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Specific mechanisms of precipitation change due to global climate variability on plant communities in coastal salt marsh ecosystems remain unknown. Hence, a field manipulative precipitation experiment was established in 2014 and 5 years of field surveys of vegetation from 2017 to 2021 to explore the effects of precipitation changes on plant community composition. The results showed that changes in plant community composition were driven by dominant species, and that the dominance of key species changed significantly with precipitation gradient and time, and that these changes ultimately altered plant community traits (i.e., community density, height, and species richness). Community height increased but community density decreased with more precipitation averaged five years. Furthermore, changes in precipitation altered dominant species composition and functional groups mainly by influencing soil salinity. Salinity stress caused by decreased precipitation shifted species composition from a dominance of taller perennials and grasses to dwarf annuals and forbs, while the species richness decreased. Conversely, soil desalination caused by increased precipitation increased species richness, especially increasing in the dominance of grasses and perennials. Specifically, Apocynaceae became dominance from rare while Amaranthaceae decreased in response to increased precipitation, but Poaceae was always in a position of dominance. Meanwhile, the dominance of grasses and perennials has the cumulative effect of years and their proportion increased under the increased 60% of ambient precipitation throughout the years. However, the annual forb Suaeda glauca was gradually losing its dominance or even becoming extinct over years. Our study highlights that the differences in plant salinity tolerance are key to the effects of precipitation changes on plant communities in coastal salt marsh. These findings aim to provide a theoretical basis for predicting vegetation dynamics and developing ecological management strategies to adapt to future precipitation changes.
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The inefficient nitrogen removal in constructed wetlands (CWs) can be attributed to insufficient carbon sources for low carbon-to-nitrogen (C/N) ratio wastewater. In this study, sugarcane bagasse fermentation liquid (SBFL) was used as a supplemental carbon source in intermittently aerated CWs to enhance nitrogen removal. The impact of different regulated influent C/N ratios on nitrogen removal and greenhouse gas (GHG) emissions was investigated. Results demonstrated that SBFL addition significantly enhanced the denitrification capacity, resulting in faster NO3--N removal compared to sucrose. Moreover, intermittently aerated CWs significantly improved NH4+-N removal efficiency compared to non-aerated CWs. The highest total nitrogen removal efficiency (98.3 %) was achieved at an influent C/N ratio of 5 in intermittently aerated CWs with SBFL addition. The addition of SBFL resulted in a reduction of N2O emissions by 17.8 %-43.7 % compared to sucrose. All CWs exhibited low CH4 emissions, with SBFL addition (0.035-0.066 mg·m-2h-1) resulting in lower emissions compared to sucrose. Additionally, higher abundance of denitrification (nirK, nirS and nosZ) genes as well as more abundant denitrifying bacteria were shown in CWs of SBFL inputs. The results of this study provide a feasible strategy for applying SBFL as a carbon source to improve nitrogen removal efficiency and mitigate GHG emissions in CWs.
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Carbono , Desnitrificación , Fermentación , Nitrógeno , Eliminación de Residuos Líquidos , Aguas Residuales , Humedales , Nitrógeno/metabolismo , Aguas Residuales/química , Eliminación de Residuos Líquidos/métodos , Purificación del Agua/métodos , SaccharumRESUMEN
Sugarcane bagasse was recycled to produce fermentation liquid (FL) as a supplementary carbon source that was added to constructed wetlands (CWs) for regulating influent carbon to nitrogen ratio (C/N), and then being applied to investigate nitrogen transformations and greenhouse gas emissions. Results showed that this FL achieved faster NO3--N removal and lower N2O fluxes than sucrose did, and the lowest N2O flux (67.6 µg m-2h-1) was achieved when FL was added to CWs in a C/N of 3. In contrast, CH4 emissions were higher by the FL addition than by the sucrose addition, although the fluxes under both additions were in a lower range of 0.06-0.17 mg m-2h-1. The utilization of FL also induced significant variations in microbial communities and increased the abundance of denitrification genes. Results showed the application of FL from sugarcane bagasse can be an effective strategy for improving nitrogen removal and mitigating N2O emissions in CWs.
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Carbono , Celulosa , Fermentación , Nitrógeno , Óxido Nitroso , Saccharum , Aguas Residuales , Humedales , Saccharum/química , Saccharum/metabolismo , Óxido Nitroso/metabolismo , Celulosa/metabolismo , Aguas Residuales/química , Purificación del Agua/métodos , Metano/metabolismo , DesnitrificaciónRESUMEN
Constructed wetlands (CWs) have been used to enhance pollutant removal by filling several types of material as substrates. However, research on substrate filling order remains still limited, particularly regarding the effects of greenhouse gas (GHG) emissions. In this study, six CWs were constructed using zeolite and ferriccarbon micro-electrolysis (Fe-C) fillers to evaluate the effect of changing the filling order and ratio on pollutant removal, GHGs emissions, and associated microbial structure. The results showed that the order of substrate filling significantly impacted pollutant removal performance on CWs. Specifically, CWs filled with zeolite in the top layer exhibited superior NH4+-N removal compared to those filled in the lower layer. Moreover, the highest NH4+-N removal (95.0 % ± 1.9 %) was observed in CWs with a zeolite to Fe-C volume ratio of 8:2 (CWZe-1). Moreover, zeolite-filled at the top had lower GHGs emissions, with the lowest CH4 (0.22 ± 0.10 mg m-2 h-1) and N2O (167.03 ± 61.40 µg m-2 h-1) fluxes in the CWZe-1. In addition, it is worth noting that N2O is the major contributor to integrated global warming potential (GWP) in the six CWs, accounting for 81.7 %-90.8 %. The upper layer of CWs filled with zeolite exhibited higher abundances of nirK, nirS and nosZ genes. The order in which the substrate was filled affected the microbial community structure and the upper layer of CWs filled with zeolite had higher relative abundance of nitrifying genera (Nitrobacter, Nitrosomonas) and denitrifying genera (Zoogloea, Denitratisoma). Additionally, N2O emission was reduced by approximately 41.2 %-64.4 % when the location of the aeration of the CWs was changed from the bottom to the middle. This study showed that both the order of filling the substrate and the aeration position significantly affected the GHGs emissions from CWs, and that CWs had lower GHGs emissions when zeolites were filled in the upper layer and the aeration position was in the middle.
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Contaminantes Atmosféricos , Metano , Óxido Nitroso , Eliminación de Residuos Líquidos , Humedales , Metano/análisis , Óxido Nitroso/análisis , Eliminación de Residuos Líquidos/métodos , Contaminantes Atmosféricos/análisis , Zeolitas/química , Gases de Efecto Invernadero/análisisRESUMEN
To address the adjustment of the Chinese agricultural industry and to better promote the development of Chinese household biogas, this article summarizes and analyzes the spatial distribution characteristics and influencing factors of the type and number of biogas digesters, biogas production, biogas fermentation materials, and methods of fermentation residue utilization and ecological agriculture with household biogas by compiling a dataset covering 31 provincial administrative regions in China. The results show that hydraulic biogas digesters are distributed mainly in northwestern and northeastern China; in addition, continuously stirred biogas digesters and bottom-discharging biogas digesters are distributed mainly in southern and northern China, respectively. Because of temperature and population, the Sichuan and Henan Provinces have the highest number of biogas digesters and biogas production. The type of biogas fermentation materials depends on the local raw materials. Biogas slurry and residue are widely used as fertilizers; furthermore, biogas slurry is used for seed soaking in northeastern and southern China, and biogas residue is used as feed in central southern and northern China. The "Three-in-one" and "Four-in-one" biogas ecological models are used mostly in southern and northern China, respectively, and both are mainly affected by temperature. Finally, we propose various problems and countermeasures to enhance the development of the household biogas industry in China. Our findings are critical for China's policymakers to adopt effective measures for promoting the development of cleaner energy and the layout of the agricultural industry.
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Biocombustibles , Composición Familiar , Biocombustibles/análisis , China , Fermentación , Agricultura/métodosRESUMEN
Lack of carbon source is the main limiting factor in the denitrification of low C/N ratio wastewater in the constructed wetlands (CWs). Agricultural waste has been considered as a supplementary carbon source but research is still limited. To solve this problem, ferric carbon (Fe-C) + zeolite, Fe-C + gravel, and gravel were used as substrates to build CWs in this experiment, aiming to investigate the effects of different carbon sources (rice straw, corncobs, alkali-heated corncobs) on nitrogen removal performance and microbial community structure in CWs for low C/N wastewater. The results demonstrated that the microbial community and effluent nitrogen concentration of CWs were mainly influenced by the carbon source rather than the substrate. Alkali-heated corncobs significantly enhanced the removal of NO2--N, NH4+-N, NO3-N, and TN. Carbon sources addition increased microbial diversity. Alkali-heated corncobs addition significantly increased the abundance of heterotrophic denitrifying bacteria (Proteobacteria and Bacteroidota). Furthermore, alkali-heated corncobs addition increased the copy number of nirS, nosZ, and nirK genes while greenhouse gas fluxes were lower than common corncobs. In summary, alkali-heated corncobs can be considered as an effective carbon source.
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Aguas Residuales , Zea mays , Desnitrificación , Humedales , Nitrógeno/análisis , Carbono/química , Eliminación de Residuos Líquidos/métodosRESUMEN
Constructed wetlands (CWs) are considered a widely used cost-effective technology for pollutant removal. However, greenhouse gas emissions are a non-negligible problem in CWs. In this study, four laboratory-scale CWs were established to evaluate the effects of gravel (CWB), hematite (CWFe), biochar (CWC), and hematite + biochar (CWFe-C) as substrates on pollutants removal, greenhouse gas emissions, and associated microbial characteristics. The results showed that the biochar-amended CWs (CWC and CWFe-C) enhanced the removal efficiency of pollutants, with 92.53 % and 93.66 % of COD and 65.73 % and 64.41 % of TN removal, respectively. Both single and combined inputs of biochar and hematite significantly reduced CH4 and N2O fluxes, with the lowest average of CH4 flux obtained in CWC (5.99 ± 0.78 mg CH4 m-2 h-1) and the least N2O flux in CWFe-C (287.57 ± 44.84 µg N2O m-2 h-1). The substantial reduction of global warming potentials (GWP) was obtained in the applications of CWC (80.25 %) and CWFe-C (79.5 %) in biochar-amended CWs. The presence of biochar and hematite mitigated CH4 and N2O emissions by modifying microbial communities with higher ratios of pmoA/mcrA and nosZ genes abundances, as well as increasing the abundance of denitrifying bacteria (Dechloromona, Thauera and Azospira). This study demonstrated that biochar and the combined use of biochar and hematite could be the potential candidates as functional substrates for the efficient removal of pollutants and simultaneously reducing GWP emissions in the constructed wetlands.
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Gases de Efecto Invernadero , Humedales , Gases de Efecto Invernadero/análisis , Dióxido de Nitrógeno , Óxido Nitroso/análisis , Metano/análisisRESUMEN
ETHNOPHARMACOLOGICAL RELEVANCE: Ulcerative colitis (UC) has become a healthy burden worldwide due to its insidious onset and repetitive relapse, with a rather complex etiology, including inappropriate immune response, dysbiosis, genetic susceptibility, and unhealthy diets. The Wu-Shi-Cha (WSC) formula is a widely utilized drug to protect against gastrointestinal disorders. AIM OF THE STUDY: The study aspired to dissect the pertinent mechanisms of the WSC to treat UC. MATERIALS AND METHODS: Network pharmacology and weighted gene co-expression network analysis (WGCNA) were performed to predict the targets of WSC in the context of UC and colorectal cancer. Dextran sodium sulfate (DSS) was used to construct murine models of experimental colitis, and the WSC was given to colitis mice for 14 days. Feces and colon samples were subjected to 16S rRNA gene sequencing combined with liquid chromatography-mass spectrometry (LC-MS) and biochemical experiments, respectively. RESULTS: Network pharmacology analysis predicted that the WSC formula could orchestrate inflammation, infection, and tumorigenesis, and WGCNA based on The Cancer Genome Atlas (TCGA) database showed a potent anti-neoplastic effect of the WSC therapy for colorectal cancer. The WSC therapy rescued bursts of pro-inflammatory cytokines and colonic epithelial collapse in DSS-induced colitis mice. Moreover, the high dose of WSC treatment facilitated the alternative activation of peritoneal macrophages (Mφs) and these Mφs were conducive to the survival of intestinal stem cells (ISCs), and the disturbed homeostasis of gut microbiota was re-established after WSC treatment, as evidenced by the decreased colonization of pathological taxa in the fecal samples. CONCLUSION: The WSC formula suppresses inflammation and re-establishes the homeostasis of gut microbiota, thereby ameliorating colitis progression.
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Colitis Ulcerosa , Colitis , Neoplasias Colorrectales , Microbiota , Ratones , Animales , Colitis Ulcerosa/inducido químicamente , Colitis Ulcerosa/tratamiento farmacológico , Colitis Ulcerosa/patología , ARN Ribosómico 16S/genética , Colitis/inducido químicamente , Colitis/tratamiento farmacológico , Colitis/patología , Colon , Inflamación/patología , Homeostasis , Neoplasias Colorrectales/patología , Sulfato de Dextran/toxicidad , Modelos Animales de Enfermedad , Ratones Endogámicos C57BLRESUMEN
Colorectal cancer (CRC) is the most common cancer worldwide and develops due to a broad range of causative factors. Pingxiao (PX) formula and Xihuang (XH) formula are two commonly used drugs to treat CRC, especially as an alternative therapy for those patients who could not suffer surgery, chemotherapy, or immunotherapy, namely, elder or advanced CRC patients. However, the pertinent pharmacological mechanisms are still elusive. The investigation was designed to explain the pharmacological mechanisms of the PX formula. A murine model of CRC was established by injecting CT26.WT cells into the caecum of 4-week-old male Balb/c mice, following PX or XH treatment for 30 days. Network pharmacology analysis combined with weighted gene coexpression network analysis (WGCNA) predicted the pharmacological mechanisms and therapeutic value. High-throughput 16S rRNA sequencing determined the alterations in the gut microbiota communities. Western blotting, immunofluorescence, and flow cytometry examined the influence of PX on the tumor microenvironment (TME). Injection of CT26.WT-induced CRC in Balb/c mice was markedly attenuated by PX treatment. Compared with XH administration, PX exhibited a stronger antitumor effect, such as smaller tumor volume, lower interleukin 17 (IL-17), IL-6 and tumor necrosis factor-alpha (TNFα) serum levels, and higher interferon-gamma (IFN-γ) concentration. Network pharmacology analysis demonstrated that both PX and XH targets were enriched in cancers and inflammatory responses. RNA sequencing confirmed that PX treatment induced cancer cell apoptosis and inhibited inflammatory reactions within the tumor. Moreover, the PX formula considerably restored homeostasis of the gut microbiota, which was not observed in the XH group. PX targets, those associated with the survival probability of CRC patients, correlated with macrophage (Mφ) infiltration, which presented an independent risk factor for the CRC outcome. PX treatment promoted the transition of alternatively activated Mφs (M2 Mφs) to classically activated Mφs (M1 Mφs). Moreover, the peritoneal Mφs from the PX group inhibited the migration of CW26.WT cells, as evidenced by the wound healing experiment and transwell assay, which was consistent with the decreased expression of the vascular endothelial growth factor (VEGF). Furthermore, the coculturing system confirmed that PX-treated Mφs suppressed colorectal tumor-derived organoid proliferation. PX formula exhibits a potential antitumor effect against CRC by suppressing the colonization of pathological microorganisms, reshaping Mφ effector functions and hence inhibiting cancer cell proliferation.
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Leucine rich-repeat kinase 2 (LRRK2) has been considered a susceptibility gene for ulcerative colitis (UC), and its protein abundance was enhanced in the peripheral blood mononuclear cells (PBMCs) from UC cohorts as compared to healthy volunteers. In preclinical models of colitis, Lrrk2 deficiency ameliorated dextran sodium sulfate (DSS)-induced colitis progression, whereas the processes were aggravated by R1441C mutation. While intestinal macrophages (MФs) from Lrrk2 knock-out (Lrrk2-/-) mice exhibited a tendency to transit to alternatively activated MФs, R1441C MФs mutation facilitated the pro-inflammatory phenotype polarization, determined by RNA sequencing and qPCR. Moreover, we characterized their microbiota profiles and found that loss of Lrrk2 increased the bacterial richness and altered bacterial community structure, and this shift contributed to the alleviation of colitis development and progression. We proposed that Lrrk2 deficiency promotes M2 MФ transition and facilitates probiotics colonization, providing a protective role during colitis.
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Leucocitos Mononucleares , Ratones , AnimalesRESUMEN
Ulcerative colitis (UC) is a subtype of inflammatory bowel disease (IBD) and occurs mainly in the colon. The etiology of UC is rather complex and involves various pathological factors, including genetic susceptibility, dietary intakes, environment, and microbiota. In China, the Chang-Yan-Ning (CYN) formula has been utilized in the clinic to treat gastrointestinal disorders, but its pharmacological evidence remains elusive. The investigation was designed to explore the molecular and cellular mechanisms of CYN. Liquid Chromatography with tandem mass spectrometry (LC/MS) was performed to identify the key components in the formula; Network pharmacology analysis was executed to predict the potential targets of CYN; An experimental murine colitis model was established by utilizing 2% dextran sodium sulfate (DSS), and CYN was administered for 14 days. The pharmacological mechanism of the CYN formula was corroborated by in-vivo and in-vitro experiments, and high throughput techniques including metabolomics and 16S rRNA sequencing. Results: LC/MS identified the active components in the formula, and network pharmacology analysis predicted 37 hub genes that were involved in tumor necrosis factor (TNF), interleukin (IL)-17, hypoxia-inducible factor (HIF) signaling pathways. As evidenced by in-vivo experiments, DSS administration shortened the length of the colon and led to weight loss, with a compromised structure of epithelium, and the CYN formula reversed these pathological symptoms. Moreover, CYN suppressed the levels of pro-inflammatory cytokines, including IL-4, IL-1b, and TNFαin the serum, inhibited the protein abundance of IL17 and HIF-1αand increased PPARγ and CCL2 in the colon, and facilitated the alternative activation of peritoneal macrophages. While peritoneal macrophages of colitis mice enhanced reactive oxygen species (ROS) production in murine intestinal organoids, the ROS level remained stable co-cultured with the macrophages of CYN-treated mice. Furthermore, the decreased microbiota richness and diversity and the prevalence of pathogenic taxa in colitis mice were rescued after the CYN treatment. The altered metabolic profile during colitis was also restored after the therapy. We posit that the CYN therapy attenuates the development and progression of colitis by maintaining the homeostasis of immune responses and microbiota.
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Orai2 is a component of store-operated Calcium channels (SOCCs) and exerts a pivotal role in immunity. In intestinal macrophages (Mφs), Orai2 deficiency influenced linoleic acid (LA)-arachidonic acid (ARA) derivatives by regulating Pla2g6 and Alox5. 16S rRNA sequencing showed that deleting Orai2 facilitated the prevalence of Akkermansia muciniphila, and untargeted metabolomics confirmed the suppressed level of leukotriene A. Moreover, Orai2 deficiency ameliorated the progression of experimental murine colitis, as shown by attenuated structural collapse of colon and pro-inflammatory cytokine concentrations, and rescued dysbiosis. The administration of a Pla2g6 inhibitor (Bromoenol lactone) not only inhibited the relative abundance of A. muciniphila in the feces of Orai2 knockout (Orai2-/-) mice, but also abolished the increased activity of Calcium-released activated Calcium channel (CRAC) in Orai2-/- intestinal Mφs, corroborating the involvement of Pla2g6 in Orai2 signaling. In conclusion, Orai2 deficiency increases Pla2g6 and hence facilitating A. muciniphila colonization, which might be a potential strategy to combat colitis.
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Calcio , Colitis , Akkermansia , Animales , Ácido Araquidónico , Calcio/metabolismo , Canales de Calcio/genética , Colitis/genética , Citocinas , Fosfolipasas A2 Grupo VI , Leucotrieno A4 , Ácido Linoleico , Ratones , Proteína ORAI2/genética , ARN Ribosómico 16SRESUMEN
ETHNOPHARMACOLOGICAL RELEVANCE: Inflammatory bowel disease (IBD) is pathologically characterized by an immune response accommodative insufficiency and dysbiosis accompanied by persistent epithelial barrier dysfunction, and is divided into ulcerative colitis (UC) and Crohn's disease (CD). Its progression increases the susceptibility to colitis-associated cancer (CAC), as well as other complications. The Xiao-Jian-Zhong (XJZ) formula has a historical application in the clinic to combat gastrointestinal disorders. AIM OF THE STUDY: The investigation aimed to explore the molecular and cellular mechanisms of XJZ. MATERIALS AND METHODS: Dextran sodium sulfate (DSS) was diluted in drinking water and given to mice for a week to establish murine models of experimental colitis, and the XJZ solution was administered for two weeks. Network pharmacology analysis and weighted gene co-expression network analysis (WGCNA) were utilized to predict the therapeutic role of XJZ against UC and CAC. 16S rRNA sequencing and untargeted metabolomics were conducted utilizing murine feces to examine the changes in the microbiome profile. Biochemical experiments were conducted to confirm the predicted functions. RESULTS: XJZ treatment markedly attenuated DSS-induced experimental colitis progression, and the targets were enriched in inflammation, infection, and tumorigenesis, predicted by network pharmacology analysis. Based on The Cancer Genome Atlas (TCGA) database, the XJZ-targets were related to the survival probability in patients with colorectal cancer, underlying a potential therapeutic value in cancer intervention. Moreover, the XJZ therapy successfully rescued the decreased richness and diversity of microbiota, suppressed the potentially pathogenic phenotype of the gut microorganisms, and reversed the declined linoleic acid metabolism and increased cytochrome P450 activity in murine colitis models. Our in-vitro experiments confirmed that the XJZ treatment suppressed Caspase1-dependent pyroptosis and increased peroxisome proliferators-activated receptor-γ(PPAR-γ) expression in the colon, facilitated the alternative activation of macrophages (Mφs), inhibited tumor necrosis factor-α (TNFα)-induced reactive oxygen species (ROS) level in intestinal organoids (IOs), thereby favoring the mucosal healing. CONCLUSION: The XJZ formula is efficacious for colitis by a prompt resolution of inflammation and dysbiosis, and by re-establishing a microbiome profile that favors re-epithelization, and prevents carcinogenesis.
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Colitis Ulcerosa , Colitis , Animales , Colitis/inducido químicamente , Colitis Ulcerosa/inducido químicamente , Colitis Ulcerosa/tratamiento farmacológico , Colon/patología , Sulfato de Dextran , Modelos Animales de Enfermedad , Disbiosis/metabolismo , Inflamación/patología , Metabolómica , Ratones , Ratones Endogámicos C57BL , Farmacología en Red , ARN Ribosómico 16SRESUMEN
BACKGROUND: Ulcerative colitis (UC) is a type of inflammatory bowel disease (IBD) characterized by an overactive immune response and destruction of the colorectal epithelium with intricate pathological factors. Shenlingbaizhu (SLBZ) formula, included in the Chinese Pharmacopoeia 2020, has been widely utilized to treat UC. PURPOSE: The present study was designed to uncover the underlying molecular mechanisms of SLBZ formula against UC. METHODS: A murine model of experimental colitis was established by orally feeding 2% dextran sodium sulfate (DSS) to mice for 7 days, followed by SLBA treatment for the next 15 days. Network pharmacology analysis was performed to predict the pharmacological mechanisms. High-throughput 16S rRNA sequencing integrated with liquid chromatography-mass spectrometry (LC-MS) was conducted on mouse stool in order to determine alterations in the composition of the intestinal microbiota and metabolites. Western blotting, immunofluorescence, and flow cytometry were performed to examine the anti-inflammatory role of SLBZ. RESULTS: DSS treatment induced experimental colitis, and this induction was alleviated by SLBZ treatment, as evidenced by rescued pathological symptoms in the experimental colitis mouse groups. Network pharmacology analysis showed that SLBZ-target genes were enriched in pathogen-induced infectious and inflammatory pathways, as well as neoplastic processes. SLBZ administration also modulated the gut microbiota composition and metabolic profiles of experimental colitis mice and alleviated the progression of experimental colitis. We further showed via in-vitro experiments that SLBZ suppressed macrophage (Mφ) transition to pro-inflammatory phenotype (M1), rescued tumor necrosis factor-α (TNFα)-induced pyroptosis of intestinal organoids (IOs), and decreased the recruitment of Mφs by epithelial cells. CONCLUSION: SLBZ formula is an effective treatment for murine colitis and showed a stronger therapeutic capacity than melasazine. The pharmacological mechanisms of SLBZ involve the re-establishment of an anti-inflammatory milieu and healthy microbiome, which favors mucosal healing.
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Ammonia (NH3) volatilization is a major pathway of soil nitrogen loss in tropical farmland, causing many environmental issues. Biochar can improve soil quality and affect soil NH3 volatilization. However, little is known about the effects of tropical crop residue biochar on soil NH3 volatilization in tropical farmland. Therefore, a laboratory incubation study was conducted using four kinds of tropical crop residue biochar (pineapple straw (stem and leaves), banana straw, cassava straw and sugarcane bagasse pyrolyzed at 500 °C) with five addition rates (0.5%, 1%, 2%, 4%, and 6%) to evaluate their impact on NH3 volatilization from tropical latosols. The results showed that NH3 volatilization peaked twice under biochar application, once at 1-5 days and again at 12-16 days. The cumulative NH3 volatilization (0.14-0.47 mg kg-1) of the 20 biochar treatments was higher than that of the control (0.12 mg kg-1). With the increase in the biochar addition rate, the soil pH, soil organic matter (SOM), urease activity, nitrate nitrogen content (NO3--N), nitrification rate and cumulative NH3 volatilization increased gradually, and the 6% biochar treatment resulted in the highest NH3 volatilization loss (0.19-0.47 mg kg-1). The type of biochar is also a main factor affecting soil NH3 volatilization. The cumulative NH3 volatilization was the highest under pineapple straw biochar, as it was 19-43% higher than when the other three biochars were applied. However, sugarcane bagasse biochar had the lowest cumulative NH3 volatilization due to its low quartz, sylvite and calcite contents, lack of -OH hydroxyl groups and high adsorbability. NH3 volatilization was positively correlated with the soil pH, SOM, urease activity, NO3--N and nitrification rate. In conclusion, four tropical crop residue biochars can increase NH3 volatilization in tropical latosols, so reducing NH3 volatilization needs to be further considered in tropical crop residue biochar applications.