Soil organic matter composition and soil lightness

Relationships between soil lightness, soil organic matter (SOM) composition, content of organic C, CaCO₃, and texture were studied using 42 top‐soil horizons from different soil types located in southern Germany. SOM composition was determined by CPMAS ¹³C NMR spectroscopy, soil color was measured by diffuse‐reflectance spectrophotometry and given in the CIE L*a*b* color coordination system (Commission Internationale de l'Eclairage, 1978). Multiple‐regression analysis showed, that soil lightness of top‐soil horizons is principally determined by OC concentration, but CaCO₃ and soil texture are also major variables. Soil lightness decreased with increasing OC content. Carbonate content had an important effect on soil lightness even at low concentrations due to its lightening property. Regressions between soil lightness and organic C content were strongly linear, when the soils were differentiated according to texture and CaCO₃ content. The aryl‐C content was the only SOM component which correlated significantly with soil lightness (r_S = –0.87). In the linear regressions carried out on the different soil groups, soil aryl‐C content was a more significant predictor for soil lightness than total OC content.     

Systemic infection in European perch with thermoadapted virulent Aeromonas salmonicida (Perca fluviatilis)

In non‐salmonid fish, Aeromonas salmonicidacan cause local infections with severe skin ulcerations, known as atypical furunculosis. In this study, we present a systemic infection by a virulent A. salmonicidain European perch (Perca fluviatilis).This infection was diagnosed in a Swiss warm water recirculation aquaculture system. The isolate of A.  salmonicida encodes a type three secretion system (TTSS) most likely located on a plasmid similar to pAsa5/pASvirA, which is known to specify one of the main virulence attributes of the species A. salmonicida. However, the genes specifying the TTSS of the perch isolate show a higher temperature tolerance than strains isolated from cold‐water fish. The function of the TTSS in virulence was verified in a cytotoxicity test using bluegill fry and epithelioma papulosum cyprinid cells.     

Wet-chemical silvering of inert polyethylene terephthalate yarn in a spool dyeing apparatus

Inert polyethylene terephthalate (PET) yarns, which were spooled crosswise onto a cylindrical dyeing bobbin, were silvered successfully with a wet-chemical method by using a newly developed one-bath method on a laboratory scale. In order to characterize the silver coating such as design, homogeneity, and crack formation, the surface morphology (SM) was analyzed using scanning electron microscopy (SEM). The chemical compositions of the surface (percentage of carbon, oxygen, nitrogen, silicium, and silver) were investigated with energy-dispersive x-ray spectroscopy (EDX). Furthermore, the testing of textile-chemical and textile-physical properties such as the washing-fastness, tensile strength, and electrical conductivity was carried out.     

Humic acid composition and soil fertility of soils near an ancient charcoal kiln: are they similar to Terra Preta de Índios soils?

Journal of Soils and Sediments - Charcoal production during the nineteenth century transformed landscapes in the Brazilian Atlantic Forests in Rio de Janeiro city. These paleo-territories were...     

Conversion of tropical moist forest into cacao agroforest: consequences for carbon pools and annual C sequestration

Tropical forests store a large part of the terrestrial carbon and play a key role in the global carbon (C) cycle. In parts of Southeast Asia, conversion of natural forest to cacao agroforestry systems is an important driver of deforestation, resulting in C losses from biomass and soil to the atmosphere. This case study from Sulawesi, Indonesia, compares natural forest with nearby shaded cacao agroforests for all major above and belowground biomass C pools (n = 6 plots) and net primary production (n = 3 plots). Total biomass (above- and belowground to 250 cm soil depth) in the forest (approx. 150 Mg C ha^?1) was more than eight times higher than in the agroforest (19 Mg C ha^?1). Total net primary production (NPP, above- and belowground) was larger in the forest than in the agroforest (approx. 29 vs. 20 Mg dry matter (DM) ha^?1 year^?1), while wood increment was twice as high in the forest (approx. 6 vs. 3 Mg DM ha^?1 year^?1). The SOC pools to 250 cm depth amounted to 134 and 78 Mg C ha^?1 in the forest and agroforest stands, respectively. Replacement of tropical moist forest by cacao agroforest reduces the biomass C pool by approximately 130 Mg C ha^?1; another 50 Mg C ha^?1 may be released from the soil. Further, the replacement of forest by cacao agroforest also results in a 70–80 % decrease of the annual C sequestration potential due to a significantly smaller stem increment.     

Sorption of HOC in soils with carbonaceous contamination: Influence of organic‐matter composition

Detailed information about structure and composition of organic sorbents is required to understand their impact on sorption capacity and sorption kinetic of organic pollutants. Therefore, the chemical composition of organic material from 18 geosorbents was investigated by solid‐state ¹³C nuclear‐magnetic‐resonance (NMR) spectroscopy. Structural parameters such as aromaticity, polarity, and alkyl‐C content were related to the Freundlich sorption exponent (1/n) and the sorption coefficient . The geosorbents included three natural and four combusted coals (carbonaceous material), three Histosols, five mineral soils from Germany containing inputs of technogenic carbonaceous material, derived from industrial activities, and four non‐contaminated mineral soils from Germany. Equilibrium sorption was measured for five hydrophobic organic compounds and analyzed with the solubility‐normalized Freundlich sorption isotherm. With increasing maturation degree, the proportion of polar constituents decreases from the natural soils to the coals. In contrast to the non‐polluted mineral soils, the soils with technogenic input are characterized by high aromaticity and low polarity. A positive correlation between sorption coefficient and aromaticity was found. The Freundlich exponent (1/n) is negatively correlated with the aromaticity, denoting an increase of adsorption processes with increasing aromaticity. Likewise, the contribution of partitioning decreases. This sorption mechanism predominates only if the organic matter in the samples contains a high proportion of polar compounds.     

Der Einfluß künstlicher vertikaler Grobporen in einer verdichteten Bodenmatrix auf das Wachstum von Winterweizen I. Wachstum von Winterweizen auf einer Parabraunerde aus Löß

The influence of artificial vertical macropores in a compacted soil on the growth of winterwheat. I. Growth of winterwheat on an alfisol derived from loess In field experiments on a compacted alfisol it was investigated, how artificially made vertical macropores in the compacted structure influence water extraction and growth of winterwheat compared to the compacted structure without vertical macropores and to the loosened structure. The experiments were carried out in two subsequent years with different precipitation (308, 0 and 440, 1 mm in the period of November until August of both growth periods). The influence of the different soil structure was most pronounced during periods of increasing water tension. Compared to the compacted structure, water extraction as well as yield was improved by the vertical artificial macropores to a similar extend as by the loosened structure. Both structures increased water extraction from deeper parts of the soil (25-50 cm). The beneficial effects of the vertical macropores were more pronounced in the dry compared to the wet year. Despite of the unequal distribution of roots in the compacted structure with vertical macropores, water extraction from the soil between the macropores was not negatively affected.     

Mating patterns and pollen dispersal in four contrasting wild cherry populations (Prunus avium L.)

Although pollen dispersal has been extensively studied in trees, parameters influencing between-population variation are still poorly understood. In this study, we conducted paternity analyses on open-pollinated seeds in four natural populations of wild cherry (Prunus avium) with contrasting density and clonal propagation, using eight microsatellite loci and one self-incompatibility system locus. We also measured four quantitative traits and spatial positions as potential correlates of reproductive success. Levels of polyandry differed among populations and 30% of the seed families exhibited unequal paternal contributions, suggesting variation in reproductive success rather than variation in mate availability. Mating occurred preferentially among neighbours in all populations, suggesting that it is a common pattern in wild cherry and probably results from pollinator behaviour. Paternal success was positively correlated with diameter at breast height, as indicated in previous studies and tree dominance only resulted in higher paternal success in low density plots. Mating patterns were thus also affected by both density and tree size. Large-scale studies are needed to disentangle relative influences of these factors on the mating system and pollination success.     

Antifeedant effect,biological efficacy and high affinity binding of imidacloprid to acetylcholine receptors in Myzus persicae and Myzus nicotianae

It is known from laboratory studies that tobacco-associated forms of Myzus persicae (Sulzer) and the closely related tobacco aphid Myzus nicotianae (Blackman) are often somewhat less susceptible to imidacloprid than non-tobacco strains of M. persicae. Choice tests (floating leaf technique) showed that tobacco aphids were also less susceptible to the antifeedant potential of imidacloprid in contact bioassays. Synergists like piperonyl butoxide or DEF did not enhance the susceptibility of tobacco-associated morphs of Myzus ssp. to imidacloprid, thus providing evidence that neither oxidative detoxication nor hydrolytic metabolization took place. However, in an attempt to study the influence of endosymbiotic bacteria on the efficacy of imidacloprid, we allowed small populations of tobacco aphids to feed on diets containing the antibiotic chlortetracycline prior to imidacloprid treatment. While the effectiveness of imidacloprid, i.e. lower LC₅₀ values, could be improved in all strains, including the susceptible reference strain, there was no change in overall tolerance factors. In order to investigate any possible alteration of the target site, the affinity of imidacloprid and nicotine to nicotinic acetylcholine receptors in whole-aphid homogenates was measured. All strains (and clones) showed the same high-affinity binding sites and no detectable difference. Studies using the FAO dip method revealed that the lower susceptibility of M. nicotianae is not restricted to chloronicotinyls like imidacloprid or acetamiprid, because other insecticides with different modes of action such as pymetrozine and fipronil were also affected in laboratory studies. It is considered that the observed tolerance to chloronicotinyls in certain strains of Myzus ssp. is a natural variation in response, probably not coupled with any known mechanism of resistance in this species complex. © 1998 SCI