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Biochar has gained significant attention in agricultural and environmental research over the last two decades. This comprehensive review evaluates the effects of biochar on soil organic carbon (SOC), emission of non-CO2 greenhouse gases, and crop yield, including related mechanisms and major influencing factors. The impacts of biochar on SOC, methane and nitrous oxide emissions, and crop yield are controlled by biochar and soil properties and management practices. High-temperature biochar produced from lignin-rich feedstocks may decrease methane and nitrous oxide emissions in acidic soils and strengthen long-term carbon sequestration due to its stable aromatic structure. In contrast, low-temperature biochar from manure may increase crop yield in low-fertility soils. Applying biochar to farmlands in China can increase SOC content by 1.9 Pg C and reduce methane and nitrous oxide emissions by 25 and 20 Mt CO2-eq year−1, respectively, while increasing crop yields by 19%. Despite the increasing evidence of the positive effects of biochar, future research needs to explore the potential factors that could weaken or hinder its capacity to address climate change and secure crop production. We conclude that biochar is not a universal solution for global cropland; however, targeted applications in fields, landscapes, or regional scales, especially in low fertility and sandy soils, could realize the benefits of biochar as a climate-smart measure. Highlights The findings of research on biochar's effects on soil C sequestration, GHG mitigation, and crop production were summarized. The factors influencing the impact of biochar on soil functioning were reviewed. The effects of biochar on soil C sequestration and GHG mitigation in farmlands of China were quantified. [ABSTRACT FROM AUTHOR]

Rapid urban development in China has aggravated land subsidence, which poses a potential threat to sustainable urban development. It is imperative to monitor and predict land subsidence over large areas. To address these issues, we chose Henan Province as the study area and applied small baseline subset-interferometric synthetic aperture radar (SBAS-InSAR) technology to obtain land deformation information for monitoring land subsidence from November 2019 to February 2022 with 364 multitrack Sentinel-1A satellite images. The current traditional time-series deep learning models suffer from the problems of (1) poor results in extracting a sequence of information that is too long and (2) the inability to extract the feature information between the influence factor and the land subsidence well. Therefore, a long short-term memory-temporal convolutional network (LSTM-TCN) deep learning model was proposed in order to predict land subsidence and explore the influence of environmental factors, such as the volumetric soil water layer and monthly precipitation, on land subsidence in this study. We used leveling data to verify the effectiveness of SBAS-InSAR in land subsidence monitoring. The results of SBAS-InSAR showed that the land subsidence in Henan Province was obvious and uneven in spatial distribution. The maximum subsidence velocity was −94.54 mm/a, and the uplift velocity was 41.23 mm/a during the monitoring period. Simultaneously, the land subsidence in the study area presented seasonal changes. The rate of land subsidence in spring and summer was greater than that in autumn and winter. The prediction accuracy of the LSTM-TCN model was significantly better than that of the individual LSTM and TCN models because it fully combined their advantages. In addition, the prediction accuracies, with the addition of environmental factors, were improved compared with those using only time-series subsidence information. [ABSTRACT FROM AUTHOR]

In grassland open-pit mining areas, net primary productivity (NPP) is mainly affected by climate conditions and human activities. The identification and assessment of the influence of human activities on NPP is important for mining production and the implementation of ecological restoration. In this study, we explored the influence of human activities on the NPP in the Shengli mining area in Inner Mongolia, China by using the Carnegie–Ames–Stanford Approach (CASA) model and the Chikugo model, in which a calibration method was applied. An analysis of four representative years showed that the proportion of NPP induced by human activities reached 56.2%, that the percentage of pixels with an inhibitory effect on NPP was 99% in 2011 with the highest intensity of mining activity, and that these two values decreased to 11.9% and 69% in 2020, respectively, with the steady implementation of ecological restoration. Moreover, from the analysis of global and local spatial correlation, mining activities and ecological restoration aggravated and weakened the aggregation of NPP induced by human activities, respectively. [ABSTRACT FROM AUTHOR]

High fertilizer input and nitric oxide (NO) emissions characterize the intensive vegetable production system. However, the amount, geographic distribution, and effective mitigation strategies of NO emissions over Chinese vegetable fields remain largely uncertain. In this study, we developed a data-driven estimate of NO emissions and their spatial pattern in Chinese vegetable fields based on the Random Forest (RF) model. Additionally, we conducted a field experiment in a subtropical vegetable field to investigate the effect of climate-smart practices on NO emissions. The RF model results showed that soil NO emissions from Chinese vegetable fields were sensitive to nitrogen application amount, soil clay content, and pH. The total NO emission from Chinese vegetable fields in 2018 was estimated to be 75.9 Gg NO–N. The urgency to reduce NO emissions in vegetable fields was higher in northern than in southern China. Our meta-analysis and field experiment results suggested that biochar amendment and replacing chemical fertilizers with bio-organic fertilizers were win-win climate-smart management practices for mitigating NO emissions while improving vegetable production. Overall, our study provided new insights into NO emissions in vegetable soil ecosystems and can facilitate the development of regional NO emission inventories and effective mitigation strategies. These findings highlight the importance of adopting sustainable and climate-smart agricultural practices to reduce NO emissions and mitigate their adverse environmental impacts. [Display omitted] • Chinese vegetable fields are a hotspot of NO emissions. • The spatial distribution of NO emissions from vegetable farms has great variability. • The total NO emissions from Chinese vegetable fields were 75.9 Gg NO–N in 2018. • Biochar and bio-organic fertilizer substitution are promising practices to mitigate NO emissions. [ABSTRACT FROM AUTHOR]

Tropical and subtropical acidic soils have been well documented as hotspots of global soil nitrogen (N) oxide (i.e., nitrous oxide (N2O) and nitric oxide (NO) emissions). While the effectiveness of possible mitigation options has been extensively examined in croplands, little is known about their effectiveness in reducing N‐oxide emissions from acidic soils of rapidly expanding tea plantations in China. Here, we conducted a 2‐year field experiment to investigate how organic substitution for synthetic fertilizer and biochar amendment affect soil N‐oxide emissions from a subtropical tea plantation. Across the 2‐year measurement period, full organic substitution for synthetic fertilizer significantly increased N2O emissions by an average of 17% while had a lower NO emission compared to synthetic fertilizer alone. Our global meta‐analysis further revealed that full or partial organic fertilizer substitution resulted in a 29% (95% confidence interval: 5%–60%) increase of N2O emissions from acidic soils. In contrast, irrespective of fertilizer type, biochar amendment significantly reduced N2O emissions by 14% in the first but not second experimental year, suggesting a transient effect. The trade‐off effect of full organic substitution on N2O and NO emissions may be attributed to the favorable conditions for N2O production due to the stimulated activity of nitrifiers and denitrifiers. The suppression of N2O emission following biochar amendment was probably due to promoted further reduction of N2O to dinitrogen. The fertilizer‐induced emission factor (EF) of N2O (2.1%) in the tea plantation was greater than the current IPCC default value, but the EF of NO (0.8%) was comparable to the global estimate. Taken together, while biochar amendment could have mitigation potential, cautions are needed when applying organic substitution for synthetic fertilizer as mitigation options for acidic soils as hotspots of N‐oxide emissions. [ABSTRACT FROM AUTHOR]

Inland freshwater ecosystems are of increasing concerns in global methane (CH 4) budget in the atmosphere. Agricultural irrigation watersheds are a potential CH 4 emission hotspot owing to the anthropogenic carbon and nutrients loading. However, large-scale spatial variations of CH 4 concentrations and fluxes in agricultural catchments remain poorly understood, constraining an accurate regional estimate of CH 4 budgets. Here, we examined the spatiotemporal variations of dissolved CH 4 concentrations and fluxes from typical freshwater types (ditch, reservoir and river) within an agricultural irrigation watershed from Hongze catchment, which is subjected to intensive agricultural and rural activities in Eastern China. The dissolved CH 4 concentrations and fluxes showed similar temporal variations among the three freshwater types, with the highest rates in summer and the lowest rates in winter. The total CH 4 emission from this agricultural irrigation watershed was estimated to be 0.002 Gg CH 4 yr−1, with annual mean CH 4 concentration and flux of 0.12 μmol L−1 and 0.58 mg m−2 d−1, respectively. Diffusive CH 4 fluxes varied in samples taken from different freshwater types, the annual mean CH 4 fluxes for ditch, reservoir and river were 0.31 ± 0.06, 0.71 ± 0.13 and 0.72 ± 0.25 mg m−2 d−1, respectively. Among three freshwater types, the CH 4 fluxes were the lowest in ditch, which was associated with the lowest responses of CH 4 fluxes to water dissolved oxygen (DO), nitrate nitrogen (NO 3 −-N) and sediment dissolved organic carbon (DOC) concentrations in ditch. In addition, water velocity and wind speed were significantly lower in ditch than in reservoir and river, suggesting that they also played important roles in explaining the spatial variability of dissolved CH 4 concentrations and fluxes. These results highlighted a need for more field measurements with wider spatial coverage and finer frequency, which would further improve the reliability of flux estimates for assessing the contribution of agricultural watersheds to the regional and global CH 4 budgets. [Display omitted] • CH 4 concentrations and fluxes showed similar temporal variations among water types. • The CH 4 fluxes were significantly lower in ditches than in reservoirs and rivers. • The most sensitive responses of CH 4 fluxes to water parameters were found in rivers. • Water velocity and wind speed are responsible for spatial variability of CH 4 fluxes. [ABSTRACT FROM AUTHOR]

The emergence and spread of antibiotic resistance genes (ARGs) in soil due to animal excreta and organic waste is a major threat to human health and ecosystems, and global efforts are required to tackle the issue. However, there is limited knowledge of the variation in ARG prevalence and diversity resulting from different land-use patterns and underlying driving factors in soils. This study aimed to comprehensively characterize the profile of ARGs and mobile genetic elements and their drivers in soil samples collected from 11 provinces across China, representing three different land-use types, using high-throughput quantitative polymerase chain reaction and 16S rRNA amplicon sequencing. Our results showed that agricultural soil had the highest abundance and diversity of ARGs, followed by tea plantation and forest land. A total of 124 unique ARGs were detected in all samples, with shared subtypes among different land-use patterns indicating a common origin or high transmission frequency. Moreover, significant differences in ARG distribution were observed among different geographical regions, with the greatest enrichment of ARGs found in southern China. Biotic and abiotic factors, including soil properties, climatic factors, and bacterial diversity, were identified as the primary drivers associated with ARG abundance, explaining 71.8% of total ARG variation. The findings of our study demonstrate that different land-use patterns are associated with variations in ARG abundance in soil, with agricultural practices posing the greatest risk to human health and ecosystems regarding ARGs. Our identification of biotic and abiotic drivers of ARG abundance provides valuable insights into strategies for mitigating the spread of these genes. This study emphasizes the need for coordinated and integrated approaches to address the global antimicrobial resistance crisis. [Display omitted] • The highest ARG abundance and diversity occurred in agricultural soil. • Forest soil showed high contamination trends owing to the spread of ARGs. • Large differences in ARG abundance across geographic regions in China. • Bacterial communities, soil properties, and climatic factors jointly to determine ARG profiles. [ABSTRACT FROM AUTHOR]

To gain insight into the microbial mechanisms associated with the replacement of chemical fertilizers with organic or bio-organic fertilizers to mitigate soil nitrous oxide (N 2 O) emissions, we measured N 2 O emissions from greenhouse vegetable soils through field observations and pot experiments. Results showed that organic substitution suppressed N 2 O emissions by reducing soil mineral N content and stimulating the abundance of the nosZII gene. The trade-off effect of bio-organic substitution on N 2 O emissions may be due to the stimulated activity of the AOA-amoA gene, resulting in unfavorable conditions for N 2 O production and thus reduced N 2 O loss. We also linked the inhibitory effect of organic and bio-organic substitution on N 2 O emissions to the increased abundance of key species in bacterial co-occurrence networks represented by Patescibacteria as they were significantly and negatively correlated with N 2 O emissions. However, the mitigation effect of bio-organic substitution on N 2 O emissions was conteracted by an increase in Bacillus abundance due to the direct negative effect of Bacillus on the nosZII gene abundance. These findings suggest that conventional or bio-organic substitution is a promising strategy for alleviating the environmental costs of crop production., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Climate change and air pollution are one of the global environmental problems. It is significant to grasp the air pollution situation of Western Europe in recent 10 years for its or the global pollution control. Based on the OMI tropospheric nitrogen dioxide (NO 2 ) column density data, the spatial and temporal distribution characteristics, variation trend, transmission path, and influencing factors of NO 2 in 15 countries in Western Europe from 2011 to 2022 are discussed in this paper. Meanwhile, the annual average spatial and temporal distribution in 2023 is predicted by the random forest (RF) model. The results showed that (1) the 12-year spatial distribution map showed an increasing trend from southwest to northeast, with the border area of the Netherlands and Germany and Milan as two high-value areas, and the overall trend over time was that the high-concentration area gradually shrank, the low-concentration area gradually expanded, and the annual average concentration gradually decreased. (2) The inter-month trend presents a "U" shape, with the mean NO 2 pollution ranking in winter > autumn > spring > summer. (3) Natural factors are one of the reasons affecting NO 2 ; for instance, NO 2 pollution has a strong positive correlation with the lifted index, relative humidity, and wind speed and a moderately strong negative correlation with precipitable water and air temperature. (4) Exogenous atmospheric transport is another important factor affecting the change of NO 2 pollution in Western Europe. The HYSPLIT model is used to analyze the backward trajectory of Milan, Italy, and Nijmegen, Netherlands, in the four seasons of 2022. Both are mainly influenced by westerly airflows, and therefore, the transport effect in the atmosphere brings air pollutants from westerly regions in the atmosphere., (© 2023. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

Inland freshwater ecosystems are of increasing concerns in global methane (CH 4 ) budget in the atmosphere. Agricultural irrigation watersheds are a potential CH 4 emission hotspot owing to the anthropogenic carbon and nutrients loading. However, large-scale spatial variations of CH 4 concentrations and fluxes in agricultural catchments remain poorly understood, constraining an accurate regional estimate of CH 4 budgets. Here, we examined the spatiotemporal variations of dissolved CH 4 concentrations and fluxes from typical freshwater types (ditch, reservoir and river) within an agricultural irrigation watershed from Hongze catchment, which is subjected to intensive agricultural and rural activities in Eastern China. The dissolved CH 4 concentrations and fluxes showed similar temporal variations among the three freshwater types, with the highest rates in summer and the lowest rates in winter. The total CH 4 emission from this agricultural irrigation watershed was estimated to be 0.002 Gg CH 4 yr -1 , with annual mean CH 4 concentration and flux of 0.12 μmol L -1 and 0.58 mg m -2 d -1 , respectively. Diffusive CH 4 fluxes varied in samples taken from different freshwater types, the annual mean CH 4 fluxes for ditch, reservoir and river were 0.31 ± 0.06, 0.71 ± 0.13 and 0.72 ± 0.25 mg m -2 d -1 , respectively. Among three freshwater types, the CH 4 fluxes were the lowest in ditch, which was associated with the lowest responses of CH 4 fluxes to water dissolved oxygen (DO), nitrate nitrogen (NO 3 - -N) and sediment dissolved organic carbon (DOC) concentrations in ditch. In addition, water velocity and wind speed were significantly lower in ditch than in reservoir and river, suggesting that they also played important roles in explaining the spatial variability of dissolved CH 4 concentrations and fluxes. These results highlighted a need for more field measurements with wider spatial coverage and finer frequency, which would further improve the reliability of flux estimates for assessing the contribution of agricultural watersheds to the regional and global CH 4 budgets., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)