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The subsurface flow volume and E. coli populations in subsurface drainage water from zero tillage (ZT) and conventional tillage (CT) fields were investigated for two years (2002-2004) from field scale plots following spring application of liquid dairy manure. The subsurface flow volume was significantly higher under ZT than CT during 2002-2003.The annual flow weighted concentration of E. coli in tile drainage water from ZT fields (4,212 CFU 100 mL-1) were 3.2x greater than that from CT fields (1318 CFU 100 mL-1) during 2002-2004. In a load perspective, ZT (1.55 X 1010 CFU ha-1 y-1) discharged 6.7x more E. coli than that from CT (0.23 X 1010 CFU ha-1 y-1). These results suggested that the tillage system influenced the loads of E. coli leached in subsurface drainage water. The undisturbed macropore structures established under ZT soils promoted heavy leaching of E. coli through soil medium, while CT soils prohibited the rapid movement of E. coli by disrupting the macropore structures in the soil. Increased flow volumes under ZT also contributed greatly to this behaviour. However, the statistical results proved no significant differences among the treatments.