Sub-objective 2.1. Identify factors affecting enteric pathogen survival in soils containing BSAAO in the Southeastern U.S.

Methods:

Studies in Florida and Georgia in separate seasons will be conducted to determine effect of treated and untreated BSAAO in soils on survival of E. coli and other enteric bacterial surrogates. Factors that will be investigated:

• Survival of pathogens in soils containing different BSAAOs over time (longitudinal study)
• The effect of depth (till vs no-till) on survival of pathogens in soils
• Transfer of bacteria (E. coli) from soils to onions planted in the field
• Microbial communities in soils containing BSAAO

Expected Outcomes:

• Field studies will determine the extent that agricultural, temporal and biological factors influence survival of enteric pathogens in soils.
• Data collected will determine if the 90 or 120-day interval between BSAAO application and harvest of crops is appropriate to minimize contamination to edible crops through untreated BSAAO in the Southeast US.
• Data will be incorporated into statistical models to determine if pathogen decline/survival can be predicted in the Southeast US.
• Soil microbiome analyses will determine if BSAAO amendment affects the soil microbiome in a manner that influences E. coli population declines.

Sub-objective 2.2. Characterize population dynamics in response to the addition of treated BSAAO during leafy green growing season.

Methods:

• Non-pathogenic E. coli used in field trials will be introduced to fields used to grow leafy green commodities as ‘side-dressing’ in California and Maryland immediately prior to planting of leafy green seedlings. BSAAO will be added at agronomically appropriate rates through the growing season.

Expected Outcomes:

• The results will aid organic growers who use treated BSAAOs as fertilizer during leafy green production by determining if this fertilizer application increases the likelihood of transfer of E. coli to growing leafy greens.

Sub-objective 2.3. Evaluate enteric pathogen survival in dust containing BSAAO in lab setting to gain understanding of potential for aerial contamination from adjacent land use.

Methods:

• Analysis of survival of pathogens (non-pathogenic E. coli, E. coli O157:H7 and S. Newport) in dust generated from field soils amended with HTPP or composted poultry litter (CPL) over time.

Expected Outcomes:

• The duration of survival of pathogens, and the effect of moisture levels and particle size, will be determined in these laboratory and growth chamber experiments, which will narrow data gaps related to dusts generated from soils containing BSAAO.