Search Results (26,284)

Restoring native plant species on degraded landscapes is challenging. Symbiotic partners in the plant rhizosphere can aid in nutrient acquisition, pathogen protection, stress tolerance, and many other processes. However, these microbes are often absent in altered landscapes and need to be re-integrated to improve restoration efforts. We evaluated, within a laboratory setting, the ability of commercial and indigenous rhizobia strains to form nodules on lupine species used for rangeland seedings in the Great Basin region of the Western United States and ascertained if these strains could be applied through a seed coating. We also evaluated if a compost amendment applied via seed coating could further enhance the performance of the rhizobia strains. Our analysis showed that successful nodulation could occur using commercial and wildland-collected indigenous strains through either a liquid culture applied to seedlings or as a dry seed coating. However, the number of root nodules and the presence of a pink color (indicating nitrogen fixation) were typically higher in the commercial product than in the indigenous strains. Compost did not improve nodulation or the performance of the nodules; however, this treatment alone improved shoot growth. Overall, these results suggest that commercial rhizobium may be more effective in improving plant growth, and future research with native rhizobia may want to consider identifying strains compatible with seed-coating delivery. Longer-term studies are now merited for assessing how the rhizobia strains evaluated in this study influence plant growth, particularly in a field setting. Full article

Expressway systems play a vital role in facilitating intercity travels for both passengers and freights, which are also a significant source of vehicle emissions within the transportation sector. This study investigates vehicle emissions from expressway systems using the COPERT model to develop multi-year emission inventories for different pollutants, covering the past and future trends from 2005 to 2030. Thereinto, an integrated SARIMA-SVR method is designed to portray the temporal variation of vehicle population, and the possible future trends of expressway vehicle emissions are predicted through policy scenario analysis. The Jiang–Zhe–Hu Region of China is taken as the case study to analyze emission control in expressway systems. The results indicate that (1) carbon monoxide (CO) and volatile organic compounds (VOCs) present a general upward trend primarily originating from passenger vehicles, while nitrogen oxides (NOx) and inhalable particles (PM) display a slowing upward trend with fluctuations mainly sourcing from freight vehicles; (2) vehicle population constraint is an effective emission control policy, but upgrading the medium- and long-haul transportation structure is necessary to meet the continuous growth of intercity trips. Expressway vehicle emission reduction effectiveness can be further enhanced by curtailing the update frequency of emission standards, along with the scrapping of high-emission vehicles. Full article

The aim of this study was to explore the connection between growth and feeding ecology and mercury (Hg) levels in Japanese anchovy (Engraulis japonicus). We measured the amounts of Hg and stable carbon and nitrogen isotopes in the muscle of 143 Japanese anchovy specimens obtained from the open seas of the Northwest Pacific Ocean (39°2′ N~42°30′ N, 154°02′ E~161°29′ E) between June and July 2021. The results showed that there were significant differences (p < 0.05) in the δ¹³C and δ¹⁵N values of Japanese anchovies across all body length groups. As individuals grew, δ¹³C tended to decrease first and then increase, and δ¹⁵N tended to gradually increase. The standard ellipse corrected area showed an increasing and subsequently decreasing pattern with growth. It reached its greatest value (0.80) in the 111–120 mm group. Compared to the body length group of 91–120 mm, the niche overlap decreased for the 121–140 mm group in Japanese anchovy. Hg levels increased gradually with body length. Linear regression models revealed a positive correlation between Hg levels and δ¹³C in fish. Hg levels increased gradually, while δ¹⁵N remained relatively constant in the 7–9‰ range. In our study, a distinct shift in diet was observed for Japanese anchovy with increasing body length, and the differences in diet among life stages could be responsible for the changes in Hg levels. Full article

Waste cooking oil is a common byproduct in the culinary industry, often posing disposal challenges. This study explores its conversion into the valuable bioplastic material, medium-chain-length polyhydroxyalkanoate (mcl-PHA), through microbial biosynthesis in controlled bioreactor conditions. Twenty-four bacterial isolates were obtained from oil-contaminated soil and waste materials in Mahd Ad-Dahab, Saudi Arabia. The best PHA-producing isolates were identified via 16S rDNA analysis as Neobacillus niacini and Metabacillus niabensis, with the sequences deposited in GenBank (accession numbers: PP346270 and PP346271). This study evaluated the effects of various carbon and nitrogen sources, as well as environmental factors, such as pH, temperature, and shaking speed, on the PHA production titer. Neobacillus niacini favored waste cooking oil and yeast extract, achieving a PHA production titer of 1.13 g/L, while Metabacillus niabensis preferred waste olive oil and urea, with a PHA production titer of 0.85 g/L. Both strains exhibited optimal growth at a neutral pH of 7, under optimal shaking -flask conditions. The bioreactor performance showed improved PHA production under controlled pH conditions, with a final titer of 9.75 g/L for Neobacillus niacini and 4.78 g/L for Metabacillus niabensis. Fourier transform infrared (FT-IR) spectroscopy and gas chromatography–mass spectrometry (GC-MS) confirmed the biosynthesized polymer as mcl-PHA. This research not only offers a sustainable method for transforming waste into valuable materials, but also provides insights into the optimal conditions for microbial PHA production, advancing environmental science and materials engineering. Full article

Sustainable nitrogen (N) fertilizer management practices in the Midwest U.S. strive to optimize crop production while minimizing N gas emission losses and nitrate-N (NO₃-N) losses in subsurface drainage water. A replicated site in upstate Missouri from 2018 to 2020 investigated the influence of different N fertilizer management practices on nutrient concentrations in drainage water, nitrous oxide (N₂O) emissions, and ammonia (NH₃) volatilization losses in a corn (Zea mays, 2018, 2020)–soybean (Glyince max, 2019) rotation. Four N treatments applied to corn included fall anhydrous ammonia with nitrapyrin (fall AA + NI), spring anhydrous ammonia (spring AA), top dressed SuperU and ESN as a 25:75% granular blend (TD urea), and non-treated control (NTC). All treatments were applied to subsurface-drained (SD) and non-drained (ND) replicated plots, except TD urea, which was only applied with SD. Across the years, NO₃-N concentration in subsurface drainage water was similar for fall AA + NI and spring AA treatments. The NO₃-N concentration in subsurface drainage water was statistically (p < 0.0001) lower with TD urea (9.1 mg L⁻¹) and NTC (8.9 mg L⁻¹) compared to fall AA + NI (14.6 mg L⁻¹) and spring AA (13.8 mg L⁻¹) in corn growing years. During corn years (2018 and 2020), cumulative N₂O emissions were significantly (p < 0.05) higher with spring AA compared to other fertilizer treatments with SD and ND. Reduced corn growth and plant N uptake in 2018 caused greater N₂O loss with TD urea and spring AA compared to the NTC and fall AA + NI in 2019. Cumulative NH₃ volatilization was ranked as TD urea > spring AA > fall AA + NI. Due to seasonal variability in soil moisture and temperature, gas losses were higher in 2018 compared to 2020. There were no environmental benefits to applying AA in the spring compared to AA + NI in the fall on claypan soils. Fall AA with a nitrification inhibitor is a viable alternative to spring AA, which maintains flexible N application timings for farmers. Full article

Excessive use of chemical fertilizer is a global concern. Arbuscular mycorrhizal fungi (AMF) are considered a potential solution due to their symbiotic association with crops. This study assessed AMF’s effects on maize yield, fertilizer efficiency, plant traits, and soil nutrients under different reduced-fertilizer regimes in medium–low fertility fields. We found that phosphorus supplementation after a 30% fertilizer reduction enhanced AMF’s positive impact on grain yield, increasing it by 3.47% with pure chemical fertilizers and 6.65% with mixed fertilizers. The AMF inoculation did not significantly affect the nitrogen and phosphorus fertilizer use efficiency, but significantly increased root colonization and soil mycelium density. Mixed fertilizer treatments with phosphorus supplementation after fertilizer reduction showed greater mycorrhizal effects on plant traits and soil nutrient contents compared to chemical fertilizer treatments. This study highlights that AMF inoculation, closely linked to fertilization regimes, can effectively reduce fertilizer use while sustaining or enhancing maize yields. Full article

Nitrogen application significantly affects microorganisms in agricultural ecosystems. However, it is still unclear how nitrogen application affects soil chemical properties and microbial communities in purple mudstone weathering products. In this study, a field soil column experiment was conducted in a typical purple soil area with four nitrogen fertilizer application gradients of 0 [CK], 280 [N1], 560 [N2], and 840 [N3] N kg ha⁻¹. Nitrogen addition decreased the bacterial chao1 value and increased the bacterial evenness index. For both α- and β-diversity, the effect of nitrogen addition on bacteria was much greater than that on fungi. Nitrogen addition significantly increased the relative abundance of Proteobacteria, Gemmatimonadetes, Bacteroidetes, and Ascomycota and decreased the relative abundance of Actinobacteria, Cyanobacteria, and Basidiomycota. Both pH and TC are the most important soil chemical properties influencing the bacterial and fungal communities. With the increases in the nitrogen application rate, the co-occurrence network complexity increased and then decreased. In summary, nitrogen fertilizer application could significantly change the soil chemical properties, microbial community diversity, composition, and co-occurrence network of purple mudstone weathering products. Among them, the N2 treatment (560 N kg∙ha⁻¹) can more effectively stimulate the soil nutrients, enhance microbial network complexity, and promote further weathering of purple mudstone. Full article

Proper nitrogen management in crops is crucial to ensure optimal growth and yield maximization. While hyperspectral imagery is often used for nitrogen status estimation in crops, it is not feasible for real-time applications due to the complexity and high cost associated with it. Much of the research utilizing RGB data for detecting nitrogen stress in plants relies on datasets obtained under laboratory settings, which limits its usability in practical applications. This study focuses on identifying nitrogen deficiency in maize crops using RGB imaging data from a publicly available dataset obtained under field conditions. We have proposed a custom-built vision transformer model for the classification of maize into three stress classes. Additionally, we have analyzed the performance of convolutional neural network models, including ResNet50, EfficientNetB0, InceptionV3, and DenseNet121, for nitrogen stress estimation. Our approach involves transfer learning with fine-tuning, adding layers tailored to our specific application. Our detailed analysis shows that while vision transformer models generalize well, they converge prematurely with a higher loss value, indicating the need for further optimization. In contrast, the fine-tuned CNN models classify the crop into stressed, non-stressed, and semi-stressed classes with higher accuracy, achieving a maximum accuracy of 97% with EfficientNetB0 as the base model. This makes our fine-tuned EfficientNetB0 model a suitable candidate for practical applications in nitrogen stress detection. Full article

Organic amendment and green manuring are two agricultural practices highly recommended to improve sustainability in agriculture since they show numerous beneficial effects on both soils and crops. The main aim of the present study was to evaluate the effect of both, specifically organic fraction municipal solid waste (OFMSW) compost and horse bean (Vicia faba L., cv minor) green manure, combined separately or together with a mineral fertilization using synthetic products and in comparison with a mineral fertilization alone (control), on a top-quality tobacco crop (dark fire-cured Kentucky) grown in the cultivation district of Central Italy (High Tiber Valley, Tuscany region) in 2020 and 2021. The following parameters were measured: (i) leaf emergence rate (LER, leaves day⁻¹); (ii) crop growth rate (CGR, kg dry biomass ha⁻¹ day⁻¹); (iii) root weight density (RWD, mg cm⁻³); (iv) yield of cured product (CLY, Mg ha⁻¹). Analytical determinations were carried out on soil, sampled at the 0–0.3 m depth (organic matter, %; total N, %; NO₃-N, mg kg⁻¹; C/N; P and K, mg kg⁻¹), and on plant biomass (total N, %; NO₃-N, kg ha⁻¹). Soil water retention measures were also made. Water productivity (WP, kg cured product m⁻³ gross crop evapotranspiration, ET_c gross), irrigation water use efficiency (IWUE, kg cured product m⁻³ seasonal irrigation volume) and N agronomic efficiency (NAE, kg cured product kg⁻¹ mineral N applied by synthetic fertilizers) were calculated. Both the applications of OFMSW compost and horse bean green manure increased soil content of organic matter and main nutrients (N, P and K), as well as C/N, when compared with control conditions. There was an increase in soil water content in C conditions over the entire soil matric potential interval (0.04 to 1.2 MPa) with a maximum value at 1.2 MPa in both years. Both practices appeared promising for tobacco cultivation and could help to better address the nitrogen needs of the crop during the season and reduce potential water pollution due to nitrates. Considering the amount of synthetic nitrogen fertilizer saved by using both organic soil amendment and green manuring, there should be fewer potential carbon emissions due to the production, transportation and field application of synthetic nitrogen fertilizers. Full article

Peat soils, when drained and transformed for different land uses, can release pollutants such as nitrate and phosphate into nearby water bodies and ecosystems through ditch networks. However, there have been limited studies to ascertain the extent and impact of these nutrient releases under various peatland use types. A total of fifty-four water samples were collected between October 2021 and January 2022 from five industrial cutaway bogs, twenty-five grasslands, and twenty-four forest plantations. The water samples were subsequently examined for nitrate–nitrogen and phosphate–phosphorus using the HACH DR890 colorimeter. This study showed that the nitrate–nitrogen concentration of the discharge water ranged from 6.9 mg/L from forestry to 10.52 mg/L from grassland. The phosphate–phosphorus concentration ranged from 0.43 mg/L from forestry to 0.78 mg/L from grassland. The nitrate–nitrogen and phosphate–phosphorus concentrations in the drainage channel exhibited by the grassland and the cutover did not differ significantly (p > 0.05). Upon comparing the results obtained with the established safety limits set by the European Union (EU) and World Health Organization (WHO), it was observed that phosphate–phosphorus and nitrite–nitrogen concentration in the surface water (specifically, discharge water) exceeded the permissible threshold concentrations in surface water. The nutrient pollution index revealed that the discharge water from the ditch networks across the studied peatland use type was highly polluted, with a trend following the order of grassland > cutover > forestry. These results are in line with the broader issue of excessive nutrient inputs in freshwater ecosystems, which can lead to eutrophication. This study promotes sustainable water resources and peatland management practices by determining nitrate–nitrogen and phosphate–phosphorus concentrations in discharge water from ditch networks associated with different peatland use types: grassland, forestry, and cutover. This research emphasizes the critical need for sustainable peatland management to improve water quality in the river basin districts under the Water Framework Directive. Full article

(1) The development of sweet potato storage roots is impacted by nitrogen (N) levels, with excessive nitrogen often impeding development. Starch synthesis enzymes such as sucrose synthase (SUS) and ADP-glucose pyrophosphorylase (AGPase) are pivotal in this context. Although the effects of excessive nitrogen on the formation of sweet potato storage roots are well documented, the specific responses of IbSUSs and IbAGPases have not been extensively reported on. (2) Pot experiments were conducted using the sweet potato cultivar “Pushu 32” at moderate (MN, 120 kg N ha⁻¹) and excessive nitrogen levels (EN, 240 kg N ha⁻¹). (3) Nine IbSUS and nine IbAGPase genes were categorized into three and two distinct subgroups based on phylogenetic analysis. Excessive nitrogen significantly (p < 0.05) suppressed the expression of IbAGPL1, IbAGPL2, IbAGPL4, IbAGPL5, IbAGPL6, IbAGPS1, and IbAGPS2 in fibrous roots and IbSUS2, IbSUS6, IbSUS7, IbSUS8, IbSUS9, IbAGPL2, and IbAGPL4 in storage roots, and then significantly (p < 0.05) decreased the SUS and AGPase activities and starch content of fibrous root and storage root, ultimately reducing the storage root formation of sweet potato. Excessive nitrogen extremely significantly (p < 0.01) enhanced the expression of IbAGPL3, which was strongly negatively correlated with the number and weight of storage roots per plant. (4) IbAGPL3 may be a key gene in the response to excessive nitrogen stress and modifying starch synthesis in sweet potato. Full article

Covalent cross-linked hydrogels based on chitosan and poly(maleic acid-alt-vinyl acetate) were prepared as spherical beads. The structural modifications of the beads during the preparation steps (dropping in liquid nitrogen and lyophilization, thermal treatment, washing with water, and treatment with NaOH) were monitored by FT-IR spectroscopy. The hydrogel beads have a porous inner structure, as shown by SEM microscopy; moreover, they are stable in acidic and basic pH due to the covalent crosslinking. The swelling degree is strongly influenced by the pH since the beads possess ionizable amine and carboxylic groups. The binding capacity for Cu²⁺ ions was examined in batch mode as a function of sorbent composition, pH, contact time, and the initial concentration of Cu²⁺. The kinetic data were well-fitted with the pseudo-second-order kinetic, while the sorption equilibrium data were better fitted with Langmuir and Sips isotherms. The maximum equilibrium sorption capacity was higher for the beads obtained with a 3:1 molar ratio between the maleic copolymer and chitosan (142.4 mg Cu²⁺ g⁻¹), compared with the beads obtained using a 1:1 molar ratio (103.7 mg Cu²⁺ g⁻¹). The beads show a high degree of reusability since no notable decrease in the sorption capacity was observed after five consecutive sorption/desorption cycles. Full article

Sea buckthorn leaves (SBT_LVs) form notable by-product during harvesting and post-harvest management of the berries. It is already known that sea buckthorn berries are important for their chemical composition and based on this, they occupy a wide field in nutrition. SBT_LVs also have a rich chemical composition, like the berries. The aim of this study was to describe these by-products in the context of protein and complex carbohydrates–dietary fiber fractions, including qualitative and quantitative composition of amino acids. Proximate composition, amino acids, nutritional values of the protein, and dietary fiber fractions of SBT_LVs of four cultivars (cvs.) Ascola, Habego, Hergo, and Leikora were assessed. SBT_LVs from different years of the study had statistically different levels of crude protein, ether extract, crude ash, and nitrogen-free extract (NFE), confirming that the quality of the raw material (leaves) can be significantly modified by habitat conditions. The largest fraction of dietary fiber was neutral detergent fiber (NDF), including the sum of hemicellulose, cellulose, and lignin, followed by the acid detergent fiber fraction (ADF), consisting of lignin and cellulose. The content of essential amino acids in SBT_LV protein was high. Overall, this study confirms that SBT_LVs hold promise as a valuable resource for use as a food ingredient, functional food, and dietary supplement for both humans and animals. Full article

By changing the physicochemical and biological properties of soil, erosion profoundly affects soil nitrogen levels, but knowledge about the erosion impact on soil nitrogen (N) dynamics is still rather incomplete. We compared soil N contents at the early stage of vegetation self-restoration in response to soil erosion thickness (0, 10, 20, 30 and 40 cm), by conducting a simulated erosion experiment on sloping arable land in the dry-hot valley of Yunnan Province, southwestern China. The results showed total nitrogen (TN), ammonium nitrogen (NH₄⁺-N) and nitrate nitrogen (NO₃⁻-N) contents reduced with increasing soil erosion thickness and decreased significantly at the soil erosion thickness of 10, 40 and 10 cm in the rainy season and 30, 10 and 10 cm in the dry season compared with 0 cm. Structural equation modeling (SEM) indicated that soil erosion thickness and seasonal variation were the important drivers of mineral nitrogen (NH₄⁺-N and NO₃⁻-N) content. Soil erosion thickness indirectly affected mineral nitrogen through negative on TN, carbon content and Diazotrophs (nifH genes). Dry–wet season change had an effect on mineral nitrogen mediated by arbuscular mycorrhizal fungi (AMF) and nifH genes. We also found AMF had a promotion to nifH genes in eroded soil, which can be expected to benefit nitrogen fixing. Our findings highlight the importance of considering soil erosion thickness and sampling time for nitrogen dynamics, in particular, the investigation of nitrogen limitation, in the early stage of vegetation self-restoration. Full article

This study investigated the antibacterial effects of S-nitroso-N-acetylcysteine (SNAC) and sodium nitrite (NaNO₂) against Escherichia coli and their application in beef sausages. Both SNAC and NaNO₂ demonstrated pH-responsive antibacterial activity, with SNAC showing greater efficacy than NaNO₂ (p < 0.05) at the same pH (3, 5, and 7). The reactive oxygen species (ROS) and reactive nitrogen species (RNS) induced in E. coli by SNAC were significantly higher than those induced by NaNO₂ (p < 0.05), and both ROS and RNS values increased as the pH decreased. In addition, a lower pH led to more pores on the E. coli cell surface and increased membrane permeability, resulting in a more pronounced inhibitory effect. When applied to a beef sausage, SNAC-treated sausages had significantly lower total colony counts and carbonyl content compared to NaNO₂-treated ones (p < 0.05). Consequently, SNAC shows great potential as a replacement for NaNO₂ in meat products. Full article