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Published on: July 19, 2018
Rainfall-induced release of microbes from manure: model development, parameter estimation, and uncertainty evaluation
Keewook Kim1, Gene Whelan2, Marirosa Molina2
1Oak Ridge Institute for Science and Education, US Department of Energy, Oak Ridge, TN 37830, USA and Idaho Falls Center for Higher Education, University of Idaho, Idaho Falls, ID 83402, USA E-mail: kkeewook@uidaho.edu; National Exposure Research Laboratory, Ecosystem Research Division, US Environmental Protection Agency, Athens, GA 30605, USA.
Manure type affects microbial release rates during rainfall. Cattle manure releases microbes slower than poultry or swine manure, informing water quality models.
Area of Science:
- Environmental Science
- Microbiology
- Agricultural Engineering
Background:
- Microbial contamination from manure is a significant water quality concern.
- Understanding microbial release dynamics from different manure types is crucial for risk assessment.
Purpose of the Study:
- To evaluate the modified Bradford-Schijven model for predicting microbial release from various manures.
- To determine the influence of manure type, age, season, and microbe on release rates.
Main Methods:
- Conducted simulated rainfall-runoff experiments on 36 plots with four manure types across four seasons.
- Applied inverse modeling (PEST) and bootstrap procedures to calibrate the modified Bradford-Schijven model.
- Monitored release of Escherichia coli, enterococci, and fecal coliforms.
Main Results:
- Manure age, microbe type, and season did not significantly impact microbial release curves.
- Cattle solid pats exhibited a slower microbial release rate compared to poultry dry litter and swine slurry.
- Poultry and swine manures showed similar microbial release patterns.
Conclusions:
- The modified Bradford-Schijven model effectively simulates microbial release from manure.
- Manure type is a key factor influencing microbial release kinetics, with cattle manure being slower releasing.
- Findings support the application of the model for predicting microbial transport in agricultural watersheds.
