maize leaf litter to answer the questions: (1) Is the decomposition process altered by chemical manipulations due to differences in the colonization of maize leaf litter? (2) Do organisms using this maize material contribute significantly to the soil microbial biomass? The extraction of the maize straw reduced its initial microbial biomass C content by 25%. Fumigation and extraction eliminated the microbial biomass by 88%. In total, 17% of added maize straw C was mineralized to CO₂ during the 28-day incubation at 12°C in the treatment with non-manipulated straw. Only 14% of added C was mineralized in the treatment with extracted straw as well as in the treatment with fumigated and extracted straw. The net increase in microbial biomass C was 79 μg g^?1 soil in the treatment with non-manipulated straw and an insignificant 9 μg g^?1 soil in the two treatments with manipulated straw. However, the net increase did not reflect the fact that the addition of maize straw replaced an identical 58% (≈180 μg g^?1 soil) of the autochthonous microbial biomass C₃-C in all three straw treatments. In the two treatments with manipulated straw, the formation of maize-derived microbial biomass C₄-C was significantly reduced by 25%. In the three straw treatments, the ratio of fungal ergosterol-to-microbial biomass C ratio showed a constant 60% increase compared to the control, and the contents of glucosamine and muramic acid increased by 18%. The average fungal C/bacterial C ratio was 3.6 in the soil and 5.0 in the recovered maize straw, indicating that fungal dominance was not altered by the initial chemical manipulations of the maize straw-colonizing microorganisms.     

Do farmers in Germany exploit the potential yield and nitrogen benefits from preceding oilseed rape in winter wheat cultivation?

Field experiments show that wheat grown after oilseed rape (OSR) achieves higher yield levels, while the nitrogen (N) application is reduced. However, field experiment data are based on few locations with optimised management. We analysed a large dataset based on farm data to assess the true extent of break crop benefits (BCB) for yield and N fertilisation within German commercial farming.

Across all German states and years, average yield of wheat preceded by OSR was 0.56 Mg ha^?1 higher than yield of wheat preceded by cereals (7.09 Mg ha^?1), although considerable variation between regions was observed. Mean N application across all states to wheat after OSR was 5 kg ha^?1 lower than to wheat after cereals. Choice of wheat types for different end uses (bread flour or animal feed) showed higher (0.77 Mg ha^?1) or lower (0.44 Mg ha^?1) BCB for yield of wheat cultivated after OSR compared with after cereals. The calculated BCB for yield and N fertilisation were lower than expected from dedicated field experiments and fertiliser recommendations. Thus the advantages of OSR as a preceding crop are generally utilised by commercial farmers in Germany but there is room for improvement.