Principal Researcher: Dr. Amy Schmidt, University of Nebraska
Key Points:
- Soil or manure pH of 7.5 or greater is sufficient to inactivate the porcine epidemic diarrhea virus (PEDV).
- If the soil pH is lower than 7.5, adding lime to the soil is recommended to prevent PEDV survival.
- Adding lime to manure-pit storage is not recommended; adding lime to a manure-tank wagon prior to transporting to land application is preferred.
Summary:This project was conducted to determine the PEDV transmission risk in stored manure and manure-amended soil. Specific objectives were to: 1) determine PEDV survivability over time in two common soils at two moisture regimes treated with PEDV-positive swine slurry and held at temperatures representing three climates; and 2) determine the impact of lime application to manure on PEDV survivability. Multiple experiments were conducted. The manure+soil incubation experiment investigated how PEDV survived in silty clay loam and loamy fine sand at 10 percent and 30 percent water-holding capacity, under three winter climate conditions. PEDV-positive manure slurry was divided into samples to which variations of quick lime were added to test different pH levels and time exposures. PEDV survivability was evaluated. Results revealed that PEDV RNA decreased immediately following manure addition to soil, regardless of whether the manure was limed or un-limed. No differences were observed based on soil type, initial soil moisture, or incubation condition. Next, three separate manure slurry studies were conducted to determine whether adding quick lime could impact pH levels and PEDV survivability in slurry. The study also looked at lime addition levels and exposure timelines required to inactivate PEDV. Worth noting, adding lime to manure in a storage pit is not recommended due to significant precipitation of solids that result, which can result in a thick sludge that’s difficult to remove. Likewise, ammonia volatilizes more rapidly as pH increases so liming of stored manure can create significant odor and a potentially harmful concentration of ammonia gas. Liming of manure in a tank wagon prior to transporting to land application is the recommended alternative.
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