Project: MLMMI 03-HERS-02
Characterize current manure storage conditions and examine land management practices for their influence upon Salmonella survival in manure and manure amended soil in Manitoba.
KEYWORDS: Salmonella survival, hog manure, soil, nutrient profile, temperature profile, hog manure management practices
University of Manitoba
Funding Partners: who have contributed to MLMMI in support of this project:
SDIF - $25,000
Manitoba Pork Council and industry groups - $49,780
Amount Funded: $74,780.00
Performer Funded: $0.00
Total Cost: $74,780.00
First Progress Report received on May 21, 2004.
Second Progress Report received on November 17, 2004.
Final Report due May 17, 2005.
Extension granted for Final Report to July 15, 2005.
Final Report received on July 19, 2005
There is concern that the application of hog manure slurry to fields used to raise crops or graze animals may increase risk that both animals and humans which/who consume products and produce from manure-treated fields could be exposed to potentially pathogenic organisms. Salmonella is carried and shed by a variable but measurable portion of cattle and hogs. There is also concern that use of contaminated manure on fields may increase the frequency of pathogen shedding by animals and establish an undesirable increase in the cyclic pattern of shedding. Concern regarding the quality of water in adjacent areas is also justifiable, should there be development of pathogen reservoirs in manure-treated soils.
To determine the potential survival of pathogens, using Salmonella as the test group of organisms, three studies were conducted. Since earlier work had shown that these and other pathogens would not be problematic in agricultural environments if manure could be held at 25 C for 90d or longer before being spread on land, the first study was designed to monitor the temperature at different depths in both above-ground and earthen manure storage reservoirs in Manitoba over a period of about a year. The second study evaluated the survival of Salmonella added to manure slurry from sow, feeder and nursery barns stored at 4, 25 or 37 C for 90d, with those stored at 4 C being tested up to 300d. The third study examined the survival of Salmonella in inoculated manure added to clay or sandy loam soils subjected to seasonal sequences of temperatures representing exposures likely over 180d in Manitoba during the winter/summer, spring/summer or summer/winter seasons.
Temperature histories from the above-ground and earthen manure storage reservoirs which were located near La Broquerie, MB, showed that for spring application to fields, manure temperatures had previously ranged from 0.5 to 8 C in the above-ground storage and from 1.5 to 11 C in the earthen storage. In contrast, manure applied in the fall had previously been exposed to temperatures of 14 to 19 C and 16 to 17 C in the above ground and earthen manure storage reservoirs, respectively. Thus, storage temperatures experienced by hog manure slurry, regardless of the type of storage reservoir, would not be high enough to ensure that slurry was pathogen-free at the time it was applied to soil.
In the second study it was found that inoculated Salmonella survived slightly longer in nursery manure slurry stored at 4 C than in sow or feeder manures. At 37 C no Salmonella was recoverd after a week from any samples and at 25 C the organisms survived up to 90d. At 4 C Salmonella survived 300d in the manure slurry. While Salmonella did not grow in any of the samples, its ability to survive in manure slurry at cooler temperatures suggests that organisms can survive both over the winter and possibly during summer storage in reservoirs in Manitoba.
In the third study, which examined the effects of exposure to seasonal temperature sequences upon Salmonella survival in soils amended with hog manure from a nursery barn, it was found that the organisms survived better in the clay loam than the sandy soil and survived best when soil moisture was higher. Regardless of season at manure application, the largest decrease in Salmonella viability occurred within one week. Salmonella survived longest (180d) in both soils during the summer-winter exposure but was not isolated after 160d from sandy soil exposed to other seasonal treatments. For all but one treatment, reduction in Salmonella viability was rapid enough to suggest that a 30d delay between field application of manure in the spring or fall and use of the land would provide reasonable assurance that crop and animal contamination by Salmonella originally present in the manure would be minimized.