Heavy metals and potential health risk assessment of Lactuca sativa and Daucus carrota from soil treated with organic manures and chemical fertilizer.

The large-scale production of food crops with heavy application of chemical fertilizers in the effort to meet the astronomical increase in food demands may be counterproductive to the goal of food security. This study investigated the effect of different soil treatments on the levels of heavy metals (Cr, Cu, Fe, Ni, Pb, and Zn) in two types of vegetables Lactuca sativa (lettuce) and Daucus carrota (carrot). The potential carcinogenic and non-carcinogenic health risks from their consumption were also evaluated. Planting experiment was set up in a randomized block design, with different soil treatments of soil + cow dung (CD), soil + sewage sludge (SS), soil + chemical fertilizer (nitrogen-phosphorus-potassium (NPK)), and untreated soil (UNTRD). The vegetables were harvested at maturity, washed with distilled water, and subjected to an acid digestion process before the levels of heavy metals were measured by inductively coupled plasma spectrometry (ICP-MS). The mean concentrations of the metals in the vegetables across all treatments were below the maximum permissible limits. The pattern of heavy metal accumulation by the vegetables suggested that the lettuce from SS treatment accumulated higher concentrations of heavy metals like Cr (0.20 mg/kg), Cu (3.91 mg/kg), Ni (0.33 mg/kg), and Zn (20.44 mg/kg) than carrot, with highest concentrations of Fe (90.89 mg/kg) and Pb (0.16 mg/kg) recorded in lettuce from NPK treatment. The bioaccumulation factor (BAF) showed that lettuce, a leafy vegetable, has bioaccumulated more heavy metals than carrot, a root vegetable. The BAF was generally below the threshold value of 1 in both vegetables, except in lettuce from NPK and CD treatments and carrot from NPK treatments, with BAF values of 1.6, 1.69, and 1.39, respectively. The cancer risk assessment factors were well below the unacceptable maximum range of 10-4 suggesting that consuming these vegetables might not expose an individual to potential risk of cancer development. The hazard quotient estimations were below the threshold values of 1 for all heavy metals; however, the hazard index (HI) values of 1.27 and 1.58 for lettuce from NPK and SS treatments indicate a potential non-carcinogenic health risk to consumers from intake of all the heavy metals.

Transmission of antibiotic resistance through organic amendments in arable land: A 3-year field study with pigeonpea-wheat cropping system.

The worldwide emergence of antimicrobial resistance (AMR) poses a substantial risk to human health and environmental stability. In agriculture, organic amendments (derived from organic sources such as manure, and plant residues) are beneficial in restoring soil properties and providing essential nutrients to crops but raise concerns about harboring antibiotic resistance, which emphasizes the need for vigilant monitoring and strategic interventions in their application. The current study assessed the impact of farming practices (organic and conventional) in a three-year field experiment with pigeonpea-wheat cropping system, focusing on the transmission of AMR using culture-dependent and -independent approaches, and soil nutrient content. Markers for antibiotic resistance genes (ARGs) (aminoglycoside-aacA, ß-lactam-blaTEM, chloramphenicol-cmlA1, macrolide-ermB, sulfonamides-sul1, sul2, and tetracycline-tetO) and integrons (intl1 and intl2) were targeted using qPCR. Manure amendments, particularly FYM1, exhibited a higher abundance of copies of ARGs compared to the rhizospheric soil. Organic farming was associated with higher copies of intl2, sul1, blaTEM, and tetO genes, while conventional farming showed increased copies of sul2 and ermB genes in the rhizosphere. Significant positive correlations were observed among soil nutrient contents, ARGs, and MGEs. The notable prevalence of ARGs linked to manure amendments serves as a cautionary note, demanding responsible management practices.

Effects of slatted frame placed in compost pile on enhancing heat generation and organic matter degradation during high-moisture cow manure composting.

Excess moisture content in cow manure inhibits the process of composting. This study examined the effects of introducing a slatted frame on temperature development, organic matter degradation, and moisture content during high-moisture composting. Twelve tons of cow manure was piled individually, and an iron slatted frame with a pipe and a plain frame filled inside with styrofoam was introduced in the treatment and control piles, respectively. Two hours after the start, running leachate via the pipe in the treatment pile was observed, but not in the control pile. The maximum temperatures as well as durations of the temperatures above 55°C of the treatment piles at all seven positions were higher than those of the control piles. In particular, four of the seven positions in the treatment pile exhibited more than twice the duration. Installing the slatted frame improved the organic matter degradation; the values of organic matter loss in the control and treatment were 48.0% and 58.4%, respectively. The final moisture content in the treated compost was 5% lower than that in the control. Overall, the introduction of a slatted frame generated higher temperatures and produced relatively dried and well-degraded compost.

Responses of soil physico-chemical properties, structure of the microbial community and crop yields to different fertilization practices in Russia's conventional farming system.

The use of fertilizers affects not only the soil fertility and crop yield, but also significantly changes the taxonomic structure of the soil microbiocenosis. Here, based on stationary field experiment, we studied the influence of organo-mineral fertilizer (ОМF), modified by bacteria Bacillus subtilis, H-13 in comparison with different fertilizer systems (organic, mineral, organo-mineral) on (i) crop yield, (ii) physical and chemical properties, and (iii) alpha and beta diversity of the microbial community Albic Retisol (Loamic, Aric, Cutanic, Differentic, Ochric). The studies were carried out against the background of liming (рНКCl - 5.9) and without it (рНКCl - 5.1). The use of only one cattle farmyard manure was less effective than its co-application with mineral fertilizers in half doses. A similar effect was obtained when applying ОМF. In addition, the use of OMF contributes to a significant increase in the reserves of soil organic carbon in the soil layer 0-20 cm by 18%-32%. Using high-throughput sequencing of the 16S rRNA variable V4 gene sequence libraries, 10.759 taxa from 456 genera were identified, assigned to 34 fila (31 bacterial and 3 archaeotic. Unilateral application of mineral fertilizers leads to a significant decrease in the alpha diversity of the structure of soil microbial communities (OTE (other things equal) and Shannon index). A clear clustering of the microbiota was found in the variants with and without the introduction of сattle farmyard manure. It is revealed that the taxonomic structure of the microbiocenosis is formed under the influence of two main factors: crop rotation culture and applied fertilizers. The type of cultivated crop determines the dynamics of the microbiota at the level of larger taxa, such as domains, and fertilizers affect the structure of the microbial community at a lower taxonomic level (phyla, orders, bloodlines). On the basis of the Deseq analysis, marker taxa were identified, according to the share participation of which it is possible to determine the type of cultivated crop and fertilizers used in the experiment. Understanding the dynamics of taxa association and other influential factors can lead to the creation of universal systems of metagenomic indication, where tracking the dynamics of microbial communities will allow for a comprehensive assessment of the agroecological state of soils and timely decisions to prevent their degradation.

Multidrug-resistant Escherichia coli strains isolated from swine manure biofertilizer in Brazil.

Escherichia coli is one of the key bacteria responsible for a variety of diseases in humans and livestock-associated infections around the globe. It is the leading cause of mortality in neonatal and weaned piglets in pig husbandry, causing diarrhea and significant harm to the industry. Furthermore, the frequent and intensive use of antimicrobials for the prevention of diseases, particularly gastrointestinal diseases, may promote the selection of multidrug-resistant (MDR) strains. These resistant genotypes can be transmitted through the excrement of animals, including swine. It is common practice to use porcine manure processed by biodigesters as fertilizer. This study aimed to examine the antimicrobial susceptibility, the presence of virulence genes frequently associated with pathotypes of intestinal pathogenic E. coli (InPEC), and antimicrobial resistance genes (ARGs) of 28 E. coli isolates collected from swine manure fertilizers. In addition, the enterobacterial repetitive intergenic consensus-PCR (ERIC-PCR) technique was used to investigate the genetic relationship among the strains. Using disk diffusion, the antimicrobial susceptibility profiles of the strains were determined. Using polymerase chain reaction (PCR), 14 distinct virulence genes associated with the most prevalent diarrhea and intestinal pathogenic E. coli (DEC/InPEC) and five ARGs were analyzed. All isolates tested positive for multidrug resistance. There was no detection of any of the 14 virulence genes associated with InPECs, indicating the presence of an avirulent commensal microbiota. Molecular classification by ERIC-PCR revealed that the majority of isolates (27 isolates) coalesced into a larger cluster with a genetic similarity of 47.7%; only one strain did not cluster in this cluster, indicating a high level of genetic diversity among the analyzed isolates. Thus, it is of the utmost importance to conduct epidemiological surveillance of animal breeding facilities in order to determine their microbiota and formulate plans to reduce the use of antimicrobials and improve animal welfare.

Farmer's climate smart livestock production adoption and determinant factors in Hidebu Abote District, Central Ethiopia.

This study aimed to identify the status, determining factors, and challenges in adopting climate smart livestock production practices by farmers. Three-staged sampling techniques were used to select the research sites and 233 sample farmer household respondents. Data were collected mainly using a pre-tested structured questionnaire. Key informant interviews and focus group discussions were also conducted to complement the household survey data. Descriptive statistics and an ordered logistic regression model were applied to analyze the quantitative data. The result revealed that the most adopted practices were composting (85.41%) and manure management (70.39%) while the least adopted technologies were biogas generation (3.86%) and rotation grazing (22.32%). The adoption status of the sampled farmers was also categorized into low (19.74%), medium (67.81%), and high adopter (12.45%). The high cost of improved breed, use of manure for fuel, free grazing, lack of information and awareness were the major constraints to adopting the climate smart livestock production technologies. The result also revealed that education, grazing land, total livestock holding, and extension agent contact contributed significantly and positively to the adoption of smart livestock production technology, while the distance from the water source had an insignificant and negative effect on the adoption status of climate smart livestock production practices. The study suggests the relevance of the cooperation of stakeholders and strengthening extension services for the maximum benefits of climate smart livestock production.

Chicken manure-derived biochar enhanced the potential of Comamonas testosteroni ZG2 to remediate Cd contaminated soil.

The combined remediation of Cd-contaminated soil using biochar and microorganisms has a good application value. In this study, the effect of chicken manure-derived biochar on CdCO3 precipitation induced by Comamonas testosteroni ZG2 was investigated. The results showed that biochar could be used as the carrier of strain ZG2, enhance the resistance of strain ZG2 to Cd, and reduce the toxicity of Cd to bacterial cells. Cd adsorbed by biochar could be induced by strain ZG2 to form CdCO3 precipitation. Strain ZG2 could also induce CdCO3 precipitation when biochar was added during precipitation formation and fermentation broth formation. The CdCO3 precipitation could enter the pores of the biochar and attach to the surface of the biochar. The single and combined effects of strain ZG2 and biochar could realize the remediation of Cd-contaminated soil to a certain extent. The overall effect was in the order of strain ZG2 with biochar > biochar > strain ZG2. The combination of strain ZG2 and biochar reduced soil available Cd by 48.2%, the aboveground biomass of pakchoi increased by 72.1%, and the aboveground Cd content decreased by 73.3%. At the same time, it promoted the growth and development of the root system and improved the microbial community structure of the rhizosphere soil. The results indicated that chicken manure-derived biochar could enhance the stability of CdCO3 precipitation induced by strain ZG2, and strain ZG2 combined with biochar could achieve a more stable remediation effect on Cd-contaminated soil.

Ca(H2PO4)2 and MgSO4 activated nitrogen-related bacteria and genes in thermophilic stage of compost.

This study was conducted to investigate the effects of Ca(H2PO4)2 and MgSO4 on the bacterial community and nitrogen metabolism genes in the aerobic composting of pig manure. The experimental treatments were set up as control (C), 1% Ca(H2PO4)2 + 2% MgSO4 (CaPM1), and 1.5% Ca(H2PO4)2 + 3% MgSO4 (CaPM2), which were used at the end of composting for potting trials. The results showed that Ca(H2PO4)2 and MgSO4 played an excellent role in retaining nitrogen and increasing the alkali-hydrolyzed nitrogen (AN), available phosphorus (AP), and available potassium (AK) contents of the composts. Adding Ca(H2PO4)2 and MgSO4 changed the microbial community structure of the compost. The microorganisms associated with nitrogen retention were activated. The complexity of the microbial network was enhanced. Genetic prediction analysis showed that the addition of Ca(H2PO4)2 and MgSO4 reduced the accumulation of nitroso-nitrogen and the process of denitrification. At the same time, despite the reduction of genes related to nitrogen fixation, the conversion of ammonia to nitrogenous organic compounds was promoted and the stability of nitrogen was increased. Mantel test analysis showed that Ca(H2PO4)2 and MgSO4 can affect nitrogen transformation-related bacteria and thus indirectly affect nitrogen metabolism genes by influencing the temperature, pH, and organic matter (OM) of the compost and also directly affected nitrogen metabolism genes through PO43- and Mg2+. The pot experiment showed that composting with 1.5% Ca(H2PO4)2 + 3% MgSO4 produced the compost product that improved the growth yield and nutrient content of cilantro and increased the fertility of the soil. In conclusion, Ca(H2PO4)2 and MgSO4 reduces the loss of nitrogen from compost, activates nitrogen-related bacteria and genes in the thermophilic phase of composting, and improves the fertilizer efficiency of compost products. KEY POINTS: • Ca(H2PO4)2 and MgSO4 reduced the nitrogen loss and improved the compost effect • Activated nitrogen-related bacteria and altered nitrogen metabolism genes • Improved the yield and quality of cilantro and fertility of soil.

Global nitrous oxide emissions from livestock manure during 1890-2020: An IPCC tier 2 inventory.

Nitrous oxide (N2O) emissions from livestock manure contribute significantly to the growth of atmospheric N2O, a powerful greenhouse gas and dominant ozone-depleting substance. Here, we estimate global N2O emissions from livestock manure during 1890-2020 using the tier 2 approach of the 2019 Refinement to the 2006 IPCC Guidelines. Global N2O emissions from livestock manure increased by ~350% from 451 [368-556] Gg N year-1 in 1890 to 2042 [1677-2514] Gg N year-1 in 2020. These emissions contributed ~30% to the global anthropogenic N2O emissions in the decade 2010-2019. Cattle contributed the most (60%) to the increase, followed by poultry (19%), pigs (15%), and sheep and goats (6%). Regionally, South Asia, Africa, and Latin America dominated the growth in global emissions since the 1990s. Nationally, the largest emissions were found in India (329 Gg N year-1), followed by China (267 Gg N year-1), the United States (163 Gg N year-1), Brazil (129 Gg N year-1) and Pakistan (102 Gg N year-1) in the 2010s. We found a substantial impact of livestock productivity, specifically animal body weight and milk yield, on the emission trends. Furthermore, a large spread existed among different methodologies in estimates of global N2O emission from livestock manure, with our results 20%-25% lower than those based on the 2006 IPCC Guidelines. This study highlights the need for robust time-variant model parameterization and continuous improvement of emissions factors to enhance the precision of emission inventories. Additionally, urgent mitigation is required, as all available inventories indicate a rapid increase in global N2O emissions from livestock manure in recent decades.

Effect of aqueous phase from hydrothermal carbonization of sewage sludge on heavy metals and heavy metal resistance genes during chicken manure composting.

Livestock manure is often contaminated with heavy metals (HMs) and HM resistance genes (HMRGs), which pollute the environment. In this study, we aimed to investigate the effects of the aqueous phase (AP) produced by hydrothermal carbonization (HTC) of sewage sludge (SS) alone and the AP produced by co-HTC of rice husk (RH) and SS (RH-SS) on humification, HM bioavailability, and HMRGs during chicken manure composting. RH-SS and SS increased the humic acid content of the compost products by 18.3 % and 9.7 %, respectively, and significantly increased the humification index (P < 0.05) compared to the CK (addition of tap water). The passivation of HMs (Zn, Cu, As, Pb, and Cr) increased by 12.17-23.36 % and 9.74-15.95 % for RH-SS and SS, respectively, compared with that for CK. RH-SS and SS reduced the HMRG abundance in composted products by 22.29 % and 15.07 %, respectively. The partial least squares path modeling results showed that SS and RH-SS promoted compost humification while simultaneously altering the bacterial community and reducing the bioavailability of metals and host abundance of HMRGs, which has a direct inhibitory effect on the production and distribution of HMRGs. These findings support a new strategy to reduce the environmental risk of HMs and HMRGs in livestock manure utilization.

Quantifying the mitigating effect of organic matter on heavy metal availability in soils with different manure applications: A geochemical modelling study.

Manure is one of the main sources of heavy metal (HM) pollution on farmlands. It has become the focus of global ecological research because of its potential threat to human health and the sustainability of food systems. Soil pH and organic matter are improved by manure and play pivotal roles in determining soil HM behavior. Geochemical modeling has been widely used to assess and predict the behavior of soil HMs; however, there remains a research gap in manure applications. In this study, a geochemical model (LeachXS) coupled with a pH-dependent leaching test with continuously simulations over a broad pH range was used to determine the effects and pollution risks of pig or cattle manure separate application on soil HMs distribution. Both pig and cattle manure applications led to soil pH reduction in alkaline soils and increased organic matter content. Pig manure application resulted in a potential 90.5-156.0 % increase in soil HM content. Cattle manure did not cause significant HM contamination. The leaching trend of soil HMs across treatments exhibited a V-shaped change, with the lowest concentration at pH = 7, gradually increasing toward strong acids and bases. The dissolved organic matter-bound HM content directly increased the HM availability, especially for Cu (up to 8.4 %) after pig manure application. However, more HMs (Cr, Cu, Zn, Ni) were in the particulate organic matter-bound state than in other solid phases (e.g., Fe-Al(hydr) oxides, clay minerals), which inhibited the HMs leaching by more than 19.3 % after cattle manure application. Despite these variations, high HM concentrations introduced by pig manure raised the soil contamination risk, potentially exceeding 40 times at pH ±1. When manure is returned to the field, reducing its HM content and mitigating possible pollution is necessary to realize the healthy and sustainable development of circular agriculture.

Manure replacing synthetic fertilizer improves crop yield sustainability and reduces carbon footprint under winter wheat-summer maize cropping system.

Manure replacing synthetic fertilizer is a viable practice to ensure crop yield and increase soil organic carbon (SOC), but its impact on greenhouse gas (GHG) emissions is inconsistent, thus remains its effect on CF unclear. In this study, a 7-year field experiment was conducted to assess the impact of replacing synthetic fertilizer with manure on crop productivity, SOC sequestration, GHG emissions and crop CF under winter wheat-summer maize cropping system. Five treatments were involved: synthetic nitrogen, phosphorus, and potassium fertilizer (NPK) and 25%, 50%, 75%, and 100% of manure replacing synthetic N (25%M, 50%M, 75%M, and 100%M). Compared with NPK treatment, 25%M and 50%M treatments maintained annual yield (winter wheat plus summer maize) and sustainable yield index (SYI), but 75%M and 100%M treatments significantly decreased annual yield, and 100%M treatment also significantly reduced annual SYI. The SOC content exhibited a significant increasing trend over years in all treatments. After 7 years, SOC storage in manure treatments increased by 3.06-11.82 Mg ha-1 relative to NPK treatment. Manure treatments reduced annual GHG emissions by 14%-60% over NPK treatment. The CF of the cropping system ranged from 0.16 to 0.39 kg CO2 eq kg-1 of grain without considering SOC sequestration, in which the CF of manure treatments lowered by 18%-58% relative to NPK treatment. When SOC sequestration was involved in, the CF varied from -0.39 to 0.37 kg CO2 eq kg-1 of grain, manure treatments significantly reduced the CF by 22%-208% over NPK treatment. It was concluded that replacing 50% of synthetic fertilizer with manure was a sound option for achieving high crop yield and SYI but low CF under the tested cropping system.

Comparison of pyrolysis gasification of livestock manure, food wastewater, and their co-digested sludge.

For energy recovery, anaerobic digestion is applied to organic waste, such as livestock manure (LM) and food wastewater (FW). Digested sludge(DS), a residue from the anaerobic co-digestion of LM and FW, is another type of organic waste that can be converted into energy through pyrolysis. This study compared the pyrolysis characteristics of LM, FW, and DS. The product content varied with the pyrolysis temperature, rate of temperature increase, reaction time, and final reaction temperature. Gas production from FW and DS was similar; however, gas production from LM was low. As the pyrolysis temperature increased, the H2 content increased, and the CO2 content decreased, respectively. At 1000 °C, the H2 content of LM increased to 45%, and FW produced the most gas but the lowest H2 content. The H2/CO ratios of LM and FW ranged from 3.5 to 5.2, while those of DS ranged from 5.5 to 12.4, with the highest values. The carbon conversion rate was the highest for the gaseous products of LM (30-54%) and lowest for the gaseous products of digested sludge (26-36%). Conversely, the cold gas efficiency was the highest for the DS and lowest for the LM. Following anaerobic digestion, the DS generated less tar than the untreated LM and FW, showed higher efficiency in gas generation and gas properties, and exhibited a higher value as a char fuel.

Enhanced humification of full-scale apple wood and cow manure by promoting lignocellulose degradation via biomass pretreatments.

Agroforestry waste and cow manure pollute the environment, of which, agroforestry waste is difficult to degrade. Compost is an effective way to dispose agroforestry waste; however, the low degradation efficiency of lignocellulose in agroforestry waste affects the process of composting humification. This study investigated lignocellulose degradation and composting humification in full-size apple wood and cow manure composting processes by applying different pretreatments (acidic, alkaline, and high-temperature) to apple wood. Simultaneously, physicochemical characterization and metagenome sequencing were combined to analyze the function of carbohydrate-active enzymes database (CAZy). Therefore, microbial communities and functions were linked during the composting process and the lignocellulose degradation mechanism was elaborated. The results showed that the addition of apple wood increased the compost humus (HS) yield, and pretreatment of apple wood enhanced the lignocellulose degradation during composting processes. In addition, pretreatment improved the physicochemical properties, such as temperature, pH, electric conductivity (EC), ammonium nitrogen (NH4+), and nitrate nitrogen (NO3-) in the compost, of which, acid treated apple wood compost (AcAWC) achieved the highest temperature of 58.4 °C, effectively promoting nitrification with NO3- ultimately reaching 0.127 g/kg. In all composts, microbial networks constructed a high proportion of positively correlated connections, and microorganisms promoted the composting process through cooperation. The proportions of glycosyltransferase (GT) and glycoside hydrolase (GH) promoted the separation and degradation of lignocellulose during composting to form HS. Notably, the adverse effects of the alkali-treated apple wood compost on bacteria were greater. AcAWC showed significant correlations between bacterial and fungal communities and both lignin and hemicellulose, and had more biomarkers associated with lignocellulose degradation and humification. The lignin degradation rate was 24.57 % and the HS yield increased by 27.49 %. Therefore, AcAWC has been confirmed to enhance lignocellulose degradation and promote compost humification by altering the properties of the apple wood and establishing a richer microbial community.

Design expert based optimization of the pyrolysis process for the production of cattle dung bio-oil and properties characterization.

This study aimed to optimize pyrolysis conditions to maximize bio-oil yield from cattle dung, a waste product of livestock practices. Pyrolysis of cattle dung was carried out in batch type reactor. The pyrolysis process was optimized using a central composite design in response surface methodology, with conversion parameters such as pyrolysis temperature, vapor cooling temperature, residence time, and gas flow rate taken into account. The cattle dung bio-oil was analyzed using gas chromatography/mass spectroscopy (GC/MS), an elemental analyzer, a pH probe, and a bomb calorimeter. Furthermore, the ASTM standard procedures were used to determine the bio-fuel characteristics. The optimized conditions were found to be a pyrolysis temperature of 402 °C, a vapor cooling temperature of 2.25 °C, a residence time of 30.72 min, and a gas flow rate of 1.81 l min-1, resulting in a maximum bio-oil yield of 18.9%. According to the findings, the yield of bio-oil was predominantly affected by pyrolysis temperature and vapor cooling temperature. Moreover, the bio-oil that was retrieved was discovered to be similar to conventional liquid fuels in numerous ways.

Does livestock-Manure-Derived Biochar Suitable for the Stabilization of Cadmium and Zinc in Contaminated Soil?

Both livestock-manure and livestock-manure-derived biochar have been used to remediate heavy metal-contaminated soil. However, direct comparisons of the heavy metal stabilization efficiency of livestock-manure and EQC-manure-biochar (derived from an equal quantity of corresponding livestock-manure) are limited. In the present study, the effect of livestock-manures and EQC-manure-biochars on soil properties and heavy metal bioavailability and leachability were compared using two contrasting soils (Ferralsols and Fluvisols). The results showed that both the livestock-manures and EQC-manure-biochars significantly changed soil pH, available phosphorus, available potassium, alkaline nitrogen and organic matter content (p < 0.05), but the trends were variable. In Ferralsols, the DTPA-extractable Cd and Zn decreased by -0.38%~5.70% and - 3.79%~9.98% with livestock-manure application and by -7.99%~7.23% and - 5.67%~7.17% with EQC-manure-biochars application. In Fluvisols, the DTPA-extractable Cd and Zn decreased by 13.39%~17.41% and - 45.26%~14.24% with livestock-manure application and by 10.76%~16.90% and - 36.38%~16.37% with EQC-manure-biochar application. Furthermore, the change in TCLP-extractable Cd and Zn in both soils was similar to that of DTPA-extractable Cd and Zn. Notably, the Cd and Zn stabilization efficiency of the EQC-manure-biochars was no better than that of the corresponding livestock-manures. These results suggest that the use of livestock-manure-derived biochar is not cost-effective for the remediation of heavy metal-contaminated soil.

Pathways of soil organic carbon accumulation are related to microbial life history strategies in fertilized agroecosystems.

Although the formation, turnover, and accumulation of soil organic carbon (SOC) are driven by different fertilizer inputs and their subsequent microbial-mediated transformation, the relationship between changes in plant-derived and microbial-derived components and soil microbial life history strategies under different fertilization regimes has not been well explored. In this study, the changes in microbial necromass carbon (MNC), lignin phenols, and glomalin-related soil protein (GRSP), as well as soil microbial life history strategy were determined in a 16-year field experiment in response to different fertilization regimes, including a no-fertilizer control (C), conventional chemical NPK fertilization (NPK), and partial substitutions of the NPK in chemical fertilizers with a low (30 %) or high (60 %) level of straw (0.3S and 0.6S) or cattle manure (0.3M and 0.6M). The results showed that total lignin phenol content and its contribution to SOC were significantly increased by 88.7 % and 74.2 %, respectively, in high-level straw substitution treatment as compared to chemical fertilization. Both high-level straw and cattle manure substitution increased MNC and total GRSP contents, but did not alter their contributions to SOC compared to chemical fertilization. In fertilized treatments, the high-level cattle manure substitution had the lowest and highest bacterial and fungal K/r ratio, respectively. Bacterial K/r ratio was an important factor in predicting bacterial necromass carbon content and there was a significant negative correlation between them. The ratio of ectomycorrhizal to saprotrophic fungi and fungal diversity were important factors for predicting lignin phenol and GRSP contents, respectively. In addition, the SEMs modeling indicated that straw substitution directly affected lignin phenol and MNC accumulation, whereas cattle manure substitution indirectly affected MNC accumulation by affecting microbial life history strategies. In conclusions, agricultural residues inputs support the formation of a multiple carbon pool of SOC compared to chemical fertilization; and microbial life history strategy is an important driver of SOC formation and affects SOC accumulation and stability in agroecosystems.

[Effects of Application of Different Organic Materials on Phosphorus Accumulation and Transformation in Vegetable Fields].

Presently, the improvement of soil organic matter is the basis to ensure food security, but the accumulation and transformation characteristics of soil phosphorus (P) as affected by organic matter remain unclear. The accumulation, transformation, and migration characteristics of soil P in different soil layers of vegetable fields were researched under the application of organic materials. Six treatments were set up in the experiment:control (no fertilization), traditional fertilizer application by farmers, biochar, chicken manure, food waste, and straw application. Available phosphorus (Olsen-P), water-soluble phosphorus (CaCl2-P) content, soil phosphorus forms, soil organic matter (SOM), and pH were determined during the pepper harvest period. In the 0-5 cm and 5-10 cm soil layers, the available phosphorus content of traditional fertilization of farmers was higher, and the available phosphorus content of the four organic materials was in the order of straw > biochar > chicken manure > food waste. Compared to that with food waste, the straw and biochar treatments increased soil available phosphorus by 59.6%-67.3% and 29.1%-36.9%, respectively. The straw treatment could easily enhance the soil labile P pool, and soil labile P in the 0-5 cm soil layer increased by 47.3% and 35.1% compared with that under the chicken manure and food waste treatments, respectively. With the increase in soil depth, the proportion of available phosphorus in the chicken manure treatment decreased the least, and available phosphorus of the 20-30 cm soil layer accounted for 55.9% of the topsoil layer but only accounted for 16.0%-34.0% under treatment with the other three materials. Compared with that under the traditional fertilization of farmers, the pH significantly increased by 0.18-0.36 units after the application of organic fertilizer, and the pH of the chicken manure and food waste treatments was significantly higher than that of biochar and straw (P < 0.05). SOM content under the biochar treatment significantly increased by 7.7%-17.6% compared to that under the other three organic materials. Among the four organic materials, the straw treatment boosted the labile P pool the most, which was conducive to the rapid increase in plant-available P. Phosphorus was most likely to migrate downward under the chicken manure treatment. In the field management based on soil fertility enhancement, the application of biochar could not only improve soil pH and SOM but also avoid excessive accumulation of phosphorus in the surface layer, which decreases environmental risks.

Mobile genetic elements mediate the cross-media transmission of antibiotic resistance genes from pig farms and their risks.

Manure composting in traditional small-scale pig farms leads to the migration and diffusion of antibiotics and antibiotics resistance genes (ARGs) along the chain of transmission to the surrounding environment, increasing the risk of environmental resistance. Understanding the transmission patterns, driving factors, and health risks of ARGs on small-scale pig farms is important for effective control of ARGs transmission. This study was conducted on a small pig farm and its surrounding environment. The cross-media transmission of ARGs and their risks in the farming habitat were investigated using Metagenomic annotation and qPCR quantitative detection. The results indicate that ARGs in farms spread with manure pile-soil-channel sediment-mudflat sediment. Pig farm manure contributed 22.49 % of the mudflat sediment ARGs. Mobile genetic elements mediate the spread of ARGs across different media. Among them, tnpA and IS26 have the highest degree. Transmission of high-risk ARGs sul1 and tetM resulted in a 50 % and 116 % increase in host risk for sediment, respectively. This study provides a basis for farm manure management and control of the ARGs spread.

Enhancing nutritional status, growth, and fruit quality of dried figs using organic fertilizers in rain-fed orchards: A case study in Estahban, Iran.

The majority of Iranian fig production is exported, making it one of the world's most well-known healthy crops. Therefore, the main objective of the current experiment was to investigate the effects of various types of organic fertilizers, such as animal manure (cow and sheep), bird manure (partridge, turkey, quail, and chicken), and vermicompost, on the nutritional status of trees, vegetative and reproductive tree characteristics, fruit yield, and fruit quality traits in dried fig cultivar ("Sabz"). According to the findings, applying organic fertilizers, particularly turkey and quail, significantly improves vegetative and reproductive characteristics. However, other manures such as sheep, chicken, and vermicompost had a similar effect on the growth parameters of fig trees. Additionally, the findings indicated that except for potassium, use of all organic fertilizers had an impact on macro and microelements such as phosphorus, nitrogen, and sodium amount in fig tree leaves. Also, based on fruit color analysis in dried figs, the use of all organic fertilizers improved fruit color. Moreover, the analyses fruit biochemical showed that the use of some organic fertilizers improved that TSS and polyphenol compounds such as coumarin, vanillin, hesperidin gallic acid and trans frolic acid. In general, the results indicated that the addition of organic fertilizers, especially turkey manure, led to increased vegetative productivity and improvement in the fruit quality of the rain-fed fig orchard.