Leaching of viruses and other microorganisms naturally occurring in pig slurry to tile drains on a well-structured loamy field in Denmark

Abstract

The amount of animal manure used in modern agriculture is increasing due to the increase in global animal production. Pig slurry is known to contain zoonotic bacteria such as E. coli, Salmonella spp. and Campylobacter spp., and viruses such as hepatitis E virus and group A rotavirus. Coliform bacteria, present in manure, have previously been shown to leach into tile drains. This poses a potential threat to aquatic environments and may also influence the quality of drinking water. As knowledge is especially scarce about the fate of viruses when applied to fields in natural settings, this project sets out to investigate the leaching potential of six different microorganisms: E. coli and Enterococcus spp. (detected by colony assay), somatic coliphages (using plaque assays), and hepatitis E virus, porcine circovirus type 2, and group A rotavirus (by real-time polymerase chain reaction). All six microorganisms leached through the soil entering the tile drains situated at 1-m depth the first day following pig slurry application. The leaching pattern of group A rotavirus differed substantially from the pattern for somatic coliphages, which are otherwise used as indicators for virus contamination. Furthermore, group A rotavirus was detected in monitoring wells at 3.5-m depth up to 2 months after pig slurry application. The detection of viral genomic material in drainage water and shallow groundwater signifies a potential hazard to human health that needs to be investigated further, as water reservoirs used for recreational use and drinking water are potentially contaminated with zoonotic pathogens.

Bacteriophages specific to Shiga toxin-producing Escherichia coli exist in goat feces and associated environments on an organic produce farm in Northern California, USA

“…Ruminants, such as cattle and goats, asymptomatically carry STEC in their digestive tracts [6], and their feces are the primary sources of STEC contamination on produce and in the environment [7][8][9]. Irrigation water sources and produce-growing soils are exposed to ruminant feces in agricultural settings inadvertently if STECs leach from ruminant enclosures through the soil, or via direct application of improperly treated animal manure [10,11]. Fresh produce that contacts contaminated irrigation water or soil can serve as a vehicle for transmission of STEC to humans [11].…”

“…Fresh produce that contacts contaminated irrigation water or soil can serve as a vehicle for transmission of STEC to humans [11]. In addition, livestock manure is frequently used for amending soils by the agricultural industry in the U.S. and abroad [10]. Organic farming operations, continually on the rise in the U.S. [12], must rely on the application of fresh or composted animal manure or plant debris alone for amending soil because the application of synthetic fertilizers does not comply with organic standards [13][14][15].…”

Horticulture and Orchards as New Markets for Manure Valorisation with Less Environmental Impacts

“…The impact of soil characteristics and conditions on pathogens' survival has been extensively reviewed by Alegbeleye and Sant'ana [60]. The manure-borne pathogens may contaminate agricultural products, which is critical in horticulture, and eventually may be transported along the soil profile and reach the water bodies [66,67].…”

Using High-Resolution Monitoring to Determine the Preferential Transport of Enteric Bacteria and Antibiotic Resistance Genes from Liquid Pig Manure Applied to Tile-Drained Arable Fields

“…Recent field-scale studies have looked into the leaching or presence of bacteria and ARGs in the subsurface, covering percolating water, drainage, and groundwater. − These studies commonly provide substantial details about leached bacteria, communities, or ARGs but lack the hydrogeological link. The most detailed field-scale studies include weekly leaching samples combined with precipitation, drainage, and/or the depth of the groundwater table. ,, …”

“…The most detailed field-scale studies include weekly leaching samples combined with precipitation, drainage, and/or the depth of the groundwater table. 25,26,35 Therefore, to improve our understanding of how liquid manure applied to fields impairs drainage quality, a detailed monitoring field-scale study that combined hydrogeological processes with the leaching of microbial contaminants to drainage was undertaken. Two arable tile-drained clayey till fields prone to preferential transport 25,36 were treated agriculturally identically, and liquid manure was applied according to Danish regulations.…”