Impact of residual antibiotics on microbial decomposition of livestock manures in Eutric Regosol: Implications for sustainable nutrient recycling and soil carbon sequestration.

The land application of livestock manure has been widely acknowledged as a beneficial approach for nutrient recycling and environmental protection. However, the impact of residual antibiotics, a common contaminant of manure, on the degradation of organic compounds and nutrient release in Eutric Regosol is not well understood. Here, we studied, how oxytetracycline (OTC) and ciprofloxacin (CIP) affect the decomposition, microbial community structure, extracellular enzyme activities and nutrient release from cattle and pig manure using litterbag incubation experiments. Results showed that OTC and CIP greatly inhibited livestock manure decomposition, causing a decreased rate of carbon (28%-87%), nitrogen (15%-44%) and phosphorus (26%-43%) release. The relative abundance of gram-negative (G-) bacteria was reduced by 4.0%-13% while fungi increased by 7.0%-71% during a 28-day incubation period. Co-occurrence network analysis showed that antibiotic exposure disrupted microbial interactions, particularly among G- bacteria, G+ bacteria, and actinomycetes. These changes in microbial community structure and function resulted in decreased activity of urease, ß-1,4-N-acetyl-glucosaminidase, alkaline protease, chitinase, and catalase, causing reduced decomposition and nutrient release in cattle and pig manures. These findings advance our understanding of decomposition and nutrient recycling from manure-contaminated antibiotics, which will help facilitate sustainable agricultural production and soil carbon sequestration.

Estimation of methane greenhouse gas emissions from livestock in Egypt during 1989 to 2021.

This study investigates methane emissions from the livestock sector, representing by enteric fermentation and manure management, in Egypt from 1989 to 2021, focusing on spatial and temporal variations at the governorate level. Utilizing IPCC guidelines and emission factors, methane emissions were estimated for dairy and non-dairy cattle, buffalo, sheep and goat, poultry, and other livestock categories. Results reveal fluctuating emission patterns over the study period, with notable declines in certain governorates such as Kafr El-Sheikh and Red Sea, attributed to reductions in livestock populations. However, increasing trends were observed overall, driven by population growth in other regions. Hotspots of methane emissions were identified in delta governorates like Behera and Sharkia, as well as agriculturally rich regions including Menia and Suhag. While livestock populations varied between regions, factors such as water availability, climatic conditions, and farming practices influenced distribution. Notably, cluster analysis did not reveal regional clustering among governorates, suggesting emissions changes were not dependent on specific geographic or climatic boundaries. Manure management accounted for only 5-6% of total emissions, with emissions at their lowest in the last three years due to population declines. Despite the highest livestock populations being sheep and goats, emissions from enteric fermentation and manure management were highest from buffalo and cattle. This study underscores the importance of accurate data collection and adherence to IPCC recommendations for estimating GHG emissions, enabling the development of targeted mitigation strategies to address climate change challenges in the livestock sector.

Non-thermal technologies for broiler litter processing: Microbial safety, chemical composition, nutritional value, and fermentation parameters in vitro.

BACKGROUND: Annually, a massive amount of broiler litter (BL) is produced in the world, which causes soil and surface water pollution due to its high nitrogen content and microbial count. While ruminants can use this non-protein nitrogen (NPN) source for microbial protein synthesis. This issue becomes more critical when protein sources are unavailable or very expensive. One of the sources of NPN is BL which is produced at a considerable amount in the world yearly. OBJECTIVES: This aim of this research was to conduct a survey of non-thermal technologies such as electrocoagulation (EC), ultraviolet (UV) radiation, and ultrasound (US) waves on the microbial safety and nutritional value of BL samples as a protein source in ruminant diets. MATERIALS AND METHODS: The methodology of this study was based on the use of an EC device with 24 V for 60 min, UV-C light radiation (249 nm) for 1 and 10 min, and US waves with a frequency of 28 kHz for 5, 10 and 15 min to process BL samples compared with shade-dried samples. Chemical composition and nutritional values of processed samples were determined by gas production technique and measurement of fermentation parameters in vitro. RESULTS: Based on the results, microbial safety increased in the samples processed with the US (15 min). The EC method had the best performance in reducing the number of fungi and mould. However, none of the methods could remove total bacteria and fungi. Digestibility of BL was similar in shade-dried, EC, and US (10 min) treatments. In general, the use of EC and US15 without having adverse effects on gas production caused a decrease in the concentration of ammonia nitrogen. In contrast, it caused a decrease in neutral detergent fibre (NDF) in the investigated substrate. CONCLUSIONS: In general, it can be concluded that the use of US5 and EC methods without having a negative effect on the parameters of gas production and fermentation in vitro, while reducing NDF, causes a significant reduction in the microbial load, pathogens, yeast, and mould. Therefore, it is suggested to use these two methods to improve feed digestibility for other protein and feed sources.

Agronomic performance and technological quality of sugarcane submitted to different poultry litter dosages.

Sugarcane is a central crop for sugar and ethanol production. Investing in sustainable practices can enhance productivity, technological quality, mitigate impacts, and contribute to a cleaner energy future. Among the factors that help increase the productivity of sugarcane, the physical, chemical and biological parameters of the soil are amongst the most important. The use of poultry litter has been an important alternative for soil improvement, as it acts as a soil conditioner. Therefore, this work aimed to verify the best doses of poultry litter for the vegetative, reproductive and technological components of sugarcane. The experiment was carried out at Usina Denusa Destilaria Nova União S/A in the municipality of Jandaia, GO. The experimental design used was a complete randomized block design with four replications: 5 × 4, totaling 20 experimental units. The evaluated factor consisted of four doses of poultry litter plus the control (0 (control), 2, 4, 6 and 8 t ha-1). In this study, were evaluated the number of tillers, lower stem diameter, average stem diameter, upper stem diameter, plant height, stem weight and productivity. The technological variables of total recoverable sugar, recoverable sugar, Brix, fiber, purity and percentage of oligosaccharides were also evaluated. It was observed, within the conditions of this experiment, that the insertion of poultry litter did not interfere significantly in most biometric, productive and technological variables of the sugarcane. But it can also be inferred that there was a statistical trend toward better results when the sugarcane was cultivated with 4 t ha-1 of poultry litter.

National Greenhouse Gas Emission Reduction Potential from Adopting Anaerobic Digestion on Large-Scale Dairy Farms in the United States.

Waste-to-energy systems can provide a functional demonstration of the economic and environmental benefits of circularity, innovation, and reimagining existing systems. This study offers a robust quantification of the greenhouse gas (GHG) emission reduction potential of the adoption of anaerobic digestion (AD) technology on applicable large-scale dairy farms in the contiguous United States. GHG reduction estimates were developed through a robust life cycle modeling framework paired with sensitivity and uncertainty analyses. Twenty dairy configurations were modeled to capture important differences in housing and manure management practices, applicable AD technologies, regional climates, storage cleanout schedules, and methods of land application. Monte Carlo results for the 90% confidence interval illustrate the potential for AD adoption to reduce GHG emissions from the large-scale dairy industry by 2.45-3.52 MMT of CO2-eq per year considering biogas use only in renewable natural gas programs and as much as 4.53-6.46 MMT of CO2-eq per year with combined heat and power as an additional biogas use case. At the farm level, AD technology may reduce GHG emissions from manure management systems by 58.1-79.8% depending on the region. Discussion focuses on regional differences in GHG emissions from manure management strategies and the challenges and opportunities surrounding AD adoption.

The application of varying amount of green manure combined with nitrogen fertilizer altered the soil bacterial community and rice yield in karst paddy areas.

Long-term application of green manure (GM) and nitrogen (N) fertilizers markedly improved soil fertility and boosted rice yield in ecologically fragile karst paddy fields. However, the precise response mechanisms of the soil bacterial community to varying amounts of green manure alone and in combination with N fertilizer in such environments remain poorly elucidated. In this study, we investigated the soil bacterial communities, keystone taxa, and their relationship with soil environmental variables across eight fertilization treatments. These treatments included group without N addition (N0M0, no N fertilizer and no GM; N0M22.5, 22.5 t/ha GM; N0M45, 45 t/ha GM, N0M67.5, 67.5 t/ha GM) and group with N addition (NM0, N fertilizer and no GM; NM22.5, N fertilizer and 22.5 t/ha GM; NM45, N fertilizer and 45 t/ha GM; NM67.5, N fertilizer and 67.5 t/ha GM). The results revealed that increasing green manure input significantly boosted rice yield by 15.51-22.08% and 21.84-35% in both the group without and with N addition, respectively, compared to N0M0 treatment. Moreover, with escalating green manure input, soil TN, AN, AK, and AP showed an increasing trend in the group without N addition. However, following the addition of N fertilizer, TN and AN content initially rose, followed by a decline due to the enhanced nutrient availability for rice. Furthermore, the application of a large amount of N fertilizer decreased the C: N ratio in the soil, resulting in significant changes in both the soil microbial community and its function. Particularly noteworthy was the transition of keystone taxa from their original roles as N-fixing and carbon-degrading groups (oligotrophs) to roles in carbon degradation (copiotrophs), nitrification, and denitrification. This shift in soil community and function might serve as a primary factor contributing to enhanced nutrient utilization efficiency in rice, thus significantly promoting rice yield.

Impacts of poultry manure and biochar amendments on the nutrients in sweet potato leaves and the minerals in the storage roots.

Poultry manure (PM) has demonstrated its potential to enhance crop nutritional quality. Nevertheless, there remains a dearth of knowledge regarding its synergistic effects when combined with wood biochar (B) on the nutrient concentrations in sweet potato leaves (Ipomoea batatas L.) and the mineral content stored in sweet potato storage roots. Hence, a two-year field trial was undertaken during the 2019 and 2020 cropping seasons in southwestern Nigeria, spanning two locations (Owo-site A and Obasooto-site B), to jointly apply poultry manure and wood biochar as soil amendments aimed at enhancing the nutritional quality of sweet potato crop. Each year, the experiment involved different combinations of poultry manure at rates of 0, 5.0, and 10.0 t ha-1 and biochar at rates of 0, 10.0, 20.0, and 30.0 t ha-1, organized in a 3 × 4 factorial layout. The results of the present study demonstrated that the individual application of poultry manure (PM), biochar (B), or their combination had a significant positive impact on the nutrient composition of sweet potato leaves and minerals stored in the sweet potato storage roots, with notable synergistic effects between poultry manure and biochar (PM × B) in enhancing these parameters. This highlights the potential of biochar to enhance the efficiency of poultry manure utilization and improve nutrient utilization from poultry manure. The highest application rate of poultry manure at 10.0 t ha-1 and biochar at 30.0 t ha-1 (PM10 + B30), resulted in the highest leaf nutrient concentrations and mineral composition compared to other treatments at both sites. Averaged over two years, the highest application rate of poultry manure at 10.0 t ha-1 and biochar at 30.0 t ha-1 (PM10 + B30) significantly increased sweet potato leaf nutrient concentrations: nitrogen by 88.2%, phosphorus by 416.7%, potassium by 123.8%, calcium by 927.3%, and magnesium by 333.3%, compared to those in the control (PM0 + B0). The same treatment increased the concentration of sweet potato root storage minerals: phosphorus by 152.5%, potassium by 77.4%, calcium by 205.5%, magnesium by 294.6%, iron by 268.4%, zinc by 228.6%, and sodium by 433.3%, compared to the control. The highest application rate of poultry manure at 10.0 t ha-1 and biochar at 30.0 t ha-1 yielded the highest economic profitability in terms of gross margin (44,034 US$ ha-1), net return (30,038 US$ ha-1) and return rate or value-to-cost ratio (VCR) (263). The results suggested that the application of poultry manure at 10 t ha-1 and biochar at 30 t ha-1 is economically profitable in the study areas and under similar agroecological zones and soil conditions.

Effect of soil additives on biogeochemistry of ultramafic soils-an experimental approach with Brassica napus L.

Ultramafic soils are characterized by low productivity due to the deficiency of macroelements and high content of Ni, Cr, and Co. Incorporation of ultramafic soils for agricultural and food production involves the use of fertilizers. Therefore, this study aims to find the soil additive that decreases the metallic elements uptake by plant using Brassica napus as an example. In this study, we evaluate the effect of manure (0.5 g N/kg of soil), humic acids (1 g of Rosahumus/1 dm3 H2O; 44% C), KNO3 (0.13 g K/kg of soil), lime (12.5 g/kg of soil), (NH4)2SO4 (0.15 g N/kg of soil), and Ca(H2PO4)2) (0.07 g P/kg of soil) on the phytoavailability of metallic elements. The effect of soil additives on metallic elements uptake by Brassica napus was studied in a pot experiment executed in triplicates. Statistical analysis was applied to compare the effects of additives in ultramafic soil on plant chemical composition relative to control unfertilized ultramafic soil (one-way ANOVA and Kruskal-Wallis test). The study shows that in almost all treatments, metallic elements content (Ni, Cr, Co, Al, Fe, Mn) is higher in roots compared to the aboveground parts of Brassica napus except for (NH4)2SO4, in which the mechanism of Mn accumulation is opposite. The main differences between the treatments are observed for the buffer properties of soil and the accumulation of specific metals by studied plants. The soils with the addition of lime and manure have the highest buffer properties in acidic conditions (4.9-fold and 2.1-fold increase relative to control soil, respectively), whereas the soil with (NH4)2SO4 has the lowest effect (0.8-fold decrease relative to control soil). Also, the addition of manure increases the biomass of aboveground parts of B. napus (3.4-fold increase) and decreases the accumulation of Ni (0.6-fold decrease) compared to plants cultivated in the control soil. On the contrary, the addition of (NH4)2SO4 noticeably increases the accumulation of Ni, Co, Mn, and Al in aboveground parts of B. napus (3.2-fold, 18.2-fold, 11.2-fold, and 1.6-fold, respectively) compared to plant grown in control soil, whereas the humic acids increase the accumulation of Cr in roots (1.6-fold increase). Therefore, this study shows that manure is a promising fertilizer in agricultural practices in ultramafic soil, whereas (NH4)2SO4 and humic acids must not be used in ultramafic areas.

Surface water monitoring of chemicals associated with animal husbandry in an agricultural region in the Netherlands using passive sampling.

Compounds originating from animal husbandry can pollute surface water through the application of manure to soil. Typically, grab sampling is employed to detect these residues, which only provides information on the concentration at the time of sampling. To better understand the emission patterns of these compounds, we utilized passive samplers in surface water to collect data at eight locations in a Dutch agricultural region, during different time intervals. As a passive sampler, we chose the integrative-based Speedisk® hydrophilic DVB. In total, we targeted 46 compounds, among which 25 antibiotics, three hormones, nine antiparasitics, and nine disinfectants. From these 46 compounds, 22 compounds accumulated in passive samplers in amounts above the limit of quantification in at least one sampling location. Over the 12-week deployment period, a time integrative uptake pattern was identified in 53% of the examined cases, with the remaining 47% not displaying this behavior. The occurrences without this behavior were primarily associated with specific location, particularly the most upstream location, or specific compounds. Our findings suggest that the proposed use of passive samplers, when compared in this limited context to traditional grab sampling, may provide enhanced efficiency and potentially enable the detection of a wider array of compounds. In fact, a number of compounds originating from animal husbandry activities were quantified for the first time in Dutch surface waters, such as flubendazole, florfenicol, and tilmicosine. The set-up of the sampling campaign also allowed to distinguish between different pollution levels during sampling intervals on the same location. This aspect gains particular significance when considering the utilization of different compounds on various occasions, hence, it has the potential to strengthen ongoing monitoring and mitigation efforts.

Mitigation of ammonia and hydrogen sulfide emissions during aerobic composting of laying hen waste through NaOH-modified biochar.

The impact of NaOH-modified biochar on the release of NH3 and H2S from laying hens' manure was examined for 44 days, using a small-scale simulated aerobic composting system. The findings revealed that the NaOH-modified biochar reduced NH3 and H2S emissions by 40.63% and 77.78%, respectively, compared to the control group. Moreover, the emissions of H2S were significantly lower than those of the unmodified biochar group (p < 0.05). The increased specific surface area and microporous structure of the biochar, as well as the higher content of alkaline and oxygenated functional groups, were found to facilitate the adsorption of NH3 and H2S. This enhanced adsorption capability was the primary reason for the significant reduction in NH3 emissions. Furthermore, during the high-temperature phase of composting, there was a notable alteration in the microbial community. The abundance of Limnochordaceae, Savagea, and IMCC26207 increased significantly which aided in the conversion of H2S to stable sulfate. These microorganisms also influenced the abundance of functional genes involved in sulfur metabolism, thereby inhibiting cysteine synthesis, along with the decomposition and conversion of sulfate to sulfite. This led to a significant decrease in H2S emissions. This study provides valuable data for the selection of deodorizers in the composting process of egg-laying hens. The results have significant implications for the application of NaOH-modified biochar for odor reduction in aerobic composting processes.

Earthworms and lactic acid bacteria (LAB) cooperate to promote the biodegradation of tetracycline residues in livestock manure.

Tetracycline is an antibiotic with extensive veterinary use in the livestock industry. However, their widespread application poses risks to soil health as residue in livestock feces, and their removal is crucial for sustainable soil-ecosystem development. Physical and chemical approaches to extract tetracycline may have adverse effects on soil ecosystems, but no studies have thus far examined the potential for biological methods, such as collective degradation action of soil fauna. Thus, this study aimed to investigate the synergistic effects of lactic acid bacteria (LAB) and earthworms (Eisenia fetida) on biodegradation of tetracycline residues in sheep manure. We assessed earthworm biomass, tetracycline residue, and bacterial communities in both earthworm intestines and vermicompost. Earthworm biomass and tetracycline degradation efficiency increased significantly with LAB addition, with a degradation rate of up to 80.16%. This increase may be attributable to LAB acting as electron donors to spur tetracycline degradation. Additionally, we noted that tetracycline presence significantly influenced bacterial communities in earthworm intestines and vermicompost, elevating the abundance of potential pathogenic bacteria (e.g., Flavobacterium, Gammaproteobacteria, and Enterobacteriaceae). This finding suggests that heightened environmental stress from antibiotics could actually facilitate the growth of less prevalent bacteria, including potential pathogens. In conclusion, our study provides evidence supporting the effectiveness of LAB and earthworms in degrading tetracycline residues. In particular, LAB appears to mitigate stress from tetracycline exposure in earthworms, thus increasing their vermicomposting efficacy. Our work has important implications for soil management, with the potential to enhance pollution clean-up rates while minimizing negative side-effects to soil microbial communities.

Enhancing crop production and carbon sequestration of wheat in arid areas by green manure with reduced nitrogen fertilizer.

Green manure with appropriate amount of chemical nitrogen fertilizer can increase crop yield, but also aggravate soil carbon emissions. However, it is unclear whether incorporation of green manure into the cropping pattern with reduced nitrogen amount can alleviate this situation and enhance carbon sequestration potential. So, a field experiment with split-plot design was set up in 2018 of northwest China, and studied the effects of nitrogen reduction on crop productivity, carbon emissions, and carbon sequestration potential in 2021-2023. The main plots were two cropping patterns, including multiple cropped green manure after wheat harvest (W-G) and fallow after wheat harvest (W). Three nitrogen application levels formed the split-plots, including local conventional nitrogen amount (N3, 180 kg ha-1), nitrogen amount reduced by 15% (N2, 153 kg ha-1) and 30% (N3, 126 kg ha-1). The results showed that W-G increased grain yield of wheat and energy yield of wheat multiple cropped green manure pattern. The multiple cropped green manure after wheat harvest with local conventional nitrogen amount reduced by 15% (W-GN2) had the significant increasing-effect, and increased grain yield of wheat by 9.6% and increased total energy yields by 39.3% compared to fallow after wheat harvest with local conventional nitrogen amount (W-N3). Relative to W-N3, W-GN2 did not significantly increase carbon emissions of wheat season, and increased total carbon emissions of cropping pattern by 11.1%. Compared to multiple cropped green manure after wheat harvest with local conventional nitrogen amount (W-GN3), W-GN2 decreased carbon emissions by 5.8% in wheat season and decreased by 3.9% in the whole cropping pattern. Therefore, W-GN2 gained high carbon emission efficiency based on grain yield, and were 9.9% and 11.2% higher than W-N3 and W-GN3, respectively. In addition, W-GN2 enhanced soil total nitrogen, carbon, and organic carbon contents, compared with W-N3, thus increasing soil carbon sequestration potential index (net primary productivity/carbon emissions). We conclude that multiple cropped leguminous green manure after wheat harvest with local conventional nitrogen amount reduced by 15% can enhance crop productivity and carbon sequestration potential of farmland in arid areas.

Accumulation and translocation of lead in vegetables through intensive use of organic manure and mineral fertilizers with wastewater.

In many countries with wastewater irrigation and intensive use of fertilizers (minerals and organics), heavy metal deposition by crops is regarded as a major environmental concern. A study was conducted to determine the impact of mineral fertilizers, cow manure, poultry manure, leaf litter, and sugarcane bagasse on soil's trace Pb content and edible parts of vegetables. It also evaluated the risk of lead (Pb) contamination in water, soil, and food crops. Six vegetables (Daucus carota, Brassica oleracea, Pisum sativum, Solanum tuberosum, Raphanus sativus, and Spinacia oleracea) were grown in the field under twelve treatments with different nutrient and water inputs. The lead concentrations in soil, vegetables for all treatments and water samples ranged from 1.038-10.478, 0.09346-9.0639 mg/kg and 0.036-0.26448 mg/L, The concentration of lead in soil treated with wastewater in treatment (T6) and vegetable samples was significantly higher, exceeding the WHO's permitted limit. Mineral and organic fertilizers combined with wastewater treatment reduced lead (Pb) concentrations in vegetables compared to wastewater application without organic fertilizers. Health risk indexes for all treatments except wastewater treatment (T6) were less than one. Pb concentrations in mineral fertilizers, cow manure, poultry manure, leaf litter, and sugarcane bagasse treated were determined to pose no possible risk to consumers.

Multiomics analysis of the effects of manure-borne doxycycline combined with oversized fiber microplastics on pak choi growth and the risk of antibiotic resistance gene transmission.

In this study, oversized microplastics (OMPs) were intentionally introduced into soil containing manure-borne doxycycline (DOX). This strategic approach was used to systematically examine the effects of combined OMP and DOX pollution on the growth of pak choi, analyze alterations in soil environmental metabolites, and explore the potential migration of antibiotic resistance genes (ARGs). The results revealed a more pronounced impact of DOX than of OMPs. Slender-fiber OMPs (SF OMPs) had a more substantial influence on the growth of pak choi than did coarse-fiber OMPs (CF OMPs). Conversely, CF OMPs had a more significant effect on the migration of ARGs within the system. When DOX was combined with OMPs, the negative effects of DOX on pak choi growth were mitigated through the synthesis of indole through the adjustment of carbon metabolism and amino acid metabolism in pak choi roots. In this process, Pseudohongiellaceae and Xanthomonadaceae were key bacteria. During the migration of ARGs, the potential host bacterium Limnobacter should be considered. Additionally, the majority of potential host bacteria in the pak choi endophytic environment were associated with tetG. This study provides insights into the intricate interplay among DOX, OMPs, ARGs, plant growth, soil metabolism, and the microbiome.

Streambed immobilization controls the transport of antibiotic resistance genes in flowing water.

Antibiotic resistance is a serious global health issue, resulting in at least 1.2 million deaths in 2019. The environment is a potentially important reservoir of antibiotic resistance; however, the fate of Antibiotic Resistance Genes (ARGs) in the environment remains poorly characterized. One important environmental source of ARGs is manure used as a soil amendment. ARGs from manure may then enter nearby flowing waterbodies, where the factors governing their downstream transport remain unknown. To address this, we conducted experiments by spiking cattle manure in an artificial stream to estimate removal rates (k; m-1) for three ARGs (mefA, tetQ, and tetW) and a ruminant fecal marker (bacR). We then used a Stochastic Mobile-Immobile Model (SMIM) to separate the overall removal into two components, rs, and rh, corresponding to immobilizations in the surface (i.e., water column) and subsurface (i.e., streambed), respectively. Finally, we applied the SMIM across four model streams to predict the downstream travel distance of ARGs and bacR. Our results showed measurable removal for all targets in all experimental replicates (n = 3) and no differences were found in the removal rates among replicates for any target (ANCOVA; p > 0.05). We found that the removal of bacR was significantly lower than tetW (p < 0.05) and slightly lower than mefA (p = 0.088), while tetQ removal was slightly different from tetW's (p = 0.072). We also found that rh values were orders of magnitude larger than rs for ARGs and bacR (t-test; p < 0.05). These findings suggest that ARGs and bacR are being removed from the water column through immobilization reactions occurring in the streambed. Additionally, we predicted that the 90 % removal (or D90) of targets occurs within the first 500 m in all model streams except in a slow-flow pastoral stream, which required 1400 m of downstream transport for 90 % removal. Our findings and model stand out as promising tools to predict the fate of ARGs in streams and will contribute to improving and managing agricultural practices that employ animal manure.

[Effects of Fly Ash on the Efficiency and Bacterial Community Structure of Urban Multi-source Organic Solid Waste].

To achieve efficient resource utilization of fly ash and multi-source organic waste, a composting experiment was carried out to investigate the effects of fly ash on co-aerobic composting using kitchens, chicken manure, and sawdust (15:5:2). The effects of different application doses (5 % and 10 %, calculated in total wet weight of organic solid waste) of fly ash on physical and chemical properties, nutrient elements, and bacterial community structure during co-composting were evaluated. The results showed that the addition dose of 5 % and 10 % fly ash significantly increased the highest temperature (56.6 ℃ and 56.9 ℃) and extended the thermophilic period to nine days. Compared with that in the control, the total nutrient content of compost products in the treatments of 5 % FA and 10 % FA was increased by 4.09 % and 13.55 %, respectively. The bacterial community structure changed greatly throughout the composting, and the bacterial diversity of all treatments increased obviously. In the initial stage of composting, Proteobacteria was the dominant phylum of bacteria, with a relative abundance ranging from 35.26 % to 39.40 %. In the thermophilic period, Firmicutes dominated; its relative abundance peaked at 52.46 % in the 5 % FA treatment and 67.72 % in the 10 % FA treatment. Bacillus and Thermobifida were the predominant groups in the thermophilic period of composting. The relative abundance of Bacillus and Thermobifida in the 5 % FA and 10 % FA treatments were 33.41 % and 62.89 %(Bacillus) and 33.06 % and 12.23 %(Thermobifida), respectively. The results of the redundancy analysis (RDA) revealed that different physicochemical indicators had varying degrees of influence on bacteria, with organic matter, pH, available phosphorus, and available potassium being the main environmental factors influencing bacterial community structure. In summary, the addition of fly ash promoted the harmlessness and maturation of co- aerobic composting of urban multi-source organic waste, while optimizing microbial community structure and improving the quality and efficiency of composting.

[Effects of reductive soil disinfestation and organic fertilizer application on microbial community stability in a facility vegetable soil]. / 强还原处理和施用有机肥对设施蔬菜地土壤微生物群落稳定性的影响.

Reductive soil disinfestation (RSD) is an effective method for remediating degraded facility vegetable soils. However, the effectiveness of RSD using green manure as a carbon source in the field has not yet been clarified. We investigated the effects of RSD and organic fertilizer application on soil microbial community composition, diversity, and stability in a degraded facility vegetable soil. There were six treatments, including no fertilization (CK), no fertilization and soil flooded and mulched with plastic film (FF), soil amended with chicken manure (OM), soil amended with chicken manure and flooded and mulched with plastic film (OMR), soil amended with Sesbania cannabina (TF), and soil amended with S. cannabina and flooded and mulched with plastic film (TR). The results showed that the OMR and TR treatments significantly decreased bacterial Chao1 index, altered bacterial and fungal community structure, and increased the relative abundances of Bacillus, Rhodococcus, Clostridium, and Penicillium. The TR treatment significantly reduced the relative abundance of Fusarium. Results of redundancy analysis and Mantel test analysis suggested that soil ammonium nitrogen and dissolved organic carbon contents were the key factors influencing bacterial community composition, and soil pH was the key factor affecting fungal community composition. Results of cohesion analysis showed that the OMR and TR treatments significantly improved bacterial community stability, and that there was no difference between OMR and TR treatments. The TR treatment enhanced fungal community stability, which was significantly higher than the OMR treatment. Therefore, the RSD with green manure as carbon source could be effective remediation practice to improve soil health.

Co-pyrolysis of chicken manure with tree bark for reduced biochar toxicity and enhanced plant growth in Arabidopsis thaliana.

Co-pyrolysis of chicken manure with tree bark was investigated to mitigate salinity and potentially toxic element (PTE) concentrations of chicken manure-derived biochar. The effect of tree bark addition (0, 25, 50, 75 and 100 wt%) on the biochar composition, surface functional groups, PTEs and polycyclic aromatic hydrocarbons (PAH) concentration in the biochar was evaluated. Biochar-induced toxicity was assessed using an in-house plant growth assay with Arabidopsis thaliana. This study shows that PTE concentrations can be controlled through co-pyrolysis. More than 50 wt% of tree bark must be added to chicken manure to reduce the concentrations below the European Biochar Certificate-AGRO (EBC-AGRO) threshold. However, the amount of PAH does not show a trend with tree bark addition. Furthermore, co-pyrolysis biochar promotes plant growth at different application concentrations, whereas pure application of 100 wt% tree bark or chicken manure biochar results in decreased growth compared to the reference. In addition, increased plant stress was observed for 100 wt% chicken manure biochar. These data indicate that co-pyrolysis of chicken manure and tree bark produces EBC-AGRO-compliant biochar with the potential to stimulate plant growth. Further studies need to assess the effect of these biochars in long-term growth experiments.

Enhancing soil amendment for salt stress using pretreated rice straw and cellulolytic fungi.

Rice straw breakdown is sluggish, which makes agricultural waste management difficult, however pretreatment procedures and cellulolytic fungi can address this issue. Through ITS sequencing, Chaetomium globosum C1, Aspergillus sp. F2, and Ascomycota sp. SM2 were identified from diverse sources. Ascomycota sp. SM2 exhibited the highest carboxymethyl cellulase (CMCase) activity (0.86 IU/mL) and filter-paper cellulase (FPase) activity (1.054 FPU/mL), while Aspergillus sp. F2 showed the highest CMCase activity (0.185 IU/mL) after various pretreatments of rice straw. These fungi thrived across a wide pH range, with Ascomycota sp. SM2 from pH 4 to 9, Aspergillus sp. F2, and Chaetomium globosum C1 thriving in alkaline conditions (pH 9). FTIR spectroscopy revealed significant structural changes in rice straw after enzymatic hydrolysis and solid-state fermentation, indicating lignin, cellulose, and hemicellulose degradation. Soil amendments with pretreated rice straw, cow manure, biochar, and these fungi increased root growth and soil nutrient availability, even under severe salt stress (up to 9.3 dS/m). The study emphasizes the need for a better understanding of Ascomycota sp. degradation capabilities and proposes that using cellulolytic fungus and pretreatment rice straw into soil amendments could mitigate salt-related difficulties and improve nutrient availability in salty soils.

Dose-dependent effects of sodium dodecyl sulfate and hydrogen peroxide treatments on methane emission from pig manure during storage.

Mitigation of methane (CH4) emissions from slurry pits within pig barns can be achieved through treatment of residual slurry left after frequent flushing of the slurry pits. In this study, dosages of additives such as sodium dodecyl sulfate (SDS) and hydrogen peroxide (H2O2) were optimized to achieve reduction in CH4 emissions from residual pig slurry during storage. In addition, the effects on emissions when both the treatments were combined and the effects of SDS treatment on slurry acidified with sulfuric acid (H2SO4) were studied in order to reduce CH4 and ammonia (NH3) emissions from residual pig slurry storage. A maximum of 98% and 70% reduction in CH4 emissions were achieved with SDS and H2O2 treatments, respectively. The combination of SDS and H2O2 did not increase efficiency in reducing CH4 emissions compared to SDS treatment alone. Whereas the application of SDS to slurry acidified with H2SO4 (pH 6.2) increased the CH4 mitigation efficiency by 15-30% compared to treating slurry with only SDS. The combined treatment (SDS + H2SO4) reduced NH3 emissions by 20% compared to treating slurry with H2SO4 (pH 6.2) alone. Hereby, combined treatment (SDS + H2SO4) can reduce both CH4 and NH3 emissions, with a reduced amount of chemicals required for the treatment. Hence, application of SDS at concentrations <2 g kg-1 to acidified slurry is recommended to treat residual pig manure in pig barns.