Microencapsulation alters pyraclostrobin degradation and reshapes soil microbial communities compared to conventional...

Microencapsulated pyraclostrobin (PYR-CS) has gained widespread adoption in agriculture owing to its extended efficacy and reduced risks for non-target organisms. However, knowledge remains limited regarding its degradation in soil and effects on soil microorganisms.

This study investigates the hypothesis that microencapsulation alters pyraclostrobin degradation and reshapes soil microbial communities compared with conventional formulations, including emulsifiable concentrate (PYR-EC) and technical material (PYR-TC).

We investigated the degradation behavior of three pyraclostrobin formulations-PYR-CS, PYR-TC, and PYR-EC-in five distinct soil types using LC-MS analysis. The influence of soil sterilization, moisture content, and temperature on degradation rates was systematically assessed. To evaluate formulation-induced microbial shifts, 16S rRNA sequencing was conducted, followed by PCoA, taxonomic composition analysis, LEfSe, and co-occurrence network analyses.

The results showed that PYR-CS had a significantly longer degradation period in soil, likely due to the microencapsulation barrier that prevents direct microbial contact until the capsules rupture and release the active ingredient. The study further revealed that elevated temperatures and low soil moisture accelerated PYR-CS degradation, suggesting that these factors may promote the rupture of microcapsules in soil. Analysis of 16S rRNA sequencing data revealed that PYR-CS treatment induced changes in the composition of soil microbial communities. Specifically, a significant increase in the relative abundance of Chloroflexi and Planctomycetota was observed at 21 days. In contrast, PYR-EC and PYR-TC caused notable short-term changes in microbial composition and structure but lacked lasting effects.

These findings offer critical insights into the soil ecological risks of microencapsulated pesticides from the perspective of formulation-degradation behavior-microbial interactions, providing a critical theoretical foundation for precisely formulating environmentally-friendly pesticide application strategies.