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Context. Overuse of N fertiliser in vegetable cropping systems is known to release of nitric and nitrous oxide to the atmosphere in China. Optimisation of N fertilisation regimes has the potential to mitigate NO and [N.sub.2]O emissions from these N-rich systems. Aims. We investigated the effects of different N fertilisation regimes on NO and [N.sub.2]O emissions, and vegetable yields, with particular efforts to estimate annual direct emission factors of NO and [N.sub.2]O under different N fertilisation regimes in greenhouse vegetable fields. Methods. Annual NO and [N.sub.2]O fluxes were taken simultaneously using the static chamber-based method from a greenhouse vegetable system in south-east China with four N fertiliser treatments: (I) no N fertiliser (control); (2) chemical N fertiliser application (CF); (3) organic N fertiliser application (OF); and (4) organic-chemical mixed N fertiliser application (MF). Key results. N fertilisers significantly increased NO and [N.sub.2]O emissions. Direct emission factors of N fertiliser for NO and [N.sub.2]O were the largest for MF, with an average of 0.99% and 0.67%, respectively. Vegetable yields were only significantly enhanced under OF treatment. Conclusions. Relative to the use of chemical N fertiliser, the application of organic-chemical mixed N fertiliser showed not to be effective for mitigating NO and [N.sub.2]O emissions. Instead, sole application of organic N fertiliser was a viable option to enhance vegetable yields but without increasing NO and [N.sub.2]O emissions in greenhouse vegetable systems. Implications. Substituting the use of chemical N fertiliser with organic N fertiliser input could benefitvegetable production but without stimulating NO and [N.sub.2]O emissions from vegetable cropping systems in sub-tropical China. Keywords: emissions factor, greenhouse vegetable field, nitric oxide, nitrous oxide, NO/[N.sub.2]O ratio, organic fertiliser, vegetable yields, WFPS., Introduction Nitric (NO) and nitrous oxide ([N.sub.2]O) are two trace gases that play critical roles in global nitrogen cycle. Both NO and [N.sub.2]O are involved in atmospheric photochemistry processes and [...]

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]

Simple Summary: Porcine circovirus (PCV) is widespread in the world and causes huge economic losses to the pig industry. Recently, the infection rates of PCV2 and PCV3 have been increasing year by year in China, and a new type of virus, PCV4, discovered in 2019, was found to result in complex pathogenic infection. In this study, a TaqMan-probe-based multiplex real-time PCR (qPCR) assay was developed for the differential detection of PCV2, -3, and -4. A total of 535 clinical samples from Shandong, Zhejiang, Jiangsu, and Anhui provinces, East China, were included in the analyses to evaluate the application of multiplex qPCR. The resulting data showed that the individual positive rates of PCV2, PCV3, and PCV4 were 35.33%, 40.37%, and 33.08%, respectively; the mixed infection rates of PCV2 and PCV3, PCV2 and PCV4, and PCV3 and PCV4 were 31.03%, 30.09%, and 30.84%, respectively; the mixed infection rate of the three viruses was 28.22%. The developed assay showed extreme specificity, high sensitivity, and excellent reproducibility for the simultaneous detection and differentiation of three porcine circovirus types. Porcine circovirus disease (PCVD) caused by porcine circovirus (PCV) is an important swine disease that is characterized by porcine dermatitis, nephropathy syndrome, and reproductive disorders in sows. However, disease caused by PCV2, PCV3, or PCV4 is hard to distinguish, so a rapid and sensitive detection method is urgently needed to differentiate these three types. In this study, four pairs of specific primers and the corresponding probes for PCV 2, -3, and -4, and porcine endogenous gene β-Actin as the positive internal reference index, were designed to establish a TaqMan multiplex real-time PCR (qPCR) assay for the simultaneous differential diagnosis of different types of viruses. The results showed that this assay has good specificity and no cross-reactivity with other important porcine viral pathogens. Furthermore, it has high sensitivity, with a detection limit of 101 copies/μL, and good reproducibility, with intra- and inter-group coefficients of variation below 2%. Subsequently, 535 clinical samples of suspected sow reproductive disorders collected from Shandong, Zhejiang, Anhui, and Jiangsu provinces from 2020 to 2022 were analyzed using the established assay. The results showed that the individual positive rates of PCV2, PCV3, and PCV4 were 31.03%, 30.09%, and 30.84%, respectively; the mixed infection rates of PCV2 and PCV3, PCV2 and PCV4, and PCV3 and PCV4 were 31.03%, 30.09%, and 30.84%, respectively; the mixed infection rate of PCV2, PCV3, and PCV4 was 28.22%. This indicated that this assay provides a convenient tool for the rapid detection and differentiation of PCV2, PCV3, and PCV4 in pig farms in East China. Our findings highlight that there are different types of porcine circovirus infection in pig farms in East China, which makes pig disease prevention and control difficult. [ABSTRACT FROM AUTHOR]