Three-year cattle manure application does not induce the proliferation of antibiotic resistance genes in vegetable soil

Increasing cattle manure application did not significantly increase soil ARGs.Cattle manure application exceeded a greater effect on soil beta diversity.The intl1 gene played a crucial role in facilitating the dissemination of ARGs.The application of cattle manure may significantly burden the reservoir of antibiotic resistance genes (ARGs) in agricultural soils, necessitating careful consideration. A 3-year field experiment was conducted to investigate the distribution characteristics of ARGs and bacterial communities in soil with different levels of cattle manure application, encompassing five distinct amounts of cattle manure: Control (0 t hm-2), M1 (35.28 t hm-2), M2 (68.62 t hm-2), M3 (102.87 t hm-2), and M4 (137.23 t hm-2). Applying varying rates of cattle manure slightly increased the abundance of tetracycline and sulfonamide resistance genes in vegetable fields, posing a potential risk of soil contamination with these genes. As the amount of cattle manure fertilization increased, soil bacterial 16S rRNA gene abundance gradually increased, however, the Shannon index and OTUs did not differ significantly among varying rates of cattle manure fertilization. PCoA plot based on Bray-Curtis revealed that soil bacterial community structure significantly differed between cattle manure treatments and Control. No significant difference was found for physicochemical indicators among various cattle manure treatments. In addition, the intl1 gene was significantly and positively correlated with sul1, sul2, and tetL genes, indicating that the intl1 played a crucial role in the proliferation of certain ARGs. These findings enhance our understanding of the impacts of varying rates of cattle manure fertilization on the prevalence of ARGs in vegetable fields, and assist in developing effective strategies to mitigate their spread.