Biodegradable film drip fertigation is more conducive to reducing the diversity and abundance of antibiotic resistance genes than plastic film drip fertigation

Background and aims

Mulching drip fertigation can effectively increases crop yields. However, with the insufficient recycling rate of mulch films and the continuous accumulation of film residues in the soil, mulch film residues and antibiotic resistance genes (ARGs) coexist in farmland. The impact of biodegradable mulch films on the reduction of soil ARGs remains uncertain.

Methods

This study employed high-throughput sequencing and high-throughput quantitative PCR (HT-qPCR) to examine the effects of three drip fertigation systems (drip fertigation without film (DI), drip fertigation with biodegradable film (DF), and drip fertigation with plastic film (PF) on bacteria and ARGs in farmland soils.

Results

The results indicated that compared with DI, mulched drip irrigation significantly reduced bacterial abundance and diversity (DI > DF > PF) but increased the abundance of ARGs and mobile genetic elements (MGEs) (PF > DF > DI). The ARG network structure in PF was more complex compared to DI and DF, whereas in DF, the ARG network structure was more stable compared to DI and PF. The abundance of MGEs directly influenced the abundance of ARGs, and the MGEs abundance was directly affected by the bacterial Shannon index, which also indirectly affected ARG abundance. Special attention was given to the impact of drip irrigation with different mulch films on ARG dissemination, emphasizing that biodegradable mulch films effectively reduce ecological risks compared to traditional plastic films.

Conclusions

In summary, although DF showed higher bacterial diversity than PF, it also reduced both the diversity and abundance of ARGs, thereby further decreasing soil ARG levels. This study provides new perspectives and scientific evidence for understanding the environmental dissemination mechanisms of ARGs and offers actionable recommendations for sustainable agricultural management, such as reducing mulch residue pollution and optimizing drip fertigation practices.

Graphical Abstract