Transactions of the ASABE Vol. 53(3): 779-786 E 2010 American Society of Agricultural and Biological Engineers ISSN 2151-0032 779 SURFACE RUNOFF TRANSPORT OF ESCHERICHIA COLI AFTER POULTRY LITTER APPLICATION ON P ASTURELAND J. A. Guzman, G. A. Fox, J. B. Payne ABSTRACT. Escherichia coli transported in surface runoff from dissolution of applied poultry litter is a major variable in assessing fecal contamination of streams. However, the relative magnitude of the E. coli concentration from a specific poultry litter application and relative to the time lag between litter application and rainfall are not completely understood. This research investigated E. coli transport in runoff on fourteen 2 m × 2 m pastureland plots. Poultry litter was manually applied (4,942 kg ha ‐1 ) in twelve plots followed by artificial rainfall with intensities equivalent to 2‐year and 5‐year storm events. Rainfall was applied in duplicate plots immediately after poultry litter application and 24 and 120 h after litter application. Experiments were also conducted on two control plots without poultry litter application. Surface runoff was collected using a flume installed in a trench. E. coli was quantified from sampled runoff and used as an indicator of fecal contamination by the most probable number (MPN) technique. No significant differences were observed in average event mean concentrations (EMCs) relative to storm intensity. Statistically significant differences were observed in average EMCs relative to time lag between litter application and rainfall. A nonlinear relationship was observed between average E. coli EMC and time lag, with the EMC decreasing between 0 h (1.6 × 10 5 MPN/100 mL) and 24 h (1.3 × 10 4 MPN/100 mL) and then increasing at 120 h (4.3 × 10 4 MPN/100 mL). E. coli were always detected in the control plots (average EMC of 6.8 × 10 3 MPN/100 mL), indicating the presence and transport of fecal bacteria from sources independent of the immediate poultry litter application. Even though poultry litter application may increase E. coli concentrations in runoff, other sources of fecal contamination serve as a significant component of the total E. coli EMC, especially as the time lag between litter application and rainfall events increases. Keywords. Bacteria transport, Escherichia coli, Event mean concentration, Poultry litter, Runoff. he U.S. poultry industry has provided a plentiful and affordable source of protein for consumers while generating economic revenue. However, modern livestock industries, including poultry pro‐ duction, are frequently unprofitable unless a significant economy of scale can be achieved (Bossman, 2005). To achieve this economical scale, large numbers of birds are generally reared in confinement, resulting in a large amount of animal waste, in the form of poultry litter, produced in a limited geographic area. Poultry litter consists of manure, bedding material, and other components such as feathers and soil (Kelley et al., 1994). Wood shavings, sawdust, and soy‐ bean, peanut, or rice hulls are all common manure carriers added to the poultry house floor and utilized for raising four to eight flocks on a single placement prior to complete clean‐ out. After removal from the poultry house, litter is generally Submitted for review in January 2010 as manuscript number SW 8396; approved for publication by the Soil & Water Division of ASABE in June 2010. The authors are Jorge A. Guzman, ASABE Student Member, Graduate Research Associate and Doctoral Candidate, and Garey A. Fox, ASABE Member Engineer, Associate Professor, Department of Biosystems and Agricultural Engineering, Oklahoma State University, Stillwater, Oklahoma; and Josh B. Payne, Adjunct Assistant Professor, Area Animal Waste Management Specialist, Oklahoma Cooperative Extension Service, Oklahoma State University, Muskogee, Oklahoma. Corresponding author: Garey A. Fox, Department of Biosystems and Agricultural Engineering, Oklahoma State University, 120 Ag Hall, Stillwater, OK 74078; phone: 405‐744‐8423; fax: 405‐744‐6059; e‐mail: garey.fox@okstate.edu. land‐applied as a fertilizer source to pastures and cropland. Litter is recognized as an excellent source of the plant nutri‐ ents N, P, and K, but it can also contain pathogenic microor‐ ganisms such as Salmonella , Campylobacter, and fecal indicator bacteria such as enterococci and Escherichia coli (de Rezende et al., 2001; Santos et al., 2005; Jenkins et al., 2006). Surface and subsurface waters can result in fecal bacteria contamination as a function of runoff transport, litter proper‐ ties, and rainfall events following litter application. E. coli can survive for extended periods of time in feces, soil, and water (Stoddard et al., 1998; Sørensen et al., 1999; Wang, 2003) and often serve as indicator organisms of fecal contam‐ ination (U.S. EPA, 1986, 2004; Foppen and Schijven, 2006). However, the interaction between land‐applied poultry litter and E. coli concentration transported by surface runoff is still not well understood. Jenkins et al. (2006) reported that litter can impact E. coli concentrations in runoff from cropland when runoff occurs three weeks following litter application; in addition, they concluded that litter application did not ap‐ pear to impact background concentrations when runoff events occurred seven months after application. In a second study involving poultry litter and commercial fertilizer ap‐ plications to conventional‐till and no‐till corn plots subjected to simulated rainfall, Jenkins et al. (2008) concluded that no significant differences were determined between tillage nor fertilization treatments in runoff concentrations of E. coli. Litter application appeared to have little potential of patho‐ gen contamination of surface waters. Recently, Sistani et al. (2009) compared the effect of litter application (e.g., surface‐ T