We measured Escherichia coli, and Enterococcus sp. numbers in soil and on fresh radish (Raphanus sativus L.) at 1, 7, 14, 28, 54, and 84 days after the addition of high and low amounts of solid dairy manure in combination with chisel tillage to a 20 cm depth (deep) or roller tillage to a 10 cm depth (shallow). When the high or low amount of solid dairy manure was added to the soil, E. coli populations in soil were higher in the 54 days following manure addition compared to the control treatment. Dairy manure addition increased Enterococcus sp. in soils compared to the control treatment for the entire 84 days sampling period. At harvest, which was 84 days after application, we did not detect E. coli in radish in rhizosphere soil or on radish roots. Addition of solid dairy manure increased Enterococcus sp. numbers in radish rhizosphere soil and on radish roots. We suggest that fresh animal manure be applied to soil at least 120 days prior to planting to allow die-off of human pathogenic bacteria and reduce the incidence of bacterial adhesion on or bacterial colonization of ready to eat vegetables. 1. Introduction In the last decade, there has been a major shift in animal rearing toward large-scale confined animal feeding operations (CAFOs). CAFOs are a source of agricultural pollution and pose risks to water quality and public health due to the large amount of manure generated [1]. The US Environmental Protection Agency estimated that animal waste production in 1992 was 13 times greater on a dry weight basis than human production. Sources of water pollution from CAFOs include direct discharges, open feedlots, treatment and storage lagoons, manure stockpiles, and land application of manure. Pollution of surface flow and ground water from animal waste applied to soils has been documented [2–4]. Liquid-waste discharge onto soil initiates solute and microbe movement into the soil following ground water drainage patterns and can potentially contaminate adjoining surface water. These same bodies of water are often sources of drinking water or are used for recreational activities. Human contact with recreational waters containing intestinal pathogens is an effective method of disease transmission. Thus, employing appropriate treatment strategies to maintain the quality of lakes and streams and keep them free of pathogens is important. Runoff and ground water from waste-treated agricultural land shows that enteric bacteria increase in spring flows and decrease in the dry period, increase in water after irrigation or after manure is applied, and rapidly decrease
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