Land applications of manure from confined animal systems and direct deposit by grazing animals are both major sources of bacteria in streams. An understanding of the overland transport mechanisms from land applied waste is needed to improve design of best management practices (BMPs) and modeling of nonpoint source (NPS) pollution. Plots were established on pasturelands receiving phosphorus-based livestock waste applications to measure the concentrations of Escherichia coli (E. coli), fecal coliform (FC), and Enterococcus present in overland flow at the edge of the field. The flow-weighted bacteria concentrations were highest in runoff samples from the plots treated with cowpies (1.37×105 colony forming units (cfu)/100 ml of E. coli) followed by liquid dairy manure (1.84×104 cfu/100 ml of E. coli) and turkey litter (1.29×104 cfu/100 ml of E. coli). The temporal distribution of fecal bacterial concentrations appeared to be dependent upon both the animal waste treatment and the indicator species, with peak concentrations occurring either at the beginning of the runoff event or during peak flow rates. BMPs could be selected to reduce peak flows or first flush effects depending upon the litter or manure applied to the land. The commercial Biolog System was used to identify the dominant species of Enterococcus present in the cowpie source manure (Enterococcus mundtii 55%) and in the runoff collected from the transport plots treated with cowpies (Enterococcus faecalis 37%). The identification of predominant species of Enterococcus that are associated with specific sources of fecal pollution could greatly assist with identifying the origins of NPS pollution.
Keywords: bacteria - Biolog - E. coli - Enterococcus - fecal coliform - land application of waste - nonpoint pollution