1a. Objectives (from AD-416):
Conduct controlled environmental studies to 1) compare survival of manure-borne pathogens with surrogates and 2) develop a baseline reference of pathogen and surrogate survival in manure-amended soils for comparison to field survival, accounting for environmental effects. Conduct field studies to evaluate survival of surrogates in raw manure-amended soils used for growing fresh produce. Contribute to development of a systematized protocol to determine safe practices for use of raw manure as a soil amendment in the production of fresh fruits and vegetables in a manner compliant with safety standards of the Food Drug and Cosmetics Act, and mandates put forth in the Food Safety Modernization Act of 2011.
1b. Approach (from AD-416):
For controlled environmental studies, USDA-ARS and UMES will collect raw manure from local animal production facilities, will characterize (and supplement, as necessary) the microbial load of the manure, will amend with appropriate pathogenic microorganisms, and determine survival as under different environmental conditions. For field studies, USDA-ARS and UMES will collect raw manure from local animal production facilities, will characterize (and supplement, as necessary) the microbial load of the manure, will apply manure to production fields consistent with current industry practices, and will monitor local weather and environmental impacts and the resultant survival and persistence of microorganisms of interest. USDA-ARS and UMES, in consultation with FDA, will determine selected manure types/categories for study, appropriate field application methods, sampling times, analytical protocols and methods. USDA-ARS and UMES will provide the FDA Project Officer, on at least a quarterly basis, a status report on the current state of the study, with information on data generated from completed milestones, status of current efforts, any technical difficulties encountered and plans to alleviate the issues while moving forward, and brief “next-step” discussions. No more than six months after the completion of field studies from all locations, USDA/ARS and UMES shall provide FDA/CFSAN with a final report on the project.
3. Progress Report:
The purpose of this study is to provide scientific data to address the time interval required between the application of animal manure to cropland and the harvesting of produce crops from these manure-amended soils. The results will be proposed FDA rules listed in the “Standards for the Growing, Harvesting, Packing, and Holding of Produce for Human Consumption”. Specifically, this field research focuses on determining the influence of different types of manure along with different soils, environmental, and biological factors on the survival of pathogenic bacteria in the manure and in comparison to non-manured soil. In lieu of using pathogenic bacteria, this field research study uses non-pathogenic strains of both Escherichia coli and E. coli O157:H7 and measures their decline in soils amended with various animal manures (dairy cattle, poultry, and horse). This is one of the three geographically distinct sites, with different soil types: 1) silt loam in Princess Anne, MD (University of Maryland Eastern Shore, UMES); 2) sandy silt loam, Beltsville, MD (USDA-ARS-Beltsville Agricultural Research Center (BARC); and 3) clay loam, Southeast Agriculture and Extension Center, SEAREC (Manheim PA). The research experiments are being conducted on uniform size field plots at all sites with application of either low or high populations of multiple-strains of E. coli to the replicated plots. Data collection, microbial and molecular analysis is ongoing at all sites and also involve separate plots with spring and fall applications of manure and subsequent leafy green cropping to evaluate transfer of E. coli from soil to leafy greens. In addition to determining E. coli population dynamics at the three separate field sites, a genetic fingerprint assay to distinguish among the five strains has been developed and is being used to assess survival of specific strains at each of the locations. It is anticipated that the data collected from these studies will directly impact the proposed produce safety rules issued by FDA. Preliminary results indicate that seasonality, manure and soil type influence the survival of E. coli in manure-amended soils used to grow produce and that manure prolongs survival of these bacteria. Companion studies in fields and greenhouses at the ES location are given in the progress report for project 1265-32420-005-22S, titled: Survival of Fecal Organisms and Indicators in Agricultural Soils Amended with Raw Manure.