Managing nitrate and bacteria in runoff from livestock confinement areas with vegetative filter strips

ABSTRACT:

A documented source of nitrate-nitrogen contamination of surface water is livestock waste and storage facilities. A vegetative filter strip (VFS) is effective in reducing some nutrients, sediment, and suspended solid in surface runoff from feedlots; however, results are variable in controlling water-soluble nutrients and bacteria in runoff. This study assessed the role of tall fescue (Festuca arundinacea Schreb.) as a VFS in reducing contaminants from stored animal wastes. The study evaluated the extent to which livestock manure stockpiles potentially contribute to nitrate-nitrogen (NO₃-N) and coliform bacteria contamination of surface water resources. The experiment was conducted on Amsterdam silt loam (fine-silty, mixed, superactive Typic Haploboroll) soil. Tall fescue and bare soil fallow) strips were established on a 4% slope. Treatments consisted of manure applications in the upland position for the strips. For comparisons, vegetated and bare control (non treated) strips without manure in the upland position were also studied. Manure was applied annually (approximately 2 t fresh weight per strip). Runoff was achieved by applying water at the head of the treatments and forcing the applied water to pass through the manure stockpiles and into the VFS and fallow strips. Runoff water samples were collected and analyzed for NO₃-N and coliform. Concentration of NO₃-⁻N in surface runoff from VFS with manure stockpiles in the headland was reduced up to 97% in 1997 and 99% in 1998 where a VFS was present. Coliform populations in runoff were reduced significantly by VFS in two runoff events, a 64% reduction in July 1937, and an 87% reduction in August 1998. However, the coliform counts in runoff, even from VFS treatments not receiving manure, remained substantially elevated. Dilution and residence time of water passing through the VFS appeared to be the most significant factors affecting reductions in NO₃-N and bacteria in runoff.