Impacts of soil type on the temporal dynamics of antibiotic resistance gene profiles following application of composted manure.

Farmland application of composted manure is associated with a risk of dissemination of antibiotic resistance genes (ARGs) in agricultural soils. However, the impact of soil type on the temporal dynamics of ARGs in agricultural soil remains largely unclear. The aims of this study were to study the persistence of composted manure-derived ARGs in six soil types representative for Chinese agriculture and to explore the underlying environmental drivers of soil ARG profiles in a controlled greenhouse experiment. Temporal dynamics of manure-derived ARGs was strongly affected by soil type. High persistence of fertilizer-derived ARGs was evident in red soil, yellow soil and sierozem soil, while a rapid decrease to near pre-fertilization levels (low persistence) was observed in yellow-brown soil, black soil and brown earth soil. The distribution of ARGs was linked to soil properties such as soil texture, pH and concentrations of heavy metals. More complex co-occurrence networks of ARGs and bacteria in red soil, yellow soil, and sierozem soil suggested a higher dissemination potential, which was consistent with the significantly increased abundance of MGEs in these three types of soils. Our findings highlight the necessity for developing tailored fertilization strategies for different soil types to mitigate environmental dissemination of ARGs.