title: Combined effects of two sulfonylurea herbicides on soil microbial biomass and N-mineralization.
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), 0.01 and 0.01 (B1M1), 0.01 and 0.1 (B1M2), and 0.01 and 1.0 (B1M3) microgram/g soil. Determinations of soil microbial biomass-C, N and N-mineralization 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 (Cmic) and microbial biomass-N (Nmic) decreased consistently with the increasing rates of herbicides. The results further indicated that B1M1 and B1M2 caused a significant reduction in Cmic and Nmic within first 10 and 7 days of incubation, respectively, as compared with the control. These reductions in Cmic and Nmic were also significant (P = 0.05) with B1M3 application especially within first 15 days 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.
authors.affiliation: College of Natural Resources and Environmental Sciences, Zhejiang University, Hangzhou 310029, China.
authors.forename: A M
authors.initials: AM
authors.lastname: el-Ghamry
authors.forename: C Y
authors.initials: CY
authors.lastname: Huang
authors.forename: J M
authors.initials: JM
authors.lastname: Xu
mesh_terms: D000704:Analysis of Variance; D001190:Arylsulfonates / Q000494:pharmacology*; D018533:Biomass; D002244:Carbon / Q000032:analysis; D004347:Drug Interactions; D006540:Herbicides / Q000494:pharmacology*; D008903:Minerals; D009584:Nitrogen / Q000032:analysis; D012987:Soil / Q000032:analysis; D012988:Soil Microbiology; D013453:Sulfonylurea Compounds / Q000494:pharmacology*
chemical_list: D001190:Arylsulfonates; D006540:Herbicides; D008903:Minerals; D012987:Soil; D013453:Sulfonylurea Compounds; C050296:metsulfuron methyl; D002244:Carbon; C071475:methyl bensulfuron; D009584:Nitrogen