Nitrogen fertiliser-domesticated microbes change the persistence and metabolic profile of atrazine in soil

Pesticides and fertilisers are frequently used and may co-exist on farmlands. The overfertilisation of soil may have a profound influence on pesticide residues, but the mechanism remains unclear. The effects of chemical fertilisers on the environmental behaviour of atrazine and their underlying mechanisms were investigated. The present outcomes indicated that the degradation of atrazine was inhibited and the half-life was prolonged 6.0 and 7.6 times by urea and compound fertilisers (NPK) at 1.0 mg/g (nitrogen content), respectively. This result, which was confirmed in both sterilised and transfected soils, was attributed to the inhibitory effect of nitrogen fertilisers on soil microorganisms. The abundance of soil bacteria was inhibited by nitrogen fertilisers, and five families of potential atrazine degraders (Micrococcaceae, Rhizobiaceae, Bryobacteraceae, Chitinophagaceae, and Sphingomonadaceae) were strongly (R > 0.8) and positively (sig < 0.05) related to the decreased functional genes (atzA and trzN), which inhibited hydroxylation metabolism and ultimately increased the half-life of atrazine. Nitrogen fertilisers decreased the sorption and vertical migration behaviour of atrazine in sandy loam, which might have increased the in situ residual toxicity and ecological risk of atrazine. Our findings verified the weakened atrazine degradation with nitrogen fertilisers, providing new insights into the potential risks and mechanisms of atrazine in the context of excess fertilisation.