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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]

The fruit has become the third-largest agricultural planting industry after cereals and vegetables in China. Fertilization regimes (e.g., application rate and method) in fruit orchards typically differ from cereal croplands, which would incur a pronounced difference in fertilizer-induced nitrous oxide (N 2 O) emissions between them. However, fertilizer-induced direct N 2 O emissions from orchard fields remain poorly understood. We conducted a field experiment in a peach orchard and a global meta-analysis of N 2 O emissions from fruit orchards. The emission factor (EF) of fertilizer N for N 2 O averaged 0.81%, with a background N 2 O emission of 3.4 kg N ha–1 yr-1 in our field study. A global meta-analysis suggested that the linear regression model was the best to fit N 2 O emissions by fertilizer N input for most fruit types compared to the nonlinear models. When averaging all global data, the linear model projected the EF of N 2 O from orchards to be 0.84%, with the background emission of 1.96 kg N ha–1. The estimate of direct N 2 O derived from the orchard-specific nonlinear model was substantially lower than those from the nonlinear model with global cropland measurements. The fertilizer-induced direct N 2 O emission from Chinese orchards during the 2000s was estimated to be 32–49 Gg N yr–1, equivalent to about 14% of total direct N 2 O emissions from Chinese uplands. Therefore, orchard cultivation constitutes a hotspot of N 2 O emissions in the agricultural sector, and priority should be given to emissions reduction to achieve the transition to climate-smart agriculture. [Display omitted] • N 2 O emissions from global orchards were summarized and meta-analyzed. • N 2 O emission was 32–49 Gg N yr–1 from Chinese orchards during the 2000s. • Orchard cultivation is one of the hotspots of agricultural N 2 O emissions. • Orchard N 2 O emissions were similar to emissions from vegetables and tea cultivation. [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]

Tailoring agricultural practices to enhance the soil carbon (C) stock is seen as a promising mitigation tactic to offset greenhouse gas (GHG) emissions in croplands. Tea plantations are not only the important part of economic industry but also one of the crucial agricultural sources of non-carbon dioxide emissions. Although many studies have measured GHG emissions from tea plantations, it remains unknown about the effect of knowledge-based mitigation options on the entire C budget from Chinese rapidly expanding tea plantations. Thus, we carried out a 2-year field trial to provide an insight into the influence of organic fertilizer substitution for synthetic fertilizer and biochar amendment on net ecosystem carbon budget (NECB), net greenhouse gas budget (NGB), and yield-scaled greenhouse gas intensity (GHGI) from a subtropical tea plantation. Results showed that when averaged a 2-year experimental period, both full organic substitution and biochar amendment contributed significantly to the increment in NECB, mainly due to the enhanced soil organic C content in the tea field. Compared with the conventional farm practice, the application of full organic substitution can induce a 52% decrease in both NGB and GHGI. Regardless of fertilizer type, both NGB and GHGI were negative and 2.4 times lower in the treatments with biochar amendment relative to the control. In addition to their roles in maintaining soil health and alleviating soil acidification, our results suggest that organic fertilizer substitution and biochar addition may achieve low carbon development for tea plantations. Our findings will inform efforts to implement and evaluate these tailored mitigation options in tea plantations at a national scale. • The net greenhouse gas budget was assessed in a tea plantation over two years. • Organic substitution and biochar amendment decreased net greenhouse gas budget. • Organic substitution and biochar contributed to lowering yield-scaled emission. [ABSTRACT FROM AUTHOR]