Effect of fungicides on soil respiration, microbial community, and enzyme activity: A global meta-analysis...

Fungicides effectively prevent and control crop diseases caused by microorganisms; however, they also unintentionally affect soil microorganisms and enzyme activity. This study conducted a meta-analysis of 73 published studies to investigate the effects of fungicide application concentration and duration on soil respiration, microbial diversity, and enzyme activity. Increasing the concentration of fungicide application significantly reduced soil basal respiration and microbial carbon, with inhibitory effects reaching 1.45 % and 7.37 %, respectively, at 5 times the recommended application rate. The application of fungicides significantly reduced the activities of alkaline phosphatase, neutral phosphatase, acid phosphatase, dehydrogenase, and urease, with the activities of alkaline phosphatase and urease decreasing by 15.43 % and 7.76 %, respectively. Additionally, the application of fungicides significantly reduced fungi, actinomycetes, Shannon index, Simpson index, and McIntosh index while not affecting bacterial diversity. When the fungicide concentration is at 0-1 times, 1-5 times, and > 5 times, the number of fungi decreases by 14.53 %, 19.91 %, and 33.81 %, respectively. Temporally, soil basal respiration and microbial carbon significantly declined in the first 0-21d after fungicide application, but no such inhibitory effect was observed after 21d. Even 56 days after using the fungicide, it inhibited the activities of alkaline phosphatase and catalase by 13.14 % and 7.13 %, respectively. As time after the application of fungicides increases, the number of fungi decreases significantly, while the number of actinomycetes gradually recovers. Overall, fungicides inhibit the abundance, diversity, and enzyme activity of soil microorganisms; however, precise control of fungicide dosage is essential to minimize their toxic effects on soil.