Recent research suggests that Swedish organic arable soils have been under-recognized as a potential source of phosphorus (P) loading to water bodies. The aim of this study was to compare P losses through leaching from organic and high-fertility mineral soils. In addition, the effectiveness of a magnesium-salt-coated biochar applied below the topsoil as a mitigation strategy for reducing P losses was evaluated.
Materials and methods
Phosphorus leaching was measured from four medium- to high-P arable soils, two Typic Haplosaprists (organic 1 and 2), a Typic Hapludalf (sand), and an unclassified loam textured soil (loam), in a 17-month field study utilizing 90-cm-long lysimeters. A magnesium-salt-coated biochar was produced and characterized using X-ray powder diffraction (XPD), scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS), and X-ray adsorption (XANES) spectroscopy, and its phosphate adsorption capacity was determined at laboratory scale. It was also applied as a 3-cm layer, 27 cm below the soil surface of the same lysimeters and examined as a mitigation measure to reduce P leaching.
Results and discussion
Total-P loads from the 17-month, unamended lysimeters were in the order of organic 2 (1.2 kg ha?1)?>?organic 1 (1.0 kg ha?1)?>?sand (0.3 kg ha?1)?>?loam (0.2 kg ha?1). Macropore flow, humic matter competition for sorption sites, and fewer sorption sites likely caused higher P losses from the organic soils. Analysis by XRD and SEM revealed magnesium was primarily deposited as periclase (MgO) on the biochar surface but hydrated to brucite (Mg(OH)2) in water. The Langmuir maximum adsorption capacity (Qmax) of the coated biochar was 65.4 mg P g?1. Lysimeters produced mixed results, with a 74% (P?<?0.05), 51% (NS), and 30% (NS) reduction in phosphate-P from the organic 1, organic 2, and sand, respectively, while P leaching increased by 230% (NS) from the loam.
Conclusions
The findings of this study indicate that P leached from organic arable soils can be greater than from mineral soils, and therefore, these organic soils require further investigation into reducing their P losses. Metal-enriched biochar, applied as an adsorptive layer below the topsoil, has the potential to reduce P losses from medium- to high-P organic soils but appear to be less useful in mineral soils.
A decline of unknown aetiology has become a major problem for commercial orchid production in Hawaii, one of the primary orchid‐producing states in the USA. The major symptoms of decline include root degradation, foliar blight, pseudobulb rot and sheath rot. It was unclear whether all these symptoms are caused by the same or different pathogens, but preliminary research indicated that Fusarium species may be involved. In this study, the incidence of Fusarium species was examined across 186 plants, from 29 orchid genera and intergeneric hybrids across three islands in the state of Hawaii. The main five species associated with diseased orchids were F. proliferatum (38% of samples), F. solani (16%), F. oxysporum (16%) and two previously undescribed species (8% for both species combined). The two undescribed species were similar in appearance to F. subglutinans, and were designated FS‐A and FS‐B. Pathogenicity tests established that both F. proliferatum and FS‐B caused foliar spots, foliar blight and pseudostem rot on Dendrobium orchids, and that F. proliferatum isolates from diseased tissue of several genera could also induce symptoms on Dendrobium orchids. Although orchids have increasing importance in floriculture, relatively little is known about orchid pathogens, and previous studies focused primarily on Cymbidium and Phalaenopsis. This study provides new information concerning Dendrobium orchid pathogens and suggests a much wider host range than previously recognized for the five Fusarium species recovered from tissue with symptoms. These findings can contribute to better management of Fusarium diseases, which represent a significant challenge to orchid production in Hawaii. 相似文献
A 10-year-old American Shorthair cat with nasal discharge, anorexia, and weight loss was found to have pancytopenia and hyperproteinaemia. Bone marrow aspiration revealed atypical plasma cells that totalled 50% of the nucleated bone marrow cells. The number of atypical plasma cells progressively increased in the peripheral blood during the observation period of 64 days. The cat did not respond to treatments with melphalan, chlorambucil, and prednisolone, and died 71 days after the initial presentation. Clinical, cytological, histopathological, and immunohistochemical findings in this case supported the diagnosis of myeloma-related disorder (MRD) with leukaemic progression. 相似文献
Genetic parameters for faecal egg count were estimated in naturally challenged Avikalin sheep developed and maintained at
Central Sheep & Wool Research Institute, Avikanagar, India, over a period of 4 years (2004–2007). The data on faecal egg count
for 433 animals descended from 41 sires, and 151 dams were used for the study. Genetic analyses were carried out using restricted
maximum likelihood, fitting an animal model and ignoring or including maternal genetic or permanent environmental effects.
Direct heritability for the trait was 0.149 ± 0.096 when maternal effects were ignored. In the model which takes in to account
direct genetic, maternal genetic and maternal permanent environment effect together, it was observed that maternal heritability
(m2) accounts for 0.6% of total variation whereas maternal permanent environmental effect (c2) accounts for 6.14% of total phenotypic variation. Effect of faecal egg count on the growth characteristics was observed
to be significant. It was seen that wherever FEC was high, body weight or average daily gain declined in active infective
stage. After termination of the infection, these effects were found to be non-significant. Result suggests that direct genetic
and maternal permanent environmental effects were important for this trait; thus, they need to be considered for improvement
in the trait. 相似文献
The cell-free antigen (CFA), with highly hemagglutination activity, obtained from the culture supernatant of Bordetella bronchiseptica was compounded with oil adjuvant to make a component vaccine (CFAV). In the immunization trial in mice, the offsprings whose mothers were immunized with CFAV escaped from death when challenged intrapleurally with virulent strain of B. bronchiseptica. The protective indices (difference of LD50 dose of the challenge strain between immunized and control groups) of the offsprings from CFAV-immunized mothers were over 3.0 in common logarithm value. Moreover, about 90% of the offsprings from CFAV-immunized mothers were negative in nasal turbinate atrophy, while over 80% of them from non-immunized mothers showed obvious turbinate atrophy when challenged intranasally with virulent strain. On the one hand, remarkable differences in the number of bacteria recovered from nostrils were observed between both test groups. It was concluded that CFAV is a very effective vaccine against B. bronchiseptica infection in animals. 相似文献
The aim of this study was to develop a new experimental model of Chlamydophila pneumoniae infection in the hamster. Intraperitoneal injection of C. pneumoniae purified elementary bodies (EBs) in the hamsters caused a systemic infection, since it was possible to isolate viable chlamydiae from several organs up to 14 days after infection. In particular, spleen infection was detectable up to 7 days post infection in 100% of animals. In contrast, cultures of the organs obtained from intranasally infected animals were far less frequently positive. Systemic infection probably occurred via macrophages, as demonstrated by the presence of intracellular chlamydial inclusions in peritoneal macrophages of peritoneally inoculated animals four days after infection. Furthermore, by infecting LLC-MK2 cells with supernatant preparations obtained from these macrophages, it was possible to observe the development of chlamydial intra-cytoplasmic inclusions after 96 h. Immunization of 18 hamsters with heat-inactivated purified EBs completely protected 16 animals and substantially reduced infection levels in the remaining two. Sera obtained from immunized hamsters prior to challenge reacted mainly against two C. pneumoniae proteins of about 60 kDa, when tested by immunoblot. 相似文献
The randomness of dopant atom distributions in cuprate high-critical temperature superconductors has long been suspected to cause nanoscale electronic disorder. In the superconductor Bi2Sr2CaCu2O8+delta, we identified populations of atomic-scale impurity states whose spatial densities follow closely those of the oxygen dopant atoms. We found that the impurity-state locations are strongly correlated with all manifestations of the nanoscale electronic disorder. This disorder occurs via an unanticipated mechanism exhibiting high-energy spectral weight shifts, with associated strong superconducting coherence peak suppression but very weak scattering of low-energy quasi-particles. 相似文献
