ARS | Publication request: Model of fecal coliform overland transport from agricultural lands fertilized with animal manure

Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: May 4, 2009
Publication Date: November 1, 2009
Citation: Guber, A.K., Yakirevich, A., Shelton, D.R., Sadeghi, A.M., Goodrich, D.C., Unkrich, C.L., Rowland, R.A., Pachepsky, Y.A. 2009. Model of fecal coliform overland transport from agricultural lands fertilized with animal manure. ASA-CSSA-SSSA Annual Meeting Abstracts. http://a-c-s.confex.com/crops/2009am/webprogram/Paper52269.html

Technical Abstract: Risk assessment of surface water contamination after manure applications requires developing microbial transport models. Application of such models often leads to incorrect conclusions due to lack of calibration with experimental data and ignorance of spatial variability in bacterial concentrations. The objectives of this work were: (i) to develop and calibrate an event-based model describing bacterial transport with runoff water at a field scale; and (ii) to characterize the associated uncertainties both in the input and model predictions. Experiments were carried out at the USDA-ARS Beltsville watershed site in Maryland. Bovine manure was broadcast at a 60 ton/ha application rate on a 3.6 hectare experimental field. Fecal coliform (FC) contents were measured in applied manure at 20 locations selected randomly on the field. Both runoff volume and FC concentrations in runoff water were monitored using a flume equipped with a refrigerated sampler. Precipitation data were measured in the vicinity of the experimental field. A total of 6 runoff events were recorded from May 2 through July 8, 2004. The FC concentrations were highest in the runoff water collected 7 days after the manure application and then declined over time. No clear relationship between FC content and runoff flow rates was observed. A bacteria transport add-on module was developed for the event-based kinematic runoff and erosion model (KINEROS2). The bacteria transport module described convective-dispersive overland transport and accounted for bacteria release from manure, reversible attachment-detachment to soil, and surface straining of infiltrating bacteria. The model was calibrated with the experimental runoff data and adequately described the FC transport with runoff water. Model uncertainty arose from spatial variation of FC concentrations in applied manure and number of manure samples taken for FC counting.