Biochar produced by pyrolysis of organic residues is increasingly used for soil amendment and many other applications. However, analytical methods for its physical and chemical characterization are yet far from being specifically adapted, optimized, and standardized. Therefore, COST Action TD1107 conducted an interlaboratory comparison in which 22 laboratories from 12 countries analyzed three different types of biochar for 38 physical-chemical parameters (macro- and microelements, heavy metals, polycyclic aromatic hydrocarbons, pH, electrical conductivity, and specific surface area) with their preferential methods. The data were evaluated in detail using professional interlaboratory testing software. Whereas intralaboratory repeatability was generally good or at least acceptable, interlaboratory reproducibility was mostly not (20% < mean reproducibility standard deviation < 460%). This paper contributes to better comparability of biochar data published already and provides recommendations to improve and harmonize specific methods for biochar analysis in the future.
Leaf and crown wart, marbled or beet root tumour are some of the common names given to a disease of sugar beet ( Beta vulgaris ) caused by Urophlyctis leproides (formerly Physoderma leproides ). It was first reported in Algeria in 1894 (Trabut, 1894). Since then, the disease has been recorded in Argentina, Italy, Spain, United Kingdom, Palestine and the USA (Whitney, 1971). In Egypt, the disease was observed during harvest (2003, 2004, 2005) at three locations in the Nile Delta (Behira, Gharbia and Kafr El-Sheikh) on a range of sugar beet cultivars (Gloria, Kawmera, Oscar poly, Othus poly and Pleno). Disease incidence (DI) was less than 1% in 2003, 1-2% in 2004 and 3% in 2005. Although the DI is currently low, if the trend observed over the last few years continues, the disease could reach epidemic levels in the near future.The disease exhibited typical symptoms on root crowns and occasionally on petioles and leaf blades. Galls on leaf blades and petioles are greenish brown and have a rough appearance. Affected leaves are malformed. On the crown, galls range in size from 1 cm to (most commonly) 8-10 cm. These galls are spherical, rough and are attached to the host by a narrow base. Gall colour was variable, ranging from shades of green through yellow to brown depending on the age of plant cultivar. Galls occurred singly or coalesced to form complexes. Sections made through a crown gall revealed cavities filled with thick-walled sporangia (resting spores) surrounded by thickened wall. Sporangia were light brown, spherical to ovoid or concave (25 ± 5 × 40 ± 5 µ m) in diameter (Ruppel, 1995). As the gall decomposes, resting sporangia are released into the soil. Soil surveys were carried out in the affected areas and detected resting sporangia.
Adult bean plants (Phaseolus vulgaris cv. Festival) growing in a commercial greenhouse in southeastern Spain developed symptoms of root necrosis, necrotic streaks on the basal stems, and plant wilt. A Pythium sp. was isolated consistently from roots and basal stems on selective agar (P5ARP). Single-hyphal transfers produced intercalary antheridia, oogonia (23 to 26 μm in diameter), oospores (18 to 20 μm in diameter), and zoospores in toruloid sporangia. Cardinal temperatures were a minimum of 10°C, an optimum of 28 to 34°C, and a maximum of 40°C. Daily growth rate on corn meal agar at 25°C was 15 mm. The internal transcribed spacer 1 (ITS 1) rDNA sequence of the isolate matched the sequences of Pythium aphanidermatum in GenBank. The sequence of isolate Py-294 was deposited in GenBank, Accession No. AM396563. This isolate was identified as P. aphanidermatum on the basis of morphological and cultural characteristics (1) and the ITS rDNA sequence. To fulfill Koch's postulates, 50 ml of inoculum of isolate Py-294 was used to inoculate bean plants (cvs. Donna and Emerite) at the five-leaf stage. The inoculum was prepared by homogenizing 2-week-old potato dextrose agar-petri plate cultures in 300 ml of distilled water. The plants were maintained in a greenhouse at temperatures of 18.8 to 30.3°C. Irrigation water had an electric conductivity of 0.5 to 0.6 dS·m–1 while the nutrient solution had 1.9 to 2.1 dS·m–1. Two months after sowing, 35.4 and 100% of cvs. Donna and Emerite, respectively, developed root necrosis, while control plants grown in bags containing noninoculated perlite remained healthy. The pathogen was reisolated from roots and basal stems of symptomatic plants. The test was repeated with similar results. To our knowledge, this is the first report of P. aphanidermatum as the causal agent of root and crown necrosis of adult bean plants in Spain. Reference: (1) A. J. Van der Plaats-Niterink. Stud. Mycol. 21:242, 1981.
La forma eh es empleada con bastante frecuencia en la conversación en general. Por este elevado índice de uso ha sido considerada un expletivo (Cortés Rodríguez 1991), una muletilla (Rabanales y Contreras 1992) o una pausa llena (Briz 1998). Sin embargo, algunos autores también la han incluido en la nómina de los marcadores del discurso (
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