Managing Nitrate and Bacteria in Runoff from Livestock Confinement Areas with Vegetative Filter Strips
Point and non-point source pollution of surface and ground water is a major social and environmental concern in the world. Frequently documented sources, of nitrate contamination of surface and ground water are livestock waste and storage facilities. Vegetative filter strips (VFS) are effective in reducing some nutrients, sediment, and suspended solids in surface runoff from feedlots; however, results are variable in controlling water-soluble nutrients and bacterial concentration in runoff.
The present study assessed the role of tall fescue (Festuca arundinacea Schreb.) as VFS in reducing contaminants generated by the storage of animal wastes under a relatively short growing season and short duration and high intensity rainfall. Specifically, the study evaluated the extent to which livestock manure stockpiles potentially contribute to nitrate-nitrogen (N03N) 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 cv. Fawn and bare soil (fallow) strips on a 4% slope. Treatments consisted of applications of manure in the upland position for the vegetated and fallow strips. Control strips were established without manure in upland position. Manure was applied annually (approximately 2-metric ton fresh weight per strip treated).
Runoff was achieved by applying water to the manure stockpile or the bare border at the head of the treatments (with and without manure stockpile) and then forcing the applied water to pass through the VFS and fallow strips. Runoff water samples were collected in at intervals of 0, 20, 40, and 60 minutes after initiation of runoff and analyzed for N03-N and coliform organisms. Sail samples also were taken (to a depth of two meters) in April of each year at seven positions along the strips, before the new manure was applied. Concentration of N03-N in surface runoff from manure stockpile was reduced from control in up to 97% in 1997 and 99% in 1998 by the VFS.
Coliform populations in runoff were reduced from control significantly by VFS in two
runoff events, 64% reduction in July 1997 and 87% reduction in August 1998. However,
the coliform counts in runoff, even from VFS treatments not receiving manure, remained
substantially elevated. Movement of N03-N down slope within the soil of the TFM and
FM treatments did not appear to be significant beyond the direct influence of the
manure stockpile for either year of sampling.
Bauder, J.W., Cash, S.D., and Fajardo, J.J. Managing nitrate and bacteria in runoff from livestock confinement areas with vegetative filter strips. Journal of Soil and Water Conservation. S6(4): 184-190.