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This article proposes a one-tier ultra-dense cellular network framework based on the characteristics of directional beamforming to explore the downlink signal-to-interference ratio (SIR) performance. The features of the proposed cellular network include: small base stations (SBSs) are equipped with directional antennas; the beam boresight directions of antennas are adaptively adjusted with the locations of users on the two-dimensional horizontal plane while the boresight directions are perfectly aligned with their associated users. In addition, an angle fading model, which follows from the exponential distribution, is developed to simulate the signals attenuation of interference links. The angle fading of the interference signals depends on the angle offset between the locations of users and the beam boresight directions of their interfering SBSs. With the assistance of stochastic geometry, the analytical expressions of coverage probability and average ergodic rate are derived by combining with the probability density function of angle offset variable. Then, the meta distribution of SIR is obtained to capture the performance changes of individual links for users. The numerical results indicate that the performance advantages of the proposed directional network obviously exceed that of the conventional isotropic antennas case. Monte-Carlo simulations validate the correctness of numerical results. [ABSTRACT FROM AUTHOR]

Ammonia (NH3) emissions from fertilized soils to the atmosphere and the subsequent deposition to land surface exert adverse effects on biogeochemical nitrogen (N) cycling. The region‐ and crop‐specific emission factors (EFs) of N fertilizer for NH3 are poorly developed and therefore the global estimate of soil NH3 emissions from agricultural N fertilizer application is constrained. Here we quantified the region‐ and crop‐specific NH3 EFs of N fertilizer by compiling data from 324 worldwide manipulative studies and focused to map the global soil NH3 emissions from agricultural N fertilizer application. Globally, the NH3 EFs averaged 12.56% and 14.12% for synthetic N fertilizer and manure, respectively. Regionally, south‐eastern Asia had the highest NH3 EFs of synthetic N fertilizer (19.48%) and Europe had the lowest (6%), which might have been associated with the regional discrepancy in the form and rate of N fertilizer use and management practices in agricultural production. Global agricultural NH3 emissions from the use of synthetic N fertilizer and manure in 2014 were estimated to be 12.32 and 3.79 Tg N/year, respectively. China (4.20 Tg N/year) followed by India (2.37 Tg N/year) and America (1.05 Tg N/year) together contributed to over 60% of the total global agricultural NH3 emissions from the use of synthetic N fertilizer. For crop‐specific emissions, the NH3 EFs averaged 11.13%–13.95% for the three main staple crops (i.e., maize, wheat, and rice), together accounting for 72% of synthetic N fertilizer‐induced NH3 emissions from croplands in the world and 70% in China. The region‐ and crop‐specific NH3 EFs of N fertilizer established in this study offer references to update the default EF in the IPCC Tier 1 guideline. This work also provides an insight into the spatial variation of soil‐derived NH3 emissions from the use of synthetic N fertilizer in agriculture at the global and regional scales. [ABSTRACT FROM AUTHOR]

The terrestrial carbon (C) cycle plays an important role in global climate change, but the vegetation and environmental drivers of C fluxes are poorly understood. We established a global dataset with 1194 available data across site-years including gross primary productivity (GPP), ecosystem respiration (ER), net ecosystem productivity (NEP), and relevant environmental factors to investigate the variability in GPP, ER and NEP, as well as their covariability with climate and vegetation drivers. The results indicated that both GPP and ER increased exponentially with the increase in mean annual temperature (MAT) for all biomes. Besides MAT, annual precipitation (AP) had a strong correlation with GPP (or ER) for non-wetland biomes. Maximum leaf area index (LAI) was an important factor determining C fluxes for all biomes. The variations in both GPP and ER were also associated with variations in vegetation characteristics. The model including MAT, AP and LAI explained 53% of the annual GPP variations and 48% of the annual ER variations across all biomes. The model based on MAT and LAI explained 91% of the annual GPP variations and 92.9% of the annual ER variations for the wetland sites. The effects of LAI on GPP, ER or NEP highlighted that canopy-level measurement is critical for accurately estimating ecosystem-atmosphere exchange of carbon dioxide. The present study suggests a significance of the combined effects of climate and vegetation (e.g., LAI) drivers on C fluxes and shows that climate and LAI might influence C flux components differently in different climate regions. [ABSTRACT FROM AUTHOR]

• The soil respiration model used temperature, moisture, LAI, and soil properties as key variables. • The measured soil respiration in twenty-six agroecosystems in China well validated the model. • The modeled soil respiration varied greatly across regions and months in agroecosystems in China. Characterizing the seasonal patterns of soil respiration using a biophysical model is crucial for understanding the mechanisms of the terrestrial carbon (C) cycle. We developed a biophysical soil respiration model including four submodels that were associated with the functions of soil temperature, moisture, leaf area index (LAI), and soil organic C, and the model parameters were determined and calibrated. The modeling reproducibility was examined in various crop fields at our study site, and the modeling performance was also validated in twenty-five other agroecosystems in China. The monthly and annual soil respiration was estimated using the model, and the modeling uncertainty was evaluated. The results showed that the soil respiration model had good modeling reproducibility in various crop fields at our site. The measured soil respiration in the different agroecosystems in China validated our model well. The R 2, root mean squared error (RMSE), model efficiency (ME), and mean absolute error (MAE) were within the ranges of 0.449‒0.932, 0.526‒1.465 μmol m−2 s−1, 0.176‒0.796, and 0.312‒1.377 μmol m−2 s−1, respectively, across the twelve agroecosystem sites for validation. The measured soil respiration was significantly (P < 0.001) correlated with the modeled soil respiration across all twenty-six validation sites. Adding LAI significantly improved the modeling of soil respiration when the performance of the model (with LAI) vs. that without LAI was compared. The modeled monthly soil respiration was within the range of 0.016 ± 0.001‒0.117 ± 0.006 Pg C mo−1 in 2010 in agroecosystems in China. The black soils in Northeast China are fertile, which resulted in high temperature sensitivity and a clear increasing tendency of soil respiration from winter to summer in 2010 in agroecosystems in Northeast China. The established biophysical soil respiration model was proven to be effective for characterizing the temporal variations of soil respiration in various agroecosystems in China. [Display omitted] [ABSTRACT FROM AUTHOR]

Soil respiration ( R s ) is a key process in the terrestrial carbon cycle. Measurement and simulation of R s has received much attention recently. We collected annual R s field datasets to examine key controls of temporal and spatial variability in annual R s at the global scale. Published studies that reported annual field R s , mean annual temperature (MAT), annual precipitation (AP), soil (0–20 cm) properties and vegetation characteristics were compiled. MAT, AP and soil organic carbon (SOC) were the three most important variables in these datasets, together being responsible for 50% of the variance in annual R s in a global model (MAT&AP&SOC-model). Combining other site soil properties (e.g. pH) and vegetation variables, such as tree age (TA), tree height (TH), litter fall biomass (LF) and leaf area index (LAI), into the MAT&AP&SOC-model improved model performance. The site characteristic that explained the most variation in R s was AP followed by MAT, SOC, net primary productivity (NPP), pH, TA, TH, LF, LAI, elevation (EL) and diameter at breast height (DBH). Among the simulated models, the model based on MAT, AP, SOC and pH had the best fit for annual R s variance. There was a highly significant logarithmic relationship between R r / R s (the contribution of root respiration to R s ) and AP. The AP value of 0.4 m was a threshold for R r / R s , corresponding to R r / R s of 0.4 which reflects water limitation of root growth and plant productivity. [ABSTRACT FROM AUTHOR]

Cholesterol is a critical component of lipid rafts implicated in regulating multiple signal transduction. The anthrax toxin receptor 2 (ANTXR2) is a type I membrane protein acting as the second receptor for the anthrax toxin. In this study, we first investigated the association between cholesterol and ANTXR2. We provided the evidence that cholesterol depletion by methyl-beta-cyclodextrin (MβCD) promoted ANTXR2 expression in U251 neuroglioma cell, which was reversed by cholesterol supplement. MβCD-induced ANTXR2 up-regulation contributed to ERK1/2 phosphorylation, which was responsible for MT1-MMP and MMP-2 activation. Our data suggested that cellular cholesterol regulated ANTXR2-dependent activation of MMP-2 via ERK1/2 phosphorylation in neuroglioma U251 cell. [ABSTRACT FROM AUTHOR]

Greenhouse gas emissions from rice paddies under sewage irrigation deserve much attention since domestic sewage effluents are increasingly used for agriculture in developing countries. A field experiment was conducted to simultaneously measure methane (CH4) and nitrous oxide (N2O) emissions from rice (Oryza sativa L.) paddies under sewage and unpolluted river water irrigation in southeast China. The rice paddies were under a local typical water regime, which was characterized by flooding–midseason drainage–reflooding–moist intermittent irrigation but without water logging. Relative to unpolluted river water irrigation, sewage irrigation significantly increased CH4 and N2O emissions from rice paddies. Seasonal fluxes of CH4 averaged 1.51mgm−2 h−1 for the plots irrigated by river water and 1.92mgm−2 h−1 for the plots irrigated by sewage. In contrast with river water irrigation, sewage irrigation increased CH4 by 27% and 33% for paddy plots with and without chemical N addition, respectively. Under sewage irrigation, seasonal fluxes of N2O-N averaged 26.79μgm−2 h−1 for the plots without N application and 74.07μgm−2 h−1 for the plots applied at the rate of 200kgNha−1. Relative to river water irrigation, sewage irrigation increased N2O by 68% and 170% for the plots with and without N application, respectively. The direct emission factor of fertilizer N for N2O was estimated to be 0.71% for the rice paddies under sewage irrigation and 0.52% for the plots irrigated by river water. Besides direct N2O emissions, N input by sewage irrigation induced substantial indirect N2O emission from rice paddies. The results of the net GWPs from CH4 and N2O indicate that sewage irrigation would intensify the radiative forcing of rice paddies with midseason drainage and moist irrigation... [Copyright &y& Elsevier]

Nitrogen fertilizer-induced direct nitrous oxide (N2O) emissions depend on water regimes in paddy fields, such as seasonal continuous flooding (F), flooding–midseason drainage–reflooding (F-D-F), and flooding–midseason drainage–reflooding–moist intermittent irrigation but without water logging (F-D-F-M). In order to estimate the changes in direct N2O emission from paddy fields during the rice-growing season in Mainland of China between the 1950s and the 1990s, the country-specific emission factors of N2O-N under different water regimes combined with rice production data were adopted in the present study. Census statistics on rice production showed that water management and nitrogen input regimes have changed in rice paddies since the 1950s. During the 1950s–1970s, about 20–25% of the rice paddy was continuously waterlogged, and 75–80% under the water regime of F-D-F. Since the 1980s, about 12–16%, 77%, and 7–12% of paddy fields were under the water regimes of F, F-D-F, and F-D-F-M, respectively. Total nitrogen input during the rice-growing season has increased from 87.5 kg N ha−1 in the 1950s to 224.6 kg N ha−1 in the 1990s. The emission factors of N2O-N were estimated to be 0.02%, 0.42%, and 0.73% for rice paddies under the F, F-D-F, and F-D-F-M water regimes, respectively. Seasonal N2O emissions have increased from 9.6 Gg N2O-N each year in the 1950s to 32.3 Gg N2O-N in the 1990s, which is accompanied by the increase in rice yield over the period 1950s–1990s. The uncertainties in N2O estimate were estimated to be 59.8% in the 1950s and 37.5% in the 1990s. In the 1990s, N2O emissions during the rice-growing season accounted for 8–11% of the reported annual total of N2O emissions from croplands in China, suggesting that paddy rice development could have contributed to mitigating agricultural N2O emissions in the past decades. However, seasonal N2O emissions would be increased, given that saving-water irrigation and nitrogen inputs are increasingly adopted in rice paddies in China. [ABSTRACT FROM AUTHOR]

Various water management regimes, such as continuous flooding (F), flooding-midseason drainage-reflooding (F-D-F), and flooding-midseason drainage-reflooding-moist intermittent irrigation, but without water logging (F-D-F-M), are currently practiced in paddy rice production in mainland China. These water regimes have incurred a sensitive change in direct N2O emission from rice paddy fields. We compiled and statistically analyzed field data on N2O emission from paddy fields during the rice growing season (71 measurements from 17 field studies) that were published in peer-reviewed Chinese and English journals. Seasonal total N2O was, on average, equivalent to 0.02% of the nitrogen applied in the continuous flooding rice paddies. Under the water regime of F-D-F or the F-D-F-M, seasonal N2O emissions increased with N fertilizer applied in rice paddies. An ordinary least square (OLS) linear regression model produced the emission factor (EF) of nitrogen for N2O averaged 0.42%, but background N2O emission was not pronounced under the water regime of F-D-F. Under the F-D-F-M water regime, N2O EF and background emission were estimated to be 0.73% and 0.79kg N2O-Nha−1, respectively, during the paddy rice growing season. Based on results of the present study and national rice production data, subsequently, direct N2O emissions during the rice growing season amounted to 29.0Gg N2O-N with the uncertainty of 30.1%, which accounted for 7–11% of the reported estimates of annual total emission from croplands in mainland China. The results of this study suggest that paddy rice relative to upland crop production could have contributed to mitigating N2O emissions from agriculture in mainland China. [Copyright &y& Elsevier]

The EICA hypothesis predicts that shifts in allocation of invasive plants give rise to higher growth rates and lower herbivore defense levels in their introduced range than conspecifics in their native range. These changes in traits of invasive plants may also affect ecosystem processes. We conducted an outdoor pot experiment with Chinese tallow tree ( Sapium sebiferum, Euphorbiaceae) seedlings from its native (Jiangsu, China, native ecotype) and introduced ranges (Texas, USA, invasive ecotype) to compare their relative performances in its native range and to examine ecotype effects on soil processes with and without fertilization. Consistent with predictions, plant (shoot and root) mass was significantly greater and leaf defoliation tended to be higher, while the root:shoot ratio was lower for the invasive ecotype relative to the native ecotype. Seasonal amounts of soil–plant system CO2 and N2O emissions were higher for the invasive ecotype than for the native ecotype. Soil respiration rates and N2O emission increases from fertilization were also greater for the invasive ecotype than for the native ecotype, while shoot-specific respiration rates (g CO2–C g−1 C day−1) did not differ between ecotypes. Further, soil inorganic N (ammonium and nitrate) was higher, but soil total N was lower for soils with the invasive ecotype than soils with the native ecotype. Compared with native ecotypes, therefore, invasive ecotypes may have developed a competition advantage in accelerating soil processes and promoting more nitrogen uptake through soil–plant direct interaction. The results of this study suggest that soil and ecosystem processes accelerated by variation in traits of invasive plants may have implications for their invasiveness. [ABSTRACT FROM AUTHOR]

Abstract: A field experiment was conducted in a rice–winter wheat rotation agroecosystem to quantify the direct emission of N2O for synthetic N fertilizer and crop residue application in the 2002–2003 annual cycle. There was an increase in N2O emission accompanying synthetic N fertilizer application. Fertilizer-induced emission factor for N2O (FIE) averaged 1.08% for the rice season, 1.49% for the winter wheat season and 1.26% for the whole annual rotation cycle. The annual background emission of N2O totaled 4.81kg N2O–Nha−1, consisting of 1.24kg N2O–Nha−1 for rice, 3.11kg N2O–Nha−1 for wheat seasons. When crop residue and synthetic N fertilizer were both applied in the fields, crop residue-induced emission factor for N2O (RIE) was estimated as well. When crop residue was retained at the rate of 2.25 and 4.50tha−1 for each season, the RIE averaged 0.64% and 0.27% for the whole annual rotation cycle, respectively. Based on available multi-year data of N2O emissions over the whole rice–wheat rotation cycle at 3 sites in southeast China, the FIE averaged 1.02% for the rice season, 1.65% for the wheat season. On the whole annual cycle, the FIE for N2O ranged from 1.05% to 1.45%, with an average of 1.25%. Annual background emission of N2O averaged 4.25kgha−1, ranging from 3.62 to 4.87kgha−1. It is estimated that annual N2O emission in paddy rice-based agroecosystem amounts to 169Gg N2O–N in China, accounting for 26–60% of the reported estimates of total emission from croplands in China. [Copyright &y& Elsevier]

To investigate the influence of plant residues decomposition on N2O emission, laboratory incubations were carried out for a period of 21 days using urea and five plant residues with a wide range of C:N ratios from 8 to 118. Incorporation of plant residues enhanced N2O and CO2 emissions. The two gas fluxes were significantly correlated (R2=0.775, p<0.001). Cumulative emissions of N2O and CO2 were negatively correlated with the C:N ratio in plant residues (R2=0.783 and 0.986 for N2O, and 0.854 for CO2, respectively). A negative relationship between the N2O–N/NO3-–N ratio and the C:N ratio was observed (R2=0.867) when residue plus urea was added. We calculated the changes in dissolved organic C (DOC) and the relevant changes in N2O emission. The incorporation of residues increased DOC when compared with the control, while the incorporation of residue plus urea decreased DOC. Cumulative emissions of N2O and CO2 were positively correlated with DOC concentration measured at the end of the incubation. In addition, the N2O emission fraction, defined as N2O–N emissions per unit N input, was not found to be a constant for either residue-N or urea-N amendment but dependent on C:N ratio when plant residue was incorporated. [Copyright &y& Elsevier]

Terrestrial carbon cycling is one of the hotspots in global change issues. In this paper, we presented the rationale for determination of net exchange of CO2 between terrestrial and the atmosphere (NEE) and the methods for measuring several relevant components. Three key processes for determination of NEE were addressed, including the separation of shoot autotrophic respiration from total CO2 emissions of the ecosystem, the partition of root respiration from soil CO2 efflux, and the quantification of rhizodeposition C from NPP. With an understanding of the processes involved in the CO2 exchange between terrestrial and the atmosphere, we estimated NEE of rice ecosystem in Nanjing based on field measurements of CO2 emissions and several relevant biotic components as well as abiotic factors. The field measurements of CO2 emissions were made over the rice-growing seasons in 2001 and 2002 with the static opaque chamber method. Calculations indicated that the seasonal pattern of NEE is comparable for two seasons. Either net carbon emission or fractional carbon fixation occurred during 3 weeks after rice transplanting and thereafter net carbon fixation appeared with an increasing trend as rice growing. Higher net carbon fixation occurred in the rice developmental period from elongating to heading. A decline trend in the fixation was documented after rice heading. The mean daily NEE was -6.06 gC·m−2 in 2001 season and -7.95 gC·m−2 in 2002 season, respectively. These values were comparable to the results obtained by Campbell et al. who made field measurements with the Bowen ratio-energy balance technique in irrigated rice, Texas USA. Moreover, the mean daily NEE in this study was also comparable to the values obtained from a Japanese rice paddy with the eddy covariance method under the similar water regime, either drainage course or waterlogged. It is concluded that NEE determined by the static opaque chamber method is comparable and in agreement with those measured by Bowen ratioenergy balance and eddy covariance methods. [ABSTRACT FROM AUTHOR]

Terrestrial carbon cycling is one of the hotspots in global change issues. In this paper, we presented the rationale for determination of net exchange of CO2 between terrestrial and the atmosphere (NEE) and the methods for measuring several relevant components. Three key processes for determination of NEE were addressed, including the separation of shoot autotrophic respiration from total CO2 emissions of the ecosystem, the partition of root respiration from soil CO2 efflux, and the quantification of rhizodeposition C from NPP. With an understanding of the processes involved in the CO2 exchange between terrestrial and the atmosphere, we estimated NEE of rice ecosystem in Nanjing based on field measurements of CO2 emissions and several relevant biotic components as well as abiotic factors. The field measurements of CO2 emissions were made over the rice-growing seasons in 2001 and 2002 with the static opaque chamber method. Calculations indicated that the seasonal pattern of NEE is comparable for two seasons. Either net carbon emission or fractional carbon fixation occurred during 3 weeks after rice transplanting and thereafter net carbon fixation appeared with an increasing trend as rice growing. Higher net carbon fixation occurred in the rice developmental period from elongating to heading. A decline trend in the fixation was documented after rice heading. The mean daily NEE was -6.06 gC .m-2M 2001 season and -7.95 -2 . gC . m -2in 2002 season, respectively. These values were comparable to the results obtained by Campbell et al. who made field measurements with the Bowen ratio-energy balance technique in irrigated rice, Texas USA. Moreover, the mean daily NEE in this study was also comparable to the values obtained from a Japanese rice paddy with the eddy covariance method under the similar water regime, either drainage course or waterlogged. It is concluded that NEE determined by the static opaque chamber method is comparable and in agreement with those measured by Bowen ratio energy balance and eddy covariance methods. [ABSTRACT FROM AUTHOR]

Although efforts to understand the drivers of the soil organic carbon (SOC) in terrestrial ecosystems have paid off, little is known about the temporal and spatial variations in the mean residence time (MRT) of SOC and how MRT varies with the climatic, soil, and vegetation drivers. In this study, the MRT of SOC from 1376 samples of the 0–20 cm soil layer from the main global biomes was derived based on the simultaneously measured SOC pool and soil carbon fluxes. We also evaluated the factors controlling the variations in the MRT of SOC. The results indicate that, across the different biomes, the MRT of SOC (ranging from 0.47 to 56.75 yr) exhibits large variations at the global scale and shows strong quadratic relationship with latitude. The MRT of SOC exhibits a significant and negative trend from the 1980s to the 2010s. The MRT of SOC shows strong negative and nonlinear relationships (P < 0.001) with mean annual temperature (MAT) and annual precipitation (AP). The MRT of SOC is also highly significantly (P < 0.001) correlated with soil total nitrogen (STN) (R 2 = 0.281), bulk density (BD) (R 2 = 0.097), tree age (TA) (R 2 = 0.099), and litter fall (LF) (R 2 = 0.076), respectively. MAT, AP, STN, BD, TA, and LF are the dominant drivers of the MRT of SOC in global models; however, the model including MAT, AP, STN, and BD (T&P&N&B) performs best among the models with different predictors. Moreover, the T&P&N&B model performs better for simulating the MRT of SOC in grassland than in other biomes. Further analysis indicates that simulating the MRT of SOC using biomes-specific models well explains the variations in the MRT of SOC, with an R 2 value of 0.708. • The MRT of SOC shows strong quadratic relationship with latitude. • The MRT of SOC exhibits a significant and negative trend from 1980s to 2010s. • The variations in the MRT of SOC are controlled by climatic, soil and vegetation drivers. • The biome-specific models well explain the spatial and temporal variations in the MRT of SOC. [ABSTRACT FROM AUTHOR]

Shifting from conventional tillage to a no-till system can contribute to improving soil carbon sequestration and sustaining crop productivity. However, our understanding of the soil nitrogen (N) process through insights into the no-till effect on soil denitrification remains elusive. Here, we compiled data from 323 observations in 57 studies and quantified the responses of soil denitrification and the size and activity of the denitrifying community to no-till vs. conventional tillage. Across all studies, no-till significantly increased soil denitrification (85%) compared to conventional tillage. The no-till effect on soil denitrification was significantly dependent upon N fertilizer management, with a greater increase with N fertilization than without (101 vs. 46%). The increased soil denitrification under no-till was attributed to increases in the size and activity of the denitrifying community. On average, the potential denitrification activity, the total number of denitrifiers, and the abundance of denitrifying genes were increased by 66, 116, and 14–70%, respectively, in response to no-till. Our results demonstrate that soil denitrification under no-till leads to increased soil nitrous oxide (N 2 O) emission. This is supported by a larger response of soil N 2 O emission compared to the total denitrification, together with a significant increase (33%) in the (nir K + nir S)/ nos Z ratio under no-till conditions. Therefore, the increased soil denitrification under no-till conditions may have negative impacts on soil N cycling and mitigation of N 2 O emission. • The effect of no-till on soil denitrification was meta-analyzed. • No-till significantly increased soil denitrification and N 2 O emissions. • No-till enhanced the activity and abundance of the soil denitrifying community. • An overall positive response of (nir K + nir S)/ nos Z to no-till was found. [ABSTRACT FROM AUTHOR]

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]

Applying biochar amendment and manure in tea plantation ecosystems can diminish soil acidification and degradation. However, the impact of these practices on soil respiration and associated mechanisms remains unclear. In this study, we combined a two-year field experiment and laboratory analyses based on soil properties, functional genes, and microbial co-occurrence networks to explore the determinants of soil respiration intensity in a subtropical tea plantation with biochar amendment and manure application. The results showed that the effect of biochar amendment on soil respiration was unconspicuous. Although biochar amendment increased bacterial richness and Shannon index, biochar amendment did not alter the abundance of species associated with C-cycling functional genes. Besides directly adding recalcitrant C to the soil, biochar also indirectly enhanced C sequestration by weakly increasing soil carbon dioxide (CO2) emissions. However, replacing mineral fertilizer with manure significantly stimulated soil respiration in the tea plantation, resulting in a 36% increase in CO2 emissions over two years. The increase in CO2 emissions under the manure treatment was mainly attributed to the increased soil labile C pool, the activity of hydrolytic enzymes (e.g., cellobiohydrolase and acetylglucosaminidase), and the relative abundance of functional genes associated with the C-cycle. This may also be related to the application of manure that increased the abundance of Gemmatimonadetes and altered ecological clusters in bacterial co-occurrence networks. Our correlation network analysis suggested that Gemmatimonadetes might be the potential hosts for C-cycling genes due to their strong positive correlation with the abundance of C-cycling genes. Overall, these findings provide new insights into soil respiration under biochar amendment and manure application in tea plantations and broaden the options for carbon sequestration in soils. Highlights: Manure application rather than biochar amendment increased acidic soil respiration. Biochar application promoted soil C sequestration in the tea plantation. Manure application stimulated CO2 emissions by altering ecological clusters' abundance. Gemmatimonadetes might be the dominant hosts for C-cycling genes. [ABSTRACT FROM AUTHOR]

Despite the increasing impact of atmospheric nitrogen (N) deposition on terrestrial greenhouse gas (GHG) budget, through driving both the net atmospheric CO2 exchange and the emission or uptake of non‐CO2 GHGs (CH4 and N2O), few studies have assessed the climatic impact of forests and grasslands under N deposition globally based on different bottom‐up approaches. Here, we quantify the effects of N deposition on biomass C increment, soil organic C (SOC), CH4 and N2O fluxes and, ultimately, the net ecosystem GHG balance of forests and grasslands using a global comprehensive dataset. We showed that N addition significantly increased plant C uptake (net primary production) in forests and grasslands, to a larger extent for the aboveground C (aboveground net primary production), whereas it only caused a small or insignificant enhancement of SOC pool in both upland systems. Nitrogen addition had no significant effect on soil heterotrophic respiration (RH) in both forests and grasslands, while a significant N‐induced increase in soil CO2 fluxes (RS, soil respiration) was observed in grasslands. Nitrogen addition significantly stimulated soil N2O fluxes in forests (76%), to a larger extent in grasslands (87%), but showed a consistent trend to decrease soil uptake of CH4, suggesting a declined sink capacity of forests and grasslands for atmospheric CH4 under N enrichment. Overall, the net GHG balance estimated by the net ecosystem production‐based method (forest, 1.28 Pg CO2‐eq year−1 vs. grassland, 0.58 Pg CO2‐eq year−1) was greater than those estimated using the SOC‐based method (forest, 0.32 Pg CO2‐eq year−1 vs. grassland, 0.18 Pg CO2‐eq year−1) caused by N addition. Our findings revealed that the enhanced soil C sequestration by N addition in global forests and grasslands could be only marginally offset (1.5%–4.8%) by the combined effects of its stimulation of N2O emissions together with the reduced soil uptake of CH4. [ABSTRACT FROM AUTHOR]

Existing studies suggest that biochar application can reduce soil nitrous oxide (N2O) emissions, mainly based on short‐term results. However, it remains unclear what the effects (i.e., legacy effects) and underlying mechanisms are on N2O emissions after many years of a single application of biochar. Here, we collected intact soil columns from plots without and with biochar application in a subtropical tea plantation 7 years ago for an incubation experiment. We used the N2O isotopocule analysis combined with ammonia oxidizer‐specific inhibitors and molecular biology approaches to investigate how the legacy effect of biochar affected soil N2O emissions. Results showed that the soil in the presence of biochar had lower N2O emissions than the control albeit statistically insignificant. The legacy effect of biochar in decreasing N2O emissions may be attributed to the reduced effectiveness of the soil substrate, nitrification and denitrification activities, and the promotion of the further reduction of N2O. The legacy effect of biochar reduced the relative contribution of nitrifier denitrification/bacterial denitrification, nitrification‐related N2O production, and the relative abundance of several microorganisms involved in the nitrogen cycle. Our global meta‐analysis also showed that the reduction of N2O by biochar increased with increasing application rate but diminished and possibly even reversed with increasing experimental time. In conclusion, our findings suggest that the abatement capacity of biochar on soil N2O emissions may weaken over time after biochar application, but this remains under further investigation. [ABSTRACT FROM AUTHOR]

Misuse and overuse of antibiotics have contributed to the rise of antimicrobial resistance as one of the top public health threats. Antibiotics and antibiotic resistance genes (ARGs) are prevalent in agricultural soils due to the widespread application of livestock and organic wastes. However, information about the occurrence, distribution, and risk of antibiotics and ARGs in agricultural soils is lacking for many scenarios. In this study, based on 2225 observations from 135 independent studies, we summarized the concentration or abundance of antibiotics or ARGs under different fertilizer sources and land-use patterns, analyzed the contributions of key environmental factors to the occurrence of antibiotics and ARGs in agricultural soils, and highlighted the potential ecological risk of typical antibiotics and the relationship between ARGs and mobile genetic elements (MGEs). Our results showed that cattle manure, chicken manure, swine manure, and sewage sludge were the primary pollution sources of antibiotics and ARGs in agricultural soils, and sulfonamides, tetracyclines, fluoroquinolones, and their corresponding ARGs were the main pollution types. Land-use type, soil, and climatic factors affected antibiotics concentration and ARG abundances. MGEs play a vital role in promoting the dissemination of ARGs, especially the sul1 gene is closely related to intI1. In conclusion, our findings and future research exploring these topics will contribute to better management of antibiotic and ARG contamination in agricultural soils and their risk to human health. [ABSTRACT FROM AUTHOR]

Applying biochar and 3,4-dimethylpyrazole phosphate (DMPP) is considered to be effective means of mitigating soil nitrous oxide (N2O) emissions. However, their N2O abatement efficiency can be affected by soil properties and associated functional microorganisms. In this study, we investigated the effects of biochar and/or DMPP application on N2O emissions from different agricultural soils (i.e., vegetable, tea, and peach orchards grown for 1 and 7 years) through an incubation experiment. Biochar application significantly reduced N2O emissions from vegetable and tea soils by inhibiting ammonia oxidation. In contrast, in peach orchard soils, adding biochar promoted N2O emissions due to the positive effect of biochar on ammonia-oxidizing bacteria (AOB), which accelerated ammonia oxidation and the inhibition of N2O reduction. DMPP application mitigated 57–74% of soil N2O emissions due to its inhibitory effect on AOB. When biochar and DMPP were co-applied, biochar reduced the efficiency of DMPP in mitigating N2O emissions from tea and peach soils as biochar addition weakened the inhibitory effect of DMPP on AOB. However, N2O emissions from vegetable soils could be further reduced by the synergistic inhibition of ammonia oxidation by biochar and DMPP. Our results suggest that DMPP had a stable mitigation effect on N2O emissions in different soils, while biochar addition could potentially weaken the efficiency of DMPP. The mitigation effect of the co-application of biochar and nitrification inhibitors needs to be explored in future studies under field conditions. [ABSTRACT FROM AUTHOR]

Inland waters (rivers, reservoirs, lakes, ponds, streams) and estuaries are significant emitters of methane (CH4) and nitrous oxide (N2O) to the atmosphere, while global estimates of these emissions have been hampered due to the lack of a worldwide comprehensive data set of CH4 and N2O flux components. Here, we synthesize 2997 in‐situ flux or concentration measurements of CH4 and N2O from 277 peer‐reviewed publications to estimate global CH4 and N2O emissions from inland waters and estuaries. Inland waters including rivers, reservoirs, lakes, and streams together release 95.18 Tg CH4 year−1 (ebullition plus diffusion) and 1.48 Tg N2O year−1 (diffusion) to the atmosphere, yielding an overall CO2‐equivalent emission total of 3.06 Pg CO2 year−1. The estimate of CH4 and N2O emissions represents roughly 60% of CO2 emissions (5.13 Pg CO2 year−1) from these four inland aquatic systems, among which lakes act as the largest emitter for both CH4 and N2O. Ebullition showed as a dominant flux component of CH4, contributing up to 62%–84% of total CH4 fluxes across all inland waters. Chamber‐derived CH4 emission rates are significantly greater than those determined by diffusion model‐based methods for commonly capturing of both diffusive and ebullitive fluxes. Water dissolved oxygen (DO) showed as a dominant factor among all variables to influence both CH4 (diffusive and ebullitive) and N2O fluxes from inland waters. Our study reveals a major oversight in regional and global CH4 budgets from inland waters, caused by neglecting the dominant role of ebullition pathways in those emissions. The estimated indirect N2O EF5 values suggest that a downward refinement is required in current IPCC default EF5 values for inland waters and estuaries. Our findings further indicate that a comprehensive understanding of the magnitude and patterns of CH4 and N2O emissions from inland waters and estuaries is essential in defining the way of how these aquatic systems will shape our climate. [ABSTRACT FROM AUTHOR]

Nitrogen (N) inputs and land-use conversion are management practices that affect soil greenhouse gas (GHG) and nitric oxide (NO) emissions. Here, we measured soil methane (CH4), nitrous oxide (N2O), and NO fluxes from rice fields and a peach orchard that converted from paddies to assess the impacts of nitrogen (N) inputs and land-use conversion on their emissions. Treatments included four paddy field treatments (PN0, PN160, PN220, and PN280) and one peach orchard treatment (ON280) with number indicating the N-input rate of kg N ha−1. The results showed that cumulative emissions of CH4, N2O and NO ranged from 28.6 to 85.3 kg C ha−1, 0.5 to 4.0 kg N ha−1 and 0.2 to 0.3 kg N ha−1 during the rice-growing season, respectively. In terms of greenhouse gas intensity, the PN280 treatment is the recommended N application rate. Land-use conversion significantly reduced the global warming potential from croplands. The conversion shifted soils from an essential source of CH4 to a small net sink. In addition, N2O emissions from the rice–wheat rotation system were 1.8 times higher than from the orchard, mainly due to the difference in the N application rate. In summary, to reduce agriculture-induced GHG emissions, future research needs to focus on the effects of N inputs on rice-upland crop rotation systems. [ABSTRACT FROM AUTHOR]

Efforts to advance our knowledge on the potential of bioenergy instead of fossil fuels in terms of mitigating climatic impact are in urgent need. No data is currently available on the use of urease and nitrification inhibitors in costal saline bioenergy cropping systems. An overall accounting of net greenhouse gas balance (NGHGB) and greenhouse gas intensity (GHGI) affected by combined effects of urease inhibitor hydroquinone (HQ) and nitrification inhibitor dicyandiamide (DCD) amendment was examined in a coastal saline Jerusalem artichoke bioenergy cropping system. The net ecosystem exchange of CO 2 (NEE) was determined by the difference between soil heterotrophic respiration ( R H ) and net primary production (NPP) using static chamber method. Urease and nitrification inhibitors amendment increased the NPP but exerted a suppression effect on soil R H over the Jerusalem artichoke cropping system. A trade-off relationship was observed by decreasing soil N 2 O but stimulating soil CH 4 emissions following HQ+DCD amendment. The plots combined urea with HQ+DCD application increased soil CH 4 by 167% while decreased N 2 O by 16% as compared to with urea only in the bioenergy cropping system. On average, the fertilizer N-induced emission factor of N 2 O was estimated to be 0.25% across the fertilized plots. Compared with urea, the plots with urea and HQ+DCD resulted in a further decrease by 37% and 15% in estimated NGHGB and GHGI over the Jerusalem artichoke cropping system, respectively. Overall, Jerusalem artichoke production would achieve higher biomass as source of biofuels but lower climatic impacts, particularly when together with urease and nitrification inhibitors amendment in coastal saline soils. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fe-modified biochar addition enhanced the total gross NH 4 + immobilization while decreasing the autotrophic nitrification. • AOB dominated N 2 O emissions in paddy soils with or without biochar or Fe-modified biochar amendment under aerobic conditions. • Fe-modified biochar addition decreased total N 2 O emissions mainly by inhibiting AOB activity. We investigated the potential of ferric iron-modified biochar to lessen autotrophic nitrification and lower nitrous oxide (N 2 O) emissions in paddy soils. A 15N tracing incubation was conducted to investigate the changes in soil gross nitrogen (N) transformations under various biochar amendments (control, unmodified biochar, and Fe-modified biochar). Acetylene and 1-octyne were used to assess the relative contributions of ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) to N 2 O emission from paddy soil. The Fe-modified biochar increased the rate of NH 4 + immobilization by 26 % and 383 % compared to the control and unmodified biochar treatments, respectively. The gross rate of autotrophic nitrification was reduced to 5.43 μg N g−1 d−1 in the Fe-modified biochar treatment, compared to 6.74 μg N g−1 d−1 in the control treatment and 9.38 μg N g−1 d−1 in the unmodified biochar treatment. Soil pH had varying effects on N 2 O emissions involving AOB and AOA. The N 2 O yields of AOA were more sensitive to Fe-modified biochar applications. AOB, specifically the Nitrosopira -AOB genus, dominated N 2 O production in all treatments. Overall, this study suggests that Fe-modified biochar holds greater potential than unmodified biochar in reducing N 2 O emissions from paddy soils by stimulating NH 4 + adsorption, restraining autotrophic nitrification rates, and AOB-dominant N 2 O production pathways. [ABSTRACT FROM AUTHOR]

Veterinary antibiotics are increasingly used in the livestock industry annually. Sulfonamides introduced into the soil with manure are usually largely degraded in various pathways. However, the influence of the metabolic intermediate of sulfonamides on nitrogen (N) cycling under anaerobic conditions in soils has been overlooked. To this end, we carried out a microcosm experiment to investigate the potential consequences of ADPD (2-amino-4,6-dimethylpyrimidine, a degradation product of sulfonamide) at five concentration gradients (i.e., 0, 0.01, 0.1, 1, and 10 mg kg−1) on nitrous oxide (N 2 O) emissions, associated genes involved in N cycling, antibiotic resistance genes (ARGs), and mobile genetic elements (MGEs) in soils applied with manure or urea. The results showed that ADPD application promoted N 2 O emissions under flooded conditions at environmentally relevant concentrations, and the maximum cumulative N 2 O emissions were observed at 1 mg kg−1 and 0.1 mg kg−1 ADPD for manure and urea applied, respectively. The main reasons were the imbalance of denitrifying bacteria, which affected N 2 O production and reduction, and the increase of antibiotic resistance in soil bacteria. In conclusion, these findings contribute to assessing the eco-environmental risks associated with the prevalence of sulfonamide metabolic intermediates and expand our understanding of the link between antibiotics and N transformation. Further research in the field is warranted to incorporate their recommendations into the greenhouse gas assessment system. [Display omitted] [ABSTRACT FROM AUTHOR]

High nitrogen (N) fertilizer inputs accelerate soil acidification and degradation in tea plantations, thus posing a threat to soil microbial diversity, species composition, and ecosystem service functions. The effects of organic fertilizer and biochar applications on improving soil fertility have been extensively studied on cropland; however, little is known about their effectiveness in promoting soil multifunctionality on rapidly expanding acidic soils in tea plantations. In this study, we conducted a two‐year field experiment in a subtropical tea plantation to investigate the effects of organic fertilizer substitution and biochar amendment on soil microbial communities and multifunctionality. The results showed that soil multifunctionality was enhanced in plots amended with organic fertilizer and biochar. Soil multifunctionality was significantly and positively correlated with alpha‐diversity of bacteria but not fungi. We also found that organic fertilizer substitution and biochar amendment improved soil multifunctionality by altering the abundance of keystone species. The abundance of keystone species classified as module hubs in the bacterial co‐occurrence network contributed significantly and positively to soil multifunctionality. In contrast, the keystone species categorized as module hubs in the fungal co‐occurrence network negatively affected soil multifunctionality. Soil pH was a key driver of soil microbial community composition, indicating that the increase in soil pH under organic fertilizer and biochar amendment had a crucial role in biological processes. These results suggest that organic substitution and biochar amendment are beneficial in preventing soil degradation and maintaining soil multifunctionality in subtropical tea plantations. [ABSTRACT FROM AUTHOR]

Gaseous reactive nitrogen (Nr) emissions from agricultural soils to the atmosphere constitute an integral part of global N cycle, directly or indirectly causing climate change impacts. The extensive use of N fertilizer in crop production will compromise our efforts to reduce agricultural Nr emissions in China. A national inventory of fertilizer N‐induced gaseous Nr emissions from croplands in China remains to be developed to reveal its role in shaping climate change. Here we present a data‐driven estimate of fertilizer N‐induced soil Nr emissions based on regional and crop‐specific emission factors (EFs) compiled from 379 manipulative studies. In China, agricultural soil Nr emissions from the use of synthetic N fertilizer and manure in 2018 are estimated to be 3.81 and 0.73 Tg N yr−1, with a combined contribution of 23%, 20% and 15% to the global agricultural emission total of ammonia (NH3), nitrous oxide (N2O) and nitric oxide (NO), respectively. Over the past three decades, NH3 volatilization from croplands has experienced a shift from a rapid increase to a decline trend, whereas N2O and NO emissions always maintain a strong growth momentum due to a robust and continuous rise of EFs. Regionally, croplands in Central south (1.51 Tg N yr−1) and East (0.99 Tg N yr−1) of China exhibit as hotspots of soil Nr emissions. In terms of crop‐specific emissions, rice, maize and vegetable show as three leading Nr emitters, together accounting for 61% of synthetic N fertilizer‐induced Nr emissions from croplands. The global warming effect derived from cropland N2O emissions in China was found to dominate over the local cooling effects of NH3 and NO emissions. Our established regional and crop‐specific EFs for gaseous Nr forms provide a new benchmark for constraining the IPCC Tier 1 default EF values. The spatio‐temporal insight into soil Nr emission data from N fertilizer application in our estimate is expected to advance our efforts towards more accurate global or regional cropland Nr emission inventories and effective mitigation strategies. [ABSTRACT FROM AUTHOR]

Litter decomposition is a fundamental ecosystem process in which breakdown and decay of plant detritus releases carbon and nutrients. Invasive exotic plants may produce litter that differs from native plant litter in quality and quantity. Such differences may impact litter decomposition and soil respiration in ways that depend on whether exotic and native plant litters decompose in mixtures. However, few field experiments have examined how exotic plants affect soil respiration via litter decomposition. Here, we conducted an in situ study of litter decomposition of an annual native grass (Eragrostis pilosa), a perennial exotic forb (Alternanthera philoxeroides), and their mixtures in an annual grassland in China to examine potential invasion effects on soil respiration. Alternanthera litter decomposed faster than Eragrostis litter when each was incubated separately. Mass loss in litter mixes was more rapid than predicted from rates in single species bags (only 35% of predicted mass remained at 8 months) showing synergistic effects. Notably, exotic plant litter decomposition rate was unchanged but native plant litter decomposition rate was accelerated in mixtures (decay constant k = 0.20 month−1) compared to in isolation (k = 0.10 month−1). On average, every litter type increased soil respiration compared to bare soil from which litter was removed. However, the increases were larger for mixed litter (1.82 times) than for Alternanthera litter (1.58 times) or Eragrostis litter (1.30 times). Carbon released as CO2 relative to litter carbon input was also higher for mixed litter (3.34) than for Alternathera litter (2.29) or Eragrostis litter (1.19). Our results indicated that exotic Alternanthera produces rapidly decomposing litter which also accelerates the decomposition of native plant litter in litter mixtures and enhances soil respiration rates. Thus, this exotic invasive plant species will likely accelerate carbon cycling and increase soil respiration even at intermediate stages of invasion in these annual grasslands. [ABSTRACT FROM AUTHOR]

Aims: A field experiment was conducted to quantify annual nitrous oxide (NO) fluxes from control and fertilized plots under open-air and greenhouse vegetable cropping systems in southeast China. We compiled the reported global field annual NO flux measurements to estimate the emission factor of N fertilizer for NO and its background emissions from vegetable fields. Methods: Fluxes of NO were measured using static chamber-GC techniques over the 2010-2011 annual cycle with multiple cropping seasons. Results: The mean annual NO fluxes from the controls were 46.1 ± 2.3 μg NO-N m hr and 68.3 ± 4.1 μg NO-N m hr in the open-air and greenhouse vegetable systems, respectively. For the plots receiving 900 kg N ha, annual NO emissions averaged 90.6 ± 8.9 μg NO-N m hr and 106.4 ± 6.6 μg NO-N m hr in the open-air and greenhouse vegetable systems, respectively. By pooling published field NO flux measurements taken over or close to a full year, the NO emission factor for N fertilizer averaged 0.63 ± 0.09 %, with a background emission of 2.67 ± 0.80 kg NO-N ha in Chinese vegetable fields. Annual NO emissions from Chinese vegetable systems were estimated to be 84.7 Gg NO-N yr, consisting of 72.5 Gg NO-N yr and 12.2 Gg NO-N yr in the open-air and greenhouse vegetable systems, respectively. Conclusions: While NO emissions from the greenhouse vegetable cropping system tended to be slightly higher compared to the open-air system in our experiment, the synthesis of literature data suggests that NO emissions would be greater at low N-rates but smaller at high N-rates in greenhouse systems than in open-air vegetable cropping systems. The estimates of this study suggest that vegetable cropping systems covering 11.4 % in national total cropping area, contributed 21-25 % to the total NO emission from Chinese croplands. [ABSTRACT FROM AUTHOR]

How to achieve high soil organic carbon (SOC) sequestration and low greenhouse gases emissions but without compromising yields is the challenge of rice cultivation in China. This study explored the potential to simultaneously increase SOC stocks and reduce methane (CH 4) emissions by optimizing rice cropping rotation and fertilization based on a 2-year field experiment in southeast China. We tested five optimized N management practices including directly reducing chemical N fertilizer input and replacing chemical N fertilizers with organic and controlled-release fertilizers in double-rice cropping and Chinese milk vetch-rice cropping rotation systems. Results showed higher seasonal rice yields, nitrogen use efficiency (NUE) and SOC stocks for Chinese milk vetch-rice rotation systems (CR) as compared to double-rice cropping systems (DR). Seasonal rice yields were the highest in the 2019 single-rice season (2019-SR), followed by the 2018 late (2018-LR) and early rice seasons (2018-ER). SOC stocks of CR for the treatment receiving organic N fertilizer (OF) were the largest among all rice seasons and fertilization treatments. Seasonal CH 4 emissions were 8–12% greater in the OF than in the chemical N fertilizer treatments across all rice seasons, with the greatest in 2019-SR and lowest in 2018-ER. Fertilization stimulated CH 4 emissions through enhancing mcrA gene activity, but regulated by soil properties, while rice rotation models indirectly influenced CH 4 emissions through direct effects on soil properties. However, yield-scaled CH 4 emissions remained unaffected by N fertilization in the two-year rice rotation systems. The NUE was significantly enhanced in OF than in other fertilizer treatments over all seasons. Seasonal net ecosystem C budget (NECB) was 24–41% greater in OF than in chemical N fertilizer treatments across all rice seasons, with the greatest in 2019-SR and lowest in 2018-LR. The NECB was increased by 46% in CR as compared to DR. Our results revealed that the optimized rice cropping rotation by incorporation of Chinese milk vetch with organic N fertilization is beneficial for enhancing soil C sequestration and maintaining rice yields in southeast China. [Display omitted] • Green manure rotation benefits for the enhancement of paddy soil carbon sinks. • Green manure rotation stimulates CH 4 emissions during the rice growing season. • Yield-scaled CH 4 emissions remain unaffected by N fertilization and crop rotation. • Green manure rotation can reconcile low climatic impacts with high yield of rice. [ABSTRACT FROM AUTHOR]

Abstract: Mean residence time (MRT) of topsoil organic carbon is one critical parameter for predicting future land carbon sink dynamics. Large uncertainties remain about controls on the variability in global MRT of soil organic carbon. We estimated global MRT of topsoil (0–20cm) organic carbon in terrestrial ecosystems and found that mean annual air temperature, annual precipitation, and topsoil nitrogen storage were responsible for the variability in MRT. An empirical climate and soil nitrogen-based (Clim&SN) model could be used to explain the temporal and spatial variability in MRT across various ecosystems. Estimated MRT was lowest in the low-latitude zones, and increased toward high-latitude zones. Global MRT of topsoil organic carbon showed a significant declining tendency between 1960 and 2008, particularly in the high-latitude zone of the northern hemisphere. The largest absolute and relative changes (0.2% per yr) in MRT of topsoil organic carbon from 1960 to 2008 occurred in high-latitude regions, consistent with large carbon stocks in, and greater degree of climate change being experienced by, these areas. Overall, global MRT anomalies (differences between MRT in each year and averaged value of MRT from 1960 to 2008) of terrestrial topsoil organic carbon were decreasing from 1960 to 2008. Global MRT anomalies decreased significantly (P <0.001) with the increase of global temperature anomalies, indicating that global warming resulted in faster turnover rates of topsoil organic carbon. [Copyright &y& Elsevier]

Soil respiration is an important process in terrestrial carbon cycle. Concerning terrestrial ecosystems in China, quantifying the spatiotemporal pattern of soil respiration at the regional scale is critical in providing a theoretical basis for evaluating carbon budget. In this study, we used an empirically based, semi-mechanistic model including climate and soil properties to estimate annual soil respiration from terrestrial ecosystems in China from 1970 to 2009. We further analyzed the relationship between interannual variability in soil respiration and climatic factors (air temperature and precipitation). Results indicated that the distribution of annual soil respiration showed clear spatial patterns. The highest and lowest annual soil respiration rates appeared in southeastern China and northwestern China, respectively, which was in accordance with the spatial patterns of mean annual air temperature and annual precipitation. Although the mean annual air temperature in northwestern China was higher than that in some regions of northeastern china, a greater topsoil organic carbon storage in northeastern China might result in the higher annual soil respiration in this region. By contrast, lower temperature, less precipitation and smaller topsoil organic carbon pool incurred the lowest annual soil respiration in northwestern China. Annual soil respiration from terrestrial ecosystems in China varied from 4.58 to 5.19 Pg C a between 1970 and 2009. During this time period, on average, annual soil respiration was estimated to be 4.83 Pg C a. Annual soil respiration in China accounted for 4.93%-6.01% of the global annual soil CO emission. The interannual variability in soil respiration depended on the interannual variability in precipitation and mean air temperature. In order to reduce the uncertainty in estimating annual soil respiration at regional scale, more in situ measurements of soil respiration and relevant factors (e.g. climate, soil and vegetation) should be made simultaneously and historical soil property data sets should also be established. [ABSTRACT FROM AUTHOR]

Abstract: To develop a model describing the dependence of annual soil respiration on climate and soil properties, we compiled 657 published annual soil respiration (R s ) measurements that were assembled from 147 sites globally, representing croplands, grasslands, forests and tundra ecosystems. Each of these annual soil respiration data was then aggregated with the appropriate mean air temperature (T) and annual precipitation (P) data derived from geographically referenced datasets and with soil properties gathered from the original literature. Partial correlation analyses showed that global annual R s significantly related to annual mean temperature, annual precipitation, and topsoil (0–20cm) organic carbon (SOC) storage, while topsoil total nitrogen (SN) and pH did not show a direct and clear relationship with R s across ecosystems. While we employed the T&P-model that used temperature and annual precipitation to globally predict annual soil respiration, it was able to explain 41%, 57%, and 31% of the variability of soil respiration for croplands, grasslands and forests, respectively. However, the residuals were significantly related to SOC for croplands and grasslands. Thus, we developed a T&P&C-model that includes SOC as an additional predictor of annual R s . This extended but still simple model performed better than the T&P-model and explained 69%, 89%, and 47% of the interannual and intersite variability of R s with a mean absolute error of 0.11, 0.18 and 0.28kgCm−2 yr−1 for croplands, grasslands and forests, respectively. Overall, the modeling efficiency of the T&P&C-model was nearly 60% across ecosystems. Globally, the mean turnover time of topsoil carbon (SOC/R s ) was highly comparable among croplands, grasslands and forests, equivalent to 6.1–6.3 years. Therefore, better estimates of global annual soil respiration would be obtained with the new model driven by climate and soil properties together. We expect significant improvements of global annual soil respiration predictions given that measurements of soil respiration coupling with soil properties and site productivities are widely taken across ecosystems over the world. [Copyright &y& Elsevier]

Abstract: Annual paddy rice–winter wheat rotation constitutes one of the typical cropping systems in southeast China, in which various water regimes are currently practiced during the rice-growing season, including continuous flooding (F), flooding-midseason drainage-reflooding (F-D-F), and flooding-midseason drainage-reflooding and moisture but without waterlogging (F-D-F-M). We conducted a field experiment in a rice–winter wheat rotation system to gain an insight into the water regime-specific emission factors and background emissions of nitrous oxide (N2O) over the whole annual cycle. While flooding led to an unpronounced N2O emission during the rice-growing season, it incurred substantial N2O emission during the following non-rice season. During the non-rice season, N2O fluxes were, on average, 2.61 and 2.48mg N2O–Nm− 2 day−1 for the 250kg N ha−1 applied plots preceded by the F and F-D-F water regimes, which are 56% and 49% higher than those by the F-D-F-M water regime, respectively. For the annual rotation system experienced by continuous flooding during the rice-growing season, the relationship between N2O emission and nitrogen input predicted the emission factor and background emission of N2O to be 0.87% and 1.77kg N2O–Nha−1, respectively. For the plots experienced by the water regimes of F-D-F and F-D-F-M, the emission factors of N2O averaged 0.97% and 0.85%, with background N2O emissions of 2.00kg N2O–Nha−1 and 1.61kg N2O–Nha−1 for the annual rotation system, respectively. Annual direct N2O–N emission was estimated to be 98.1Gg yr−1 in Chinese rice-based cropping systems in the 1990s, consisting of 32.3Gg during the rice-growing season and 65.8Gg during the non-rice season, which accounts for 25–35% of the annual total emission from croplands in China. [Copyright &y& Elsevier]

Abstract: Fertilized agricultural soils are a major anthropogenic source of atmospheric N2O. A credible national inventory of agricultural N2O emission would benefit its global strength estimate. We compiled a worldwide database of N2O emissions from fertilized fields that were consecutively measured for more than or close to one year. Both nitrogen input (N) and precipitation (P) were found to be largely responsible for temporal and spatial variabilities in annual N2O fluxes (N2O–N). Thus, we established an empirical model (N2O–N=1.49 P+0.0186 P·N), in which both emission factor and background emission for N2O were rectified by precipitation. In this model, annual N2O emission consists of a background emission of 1.49 P and a fertilizer-induced emission of 0.0186 P·N. We used this model to develop a spatial inventory at the 10×10km scale of direct N2O emissions from agriculture in China. N2O emissions from rice paddies were separately quantified using a cropping-specific emission factor. Annual fertilizer-induced N2O emissions amounted to 198.89GgN2O–N in 1997, consisting of 18.50GgN2O–N from rice paddies and 180.39GgN2O–N from fertilized uplands. Annual background emissions and total emissions of N2O from agriculture were estimated to be 92.78GgN2O–N and 291.67GgN2O–N, respectively. The annual direct N2O emission accounted for 0.92% of the applied N with an uncertainty of 29%. The highest N2O fluxes occurred in East China as compared with the least fluxes in West China. [Copyright &y& Elsevier]

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]

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 nos ZII gene. The trade-off effect of bio-organic substitution on N 2 O emissions may be due to the stimulated activity of the AOA- amo A 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 nos ZII gene abundance. These findings suggest that conventional or bio-organic substitution is a promising strategy for alleviating the environmental costs of crop production. [Display omitted] • Organic substitution reduced both area-scaled N 2 O emission and vegetable yield. • Bio-organic substitution lowered yield-scaled N 2 O emission and boosted crop yield. • Keystone bacterial species played a crucial role in regulating N 2 O emission. • Bacillus inoculation raised N 2 O emission by reducing the abundance of the nosZII gene. [ABSTRACT FROM AUTHOR]

Aim: Drought has been shown to alter terrestrial ecosystem carbon (C) and nitrogen (N) dynamics, and thus feedback to future climate. However, drought‐induced changes in terrestrial upland C and N pools and the drought response of soil carbon dioxide (CO2) and nitrous oxide (N2O) fluxes are yet to be quantified. Location: Global upland ecosystems. Time period: 2000–2018. Major taxa studied: Terrestrial C and N fluxes. Methods: A meta‐analysis was conducted that compiled 1,344 measurements from 128 manipulative studies worldwide to obtain a general picture of terrestrial C and N cycling responses to soil drought stress and identify the primary driving factors. Results: We showed that drought significantly decreased plant C pools, with stronger negative responses of aboveground than belowground C components. Drought significantly decreased soil respiration (RS) and N2O fluxes by 19% and 29%, respectively. There were non‐significant changes in soil organic C and N pools in response to drought; in contrast to a considerable decrease in soil dissolved organic C (−22%), there was a robust increase in soil nitrate‐N (26%) following short‐term drought impact. By relating net ecosystem productivity (NEP) to the difference between net primary production (NPP) and soil heterotrophic respiration (RH), drought was found to drive a decrease up to −37% in NEP, being equivalent to a reduction in terrestrial net C uptake of 2.91 t C/ha. Main conclusions: Our study provides insights into soil release of CO2 and N2O with a linkage to the changes in terrestrial C and N pools in response to drought across upland biomes. Our findings highlight that, despite the lowered soil C release rate, the capacity of upland biomes as a C sink to slow climate change would still be weakened due to a robust decline of plant‐derived C input to soil in a future drier climate. [ABSTRACT FROM AUTHOR]

Warming can accelerate the decomposition of soil organic matter and stimulate the release of soil greenhouse gases (GHGs), but to what extent soil release of methane (CH4) and nitrous oxide (N2O) may contribute to soil C loss for driving climate change under warming remains unresolved. By synthesizing 1,845 measurements from 164 peer‐reviewed publications, we show that around 1.5°C (1.16–2.01°C) of experimental warming significantly stimulates soil respiration by 12.9%, N2O emissions by 35.2%, CH4 emissions by 23.4% from rice paddies, and by 37.5% from natural wetlands. Rising temperature increases CH4 uptake of upland soils by 13.8%. Warming‐enhanced emission of soil CH4 and N2O corresponds to an overall source strength of 1.19, 1.84, and 3.12 Pg CO2‐equivalent/year under 1°C, 1.5°C, and 2°C warming scenarios, respectively, interacting with soil C loss of 1.60 Pg CO2/year in terms of contribution to climate change. The warming‐induced rise in soil CH4 and N2O emissions (1.84 Pg CO2‐equivalent/year) could reduce mitigation potential of terrestrial net ecosystem production by 8.3% (NEP, 22.25 Pg CO2/year) under warming. Soil respiration and CH4 release are intensified following the mean warming threshold of 1.5°C scenario, as compared to soil CH4 uptake and N2O release with a reduced and less positive response, respectively. Soil C loss increases to a larger extent under soil warming than under canopy air warming. Warming‐raised emission of soil GHG increases with the intensity of temperature rise but decreases with the extension of experimental duration. This synthesis takes the lead to quantify the ecosystem C and N cycling in response to warming and advances our capacity to predict terrestrial feedback to climate change under projected warming scenarios. [ABSTRACT FROM AUTHOR]

The data layer devices in the Software Defined Network (SDN) play an important role in packet forwarding. However, whether the forwarding task can be efficiently completed by the node has not attracted enough attention. A method called TrustBlock is proposed in this paper, which introduces trust as a security attribute in SDN routing planning. Besides, in order to enhance the integrity and controllability of trust evaluation, the double-layer blockchain architecture is established. In the first layer, the behavior data of the node is recorded, and then the trust calculation is performed in the second layer. In the evaluation model, nodes' trust is calculated from three aspects: direct trust, indirect trust and historical trust. Firstly, from the perspective of security, blockchain is used to achieve identity authentication of nodes, after that, from the perspective of reliability, the forwarding status is used to calculate the trust value. Secondly, consensus algorithm is used to filter malicious recommendation trust value and prevent colluding attacks. Finally, the adaptive historical trust weight is designed to prevent the periodic attack. In this paper, the entropy method is used to determine the weight of each evaluation attribute, which can avoid the problem that the subjective judgment method is not adaptable to the weight setting. Simulation results show that the detection rate of the TrustBlock is up to 98.89%, which means this model can effectively identify the abnormal nodes in SDN. Moreover, it is attractive in terms of integrity and controllability. [ABSTRACT FROM AUTHOR]

Rice paddies are a significant source of atmospheric methane (CH 4) threatening global warming. Methane fluxes from rice soils are mediated by both methanogens and methanotrophs, while subject to fertilization regimes. A field experiment was conducted to investigate the response of CH 4 emissions, with a close link to methanogenic and methanotrophic communities, to different fertilization strategies over two consecutive rice growing seasons in a paddy field. Four fertilized treatments were established consisting of chemical phosphorous (P) and potassium (K) fertilizer (PK), chemical nitrogen (N) PK fertilizer (NPK), chemical NPK combined with organic manure (NPKM), and organic manure alone (M). Results showed that, relative to chemical PK treatment without N fertilizer input, the application of chemical NPK fertilizer, manure, and their combination significantly increased seasonal mean CH 4 emissions by 67.4, 20.4 and 101.2%, respectively. Methane fluxes were significantly and positively (r 2 = 0.75) related to mcrA gene copy numbers and the ratio of mcrA / pmoA , while negatively (r 2 = 0.40) related to pmoA gene copy numbers, which was mainly regulated by the dynamics of water irrigation regime. The abundance of mcrA and pmoA had trade-off relationship over the rice growing season. In comparison with PK fertilization, N fertilized treatments did not alter the seasonal trend of CH 4 fluxes, but enhanced the source strength of CH 4 emissions through increased mcrA abundances rather than reduced pmoA -dominated methanotrophic CH 4 oxidation in rice paddies. In contrast, N fertilization showed no effect on pmoA abundance and associated methanotrophic community in rice paddies. Results highlight that, given the fertilizer-driven balance between methanogenic and methanotrophic communities, fertilization options with either chemical or organic N input stimulated CH 4 emissions mainly through improving soil C substrate and methanogenic activities, especially under the combination of chemical and organic N fertilization in rice paddies. • Methane fluxes were most enhanced by combination of chemical and organic N fertilization. • Methane fluxes were positively related to abundance of mcrA and its ratio to those of pmoA. • The abundance of mcrA and pmoA had an obvious seasonal trade-off relationship. • Long-term N fertilization increased abundances of mcrA rather than those of pmoA. • The methanogenic community was largely altered under long-term organic N fertilization. [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]

Conventional and bio-organic fertilizers play an important role in maintaining soil health and promoting crop growth. However, the effect of organic fertilizers on the prevalence of antibiotic resistance genes (ARGs) in the vegetable cropping system has been largely overlooked. In this study, we investigated the impacts of soil properties and biotic factors on ARG profiles by analyzing ARG and bacterial communities in vegetable copping soils with a long-term history of manure and bio-organic fertilizer application. The ARG abundance in the soil was significantly increased by 116% with manure application compared to synthetic NPK fertilizer application. This finding was corroborated by our meta-analysis that the longer the duration of manure application, the greater the response of increased soil ARG abundance. However, bio-organic fertilizers containing Trichoderma spp. Significantly reduced ARG contamination by 31% compared to manure application. About half of the ARG variation was explained by changes in bacterial abundance and structure, followed by soil properties. The mitigation of ARG by Trichoderma spp. Is achieved by altering the structure of the bacterial community and weakening the close association between bacteria and ARG prevalence. Taken together, these findings shed light on the contribution of bio-organic fertilizers in mitigating ARG contamination in agricultural soils, which can help manage the ecological risk posed by ARG inputs associated with manure application. [Display omitted] • Manure application significantly enhanced the abundance of ARGs in vegetable soils. • Bio-organic fertilizer with Trichoderma decreased the proliferation of ARGs in the soil. • Bacterial abundance and structure and soil properties drive ARG profiles. • Trichoderma loosened bacterial community structure and weakened the link between bacteria and ARG. [ABSTRACT FROM AUTHOR]

• Agricultural ditches were significant sources of GHGs. • Ditches adjacent to farmlands observed high GHG concentrations and emissions. • Nutrient input was the primary driver stimulating GHG production and emissions. • GHG emissions from agricultural ditches should be incorporated into regional and global estimations. Agricultural ditches are pervasive in agricultural areas and are potential greenhouse gas (GHG) hotspots, since they directly receive abundant nutrients from neighboring farmlands. However, few studies measure GHG concentrations or fluxes in this particular water course, likely resulting in underestimations of GHG emissions from agricultural regions. Here we conducted a one-year field study to investigate the GHG concentrations and fluxes from typical agricultural ditch systems, which included four different types of ditches in an irrigation district located in the North China Plain. The results showed that almost all the ditches were large GHG sources. The mean fluxes were 333 μmol m-2 h-1 for CH 4 , 7.1 mmol m-2 h-1 for CO 2 , and 2.4 μmol m-2 h-1 for N 2 O, which were approximately 12, 5, and 2 times higher, respectively, than that in the river connecting to the ditch systems. Nutrient input was the primary driver stimulating GHG production and emissions, resulting in GHG concentrations and fluxes increasing from the river to ditches adjacent to farmlands, which potentially received more nutrients. Nevertheless, the ditches directly connected to farmlands showed lower GHG concentrations and fluxes compared to the ditches adjacent to farmlands, possibly due to seasonal dryness and occasional drainage. All the ditches covered approximately 3.3% of the 312 km2 farmland area in the study district, and the total GHG emission from the ditches in this area was estimated to be 26.6 Gg CO 2 -eq yr−1, with 17.5 Gg CO 2 , 0.27 Gg CH 4 , and 0.006 Gg N 2 O emitted annually. Overall, this study demonstrated that agricultural ditches were hotspots of GHG emissions, and future GHG estimations should incorporate this ubiquitous but underrepresented water course. [Display omitted] [ABSTRACT FROM AUTHOR]

Oncolytic virotherapy is a new and safe therapeutic strategy based on the inherent cytotoxicity of oncolytic viruses and their ability to replicate and spread within tumors in a selective manner. In a previous study, a new type of oncolytic herpes simplex virus type 2 (oHSV-2, named OH2) was constructed to treat human cancers. That study demonstrated that OH2 is genetically and biologically stable. Its antitumor activity was maintained, even after passaging the virus for >20 generations. To advance OH2 into a clinical trial, a systematic preclinical safety evaluation was performed, which included: an acute toxicity test of OH2 in BALB/c mice; repeated dose toxicity tests of OH2 in BALB/c mice and cynomolgus monkeys; and biodistribution assays of OH2 in BALB/c mice, tumor-bearing mice, tumor-bearing nude mice, and cynomolgus monkeys. The results of this preclinical safety evaluation of OH2 indicate that OH2 is safe and suitable for clinical trials. [ABSTRACT FROM AUTHOR]

Highlights • Biochar amendment reduced annual emission factor of N fertilizer for N 2 O + NO. • The ratio of NO-N/N 2 O-N was negatively correlated with soil water content. • Biochar enhanced the negative response of NO-N/N 2 O-N ratio to soil moisture. • Biochar rate of 20 t ha−1 gained the lowest N 2 O and NO emissions. Abstract Biochar impact on soil nitrous oxide (N 2 O) and nitric oxide (NO) emissions from intensive greenhouse vegetable cropping systems is not well established. Annual soil N 2 O and NO emissions were simultaneously measured from a typical greenhouse vegetable field treated with different biochar application rates in southeast China. Both N 2 O and NO emissions differed greatly across the individual vegetable cropping seasons, of which being higher in green soybean and tomato growing seasons, respectively. Over the annual vegetable cropping rotation, biochar amendment decreased soil N 2 O and NO emissions by 10–23% and 18–19% relative to N fertilization alone, respectively. Biochar rate of 20 t ha−1 gained the lowest N 2 O and NO emissions over the annual cycle. The ratio of NO/N 2 O was negatively correlated with soil moisture and depends on biochar addition or not. On average, annual emission factor (EF) of N 2 O and NO combined was accounted for 2.13% with biochar amendment, which was decreased by 22% compared with N fertilization alone (EF = 2.74%). Vegetable yield was significantly enhanced under the biochar combined with N fertilizer plots relative to control, while there is no difference among the N fertilization treatments with or without biochar amendment. Therefore, biochar could be used as an effective management mitigating soil N 2 O and NO emissions while maintaining crop yield in greenhouse vegetable cropping systems in southeast China. [ABSTRACT FROM AUTHOR]