|Knight, Charlie - STATE OF ALASKA|
Submitted to: Arctic Institute of North America
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 26, 2005
Publication Date: September 1, 2005
Citation: Sharratt, B.S., Knight, C.W. 2005. Dissipation of Bromide and Metribuzin Affected by Tillage and Crop Residue Management in Subarctic Alaska. Arctic Institute of North America. Vol. 58, No. 3 (September 2005) P.260–267 Interpretive Summary: Prudent use of agricultural chemicals is paramount for sustaining or improving surface and ground water quality, but virtually no information is available that documents the fate of chemicals on agricultural lands in the subarctic region of North America. Loss of spring-applied or autumn-applied bromide (a surrogate for nitrate) from a level subarctic soil sown to barley annually was not influenced by tillage practices, but loss of bromide was accentuated as a result of leaching over winter. Tillage practices influenced the loss of metribuzin from the soil profile; loss was accentuated as a result of faster degradation in conventional or reduced (disk once) tillage as compared with no tillage. This study suggests that farmers should apply agricultural chemicals in the spring to reduce the risk of chemical loss and thereby preserve water resources and wildlife habitat in subarctic regions.
Technical Abstract: Prudent use of agricultural chemicals is paramount for sustaining or improving surface and ground water quality. Little information is available, however, that documents the fate of chemicals on agricultural lands in the subarctic. This study was undertaken to ascertain the fate of solutes and herbicides in a level subarctic soil sown to barley annually and subject to various tillage practices. Bromide (a surrogate for nitrate) and metribuzin were applied in the autumn of 1996 and the spring of 1997 to a silt loam subject to conventional (CT), disk once (DO), and no tillage (NT). The fate of these chemicals was ascertained by periodic sampling of the soil profile until September 1998. Tillage treatments did not influence the recovery of autumn-applied or spring-applied bromide (Br). Recovery of Br, however, diminished with time. Approximately 30 and 45% of the Br applied in autumn and spring, respectively, remained in the soil profile by September 1998. Thus, from 55-70% of Br applied to the soil was lost as a result of leaching or plant uptake. Tillage treatments influenced the recovery of metribuzin; at the termination of this study, recovery was greater in NT as a result of slower degradation in NT than in CT and DO. This study suggests applying agricultural chemicals in the spring to reduce the risk of loss in subarctic environments.