Chicken Manure Compost Research Articles

Unraveling the characteristics of microplastics in agricultural soils upon long-term organic fertilizer application: A comprehensive study using diversity indices

Microplastics negatively impact soil health and productivity. Organic fertilizers constitute significant contributors of microplastics in agricultural soils. Nevertheless, comprehensive data on the diversity of microplastics in long-term fertilized soils remain unavailable. In this study, we assessed the presence of microplastics in soils subjected to application of three different organic fertilizers (pig manure, chicken manure, and sludge composts) over 12 years, and evaluated the potential ecological risks posed by microplastic accumulation. The average microplastic abundance in soil was 368.88 ± 207.97 (range: 90–910) items/kg. Microplastic abundance differed among fertilization treatments, with substantial increases of 16.67%, 71.67%, and 61.43% upon low to high application of the three treatments, respectively. Overall, the microplastics predominantly comprised fibers (70.94%) and fragments (25.25%), of which a substantial proportion constituted light-colored microplastics (transparent and white). The size of microplastics was mainly concentrated in the 1–2 mm range (39.96%), with rayon, polypropylene, polyester, and polyethylene being identified as the major types. The risk assessment indices of the three treatments were 229.38, 257.64, and 175.89, respectively, and were all classified as level 4 (high risk). The microplastic diversity integrated index and principal component analysis revealed that microplastics were uniformly distributed throughout the 0–20 cm soil depth consequent to tillage activity. Together, these findings provide a comprehensive assessment of microplastic pollution in long-term fertilized soils and serve as a scientific basis for reducing microplastic contamination in agricultural soils.

Pollution characteristics of microplastics in greenhouse soil profiles with the long-term application of organic compost

Organic composts are significant sources of microplastic (MP) pollution in soils, and their input is much higher in greenhouse agriculture than open-field agriculture. However, how long-term compost application affects MPs pollution in greenhouse soil profiles remains unclear. This study examined MPs characteristics in chicken manure compost and earthworms, exploring the long-term impacts of compost application on MPs accumulation and vertical migration in 0–100 cm soil depth through a 15-year greenhouse experiment. Microplastics abundance was 3965 items kg−1 in compost, 191–248 items kg−1 in compost-amended soils, and 2.73–4.52 items individual−1 in earthworms from compost-amended soils; the latter two increased significantly with compost application and were significantly higher than unamended soils. Soil MPs accumulation from long-term compost amendment contributed 45.4% of the total. The proportion of MPs <2 mm in compost (49.7%) was less than in compost-amended soils (65.5%) and earthworms (65.4%). Microplastics size and abundance decreased with increasing soil depth. Microplastics polymer types and shapes in composts, compost-amended soils, and earthworms exhibited similarities, mainly including polyethylene and polypropylene fragments and fibers. Compost-derived MPs in soils exhibited complex weathering morphology and adhered to mineral colloids. Therefore, soil MPs originating from compost gradually weathered and degraded into smaller particles and migrated to deeper soil, maybe resulting in more serious ecological issues.

Metagenomics Analysis of the Impact of Protein-Degrading Functional Microbial Agents on Composting of Chicken Manure from Cereal Hulls

In this study, four highly efficient protein-degrading bacteria (Siccibactercolletis, Bacillus thuringiensis, Bacillus cereus, and Bacillus sp. (in: Firmicutes)) were screened from soil and fermentation beds and prepared into a mixed microbial agent in a ratio of 1:1:1:1. The effects of inoculation with protein-degrading functional bacteria on nitrogen transformation rate, microbial community, and functional genes during chicken manure–rice husk composting were studied. With the addition of functional agents, the nitrogen loss in chicken manure composting was reduced to 17.05%, and ammonia emissions were also reduced. Firmicutes, Proteobacteria, Bacteroidetes, Cocci, and Actinobacteria became the dominant bacterial communities, accounting for 85.41%~98.52% of the overall bacterial community in the compost; it promoted the growth of microorganisms such as Pseudogracilibacillus and Lachnospiraceae in the compost. Metagenomic analysis revealed that the addition of functional bacterial agents enhanced the expression of nitrogen fixation genes (nifK, nifH, and glnA) during the high-temperature phase, increased the diversity of bacteria associated with the nitrogen cycle in the compost, and improved the absorption and fixation of nitrogen source elements by microorganisms. Additionally, it strengthened the correlation between microbial communities, the composting environment, and functional genes. This study provides a theoretical basis for the efficient application of microbial agents and the reduction of pollution in chicken manure hull composting.

Dynamics of antibiotic resistance genes during manure composting: Reduction in herbivores manure and accumulation in carnivores

The elevated levels of antibiotic resistance genes (ARGs) in livestock manure represent a significant threat to both the environment and human health. Composting has been recognized as an effective strategy to mitigate the abundance of ARGs in manure. However, notable rebounds in ARGs abundance have been observed during this process. This study explored the changes in ARGs abundance and the underlying influencing factors during the composting of carnivore (chicken and pig) and herbivore (sheep and cow) manures, along with mushroom residues. The findings revealed that the total relative abundance of ARGs increased by 6.96 and 10.94 folds in chicken and pig manure composts, respectively, whereas it decreased by a remarkable 91.72% and 98.37% in sheep and cow manure composts. Nitrogen content emerged as the primary physicochemical factors governing the abundance of ARGs in chicken and pig manure composts. Conversely, carbon content played a pivotal role in determining ARGs abundance in chicken and pig manure composts. Furthermore, the presence of dominant hosts, such as Corynebacterium, Bacillus, and Clostridium, along with emerging bacteria like Thermobifida, Saccharomonospora, and Actinomadura, contributed significantly to the enrichment of total ARGs, including tetG, tetO, tetX, and sul2, in chicken and pig manure composts. The coexistence of these genes with mobile genetic elements and a plethora of host bacteria, coupled with their high abundance, renders them particularly high-risk ARGs. On the other hand, the observed decrease in the abundance of total ARGs in sheep and cow manure composts can be attributed to the decline in the population of host bacteria, specifically Atopostipes, Psychrobacter, and Corynebacterium. Collectively, these results provide crucial insights into the management of ARGs risks and offer essential theoretical support for enhancing the safe utilization of organic fertilizer in agriculture.

Insight into the Effects of Norfloxacin on Bacterial Community and Antibiotic Resistance Genes during Chicken Manure Composting

Insight into the Effects of Norfloxacin on Bacterial Community and Antibiotic Resistance Genes during Chicken Manure Composting

Dissolve organic matter of mature chicken compost contributes to the protection of microorganisms from the stress of heavy metals

Dissolved organic matter (DOM), as the most active component of manure and compost, can influence heavy metal forms and microbial community structure by changing the physicochemical properties of soils. This study employed DOM extracted from fresh chicken manure (FDOM) and mature compost (MDOM) and evaluated their impacts on the physicochemical properties, heavy metal forms, and microbial communities of chernozem and dark brown soil through UV-Vis, EEM-PARAFAC, and high-throughput sequencing. The results showed that all DOM treatments decreased soil pH except for the MDOM at 150 mg C/kg applied to chernozem (CLM). MDOM treatments were more favorable in increasing soil available phosphorus content and the degree of humification of soil DOM, and FDOM treatments were more favorable in increasing soil dissolved organic carbon content and decreasing the degree of humification of soil DOM. Except for CLM treatment, the other DOM treatments decreased the content of stable state Pb, increased the risk of Pb migration and biotoxicity, and FDOM treatments were more pronounced. In addition, DOM treatments decreased the Shannon diversity of two soils and the Chao1 index in chernozem. However, DOM at 300 mg C/kg could increase the abundance of soil eutrophic and heavy metals tolerant dominant phyla (Proteobacteria and Bacteroidota) as well as dominant genera (Sphingomonas, Lysobacter, and Arthrobacter). This study provides a comprehensive understanding of the risk of manure and compost application in heavy metals-polluted soils and its interaction with microorganisms.

Effects of some types of organic fertilisers on growth, yield and quality of Cucumis sativus L. grown in Vinh Phuc province under greenhouse conditions

The study was conducted to evaluate the effects of organic fertilisers on the growth, yield, and quality of the Khassib RZ F1 cucumber variety in Vinh Phuc. The one-factor experiment was arranged in a completely randomised block design with 3 replications, including 4 treatments (fertilise for 1 hectare) including: (1) Control: Use 100% inorganic fertiliser (150 kg N + 90 kg P2O5 + 150 kg K2O); (2) CT1: 25% inorganic fertiliser + 22.5 tons of composted chicken manure; (3) CT2: 25% inorganic fertiliser + 18 tons of vermicompost; (4) CT3: 25% inorganic fertiliser + 3750 kg of Que Lam 01 microbial organic fertiliser. The results showed that using earthworm organic fertiliser (CT2) had the highest actual yield. The fruiting rate in CT2 reached the highest at 68.55%, CT3 using Que Lam 01 microbial organic fertiliser had the lowest fruiting rate of 59.71%. CT2 achieved the highest number of fruits plant-1, 4.82 fruits plant-1. The actual yield was highest in CT2 (15.96 kg plot-1), and lowest in the control treatment (11.39 kg plot-1). The nitrate accumulated in cucumbers in all treatments was below the threshold. The vermicompost fertiliser treatment (CT2) also gave good quality indicators of cucumbers such as thick intestine and very crispy taste. From these results, CT2 treatment with 25% inorganic fertiliser and 18 tons of vermicompost is suitable for the growth, development, yield, and quality of the Khassib RZ F1 cucumber variety in Vinh Phuc province.

Influence of Compost Amendments on Soil and Human Gastrointestinal Bacterial Communities during a Single Gardening Season.

To measure associations between gardening with different compost amendments and the human gut microbiota composition, gardeners (n = 25) were provided with one of three types of compost: chicken manure (CM), dairy manure and plant material (DMP), or plant-based (P). Stool samples were collected before gardening (T1), after compost amendment (T2), and at peak garden harvest (T3). Compost and soil samples were collected. DNA was extracted, 16S rRNA libraries were established, and libraries were sequenced by Illumina MiSeq. Sequences were processed using mothur, and data were analyzed in R software version 4.2.2. Fast expectation-maximization microbial source tracking analysis was used to determine stool bacteria sources. At T2/T3, the gut microbiotas of P participants had the lowest Shannon alpha diversity, which was also the trend at T1. In stool from T2, Ruminococcus 1 were less abundant in the microbiotas of those using P compost as compared to those using CM or DMP. At T2, Prevotella 9 had the highest abundance in the microbiotas of those using CM compost. In participants who used CM compost to amend their gardening plots, a larger proportion of the human stool bacteria were sourced from CM compared to soil. Soil exposure through gardening was associated with a small but detectable change in the gardeners' gut microbiota composition. These results suggest that human interactions with soil through gardening could potentially impact health through alterations to the gut microbiota.

Soil Fertility and Bacterial Community Composition in Response to the Composting of Biochar-Amended Chicken Manure

Amidst the burgeoning expanse of the poultry sector, the escalation of chicken manure production has ensued, potentially exacerbating ecological contamination. However, the application of chicken manure is bound to transmute the habitat of edaphic microorganisms, precipitating an alteration in the soil’s microbial consortium. The composting of biochar-amended chicken manure and wood chips (biochar composting products, BCPs) was used to improve Chinese cabbage (Brassica campestris L.) production and regulate soil properties and bacterial community structure. On the 40th day of Chinese cabbage growth, soil and Chinese cabbage were collected for laboratory analysis. The effects of different proportions of BCPs (0, 1%, 3%, 5% and 7% biochar) on soil fertility, enzyme activity, the microbial community and the growth of Chinese cabbage were studied under facility conditions. The results showed that the growth performance and quality of Chinese cabbage were significantly increased with increasing BCP ratios. Soil fertility indicators including pH, AN, AP, AK and SOM were significantly increased, except for the pH value in the 1% BCP group. The activities of phosphatase, catalase and urease were increased for all groups of BCP treatment. The soil microbial community response was significantly different, and the application of 5% and 7% BCPs reduced the abundance, diversity and evenness of soil bacteria. Chinese cabbage growth performance was positively correlated with an increase in BCP supplemental levels in the range of 3–5%. Also, the abundance, diversity and uniformity of the soil microbial community were improved in the 3% BCP treatment group. Therefore, the dominant bacterial phyla were Bacteroidetes, Actinobacteriota, Gemmatimonadota, Myxococcota, Bdellovibrionota and Firmicutes, especially the Bradyrhizobium of Proteobacteria. BCP treatment reduced the degradation of soil organic matter. In addition, it also improved the relative abundance of sequences associated with improving soil fertility. Collectively, these findings offer insights for the re-evaluation of application management strategies for BCP organic fertilizers.

Regulation of nitrogen transformation and microbial community by inoculation during livestock manure composting.

This study examined the effects of three Bacillus strains and one Saccharomyces cerevisiae strain on nitrogen transformation and microbial communities in pig and chicken manure compost. The findings revealed that the use of compound microbial inoculants increased the compost temperature, accelerated moisture reduction, enhanced cellulase activity, and stimulated the accumulation of NH4 +-N, NO3 --N, and total nitrogen (TN), resulting in a 9% increase in TN content. The abundance of Firmicutes decreased by 3.95% at the maturation phase, while Actinobacteria and Bacteroidetes increased by 1.64% and 1.85%, respectively. Inoculation led to an increase in amoA, nxrA and nifH gene copy numbers, while simultaneously reducing the abundance of nirK, nosZ and nirS genes. It also resulted in an increase in functional enzyme levels, specifically nif and amo, with a corresponding decrease in nor. Clostridium, Phascolarctobacterium, Eubacterium and Faecalibacterium from the class Clostridium, which have a significant correlation with nifH and nxrA genes, suggest their likely crucial role in nitrogen retention and fixation. Inoculation aided in the removal of pathogenic bacteria and antibiotic resistance genes (ARGs) like fluoroquinolones, nucleosides and nitroimidazole. This study provides effective theoretical support for the mechanism of nitrogen retention and fixation, and for improving the quality of compost.

Potential of combined reactor and static composting applications for the removal of heavy metals and antibiotic resistance genes from chicken manure

Chicken manure (CM) can pose a serious threat to environmental and human health, and need to be managed properly. The compost can effectively treat CM. However, there is limited research on the heavy metals and antibiotic resistance genes (ARGs) during compost CM. In this study, the combined application of reactor and static composting (RSC) was used to produce organic fertilizer of CM (OCM), and heavy metals, ARGs and bacterial community structure was investigated. The results show that RSC could be used to produce OCM, and OCM meet the National organic fertilizer standard (NY/T525-2021). Compared to the initial CM, DTPA-Cu, DTPA-Zn, DTPA-Pb, DTPA-Cr, DTPA-Ni and DTPA-As in OCM decreased by 40.83%, 23.73%, 34.27%, 38.62%, 16.26%, and 43.35%, respectively. RSC decreased the relative abundance of ARGs in CM by 84.06%, while the relative abundance of sul1 and ermC increased. In addition, the relative abundance and diversity of ARGs were mainly influenced by the bacterial community, with Actinobacteria, Firmicutes, and Proteobacteria becoming the dominant phyla during composting, and probably being the main carriers and dispersers of most of the ARGs. Network analyses confirmed that Gracilibacillus, Lactobacillus, Nocardiopsis, Mesorhizobium and Salinicoccus were the main potential hosts of ARGs, with the main potential hosts of sul1 and ermC being Mesorhizobium and Salinicoccus. The passivation and physicochemical properties of heavy metals contribute to the removal of ARGs, with sul1 and ermC being affected by the toal heavy metals. Application of RSC allows CM to produce mature, safe organic fertilizer after 32 d and reduces the risk of rebound from ARGs, but the issues of sul1 and ermC gene removal cannot be ignored.

The biotic effects of lignite on humic acid components conversion during chicken manure composting

Targeted regulation of composting to convert organic matter into humic acid (HA) holds significant importance in compost quality. Owing to its low carbon content, chicken manure compost often requires carbon supplements to promote the humification progress. The addition of lignite can increase HA content through biotic pathways, however, its structure was not explored. The Parallel factor analysis revealed that lignite can significantly increase the complexity of highly humified components. The lignite addition improved phenol oxidase activity, particularly laccase, during the thermophilic and cooling phases. The abundance and transformation functions of core bacteria also indicated that lignite addition can influence the activity of microbial transformation of HA components. The structural equation model further confirmed that lignite addition had a direct and indirect impact on enhancing the complexity of HA components through core bacteria and phenol oxidase. Therefore, lignite addition can improve HA structure complexity during composting through biotic pathways.

Dynamics of microbial functional guilds involved in the humification process during aerobic composting of chicken manure on an industrial scale.

Proper composting treatment of poultry manure waste is recommended before its use as a fertilizer. This involves many bioprocesses driven by microorganisms. Therefore, it is important to understand microbial mechanisms behind these bioprocesses in manure composting systems. Many efforts have been made to study the microbial community structure and diversity in these systems using high-throughput sequencing techniques. However, the dynamics of microbial interaction and functionality, especially for key microbial functional guilds, are not yet fully understood. To address these knowledge gaps, we collected samples from a 150-day industrial chicken manure composting system and performed the microbial network analysis based on the sequencing data. We found that the family Bacillaceae and genus Bacillus might play important roles in organic matter biodegradation at the mesophilic/thermophilic phases. Genera Virgibacillus, Gracilibacillus, Nocardiopsis, Novibacillus, and Bacillaceae_BM62 were identified as the key ones for humic acid synthesis at the mature phases. These findings improve our understanding about the fundamental mechanisms behind manure composting and can aid the development of microbial agents to promote manure composting performance.

POTENTIAL OF COMPOST EXTRACT ON PHYSICO-CHEMICAL PROPERTIES OF SOIL AFTER HARVEST

In an attempt to improve soil physico-chemical properties for subsequent production of crop, the potential of compost extract was investigated along with effect of its processing parameters on some soil physico-chemical properties after harvest. This compost extract (liquid organic fertilizer) was produced from composted chicken manure under three processing parameters. The parameters are compost/water ratio (1:6, 1:4, and 1:3), immersion period (24, 48 and 72 h) and water temperature (25, 35 and 45˚C). The application of compost extract made was applied to the soil by means of an improvised drip irrigation system to produced two vegetables (A. cruentus and C. argentea) via pot experiment in a greenhouse. The soil physico-chemical properties were analyzed before planting and after harvest using standard methods. The result showed an improvement in the soil physico-chemical properties after harvest. The study shows that processing parameters under different compost/water ratio, immersion period and water temperature significantly affected soil physico-chemical properties. The highest physico-chemical properties of pH (6.53 and 6.59), EC (2.42 and 2.47 mS cm-1), TN (1.68 and 1.79%), TP (7.24 and 7.34 g kg-1) and TK (7.49 and 7.73 g kg-1) were observed for A. cruentus and C. argentea soils, correspondingly after harvest. These were obtained for 1:3 compost/water ratio at 72 h immersion period under water temperature of 25˚C. Hence, compost extract produced was found to be suitable for improvement of soil physico-chemical properties even for subsequent production of vegetable in another planting seasons without any additional soil amendment.

Remediation of neonicotinoid-contaminated soils using peanut shell biochar and composted chicken manure: Transformation mechanisms of geochemical fractions

Soil remediation techniques are promising approaches to relieve the adverse environmental impacts in soils caused by neonicotinoids application. This study systematically investigated the remediation mechanisms for peanut shell biochar (PSB) and composted chicken manure (CCM) on neonicotinoid-contaminated soils from the perspective of transformation of geochemical fractions by combining a 3-step sequential extraction procedure and non-steady state model. The neonicotinoid geochemical fractions were divided into labile, moderate-adsorbed, stable-adsorbed, bound, and degradable fractions. The PSB and CCM addition stimulated the neonicotinoid transformation in soils from labile fraction to moderate-adsorbed and stable-adsorbed fractions. Compared with unamended soils, the labile fractions decreased from 47.6% ± 11.8% of the initial concentrations to 12.1 ± 9.3% in PSB-amended soils, and 7.1 ± 4.9% in PSB and CCM-amended soils, while the proportions of moderate-adsorbed and stable-adsorbed fractions correspondingly increased by 1.8–2.4 times and 2.3–4.8 times, respectively. A small proportion (<4.8%) in bound fractions suggested there were rather limited bound-residues after 48 days incubation. The PSB stimulated the -NO2-containing neonicotinoid-degraders, which promoted the degradable fractions of corresponding neonicotinoids by 8.2 ± 6.3%. Degradable fraction of neonicotinoids was the dominant fate in soils, which accounted for 58.3 ± 16.7%. The findings made beneficial theoretical supplements and provided valuable empirical evidence for the remediation of neonicotinoid-contaminated soils.

Effect of feed type on biology and nutritional indices of black soldier fly, Hermetia illucens L. (Diptera: Stratiomyidae)

Hermetia illucens L. (Black Soldier Fly) larvae are used as a source of high protein for animal feed, in cultivation they must produce larvae with fast growth and development in large numbers as well as imago with a high reproductive rate. The success factor from the type of feed given, because it can affect the growth and development of the larvae. The research to find a better type of feed for the growth and development of larvae. The research conducted from March 2022 to February 2023 at the Pesticide and Environmental Toxicology Laboratory, Department of Plant Pests and Diseases, Faculty of Agriculture, Universitas Padjadjaran. The experiment used a completely randomized design with 4 treatments and 5 replications. The treatment used grain bran feed, rice bran with kale, bran with banana stems, and bran with chicken manure compost. The results showed that the type of grain bran feed with chicken manure compost produced better scores on net reproduction rate (2210.85 females/mother/generation), intrinsic rate of increase (46.43%), population doubling (3.6 days), proportion of live individuals (0.84 individuals), number of eggs (528.8 eggs), average weight (6.534 g), consumption rate (0.0112 g/day), relative consumption rate (0.0104 g/day), growth rate (…0,0123 g/day..), relative growth rate (0,0115 g/g/day), digestibility (3.1940%), efficiency conversion of food consumed (2.0033%), and efficiency consumption of digested food (2,2029%) with increase respectively 4.58 times, 9.63 times, 4.61 times, 2.1 times, 2.27 times, 3.11 times, 2 times, 2.03 times, 1.14 times, 1.16 times, 2.88 times, 1.98 times, and 3.10 times compared to rice bran feed.

Different crystalline manganese dioxide and biochar co-conditioning aerobic composting: Reduced ammonia volatilization and improved organic fertilizer quality

Aerobic composting is a sustainable and effective waste disposal method. However, it can generate massive amounts of ammonia (NH3) via volatilization. Effectively reducing NH3 volatilization is vital for advancing aerobic composting and protecting the ecological environment. Herein, two crystal types of MnO2 (α-MnO2 and δ-MnO2) are combined with biochar (hydrochar (WHC) and pyrochar (WPC), respectively) and used as conditioners for the aerobic composting of chicken manure. Results reveal that α-MnO2 (34.6%) can more effectively reduce NH3 accumulation than δ-MnO2 (27.1%). Moreover, the combination of WHC and MnO2 better reduces NH3 volatilization (48.5–58.9%) than the combination of WPC and MnO2 (15.8–40.1%). The highest NH3 volatilization reduction effect (58.9%) is achieved using the combination of WHC and δ-MnO2. Because the added WHC and δ-MnO2 promote the humification of the compost, the humic acid to fulvic acid ratio (HA/FA ratio) dramatically increases. The combination of WHC and δ-MnO2 doubled the HA/FA ratio and resulted in a net economic benefit of 130.0 RMB/t. Therefore, WHC and δ-MnO2 co-conditioning can promote compost decomposition, improving the quality of organic fertilizers and substantially reducing NH3 volatilization.

Directing the Apple Rhizobiome toward Resiliency Post-Fumigation

Currently, there are no standard management practices to counteract the adverse effects of fumigation on the soil microbiome. In this study, a variety of pre-plant soil amendments were examined for their ability to recruit and maintain apple rhizosphere microbiomes that are suppressive to pathogen re-infestation of fumigated orchard soils. The capacity of these amendments to improve other characteristics of soil productivity was also evaluated. Results suggest that composted chicken manure and liquid chitin are likely to be detrimental to plant and soil health when used as a post-fumigation soil amendment. In comparison, insect frass (IF) resulted in a significant increase in tree trunk diameter relative to the fumigated control. Following pathogen re-infestation of fumigated soil, however, IF induced a significant increase in Pythium ultimum in the rhizosphere. Therefore, IF can benefit the growth of young apple trees in fumigated soil but may stimulate pathogen activity upon re-infestation. To date, the possibility of using soil amendments to suppress pathogen re-infestation of fumigated soils has not been tested. Results from this study ground support the use of soil amendments as an intervention strategy for “steering” the soil and rhizosphere microbiome in more beneficial and/or prophylactic directions following fumigation.

Contribution of zeolite to nitrogen retention in chicken manure and straw compost: Reduction of NH3 and N2O emissions and increase of nitrate

Co-composting of chicken manure, straw and zeolite was investigated in a water bath heating system to estimate the effect of zeolite on physicochemical properties and metabolic functions related to nitrogen conversion. The results indicated that NH3 catches by zeolite was concentrated in the early stage and zeolite with 10 % addition reduced 28 % NH3 and 55 % N2O emissions as compost ended. The nitrate content in 10 % zeolite group was 17 % higher than that in control group. There was no significant increase of NO2− in zeolite group. More NO2− formed NH3, rather than being converted to NOx through denitrification. The abundance of nitrification genes amoA and hao increased except nxrA in zeolite groups. Denitrification was the most obvious at 20 d and zeolite decreased the abundance of denitrification genes narG, nirK and nosZ at this time.

Comparing bacterial dynamics for the conversion of organics and humus components during manure composting from different sources.

The study aimed to compare the differences in organic fractions transformation, humus components and bacterial community dynamics during manure composting from different sources, and to identify the key biotic and abiotic factors driving the humification process. Five types of manure [pig manure (PM), cow dung (CD), sheep manure (SM), chicken manure (CM), and duck manure (DM)] were used as raw materials for 30 days composting. The results showed the obvious difference of organic fractions decomposition with more cellulose degradation in CD and SM composting and more hemicellulose degradation in PM and CM composting. Composting of PM and CD contained significantly higher humus fractions than the other composts. Fluorescence spectra indicated that SM composting tended to form structurally stable humic acid fractions, while CM and DM tended to form structurally complex fulvic acid fractions. Pearson correlation analysis showed that humification process of composts in category A (PM, CD) with higher humification degree than category B (SM, CM, and DM) was positively correlated with lignin and hemicellulose degradation. Bioinformatics analysis found that Lysinibacillus promoted the degradation of hemicellulose and the conversion of fulvic to humic acid in the composts of category A, and in category B, Thermobifida, Lactobacillus, and Ureibacillus were key genera for humic acid formation. Network analysis indicated that bacterial interaction patterns had obvious differences in composting with different humus and humification levels.