BACTERIOLOGICAL WATER QUALITY OF FORESTED AND PASTURED STREAMS RECEIVING LAND APPLIED POULTRY LITTER

摘要

Poultry production is a growing industry in East Texas, generating about 360,000 m tons of broiler litter eachyear as a by-product for application on pasturelands. Grab samples of fecal coliform (FC) and fecal streptococcus (FS) werecollected monthly between March and December 1996 and FC and E-coli samples were collected weekly between July andOctober 2001 at six sites on the Waffelo and Terrapin Creeks in Nacogdoches County, Texas to assess possible impacts ofpoultry litter application on bacterial water quality. Sites were grouped by three pairs with each pair consisting of oneupstream site in predominantly forested area and one downstream site in a pastured area receiving land application of poultrylitter. All pastured watersheds had a 10 to 150 m buffer of riparian forest and/or unfertilized pasture between the stream andareas on which broiler litter was applied.FC concentrations exceeded the 200 cfu/100 ml contact recreation standards in more than 50% of observations,regardless of forested or pastured conditions. E-coli samples did not violate standards and has been shown to be a betterindicator of fecal contamination. Current broiler litter land-application rates on pasturelands did not cause significantlyhigher FC concentrations than natural wildlife activities on forested watersheds. Water pH was the only parametersignificantly correlated (r > 0.50) with FC in the study areas. No significant correlations were detected between FC and otheraquatic parameters including stream discharge, temperature, salinity, specific conductance, and dissolved oxygen. The studysuggests that background variation in bacteriological parameters may mask land-use practices, though a longer period ofobservations with greater sampling frequency at more study sites may reduce observed variation in the present study.