1a.Objectives (from AD-416)
Determine dominant environmental parameters and processes involved in the fate and transport of manure-borne coliform bacteria at field and watershed scales in a hydrological context. Develop predictive models of the fate and transport of manure-borne coliform bacteria at field and watershed scales.

1b.Approach (from AD-416)
An integrated laboratory research, field research at hillslope and watershed scales, and mathematical modeling will be used. The experimental research will include evaluating effect of manure particulates on transport of coliform microorganisms in soil, relating partitioning of coliform microorganisms between sediment and runoff to soil texture, manure properties and flow rate, establishing dependencies of coliform release rates from manure on rain intensity, manure type and composition, and manure application method, evaluating predictive efficiency of laboratory data on manure-borne coliform survival data for the field conditions, assessing phosphorus as a tracer of manure-borne transport in runoff; determining effect of background coliform populations and field manure application on coliform concentrations in runoff from fields and in a perennial creek in a riparian zone. Modeling research will include determining dominant mechanisms of manure-borne coliform transport at pedon, field, and watershed scales; develop and test models to simulate those mechanisms, performing uncertainty analysis to evaluate the reliability of coliform transport model predictions given available data on variation in input parameters, transforming model computers codes to make them compatible to existing and under-development user-friendly decision support tools.

3.Progress Report
An experimental site at the OPE3 experimental watershed at the Beltsville Area Research Center (BARC) has been instrumented with replicated multiple capacitance probes and tensiometers to infer fluxes of soil water carrying bacteria and manure particulates. The multilevel sampling wells have been installed and tested to be used in the experiment on the breakthrough of fecal coliforms from surface-applied manure to ground water. In addition, E. coli and Enterococci concentrations were monitored in the creek water and in the runoff from manured fields at the OPE3 site. The creek was grab-sampled weekly, and refrigerated samplers were used on the event basis.

A mechanistic model to simulate transport of manure-borne E. coli in variably saturated soil has been developed and partially tested. Surface release, attachment, size exclusion, and straining in soils, the effect of the concurrently release manure particulates and ionic strengths can be analyzed using standard weather data as well as custom data on surface water supply, evaporation and transpiration through the distributed root system. The graphic user interface has been designed and a preliminary agreement on the programming work was reached.

4.Accomplishments
Testing and application of the model of manure-borne pathogen transport and retention in vegetated filter strips. Vegetated filter strips (VFS) are important best management practices (BMPs) to prevent contamination of waterways from agricultural sources. The efficiency of VFS is currently evaluated exclusively from a nutrient and sediment retention standpoint. Methods to evaluate BMP efficiency with respect to manure-borne pathogen retention are currently absent. The developed model STIR integrates knowledge on major processes of transport and retention of manure-borne microorganisms at the pedon scale. The use of the model in uncertainty analysis has demonstrated its potential utility in making decisions on site-specific VFS placement with respect to manure-borne pathogens. This accomplishment aligns with the “Pathogens” component of the NP 206 Action Plan in its Specific Focus Area 2e “Modeling Fate and Transport of Manure-borne Pathogens from “Pedon” to Watershed Scale.”

Demonstration of differential attachment of E. coli attachment to soils and soil particles using DNA fingerprinting techniques. Attachment of E. coli to soil particles affects the rate and extent of transport in overland flow and in soil. Using rep PCR, we have shown that the preferential attachment of different E. coli strains to particles of different size classes exists and may be quantified using DNA fingerprinting methods. This result poses a new research question whether DNA fingerprinting can be used to elucidate differences in the attachment to mineral surfaces for pathogenic and non-pathogenic E. coli strains. This accomplishment aligns with the “Pathogens” component of the NP 206 Action Plan in its Specific Focus Area 2e “Modeling Fate and Transport of Manure-borne Pathogens from “Pedon” to Watershed Scale.”

The first dataset on size distribution of manure particles released concurrently with E.coli. Manure particles are known to affect transport and retention of microbial pathogens in soil and in overland flow as they may serve as carriers, abode, and nutritional source for microorganisms. However, nothing is known so far about the amounts and sizes of manure particles released during rainfall. We applied the state-of-the-art laser diffractometry-based size distribution measurement technology to obtain the first dataset on sizes of bovine manure particles released during simulated rainfall. The developed technique can be used for further accumulation of data on suspended manure particulates as a factor of fate and transport of manure-borne microbial pathogens. This accomplishment aligns with the “Pathogens” component of the NP 206 Action Plan in its Specific Focus Area 2e “Modeling Fate and Transport of Manure-borne Pathogens from “Pedon” to Watershed Scale.”

5.Significant Activities that Support Special Target Populations
None

6.Technology Transfer

Number of non-peer reviewed presentations and proceedings	17
Number of newspaper articles and other presentations for non-science audiences	3

Review Publications
Pachepsky, Y.A., Sadeghi, A.M., Bradford, S.A., Shelton, D.R., Guber, A.K., Dao, T.H. 2006. Transport and fate of manure-borne pathogens: modeling perspective. Agricultural Water Management. Online-(doi:10.1016/j.agwat.2006.06.0l0.)