Effects of repeated applications of fungicide carbendazim on its persistenceand microbial community in soil
YU Yunlong , CHU Xiaoqiang , PANG Guohui , XIANG Yueqin , FANG Hua
DOI:
Received March 10, 2008,Revised May 28, 2008, Accepted , Available online
Volume 21,2009,Pages 179-185
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Carbendazim, a systemic benzimidazole fungicide, is applied repeatedly to control plant diseases including soilborne diseases, over
a growing season. Studies were carried out under laboratory conditions to assess the e ects of repeated carbendazim applications
on its persistence and microbial community in soil. The results indicate that dissipation of carbendazim in soil was accelerated with
its application frequency. The degradation rate constant of carbendazim was increased significantly from 0.074 d??1 to 0.79 d??1. The
corresponding half-life was shorten markedly from 9.3 d to 0.9 d after four repeated applications. No significant inhibitory e ect of
carbendazim on soil microbial utilization of the carbon sources was observed after first treatment, but a slight increase in average well
color development (AWCD) was shown after second, third, and fourth applications. It suggested that soil microorganisms become
adapted to carbendazim after repeated application. Simpson and Shannon indexes of soil microbial community from carbendazim
treated soil were also similar to those from the control soil, indicating that the richness and dominant character of soil microorganisms
remain unchangeable after repeated application. However, after first, second, and third addition of carbendazim, McIntosh indexes on
day 21 were significantly higher compared with the control, suggesting that balance of soil microorganisms was altered due to the
enrichment of the specific carbendazim-adapting strains in soil.
