Home / News / FEATURED RESEARCH: Field Trials of the Survival of E. coli in Vegetable Fields Fertilized with Raw Animal Manure

FEATURED RESEARCH:
Survival of E. coli in Vegetable Fields Fertilized with Raw Animal Manure

Michele Jay-Russell

Background

Five years ago we conducted our first field trial with contaminated manure to better understand the microbial food safety risks from pathogens in raw animal manure used as a soil amendment in vegetable fields. Initially, we studied how fast “generic” E. coli would die-off in soil amended with 4 types of contaminated manure (cattle, chicken, goat, and horse), and if there were any risk factors for persistence or regrowth. Saharuetai “Fhon” Jeamsripong, a graduate student in epidemiology at the time, designed and executed these early field trials at a UC Davis research farm. Subsequently, collaborators at the University of Georgia-Tifton joined the project and conducted a field trial with leafy greens grown in soil amended with local dairy manure and chicken litter. The multi-state teamwork allows for comparison of how E. coli survives under different regional conditions in the west vs. the southeastern US.

Public Health Significance

  • FDA is conducting a risk assessment and, in collaboration with the USDA and other stakeholders, is undertaking critical research to strengthen scientific support for any future proposal regarding the appropriate time interval(s) between application of biological soil amendments and harvest.
  • The present work by WCFS scientists and collaborators contributes to that research, and provides information about the duration, likelihood, and amount of enteric pathogen survival in soils amended with various manures.
  • This research fills critical knowledge gaps on pathogen survival times and intervals between the application of untreated biological soil amendments of animal origin and crop harvesting. Data will be used to conduct a risk assessment relevant to FSMA Produce Safety Rule proposals to ensure public health.

Methods and Results

We follow standardized protocols that can be reproduced across different laboratories as outlined in the framework document by Harris et al. The Manure Pathogen Survival Protocol for these experiments was originally developed at USDA ARS, Beltsville, MD, with collaborators Pat Millner and Manan Sharma.

Results have been shared at several scientific meetings:

Chen, Z., P. Aminabadi, A.Zwieniecka, X.Wei, M Jay-Russell. 2018.Transfer of indicator Escherichia coli to spinach grown in soil amended with raw animal manure associated with heavy winter rains in California, 2016 to 2017, (Abstract P1-191) Annual IAFP Meeting 2018, Salt Lake City, UT, July 8-11.

Jeamsripong S, Millner P, Sharma M, Oryang D, Jay-Russell M. 2015. Exploration of the impact of application intervals for the use of raw animal manure as a soil amendment on tomato contamination. (Winner FDA OFVM Outstanding Collaboration Award), 5th Annual FDA Foods and Veterinary Science and Research Conference, Silver Springs, MD, Aug 13-14.

Jeamsripong S, Millner P, Sharma M, Zwieniecka A, Wong J, Aminabadi P, Atwill E, Jay-Russell M. 2015. Field-validation of minimum application intervals for use of raw animal manure as a soil amendment in the Central Valley, California (P1-176). 2015. Annual IAFP Meeting, Portland, OR, Jul 25-28.

Research Highlights

  • Rapid die-off of inoculated E. coli was observed in soil by 30 days, but resuscitation (regrowth) occurred in all manure types following heavy spring rains.
  • No transfer of E. coli was seen from contaminated soil to fresh tomatoes grown in the summer in Davis; however, E. coli did transfer to spinach leaves in plants grown in manure-amended soil during the winter (heavy rains).
  • In Georgia, E. coli was detected in soil until Day X, but not found on collard green leaves.

Awards

In 2015, our presentation was selected for the Outstanding Collaboration Award, at the 5th Annual FDA Foods and Veterinary Science and Research Conference in Silver Springs, Maryland (Jeamsripong et al., 2015).

Resources

Fact Sheet: Biological Soil Amendments of Animal Origin

Fact Sheet: Biological Soil Amendments of Animal Origin (Spanish)

Raw Manure under the FSMA Final Rule on Produce Safety

Future Directions

Multi-regional risk analysis of farm manure use: Balancing soil health and food safety for organic fresh produce production
This collaboration is a USDA Organic Agriculture Research and Extension Initiative (OREI) funded project (PI Alda Pires, Co-PI Michele Jay-Russell) to further the study of the use of animal-based manure in organic agricultural practices in order to best prevent the risk of soil pathogens, and includes researchers from the University of California, Davis, University of Minnesota, University of Maine, the USDA Agricultural Research Service’s Beltsville Agricultural Research Center, USDA’s Economic Research Service Resource and Rural Economics Division, Cornell University, and The Organic Center.

Watch for a future Featured Research update on this project.

Funding

This research was supported by contract U19-FD004995 from the United States Food and Drug Administration (FDA) and partial grants from multi-institutional United States Department of Agriculture (USDA) National Institute of Food and Agriculture (NIFA) Specialty Crop Research Initiative integrated project at University of Maryland.