Dr. Walther Horn,Berlin-Dahlem,zum 60. Geburtstag

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Weitere Fälle von Massenauftreten der FliegeChloropisca notata flavifrons Macq. (Chloropidae) und nahe verwandter Arten

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Acidification in the Rhizosphere of Rape Seedlings and in Bulk Soil by Nitrification and Ammonium Uptake

Ammonium salts used as fertilizers may cause soil acidification by two different processes: nitrification in soil and net release of protons from roots. Their influence on soil pH may vary depending on the distance from root surface. The aim of this study was to distinguish between these two processes. For this purpose rape seedlings were grown 10 d in a system which separated roots from soil by a fine-meshed screen. As a function of distance from the plane root layer formed on the screen, pH, titratable and exchangeable acidity and NO₃- and NH₄-nitrogen were determined. The soil, a luvisol from loess, was supplied with no N or (NH₄)₂SO₄ either with or without a nitrification inhibitor (DCD). The bulk soil pH remained unaffected when no N or 400 mg NH₄? N kg^?1 soil plus DCD was applied but it decreased from 6.6 to 5.8 without DCD. In contrast, rhizosphere pH decreased in all cases, mainly within a distance of 1 mm from the root plane only, but with gradients extending to between 2 and 4 mm into the soil. The strongest pH decrease, from 6.6 to 4.9, occurred at the root surface of plants treated with both NH₄-N and DCD where most of the mineral N remained as ammonium. In this case Al was solubilized in the rhizosphere as indicated by exchangeable acidity. Total soil acidity produced in the NH₄ treatment without DCD was mainly derived from nitrification compared to root released protons. However, acidification of the rhizosphere was diminished by nitrification because nitrate ions taken up by the roots counteracted net proton release. It is concluded that nitrification inhibitors may reduce proton input from ammonium fertilizers but enhance acidification at the soil-root interface which may cause Al toxicity to plants.     

The amount of recycled crust in sources of mantle-derived melts

Plate tectonic processes introduce basaltic crust (as eclogite) into the peridotitic mantle. The proportions of these two sources in mantle melts are poorly understood. Silica-rich melts formed from eclogite react with peridotite, converting it to olivine-free pyroxenite. Partial melts of this hybrid pyroxenite are higher in nickel and silicon but poorer in manganese, calcium, and magnesium than melts of peridotite. Olivine phenocrysts' compositions record these differences and were used to quantify the contributions of pyroxenite-derived melts in mid-ocean ridge basalts (10 to 30%), ocean island and continental basalts (many >60%), and komatiites (20 to 30%). These results imply involvement of 2 to 20% (up to 28%) of recycled crust in mantle melting.     

Comparing validation of four ELISA-systems for detection of Salmonella derby- and Salmonella infantis-infected pigs

The objective of this study was the comparative evaluation of four indirect Salmonella ELISA tests at study time approved in Germany to detect Salmonella infection in pigs.Three tests are based on a LPS-antigen mix and directed against specific IgG antibodies. The fourth test is based on a purified S. Typhimurium whole-cell lysate antigen and discriminates between Salmonella-specific IgM-, IgA-, and IgG- antibodies. In a longitudinal study, two groups of six weeks old hybrid piglets were orally infected with a porcine S. Infantis or S. Derby strain. Clinical and bacteriological parameters were monitored weekly during an observation period of 130 days after infection and serum samples were investigated in parallel with the respective ELISAs. Apparently, the LPS-based ELISA systems used in this study failed to recognize S. Infantis-infected pigs although those animals shed the pathogen in high amounts throughout the study until day 81 post infection (p. i.). In contrast, the isotype-specific Salmonella Typhimurium whole-cell-lysate based ELISA was capable of detecting Salmonella-infected pigs from day ten p. i. at all tested serotypes and revealed the highest sensitivity in detection of S. Infantis-infected pigs. Furthermore, it became apparent that the often used surveillance cut-off value of 40 OD% is not appropriate for intra-vitam detection of S. Infantis- and S. Derby-infected pigs. In contrast, the cut-off values of the ELISAs given by the suppliers result in considerable higher detection rates.     

Deforestation and forest degradation monitoring and assessment of biomass and carbon stock of lowland rainforest in the Analanjirofo region, Madagascar

Madagascar is currently developing a policy and strategies to enhance the sustainable management of its natural resources, encouraged by United Nations Framework Convention on Climate Change (UNFCCC) and REDD. To set up a sustainable financing scheme methodologies have to be provided that estimate, prevent and mitigate leakage, develop national and regional baselines, and estimate carbon benefits. With this research study this challenge was tried to be addressed by analysing a lowland rainforest in the Analanjirofo region in the district of Soanierana Ivongo, North East of Madagascar. For two distinguished forest degradation stages: “low degraded forest” and “degraded forest” aboveground biomass and carbon stock was assessed. The corresponding rates of carbon within those two classes were calculated and linked to a multi-temporal set of SPOT satellite data acquired in 1991, 2004 and 2009. Deforestation and particularly degradation and the related carbon stock developments were analysed. With the assessed data for the 3 years 1991, 2004 and 2009 it was possible to model a baseline and to develop a forest prediction for 2020 for Analanjirofo region in the district of Soanierana Ivongo. These results, developed applying robust methods, may provide important spatial information regarding the priorities in planning and implementation of future REDD+ activities in the area.     

Intercropping winter cereals with Caucasian clover for forage in northern Europe

Intercropping cereal crops with perennial legumes for forage has been demonstrated as a means to improve nutritive value compared to cereal crops alone. Our objective was to determine whether sowing winter rye (Secale cereale L.) or winter triticale (x Triticosecale Wittmack) into living Caucasian clover (Trifolium ambiguum M. Bieb.) improves yield or nutritive value compared to monoculture cereal crop forage in northern Europe. The experiments were conducted near Moche?ek and Fal?cin, Poland. In autumn 2010 and 2011, winter rye was sown into existing Caucasian clover or in monoculture at Moche?ek, and winter triticale was sown into Caucasian clover or in monoculture at Fal?cin, with monoculture clover as a third crop treatment at both locations. The following spring, first harvest of forage from the three crop treatments was taken at two maturities: when monoculture cereals reached heading (BBCH 51) or grain milk stage (BBCH 71), and two additional harvests were taken from mixture plots and monoculture clover before autumn. First harvest forage yields of mixtures were similar to monoculture cereal at Fal?cin, less than monoculture cereal at Moche?ek, and greater than monoculture clover at both locations. Full season forage yields of mixtures were greater than both monoculture cereal and clover crops at both locations. The proportion of clover in mixtures was 20–31% in the first harvest, resulting in slightly lower neutral detergent fiber concentrations than in monoculture cereal crop at Fal?cin, but no improvement in nutritive value at Moche?ek. By spring 2012, most Caucasian clover had died from Sclerotinia trifoliorum infection at both locations, so forage was not harvested in the second year of the experiment. Although total season forage yields were greater for mixtures than for either monoculture cereal or Caucasian clover, this system cannot be recommended for northern Europe because of failure for Caucasian clover to persist.