Biological soil amendments of animal origin (BSAAO) increase nutrient levels in soils to support production of fruits and vegetables. BSAAOs may introduce or extend survival of bacterial pathogens which can transfer to fruits and vegetables to cause foodborne illness. Escherichia coli survival over 120 days in soil plots (3m2) covered with (mulched) or without plastic mulch (not mulched), amended with either poultry litter, composted poultry litter, heat treated poultry pellets, or chemical fertilizer and transfer to cucumbers in two years (2018, 2019) was evaluated. Plots were inoculated with E. coli (8.5 log CFU/m2) and planted with cucumber seedlings (Supremo). The number of days (d) needed to reduce E. coli levels by 4 log CFU (dpi4log) was determined using a sigmoidal decline model. RandomForest regression and one-way ANOVA (p < 0.05) identified predictors (soil properties and nutrients, weather factors) of dpi4log of E. coli and transfer to cucumbers. The combination of year, amendment and mulch (25.0%IncMSE) and year (9.75%IncMSE) were the most prominent predictors of dpi4log and transfer to cucumbers, respectively. Nitrate levels at 30d and soil moisture at 40d were also impactful predictors of dpi4log. Differing rainfall amounts in 2018 (24.9 in) and 2019 (12.6 in) affected E. coli survival in soils and transfer to cucumbers. Salmonella spp. were recovered sporadically from various plots, but were not recovered from cucumbers in either year. Greater transfer of E. coli to cucumbers was also shown to be partially dependent on dpi4log of E. coli in plots containing BSAAO. IMPORTANCE Poultry litter and other biological soil amendments are commonly used fertilizers in fruit and vegetable production and can introduce enteric pathogens like E. coli O157:H7 or Salmonella previously associated with outbreaks of illness linked to contaminated produce. E. coli survival duration in soils covered with plastic mulch or uncovered and containing poultry litter, heat-treated poultry litter pellets were evaluated. Nitrate levels on day 30 and moisture content in soils on day 40 on specific days were good predictors of E. coli survival in soils; however, knowledge of the combination of year, amendment and mulch type was a better predictor. Different cumulative rainfall totals from year to year most likely affected the transfer of E. coli from soils to cucumbers and survival durations in soil. E. coli survival in soils can be extended by the addition of several poultry litter based soil amendments commonly used in organic production of fruits and vegetables and is highly dependent on temporal variation in rainfall.

Enteric viruses (EV) are the largest contributors to foodborne illness and outbreaks globally. Their ability to persist in the environment, coupled with the challenges experienced in environmental monitoring create a critical aperture through which agricultural crops may become contaminated. This study involved a seventeen-month investigation of select human enteric viruses and viral indicators in non-traditional irrigation water sources, surface and reclaimed waters, in the Mid-Atlantic region of the United States. Real-time quantitative PCR was used for detection of Aichi virus, hepatitis A virus, noroviruses GI and GII. Pepper mild mottle virus (PMMoV), a common viral indicator of human fecal contamination, was also evaluated along with atmospheric (air and water temperature, cloud cover, and precipitation 24 h, 7 d and 14 d prior to sample collection) and physicochemical (dissolved oxygen, pH, salinity and turbidity) data to determine if there were any association between EV and measured parameters. EV were detected more frequently in reclaimed waters (32%, n=22) than in surface waters (4%, n=49) similar to PMMoV detection frequency in surface (33%, n=42) and reclaimed (67%, n=21) water. Our data show a significant correlation between EV and PMMoV (R 2 =0.628; p <0.05) detection in reclaimed water samples, but not in surface waters (R 2 =0.476; p =0.78). Water salinity significantly affected the detection of both EV and PMMoV ( p <0.05) as demonstrated by logistic regression analyses. These results provide relevant insights into the extent and degree of association between human enteric (pathogenic) viruses and water quality data in Mid-Atlantic surface and reclaimed waters as potential sources for agricultural irrigation. IMPORTANCE Microbiological analysis of agricultural waters is fundamental to ensure microbial food safety. The highly variable nature of non-traditional sources of irrigation water are particularly difficult to test for the presence of viruses. Multiple characteristics influence viral persistence in a water source as well as affect the recovery and detection methods which are employed. Testing for a suite of viruses in water samples is often too costly and labor intensive, making identification of suitable indicators for viral pathogen contamination necessary. The results from this study address two critical data gaps: enteric virus prevalence in surface and reclaimed waters of the Mid-Atlantic region of the United States and subsequent evaluation of physicochemical and atmospheric parameters used to inform the potential for use of indicators of viral contamination.

Groundwater depletion is a critical agricultural irrigation issue, which can be mitigated by supplementation with water of higher microbiological risk, including surface and reclaimed waters, to support irrigation needs in the United States. Zero-valent iron (ZVI) filtration may be an affordable and effective treatment for reducing pathogen contamination during crop irrigation. This study was performed to determine the effects of ZVI filtration on the removal and persistence of Escherichia coli, and pepper mild mottle virus (PMMoV) in irrigation water. Water was inoculated with E. coli TVS 353, filtered through a ZVI filtration unit, and used to irrigate cucurbit and cruciferous crops. Water (n = 168), leaf (n = 40), and soil (n = 24) samples were collected, the E. coli were enumerated, and die-off intervals were calculated for bacteria in irrigation water. Variable reduction of PMMoV was observed, however E. coli levels were consistently and significantly (p < 0.05) reduced in the filtered (9.59 lnMPN/mL), compared to unfiltered (13.13 lnMPN/mL) water. The die-off intervals of the remaining bacteria were significantly shorter in the filtered (−1.50 lnMPN/day), as compared to the unfiltered (−0.48 lnMPN/day) water. E. coli transfer to crop leaves and soils was significantly reduced (p < 0.05), as expected. The reduction of E. coli in irrigation water and its transfer to crops, by ZVI filtration is indicative of its potential to reduce pathogens in produce pre-harvest environments.

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