Wheat Strip Effects on Microbial Transport Following Variable Applications of Beef Cattle Manure

摘要

Vegetative filter strips (VFS) consisting of perennial vegetation have been successfully used to reduce the transport of contaminants in runoff from land application areas. The effectiveness of a winter wheat strip, which may be more acceptable to producers, in reducing microbial transport was examined in this study. A 1.4 m wheat strip was used to allow direct comparison with experimental results obtained in previous studies. Beef cattle manure was applied to 0.75 m wide by 4.0 m long plots established on an Aksarben silty clay loam located in southeast Nebraska. Manure was added at rates required to meet the 0- 1-, 2-, or 4-year phosphorus requirement for corn. The transport of selected microbes was measuredfor three 30 min simulated rainfall events separated by 24 h intervals. The narrow wheat strip did not significantly reduce counts of any of the measured microbes. The application of manure to meet the 4-year P requirement resulted in E. coli and enterococci loads that were significantly greater than the 1-year P requirement. Rainfall simulation run significantly affected measurements of phages, total coliforms, E. coli, and enterococci, with measurements during the three runs varying from 9.35 to 10.9 log plaque-forming units (PFU) ha'1, from 11.5 to 12.1 log colony-forming units (CFU) ha'1, from 12.1 to 12.5 log CFU ha'1, and from 11.1 to 11.4 log CFU ha'1, respectively. The transport ofE. coli was found to be significantly correlated to selected nutrient loads and electrical conductivityof runoff. The presence of narrow wheat strips did not reduce microbial loads in runoff.