Dissolved phosphorus composition of grassland leachates following application of dairy‐slurry size fractions

Appropriate management of P from slurry can increase crop production and decrease nutrient loss to water bodies. The present study examined how the application of different size fractions of dairy slurry influenced the quantity and composition of P leached from grassland in a temperate climate. Soil blocks were amended (day 0 = start of the experiment) with either whole slurry (WS), the > 425 μm fraction (coarse slurry fraction, CSF), the < 45 μm slurry fraction (fine liquid slurry fraction, FLF), or not amended, i.e., the control soil (CON). Deionized water was added to the soil blocks to simulate six sequential rainfall events, equivalent to 250 mm (day 0.2, 1.2, 4.2, 11.2) or 500 mm of rainfall (day 18.2 and 25.2), with leachates collected the following day. The results showed that total dissolved P (TDP), dissolved reactive P (DRP), dissolved unreactive P (DUP), orthophosphate, phosphomonoester, and pyrophosphate concentrations generally decreased with the increasing number of simulated rain events. Total dissolved P was leached in the following order WS > FLF ≈ CSF > CON. Dissolved organic C was correlated with TDP, DRP, and DUP in leachates of all treatments. The highest concentrations of dissolved phosphomonoesters and pyrophosphate (147 μg P L^–1 and 57 μg P L^–1, respectively) were detected using solution ³¹P‐NMR spectroscopy in the WS leachates. Overall, there were significant differences observed between slurry treatments (e.g., relative contributions of inorganic P vs. organic P of dissolved P in leachates). Differences were independent from the rate at which slurry P was applied, because the highest dissolved P losses per unit of slurry P applied were measured in the FLF, i.e., the treatment that received the smallest amount of P. We conclude that the specific particle‐size composition of applied slurry influences dissolved P losses from grassland systems. This information should be taken in account in farm‐management approaches which aim to minimizing dissolved slurry P losses from grassland systems.     

Soil organic matter evolution after the application of high doses of organic amendments in a Mediterranean calcareous soil

Purpose

We investigate the coevolution of soil organic matter (SOM) and soil properties in a semiarid Mediterranean agroecosystem, as well as the 1-year evolution of the different pools of soil organic and inorganic carbon and their influence on soil respiration after the application of a single high dose of three different organic amendments.

Material and methods

We applied a single high dose (160?Mg?ha^?1 in dry weight (DW)) of three types of organic amendments: aerobically digested sewage sludge (AE), anaerobically digested sewage sludge (AN), and municipal solid waste compost (MSWC), in a calcareous Mediterranean soil. The study area is located in the southeast of Madrid (Spain), characterized by a Mediterranean climate with a marked seasonal and daily contrast. We analyzed different forms of soil organic and inorganic carbon and soil respiration rates. The measurements have been performed quarterly for 1?year.

Results and discussion

The results showed that the coevolution of SOM and soil largely depends on the origin and composition of the organic amendments used. The AN sludge affected the soil chemistry more. The organic matter (OM) provided by AE treatments underwent more intense mineralization processes than AN, with the OM from MSWC being more stable. This behavior could be explained by the different pools of carbon involved in each case. The treatments contributed differently to soil respiration rates following the sequence: AE > AN > MSWC. The application of organic amendments in calcareous Mediterranean soils also modified the inorganic carbon pools.

Conclusions

SOM and soil coevolution after organic amendments application depends on the origin and chemical composition of the inputs. The decision-making process of urban organic waste application with regard to agricultural policy must take into account the different behavior in soil of the different types of amendments.     

Urea-montmorillonite-extruded nanocomposites: a novel slow-release material

The present study describes the preparation and characterization of a novel urea slow-release nanocomposite, based on urea intercalation into montmorillonite clay by an extrusion process at room temperature. Nanocomposites with urea contents ranging from 50 to 80 wt % were successfully produced and characterized. Analyses by XRD, DTA, and SEM-EDX confirmed the effectiveness of this simple process to exfoliate the clay lamellae into the urea matrix, forming a product that can be classified as a nanocomposite, due to the exfoliation degree attained. Diametral compression tests showed that the samples were very deformable, and the release rate of active components in water showed that the nanocomposite showed a slow release behavior for urea dissolution, even in low montmorillonite amounts (20% in weight).     

Limited efficacy of West Nile virus vaccines in large falcons (Falco spp.)

West Nile virus (WNV) can lead to fatal diseases in raptor species. Unfortunately, there is no vaccine which has been designed specifically for use in breeding stocks of falcons. Therefore the immunogenicity and protective capacity of two commercially available WNV vaccines, both approved for use in horses, were evaluated in large falcons. One vaccine contained adjuvanted inactivated WNV lineage 1 immunogens, while the second represented a canarypox recombinant live virus vector vaccine. The efficacy of different vaccination regimes for these two vaccines was assessed serologically and by challenging the falcons with a WNV strain of homologous lineage 1. Our studies show that the recombinant vaccine conveys a slightly better protection than the inactivated vaccine, but moderate (recombinant vaccine) or weak (inactivated vaccine) side effects were observed at the injection sites. Using the recommended 2-dose regimen, both vaccines elicited only sub-optimal antibody responses and gave only partial protection following WNV challenge. Better results were obtained for both vaccines after a third dose, i.e. alleviation of clinical signs, absence of fatalities and reduction of virus shedding and viraemia. Therefore the consequences of WNV infections in falcons can be clearly alleviated by vaccination, especially if the amended triple administration scheme is used, although side effects at the vaccination site must be accepted.     

Involving local people in the conservation of the critically endangered freshwater turtle Dermatemys mawii in southern Mexico

1. The Central American river turtle Dermatemys mawii is one of the most endangered species in the world, and continues to decline. In Mexico, this turtle is legally protected but, in the rural areas where it is found, local people are not aware of why it is important to conserve it.
2. This study confirmed that D. mawii inhabits lakes in southern Mexico, and that these areas are among the last refuges for this species inside and outside protected areas in the wild.
3. A lack of knowledge about its endangered status among local people means that a strategy of environmental education is needed.

     

The modulating effect of vitellogenin on the synthesis of 17β-estradiol by rainbow trout (Oncorhynchus mykiss) ovary

In vivo induction of vitellogenin (VTG) in response to the administration of 17-estradiol (E₂) was achieved and the protein was isolated by gel filtration column chromatography of plasma samples. Adult female trout were injected with the vitellogenic fraction every ten days from July to November and levels were measured by RIA from September to December. The results showed a significant decrease (p<0.01) in plasma E₂ levels in injected females compared with the controls. In December, after finishing the treatment, the plasma E₂ concentration increased, in injected females to reach a level similar to that of control females at vitellogenesis. The in vitro study showed that in early vitellogenic oocyte (from September) the presence of the vitellogenic fraction in the incubation medium causes a significant decrease (p<0.01) in the synthesis of E₂ by the oocytes. These data suggest that the concentration of the VTG into the oocyte can alter VTG production by the liver, moderating the production of E₂ by the ovary.     

A shot in the dark for conservation: Evidence of illegal commerce in endemic and threatened species of elasmobranch at a public fish market in southern Brazil

1. The illegal sale of endangered elasmobranchs has been recorded in a number of different Brazilian states, where sharks and rays are being marketed primarily as ‘cação’ or ‘viola’. Brazil is ranked among the top 10 nations worldwide that harvest most sharks, causing an immeasurable impact on the local elasmobranch populations.
2. The present study applied the DNA barcoding technique, based on the cytochrome C oxidase subunit I gene, for the molecular identification of the elasmobranch species sold as processed products under the generic names of ‘cação’, ‘mangona’, ‘azul’, ‘cambeva’, ‘fiuso’ and ‘lombo preto’, in the fish market of the city of Florianópolis, capital of the state of Santa Catarina, Brazil.
3. Nine elasmobranch species were identified in the 56 samples analysed, including six sharks and three rays, representing six families, the Carcharhinidae, Sphyrnidae, Squatinidae, Arhynchobatidae, Myliobatidae and Gymnuridae. Prionace glauca, identified in more than half (56%) of the samples analysed, is listed as Near Threatened by the International Union for the Conservation of Nature.
4. Six species identified in the present study, Sphyrna zygaena, Sphyrna lewini, Squatina guggenheim, Carcharhinus signatus, Gymnura altavela and Rioraja agassizii, are under some level of risk of extinction, while two others (Rhizoprionodon lalandii and Myliobatis goodei) are listed as Data Deficient.
5. Our results indicate that the commercial exploitation of endemic sharks and rays at risk of extinction is commonplace in southern Brazil. This reinforces the need for more systematic monitoring of the trade in fishery products and more effective application of the environmental legislation and conservation programmes.

     

Collection,ex situ conservation and characterization of mangaba (Hancornia speciose Gomes) germplasm in coastal lowland of Northeastern Brazil

Genetic Resources and Crop Evolution - This study aimed to evaluate the Mangaba Genebank of Embrapa Tabuleiros Costeiros, Brazil, since its implementation in 2006 and characterize the accessions in...