Maize grain production,plant nutrient concentration and soil chemical properties in response to different residue levels from two previous crops

ABSTRACT

The incorporation of previous crop residues in agricultural management benefits soil fertility, crop production, and environment. However, there is no enough information about maximum residue application level without negative effect over next crop yield. To evaluate maize (Zea mays L.) yield under short-time conservation management with incorporation and/or importation of different residue levels, a biannual rotation experiment was conducted in ash volcanic soil in south-central Chile. The experiment consisted of two previous crops, canola (Brassica napus L.) and bean (Phaseolus vulgaris L.), and four levels of residue incorporation (0%, 50%, 100%, and 200% of generated residue; from 0 to 21.4?Mg?ha^?1 for canola and from 0 to 19.0?Mg?ha^?1 for bean). Previous crop species and residue level affected some nutrients concentrations in grain and plant and some soil chemical properties, without effect in maize yield, which averaged 16.6?Mg?ha^?1. Bean residue increased Ca and reduced S in maize plant, increasing soil P, Ca, Mg and K (P?<?0.05). Maize grain Ca content was positively and proportionally affected by canola residue level and negatively and proportionally affected by bean residue level. All canola residue levels increased soil pH and Mg, but the highest level reduced soil S; soil P concentration increased proportionally with bean residue level. The highest bean residue level increased soil S. Different crop and levels of residue did not affect maize yield but did some plant nutrient concentration, and also affected some soil chemical properties.     

The Monitoring of Cr(III) and Cr(VI) in Natural Water and Synthetic Solutions: An Assessment of the Performance of the Dgt and Dpc Methods

The technique of diffusive gradients in thin films or diffusive gradient in thin films (DGT) has been used in this work for the in situ measurement of labile Cr(III) and Cr(VI) species. Direct measurement of Cr(VI) was also carried out in parallel with a field-based colourimetric technique based on the EPA 7196 diphenyl-carbohydrazide (DPC) method. The efficiency of the DGT and DPC methods were tested (a) in the laboratory, using synthetic solutions in the presence of realistic concentrations of Cr, humic substances (HS), and ethylenediaminetetraacetic acid (EDTA), and (b) in the field, in river water affected by effluents discharged by the tannery industry. The main advantage of the DGT method is that it allows the in situ separation of labile species of Cr(III) and Cr(VI), though there are still uncertainties about its performance in field conditions. The DPC method proved to be a fast, accurate, and relatively economical option for the field-based determination of Cr(VI). Sample acidification and ageing of unacidified samples from contaminated aquatic environments, produced significant errors in the determination of ‘dissolved’ Cr. The concentration of Cr(VI) determined by either the DGT or the DPC method exceeds recommended international guidelines.     

Mapping and modeling forest tree volume using forest inventory and airborne laser scanning

In this paper, we present a study on the efficiency of multi-return LIDAR (Light Detection Ranging) data in the estimation of forest stem volume over a multi-layered forest area in the Italian Alps. The goals of this paper are (1) to verify the usefulness of multi-return LIDAR data compared to single-return data in forest volume estimation and (2) to define the optimal resolution of a stem volume distribution raster map over the investigated area. To achieve these goals, raw data were segmented into a net, and different cell dimensions were investigated to maximize the relationship between the LIDAR data and the ground-truth information. Twenty predicting variables (e.g., mean height, coefficient of variation) have been extracted from multi-return LIDAR data, and a multiple linear regression analysis has been used for predicting tree stem volume. Experimental results found that the optimal resolutions of the net square cells were 40 m. The analysis indicated that in a mixed multi-layered forest, characterized by a complex vertical structure, the correct selection of the map spatial resolution and the inclusion of the secondary-return data were important factors for improving the effectiveness of the laser scanning approach in forest inventories. The experimental tests showed that the chosen model is effective for the estimation of stem volume over the analyzed area, providing good results on all the three considered validation methods.     

Ultrafast laser-driven microlens to focus and energy-select mega-electron volt protons

We present a technique for simultaneous focusing and energy selection of high-current, mega-electron volt proton beams with the use of radial, transient electric fields (10(7) to 10(10) volts per meter) triggered on the inner walls of a hollow microcylinder by an intense subpicosecond laser pulse. Because of the transient nature of the focusing fields, the proposed method allows selection of a desired range out of the spectrum of the polyenergetic proton beam. This technique addresses current drawbacks of laser-accelerated proton beams, such as their broad spectrum and divergence at the source.     

Ecological diversity of sediment rhizobacteria associated with Phragmites australis along a drainage canal in the Yellow River watershed

Journal of Soils and Sediments - Spatial distribution on a regional scale of the rhizobacterial communities of Phragmites australis stands was investigated along the Yellow River watershed, China....     

Effect of environmental factors on the fatty acid profiles and physicochemical composition of oysters (Crassostrea gasar) in Amazon estuarine farming

The objective of this study was to evaluate the effect of environmental factors on the fatty acid profiles and physicochemical composition of Crassostrea gasar cultured in two locations with differences in salinity and precipitation gradients. The study period was divided into four seasonal divisions—the rainy–dry transition period, the dry season, dry–rainy transition and the rainy season. The salinity, pH and temperature were measured at each site during specimen collection. A total of 712 oyster samples were used for fatty acid profiling and physicochemical analysis. Salinity and precipitation were the environmental parameters that influenced the fatty acid profile and physicochemical characteristics of oysters. C. gasar exhibited excellent values of n3 polyunsaturated fatty acids (DHA, EPA and eicosatrienoic), with a predominance of these acids during periods of higher precipitation. Variations in precipitation and salinity resulted in significant differences in oyster nutritional characteristics. Oysters grown in Amazonian estuaries can be considered nutritious throughout the year, with better conditions during the rainy season.     

Shrimp rearing in biofloc integrated with different mullet stocking densities

This work compared the effects of different densities of Mugil curema integrated in the rearing of Litopenaeus vannamei in a biofloc system on the yield and ecological performance of the system. For that, an experiment lasting 55 days was conducted. Four groups were evaluated as follows: (a) T0: shrimp reared without mullet, (b) T10: shrimp reared with 22 fish per tank, (c) T20: shrimp reared with 43 fish per tank, and (d) T30: shrimp reared with 65 fish per tank, each treatment with four replicates. The sludge:biomass ratio was higher in the T0 treatment, while the T10–T20 treatments were more efficient, producing more biomass and less sludge. The use of water was 17% more efficient in all treatments with mullet. Mullet survival was higher in the T10 and T20 treatments (mean: 84 ± 8%) than in the T30 (61 ± 5%) treatment. The fish final biomass and yield limits of the system were 0.37 kg and 3.7 kg/m³ respectively. Finally, there was no increase in the total nitrogen output of the system up to the T10 density. In conclusion, it is possible to integrate mullet up to 3.7 kg/m³, increasing the yield in 20% and decreasing water use.     

Spontaneous neoplasia in captive syngnathid species: A retrospective case series (2003–2014) and literature review

Syngnathidae (seahorses, pipefish and seadragons) are charismatic species commonly kept in commercial aquaria, but published literature on syngnathid diseases is limited and immunohistochemical techniques not routinely employed. A retrospective review of 2,541 syngnathid submissions received between March 2003 and October 2016 identified 18 neoplasms including germ cell tumours, exocrine pancreatic and intestinal carcinomas, chromatophoromas, and single cases of lymphoma, thyroid and renal carcinoma, swim bladder and pituitary adenoma. Big-bellied seahorses accounted for 19% of submissions, but 50% of neoplasms were diagnosed in this species. This study includes the first reported cases of germ cell tumours, chromatophoroma, thyroid carcinoma and pituitary adenoma in Syngnathidae and the first reports of neoplasia in pipefish species. Out of nine commercial antibodies trialled for immunohistochemical characterization of neoplastic tissue, only pan-cytokeratin proved cross-reactive. Electron microscopy was performed in four cases. Tumours should be considered as differential diagnosis in cases with buoyancy issues, debilitated or emaciated animals, and may predispose to secondary infections. This study highlights the value of histopathological disease surveillance for commercial aquarium settings.     

Assessing the potential of marine Natura 2000 sites to produce ecosystem‐wide effects in rocky reefs: A case study from Sardinia Island (Italy)

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Protein and lipid requirement for the growth and reproduction of the peppermint shrimp Lysmata wurdemanni

The effect of dietary protein and lipid level on growth and reproductive efficiency of the pepermint shrimp Lysmata wurdemanni was evaluated over a 90‐day period. The percentage of protein and lipid (%P/L) in the experimental diets varied as follows: 34/7, 34/8, 34/9, 37/7, 37/8, 37/9, 40/7, 40/8 and 40/9, and a commercial diet was used as control (35/7‐Silver Cup^®). Fifteen shrimps per treatment and three replicates were used. The number of moults, survival, and growth, number of ovigerous females as well as protein and carbon content of fertilized eggs were evaluated. The shrimps fed experimental diets 37/7 and 40/9 exhibited a survival of 100%, whilst the survival of shrimp fed diet 40/7 was 73%, without significant differences being observed among the treatment groups. The weight gained (g) by shrimps fed diets 37/9 and 40/8 was significantly greater than the control group. The greatest percentage of ovigerous females was observed in those fed 34/7 and 37/9 diets, and the lowest in the control group. The greatest content of protein/carbon in the eggs was found in females fed the 40/8 diet. The results indicated that a P/L relationship of 34/7% promote efficient growth; however, during the reproductive phase it is necessary to increase the P/L to 40/8% to improve the quality and viability of the eggs.