Affiliations: College of Natural Resources and Environmental
Sciences, Zhejiang University, Hangzhou 310029, China
Note:  Corresponding author
Abstract: The interaction effect of two sulfonylurea herbicides,
bensulfuron-methyl (B) and metsulfuron-methyl(M), were tested on microbial
biomass C, N, N-mineralization and C/N ratio in a loamy sand soil. The
herbicides were applied at various levels of: control (B0M0), 0.01and 0.01
(B1M1), 0.01 and 0.1 (B1M2), and 0.01 and 1.0 (B1M3) µg/g soil.
Determinations of soil microbial biomass-C, N and Nmineralization contents were
carried out at 1, 3, 5, 7, 10, 15, 25 and 45 days after herbicides application.
The results showed that the soil microbial biomass-C (C_mic) and microbial
biomass-N (N_mic) decreased consistently with the increasing rates of
herbicides. The results further indicated that B1M1 and B1M2 caused a
significant reduction in C_mic and N_mic within first 10 and 7 days of
incubation, respectively, as compared with the control. These reductions in
C_mic and N_mic were also significant ( P = 0.05) with B1M3 application
especially within first 15days of incubation. A significant reduction in
N-mineralization (N-min) was observed with high doses (B1M2, B1M3 ) of
herbicides within first 5 days of incubation, while low rate (B1M1) failed to
produce any significant effect. An increase in the soil microbial biomass C:N
ratio was also noted.