Effects of soil storage on the microbial community and degradation of metsulfuron-methyl.
The effect storage had on the microbial biomass in two soils (Trevino and Fargo) was compared to the effect storage had on each soil's capacity to degrade metsulfuron-methyl. Soils were collected from the field and used fresh (<3 weeks old) or stored at 20 and 4 degrees C for 3 or 6 months. The phospholipid fatty acid content of the soils was used to monitor changes in the microbial biomass during storage and incubation in a flow-through apparatus. In both soils, [phenyl-U-14C]metsulfuron-methyl was used to monitor changes in the route and rate of degradation along with 14CO2 evolution (mineralization). Total microbial biomasses in both soils were significantly reduced for soils incubated in the flow-through apparatus, whereas only the Trevino soil's microbial biomass was significantly reduced as a result of storage. The microbial communities of both soils were significantly different as a result of storage as shown by discriminant analysis. In both soils, degradation rate, pathway of degradation, and mineralization of metsulfuron-methyl were significantly affected by storage compared to fresh soil. The half-life of metsulfuron-methyl increased significantly (P < 0.05) in the Trevino soil from 45 days (fresh) to 63 days (stored soil), whereas in the Fargo soil half-lives increased significantly (P < 0.05) from 23 days (fresh) to 29 days (soils stored for 6 months). In both soils, mineralization of [14C]metsulfuron-methyl was significantly (P < 0.05) higher in fresh soils compared to stored soils. The degradation pathways of metsulfuron-methyl changed with storage as evidenced by the loss of formation of one biologically derived metabolite (degradate) in stored soils compared to fresh soils.
Trabue
Steven L
SL
National Soil Tilth Laboratory, Agricultural Research Service, U.S. Department of Agriculture, 2150 Pammel Drive, Ames, Iowa 50011, USA. trabue@nsric.ars.usda.gov
Palmquist
Debra E
DE
Lydick
Tara M
TM
Singles
Suzanne Koch
SK
D001190:Arylsulfonates / Q000378:metabolism*; D005227:Fatty Acids / Q000032:analysis; D010575:Pesticides / Q000378:metabolism; D010743:Phospholipids / Q000032:analysis; D012987:Soil / Q000032:analysis; D012988:Soil Microbiology
D001190:Arylsulfonates; D005227:Fatty Acids; D010575:Pesticides; D010743:Phospholipids; D012987:Soil; C050296:metsulfuron methyl