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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Environmental Microbial & Food Safety Laboratory » Research » Publications at this Location » Publication #318411
Title: Rainfall-induced release of microbes from manure: model development, parameter estimation, and uncertainty evaluation on small plots

Author
item KEEWOOK, KIM - ORISE FELLOW
item WHELAN, GENE - U.S. ENVIRONMENTAL PROTECTION AGENCY (EPA)
item MOLINA, MARIROSA - U.S. ENVIRONMENTAL PROTECTION AGENCY (EPA)
item PURUCKER, THOMAS - U.S. ENVIRONMENTAL PROTECTION AGENCY (EPA)
item Pachepsky, Yakov
item GUBER, ANDREY - MICHIGAN STATE UNIVERSITY
item CYTERSKI, MICHAEL - U.S. ENVIRONMENTAL PROTECTION AGENCY (EPA)
item FRANKLIN, DORCAS - U.S. ENVIRONMENTAL PROTECTION AGENCY (EPA)
item BLAUSTEIN, RYAN - UNIVERSITY OF MARYLAND

Submitted to: Journal of Water and Health
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/30/2016
Publication Date: 6/10/2016
Citation: Keewook, K., Whelan, G., Molina, M., Purucker, T., Pachepsky, Y.A., Guber, A., Cyterski, M., Franklin, D., Blaustein, R. 2016. Rainfall-induced release of microbes from manure: model development, parameter estimation, and uncertainty evaluation on small plots. Journal of Water and Health. 14(3):443-459.

Interpretive Summary: Land-applied manures present a potential source of pathogenic microorganisms that, once released during rainfall, can enter and compromise sources of recreational and irrigation waters. Predictive models of microbe release from manures are needed to evaluate best management practices with the goal of mitigating the microbial pollution of water sources. We ran a unique series of rainfall-runoff experiments with applications of cattle manure pats, poultry dry litter, and swine slurry over four seasons. The experimental results indicated that manure age, microbe, and/or season had no clear effect on the microbial release rates. Microbes were released form cattle pats at a slower rate than from poultry dry litter or swine slurry, which had very similar release patterns. All release data were well simulated by the modified Bradford-Schijven model. Results of this work will be used by regulators and consultants concerned with the microbial quality of water since they provide a reliable model of bacteria release from manures.

Technical Abstract: A series of simulated rainfall-runoff experiments with applications of different manure types (cattle solid pats, poultry dry litter, swine slurry) were conducted across four seasons on a field containing 36 plots (0.75 × 2 m each), resulting in 144 rainfall-runoff events. Simulating time-varying release of E. coli, enterococci, and fecal coliforms from manures applied at typical agronomic rates evaluated the efficacy the Bradford-Schijven model that was modified by adding terms for release efficiency and transportation loss to account for manures aged 0, 1, and 2 weeks. Two complementary, parallel approaches were used to calibrate the model and estimate microbial release parameters. The first was a four-step sequential procedure using the inverse model PEST which provides appropriate initial parameter values. The second utilized a PEST/Bootstrap procedure to estimate average parameters across plots, manure age and microbe, and to provide parameter distributions. When coupled with a Monte Carlo assessment, a combination of these statistical approaches calibrated key parameters, provided estimated variability and distributions, evaluated uncertainty and model performance, and provided field-scale model performance. The experiment determined that manure age, microbe, and season had no clear relationship to the release curve. Cattle solid pats released microbes at a different, slower rate than did poultry dry litter or swine slurry which had very similar release patterns. These findings were consistent with other published results for both bench- and field-scale, suggesting the modified Bradford-Schijven model can be applied to microbial release from cattle solid pats, poultry dry litter, and swine slurry.