Type and quantity of organic amendments determine the amount of carbon stabilized in particle-size fractions of a semiarid degraded soil

A 9-month lab experiment was carried out with three different amendments (vine pruning wastes, PW; composted vine pruning wastes, cPW; and sewage sludge, SS) added at three different rates (90, 180, and 240 t ha^?1, dry weight) in order to test whether the type or the quantity of the amendments applied to a semiarid, degraded soil determined the C_org accumulation in its particle-size fractions (coarse sand, 200–2,000 µm; fine sand, 63–200 µm; silt, 2–63 µm; and clay, 0.1–2 µm). All amendments, independently of their C/N ratios, resulted in similar C_org content and accumulation in coarse sand and silt-sized fractions after 9 months. In the clay-sized fraction, enrichment in C_org produced the incorporation of particles from this particle-size fraction into the silt-sized fraction. Likewise, increasing the application rates of the amendments led to larger C_org contents into the particle-size fractions of all amended soils except for the clay-sized fraction. The application of SS resulted in lower basal respiration-to-C_org ratios in the clay-sized fraction than the application of PW and cPW, suggesting a higher protection of the C_org in the SS treatment. These results indicate that organic amendments from woody plants with C/N ratios higher than 30, such as PW, favor C_org accumulation in the fine sand-sized fractions. Furthermore, our findings suggest that the application rate of such amendments, rather than the C/N ratios and amendment origin (from sludge or woody plants), is the key factor for promoting C_org accumulation in the silt-sized fractions of semiarid degraded soils.     

Meteorological drought features in northern and northwestern parts of Mexico under different climate change scenarios

Meteorological drought has been an inevitable natural disaster throughout Mexican history and the northern and northwestern parts of Mexico(i.e., the studied area), where the mean annual precipitation(MAP) is less than 500 mm, have suffered even more from droughts in the past. The aim of this study was to conduct a meteorological drought analysis of the available MAP data(1950–2013) from 649 meteorological stations selected from the studied area and to predict the drought features under the different IPCC-prescribed climate change scenarios. To determine the long-term drought features, we collected 1×10~4 synthetic samples using the periodic autoregressive moving average(PARMA) model for each rainfall series. The simulations first consider the present prevailing precipitation conditions(i.e., the average from 1950 to 2013) and then the precipitation anomalies under IPCC-prescribed RCP 4.5 scenario and RCP 8.5 scenario. The results indicated that the climate changes under the prescribed scenarios would significantly increase the duration and intensity of droughts. The most severe impacts may occur in the central plateau and in the Baja California Peninsula. Thus, it will be necessary to establish adequate protective measures for the sustainable management of water resources in these regions.     

Treated Industrial Wastewater Effects on Chemical Constitution Maize Biomass,Physicochemical Soil Properties,and Economic Balance

Irrigation with treated wastewaters can improve nutrient levels and yield of crops planted on degraded soils. This study evaluated how irrigation with treated industrial wastewater affected biomass production and nutrition of maize plants and physio-chemical properties of a degraded soil. The experiment was conducted in a greenhouse using PVC columns. Treatments consisted of 8 treatments irrigated with clean water and increasing doses of N and P, and 8 treatments with 4 proportions of wastewater irrigation (25%, 50%, 75% and 100% v/v). In general, maize biomass did not differ between irrigation water sources. Differences were largely associated with N nutrition. We observed increases in concentrations of N, P, K, S, Mn, Na, Cu, and Zn in tissue of maize under irrigation with wastewater. The addition of treated wastewater increased the P and Na concentrations, and EC values in the soil without affecting clay dispersion in water. An associated economic analysis indicated that wastewater irrigation would not be economically feasible without including environmental benefits. In southern Brazil, the proportion of irrigation water that is wastewater should not exceed 50%.     

Structure-function relationship of vermicompost humic fractions for use in agriculture

Purpose

The use of humic substances (HS) in agriculture is beneficial and has positive environmental impacts. However, to optimize the use of HS possible links between their structural characteristics and bioactivity must be shown. The goal of this study is to evaluate the bioactivity of different humic fractions extracted from vermicompost (VC) in rice plants and to shed light to possible structure-function relationships.

Materials and methods

Humic-like fractions were obtained from cattle manure vermicompost processed by African nightcrawlers (Eudrilus eugeniae spp.). Humic-like acid fraction using only water as extractor (HLAw), HLA fraction extracted following the International Humic Substances Society (IHSS) recommended method, and the solid residue (humified residual (HR)) after extraction of HLA were characterized using complementary chemical, physic, and spectroscopic technics (elemental composition, UV-Vis and Fourier transform infrared spectroscopy (FTIR) spectroscopies, ¹³C-CP MAS NMR, and MEV). Biological activity of the three HS was conducted in growth chambers and measured in roots using WinRhizo Arabidopsis software. Principal component analysis (PCA) was used to find a grouping pattern between the structural variables evaluated and the obtained root parameters.

Results and discussion

Differences were found in elemental composition among HS with larger C/N ratio in HR than in HLA and HLAw. HLA and HLAw FTIR spectra showed carboxyl band at 1714.66 cm^?1 better resolved than in HR. Bands at 1642 cm^?1 (amide I) and 1510 cm^?1 (lignin), were better resolved in HLA. ¹³C-NMR showed the following order of aromaticity: HLA > HLAw > HR. For HLAw bioactivity, the structures C_Alkyl-H,R, C_C=O, and C_COO-H,R correlated with the number and growth of smaller root. The aromatic C_Ar-H,R, C_Ar-O,N, and aliphatic C_Alkyl-O,N, C_Alkyl-O, and C_Alkyl-di-O structures in HLA, correlated with larger roots growth. HR also stimulated root growth and development in rice plants.

Conclusions

Aliphatic and oxygenated structures in HLAw showed a relation with induction of initial root emissions, whereas the presence of aromatic compounds in HLA was related with root growth stimulation activity. Higher concentration of HLAw was necessary to produce an equivalent stimulus compared with HLA; it could indicate that, although both fractions showed similar types of structures in their composition, differences in the predominant structures may be determining different effects on the root.

     

Prebiotic,probiotic, and synbiotic in the diet of Nile tilapia post-larvae during the sex reversal phase

This study evaluated the use of the prebiotic Active-MOS® (mannanoligosaccharides—Biorigin®) and two probiotics: PAS-TR® (Bacillus subtilis and Bacillus cereus var. toyoi—Imeve®) and Bioplus 2BC® (1.6 × 10¹⁰ UFC g^?1 de Bacillus subtilis and 1.6 × 10¹⁰ UFC g^?1 Bacillus licheniformis—Christian Hansen®) tested separately and together, in the diet of Nile tilapia post-larvae during the sex reversal phase. The experiment was conducted in two stages: (i) a total of 2160 3-day-old post-larvae (PL) (10.39 ± 0.85 mm and 12.28 ± 3.15 mg) were used and distributed in 24 tanks of 40 L each (3.0 PL L^?1). Growth performance, chemical analysis of carcass, bacterial recovery, and histomorphometry of intestinal villi were evaluated; (ii) 240 tilapia (4.28 ± 0.19 cm and 1.19 ± 0.09 g) from the previous experiment were used and stocked at 10 PL per aquarium. The parameters evaluated were survival and relative protection level after bacterial challenge against Aeromonas hydrophila. Six treatments with four replications in a completely randomized design were used for both experimental stages. Additives in the diet of tilapia post-larvae did not determine significant differences in growth, survival, microbiological, or histomorphometric parameters in this study. Nevertheless, after the experimental infection, advantages on the use of the additives were observed in terms of higher relative protection levels (38.10%) and relative percent survival in fish receiving Active-MOS® + Bioplus 2BC®. Therefore, we recommend the use of synbiotic (Active-MOS® + Bioplus 2BC®) in the farming of Nile tilapia PL with recurrent outbreaks of bacterial diseases during the sex reversal phase.     

<Emphasis Type="Italic">Aloysia triphylla</Emphasis> in the zebrafish food: effects on physiology,behavior, and growth performance

Dietary supplements are commonly used by animals and humans and play key roles in diverse systems, such as the immune and reproductive systems, and in metabolism. Essential oils (EOs), which are natural substances, have potential for use in food supplementation; however, their effects on organisms remain to be elucidated. Here, we examine the effects of dietary Aloysia triphylla EO supplementation on zebrafish behavior, metabolism, stress response, and growth performance. We show that fish fed diets containing A. triphylla EO presented an anxiolytic response, with reduced exploratory activity and oxygen consumption; no changes were observed in neuroendocrine stress axis functioning and growth was not impaired. Taken together, these results suggest that the A. triphylla EO supplementation is a strong candidate for use in feed, since it ensures fish welfare (anxiolytic behavior) with decreased oxygen consumption. This makes it suitable for use in high-density production systems without causing damage to the neuroendocrine stress axis and without growth performance being impaired.     

Effect of Organic Acids on Physical-Mechanical and Antifungicidal Properties of Anchovy Protein Films

The use of active biodegradable films from renewable sources like anchovy, with the incorporation of organic acids, such as sorbic acid (SA) and benzoic acid (BA), is an alternative to decrease environmental pollution and minimize the development of fungi in foods. This study investigated the respective influences of SA and BA at 0, 0.50, 0.75, and 1.50% on the growth of Aspergillus flavus and Rhizopus oryzae and on Argentine anchovy protein film properties (L*, a*, b*, tensile strength, elongation at break, solubility in water, water vapor permeability, and Fourier transform infrared spectroscopy (FTIR)). Results showed that the incorporation of SA or BA at different levels significantly increased the water vapor permeability, water solubility, and elongation at break of the films, but decreased the tensile strength and L* parameter (p < 0.05). FTIR evidenced an interaction between the BA and Argentine protein isolate. Also, the influences of the SA or BA concentration on antifungal activity was observed. The greatest effectiveness was obtained for films containing SA against R. oryzae compared to BA film treatments. In conclusion, the Argentine anchovy protein films could retain their antifungal property by incorporation of these organic acids.     

Behaviour of recreational spearfishers and its impacts on corals

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Reproduction efficiency of the crayfish Procambarus acanthophorus in relation to size and diet

Reproductive efficiency of the largest individuals and a random group of broodstock of crayfish Procambarus acanthophorus was measured using two commercial shrimp feeds, Feed 1 (F1) broodstocks (40%/9% protein/lipids) and Feed 2 (F2) growth-out (35%/7% protein/lipids). An experimental design of four treatments with two replicates was used. Females were labeled with elastomers to determine the time between spawning and number of offspring per treatment. The number of ovigerous females in the largest individuals fed F2 (58) was significantly higher than ovigerous females in the control group fed F1 (30).The number of young crayfish per female produced in the largest individuals (173 ± 71.6) treatment was significantly higher than the crayfish produced in the control group (86.6 ± 42.6). The average interval between spawns, regardless of diet, in the largest females was 2.9 months and 2.6 months in control group females.