[Impacts of Fertilization on Soil Antibiotic Resistance Genes Across Croplands: A Meta-Analysis]

The objective of this study was to clarify and quantify the impact of fertilizer applications on antibiotic resistance genes (ARGs) in cropland soil. The target was to provide scientific basis for a better understanding of the source and accumulation and transportation characteristics of ARGs in soil and adaptive management strategy-making to secure the ecological environment and human health safety. By collecting data from literature published within the last 20 years (2000-2020), we established a database with 215 and 201 groups of a paired data-set consisting of the quantity and relative abundance of ARGs under independent experimental conditions. Compared to that with no fertilizer, the combined application of organic fertilizer significantly increased the quantity and relative abundance of soil ARGs by 110.0% and 91.0%, respectively. However, chemical fertilization had no significant effect on soil ARGs. The increment of relative abundance of soil ARGs by the combined application of organic fertilizer in the subtropical region was equivalent to 2.6 times that in the warm temperate zone. Compared with that in black soil and dark brown soil, the combined application of organic fertilizer significantly increased the relative abundance of ARGs in red soil and paddy soil in the subtropical region. The increment for the quantity of ARGs (147.6%) by the combined application of organic fertilizer in soil with pH<7 was significantly higher than that in soil with pH>7(110.4%). Compared to poultry manure, livestock manure application significantly increased the quantity and relative abundance of ARGs. The increment of the relative abundance of organic fertilizer to sulfonamide, multidrug, and macrolide ARGs (170.5%-201.2%) was significantly higher than that of quinolone, tetracycline, and aminoglycoside ARGs (61.5%-115.6%). After more than 10 years of applying organic fertilizer, the quantity of soil ARGs significantly increased by 104.2%-112.3%, whereas the effect on the relative abundance was uncertain. Climate, soil spatial properties, and source and amount of organic fertilizer were the main factors affecting the accumulation of ARGs in farmland soil. Management strategies and solutions should pay more attention to effectively minimizing the accumulation and spread of ARGs in agro-ecosystems for high-quality agricultural development in the future.